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000
FXUS62 KGSP 251056
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
656 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 650 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST POPS AND
TEMPERATURES TO OBSERVATIONS. OVERALL...THE CURRENT FORECAST APPEARS
ON TRACK.

AS OF 525 AM...WIDESPREAD CONVECTION ACROSS THE NORTHERN HALF OF AL
WILL CONTINUE TO TRACK EAST THIS MORNING. A LARGE AREA OF -RA WILL
GRADUALLY INCREASE ACROSS THE WESTERN CAROLINAS AHEAD OF THE DEEP
CONVECTION. I WILL UPDATE THE FORECAST TO MAKE MINOR TWEAKS TO THE
POP TRENDS. IN ADDITION...I WILL UPDATE TEMPERATURES TO INDICATE
VALUES NEARLY STEADY THROUGH SUNRISE.

AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LLVL MOISTURE WILL RAPIDLY INCREASE FROM THE SOUTHWEST
DURING THE MID TO LATE MORNING HOURS...RESULTING IN MVFR CEILINGS
AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO THE AFTERNOON
AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING. BASED ON THE
TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES WILL DEVELOP
DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL HIGHLIGHT THE
22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE EVENING...FORECAST
SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND MODEL CLOUDS ARE
EASILY WITHIN IFR. WINDS THROUGH THIS EVENING WILL REMAIN FROM THE
SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A WELL ORGANIZED
SFC LOW OVER KY/TN. AS THE LOW PUSHES ACROSS THE PIEDMONT LATE
TONIGHT...WINDS WILL SHIFT FROM THE NE AND CLOUD BASES WILL RISE TO
VFR. IN ADDITION...IN THE WAKE OF THE LOW...LLVL WINDS SHOULD
STRENGTHEN...RESULTING IN LLWS FROM 5Z THROUGH 12Z.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. HOWEVER...EMBEDDED
THUNDERSTORMS MAY PASS ACROSS THE REGION DURING THE EARLY DAYLIGHT
HOURS. THE DEEP MOISTURE AND FORCING WILL SPREAD SW TO NE...REACHING
KHKY AROUND THE SAME PERIOD AS KCLT. KHKY MAY DEVELOP WINDS FROM THE
EAST-NORTHEAST AROUND SUNRISE...PERSISTING THROUGH THE REST OF THE
TAF PERIOD. ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30. AS THE LOW PUSHES ACROSS THE PIEDMONT LATE
TONIGHT...WINDS WILL SHIFT FROM THE NE AND CLOUD BASES WILL RISE TO
VFR. IN ADDITION...IN THE WAKE OF THE LOW...LLVL WINDS SHOULD
STRENGTHEN...RESULTING IN LLWS FROM 5Z THROUGH 12Z.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     MED   62%     MED   76%     MED   70%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   71%     HIGH  93%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   69%     LOW   53%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 251056
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
656 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 650 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST POPS AND
TEMPERATURES TO OBSERVATIONS. OVERALL...THE CURRENT FORECAST APPEARS
ON TRACK.

AS OF 525 AM...WIDESPREAD CONVECTION ACROSS THE NORTHERN HALF OF AL
WILL CONTINUE TO TRACK EAST THIS MORNING. A LARGE AREA OF -RA WILL
GRADUALLY INCREASE ACROSS THE WESTERN CAROLINAS AHEAD OF THE DEEP
CONVECTION. I WILL UPDATE THE FORECAST TO MAKE MINOR TWEAKS TO THE
POP TRENDS. IN ADDITION...I WILL UPDATE TEMPERATURES TO INDICATE
VALUES NEARLY STEADY THROUGH SUNRISE.

AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LLVL MOISTURE WILL RAPIDLY INCREASE FROM THE SOUTHWEST
DURING THE MID TO LATE MORNING HOURS...RESULTING IN MVFR CEILINGS
AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO THE AFTERNOON
AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING. BASED ON THE
TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES WILL DEVELOP
DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL HIGHLIGHT THE
22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE EVENING...FORECAST
SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND MODEL CLOUDS ARE
EASILY WITHIN IFR. WINDS THROUGH THIS EVENING WILL REMAIN FROM THE
SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A WELL ORGANIZED
SFC LOW OVER KY/TN. AS THE LOW PUSHES ACROSS THE PIEDMONT LATE
TONIGHT...WINDS WILL SHIFT FROM THE NE AND CLOUD BASES WILL RISE TO
VFR. IN ADDITION...IN THE WAKE OF THE LOW...LLVL WINDS SHOULD
STRENGTHEN...RESULTING IN LLWS FROM 5Z THROUGH 12Z.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. HOWEVER...EMBEDDED
THUNDERSTORMS MAY PASS ACROSS THE REGION DURING THE EARLY DAYLIGHT
HOURS. THE DEEP MOISTURE AND FORCING WILL SPREAD SW TO NE...REACHING
KHKY AROUND THE SAME PERIOD AS KCLT. KHKY MAY DEVELOP WINDS FROM THE
EAST-NORTHEAST AROUND SUNRISE...PERSISTING THROUGH THE REST OF THE
TAF PERIOD. ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30. AS THE LOW PUSHES ACROSS THE PIEDMONT LATE
TONIGHT...WINDS WILL SHIFT FROM THE NE AND CLOUD BASES WILL RISE TO
VFR. IN ADDITION...IN THE WAKE OF THE LOW...LLVL WINDS SHOULD
STRENGTHEN...RESULTING IN LLWS FROM 5Z THROUGH 12Z.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     MED   62%     MED   76%     MED   70%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     MED   71%     HIGH  93%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   69%     LOW   53%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 250927
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
527 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 525 AM...WIDESPREAD CONVECTION ACROSS THE NORTHERN HALF OF AL
WILL CONTINUE TO TRACK EAST THIS MORNING. A LARGE AREA OF -RA WILL
GRADUALLY INCREASE ACROSS THE WESTERN CAROLINAS AHEAD OF THE DEEP
CONVECTION. I WILL UPDATE THE FORECAST TO MAKE MINOR TWEAKS TO THE
POP TRENDS. IN ADDITION...I WILL UPDATE TEMPERATURES TO INDICATE
VALUES NEARLY STEADY THROUGH SUNRISE.

AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       HIGH 100%     MED   66%     HIGH  91%     HIGH  80%
KGSP       HIGH 100%     MED   62%     HIGH  88%     HIGH  89%
KAVL       HIGH 100%     MED   64%     MED   76%     HIGH 100%
KHKY       HIGH 100%     MED   73%     HIGH  91%     MED   75%
KGMU       HIGH 100%     MED   71%     MED   79%     HIGH  89%
KAND       HIGH 100%     MED   68%     HIGH  97%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 250927
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
527 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 525 AM...WIDESPREAD CONVECTION ACROSS THE NORTHERN HALF OF AL
WILL CONTINUE TO TRACK EAST THIS MORNING. A LARGE AREA OF -RA WILL
GRADUALLY INCREASE ACROSS THE WESTERN CAROLINAS AHEAD OF THE DEEP
CONVECTION. I WILL UPDATE THE FORECAST TO MAKE MINOR TWEAKS TO THE
POP TRENDS. IN ADDITION...I WILL UPDATE TEMPERATURES TO INDICATE
VALUES NEARLY STEADY THROUGH SUNRISE.

AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            09-15Z        15-21Z        21-03Z        03-06Z
KCLT       HIGH 100%     MED   66%     HIGH  91%     HIGH  80%
KGSP       HIGH 100%     MED   62%     HIGH  88%     HIGH  89%
KAVL       HIGH 100%     MED   64%     MED   76%     HIGH 100%
KHKY       HIGH 100%     MED   73%     HIGH  91%     MED   75%
KGMU       HIGH 100%     MED   71%     MED   79%     HIGH  89%
KAND       HIGH 100%     MED   68%     HIGH  97%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 250745
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
345 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     MED   75%     MED   73%     MED   73%
KGSP       HIGH 100%     MED   66%     HIGH  86%     HIGH  83%
KAVL       HIGH 100%     MED   75%     MED   74%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   73%     HIGH  81%
KGMU       HIGH 100%     MED   69%     MED   74%     HIGH  86%
KAND       HIGH 100%     MED   62%     HIGH  82%     HIGH  98%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 250745
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
345 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     MED   75%     MED   73%     MED   73%
KGSP       HIGH 100%     MED   66%     HIGH  86%     HIGH  83%
KAVL       HIGH 100%     MED   75%     MED   74%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   73%     HIGH  81%
KGMU       HIGH 100%     MED   69%     MED   74%     HIGH  86%
KAND       HIGH 100%     MED   62%     HIGH  82%     HIGH  98%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 250745
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
345 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     MED   75%     MED   73%     MED   73%
KGSP       HIGH 100%     MED   66%     HIGH  86%     HIGH  83%
KAVL       HIGH 100%     MED   75%     MED   74%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   73%     HIGH  81%
KGMU       HIGH 100%     MED   69%     MED   74%     HIGH  86%
KAND       HIGH 100%     MED   62%     HIGH  82%     HIGH  98%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 250745
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
345 AM EDT SAT APR 25 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE EAST FROM THE CENTRAL PLAINS
STATES INTO THE SOUTHEAST TODAY. A WARM FRONT WILL LINGER OVER OUR
AREA FOR MUCH OF THE WEEKEND PROVIDING A FOCUS OF SHOWERS AND A FEW
STORMS. DRY HIGH PRESSURE WILL MOVE IN AGAIN FOR THE START OF THE
WORK WEEK...WITH ANOTHER LOW PRESSURE SYSTEM CROSSING THE SOUTHEAST
BY MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 340 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. FURTHER WEST...WATER VAPOR LOOP INDICATED A
CLOSED MID LEVEL LOW OVER THE CENTRAL PLAINS...DRIFTING TO THE EAST-
NORTHEAST. SOUTH EAST OF THE MID LEVEL LOW...A LARGE BAND OF
CONVECTION WAS TRACKING EAST ACROSS NRN MS/AL. THIS ACTIVITY LARGELY
ORIGINATED NEAR THE SFC WARM FRONT AND WITHIN A BELT OF UPPER JET
DIVERGENCE. HOWEVER...THE CONVECTION IS TRACKING QUICKLY
EAST...OUTPACING THE MOST SUPPORTIVE ENVIRONMENT. AS A
RESULT...RECENT IR SATELLITE IMAGES INDICATED A STEADY WARMING TREND
OF CLOUD TOP TEMPERATURES...LIGHTNING COUNTS WERE ALSO DECREASING.
THESE WEAKENING TRENDS MATCH UP WELL WITH THE CONVECTION ALLOWING
MODELS...WHICH INDICATES THAT THE DEEP CONVECTION WILL STEADY WEAKEN
AS IT TRACKS EAST ALONG THE I-20 CORRIDOR. A LARGE AREA RAIN IS
FORECAST TO OCCUR ACROSS THE CWA THIS MORNING...PRIMARILY WEST OF I-
26. I WILL INDICATE THE RAINFALL TO FALL FROM SHRA WITH SOME
EMBEDDED THUNDERSTORMS. SEVERE WEATHER ASSOCIATED WITH THE MORNING
ACTIVITY APPEARS MINIMAL.

BY MID DAY...THE BULK OF THE DECAYING CONVECTION IS EXPECTED TO PUSH
EAST OF THE REGION. DURING THE AFTERNOON...THE PRIMARY CHALLENGE
WILL BE THE PLACEMENT OF A WEAK IN-SITU AREA OF COLD AIR DAMMING.
BASED OFF THE LATEST NAM...I WILL INDICATE THAT THE NC FOOTHILLS AND
NRN PIEDMONT WILL SEE LIGHT NE WINDS AND THICK AND PERSISTENT CLOUD
COVER. HOWEVER...AREAS TO THE SOUTH AND WEST MAY EXPERIENCE DEEP
SOUTHWEST FLOW AND DIURNALLY WARMING TEMPERATURES. IN FACT...THE NAM
SHOWS A HORSESHOE SHAPED AREA OF SB CAPE ACROSS THE MTNS AND
PORTIONS OF THE UPPER SAVANNAH RIVER VALLEY AND SC UPSTATE EAST OF I-
85. IN ADDITION...IMPRESSIVE SHEAR VALUES DEVELOP WITHIN THE
UNSTABLE AREAS...PEAKING DURING THE MID EVENING HOURS. HEILICITY
BETWEEN SFC-1KM IS FORECAST TO RANGE AROUND 300 M2/S2...EHI VALUES
FROM 2.5-4...AND SWEAT VALUES GENERALLY AROUND 350. HOWEVER...CIN
VALUES FROM THE NAM SOUNDING RANGE FROM 30 TO 50 J/KG THIS EVENING.
MODELS INDICATE THAT CONVECTION COVERAGE WILL BE AT A MINIMUM DURING
THE LATE AFTERNOON AND EVENING.

TONIGHT...A WELL DEVELOPED SFC LOW WILL SLIDE EAST ACROSS
KY/TN...CROSSING THE SOUTHERN APPALACHIANS AROUND MIDNIGHT. AT THE
MID LEVELS...THE CLOSED LOW FROM THIS MORNING WILL DEVELOP INTO A
POSITIVE TILTED TROF AND WILL RIPPLE EAST OVER THE SFC LOW. NEAR TERM
MODELS INDICATE THAT A MCS WILL LIKELY DEVELOP AHEAD OF THE LOW
CENTER...STEERING FLOW SHOULD RESULT IN THE SYSTEM TO TRACK EAST-
SOUTHEAST TONIGHT. BASED ON EXPERIENCE...I ANTICIPATE THAT THE MCS
SPEED WILL BE GREATER THAN THE MODEL CONSENSUS. THIS ADJUSTMENT
WOULD PLACE THE MCS OVER THE NC MTNS DURING THE EARLY MORNING HOURS
SUNDAY. BY THAT TIME...THE GREATEST SHEAR AND INSTABILITY VALUES
HAVE ENDED...LEAVING WEAK TO MODERATE VALUES ACROSS THE MTNS AND
SC/GA LINE. THIS WILL LIKELY SUPPORT THE MCS REACHING THE MTNS...BUT
STEADILY WEAKENING AS THE ACTIVITY APPROACHES THE FOOTHILLS.
HOWEVER...LOW WBZ AND LINGERING SHEAR AND INSTABILITY WOULD LIKELY
YIELD SEVERAL SEVERE WIND AND HAIL EVENTS AS THE CONVECTION ARRIVES.
WE WILL CONTINUE TO HIGHLIGHT IN THE HWO.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SHORT TERM BEGINS WITH TRYING TO TIME
THE EXIT OF THE SURFACE LOW OFF THE CAROLINA COAST. SHORT TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH EAST-WEST ELONGATED TROUGH
STRETCHING WESTWARD INTO OUR AREA FROM THE CENTER OF THE SURFACE LOW
IN THE ATLANTIC AT THE START OF THE SHORT TERM. SPLIT FLOW PATTERN
CONTINUES ALOFT...WITH SHORTWAVE ALSO PUSHING OFFSHORE AND MEAN
TROUGH TAKING OVER. STROGN DOWNSLOPING COMPONENT ON SUNDAY WILL LEAD
TO HIGHS INCREASING TO WELL ABOVE NORMAL VALUES ACROSS THE UPSTATE
AND PORTIONS OF THE PIEDMONT BEFORE THE ACTUAL COLD FRONT PUSHES
THROUGH...THOUGH ESPECIALLY THE NORTHERN MOUNTAINS WILL BE ON THE
COOL SIDE. MIDLEVEL MOISTURE HANGS ON ENOUGH TO KEEP SOME CLOUDINESS
AND PERHAPS SOME LINGERING SHOWERS ACROSS THE AREA THROUGH THE EARLY
PART OF THE DAY...BUT WE SHOULD START SEEING A CLEARING TREND
OVERNIGHT SUNDAY NIGHT INTO MONDAY.

SHOULD SEE A PRETTY MARKED DIFFERENCE IN HIGHS ON MONDAY BEHIND THE
FRONT WITH DEEP-LAYER CAA ACROSS THE AREA...THOUGH THE MAGNITUDE OF
THE CAA DECREASES THROUGH THE DAY. ANOTHER SHORTWAVE AXIS PUSHES
DOWN THE UPPER TROUGH...STILL FIRMLY IN PLACE ACROSS THE EASTERN
PORTION OF THE COUNTRY...LATE MONDAY INTO EARLY TUESDAY. THIS TROUGH
MANAGES TO FINALLY PUSH THE DEEP UPPER LOW FARTHER OUT INTO THE
ATLANTIC BUT WILL USHER IN COOLER HIGH PRESSURE FOR THE BEGINNING OF
THE EXTENDED.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 345 AM SATURDAY...HIGH PRESSURE CENTERED ACROSS THE NORTHERN
PLAINS AND SOUTHERN CANADA WILL BE RIDGING INTO THE SOUTHEAST AS WE
START THE EXTENDED...WITH THE AFOREMENTIONED UPPER SHORTWAVE DIGGING
AROUND THE WESTERN PERIPHERY OF THE LOW OVER THE NORTHWEST ATLANTIC.
MEANWHILE...A CUTOFF LOW OVER THE SOUTHERN PLAINS WILL BEGIN TO
SLIDE EAST AS THE WAVETRAIN FINALLY PROGRESSES. HEIGHT FALLS AHEAD
OF THE UPPER LOW WILL INDUCE CYCLOGENESIS ACROSS THE NORTHERN
GULF...SPREADING MOISTURE INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST THROUGH THE MIDDLE OF THE WORK WEEK. BOTH THE GFS AND
ECMWF HAVE BEEN TRENDING THE SURFACE LOW FARTHER SOUTH WITH
SUBSEQUENT RUNS AND FOR THIS MORNING IT IS LITTLE DIFFERENT...WITH
THE LOW PUSHING EAST ACROSS THE FLORIDA PANHANDLE UNTIL WEDNESDAY
NIGHT AND ONLY LIFTING SLIGHTLY INTO SOUTH GEORGIA. THE ECMWF HAS
SPED THE SYSTEM UP WITH A DEEPER NORTH-SOUTH ELONGATED TROUGH PHASED
WITH THE GREAT LAKES TROUGH...WHEREAS THE GFS HAS TRENDED A LITTLE
SLOWER AND TAKES A LITTLE LONGER TO PHASE THE FORMER CUTOFF LOW WITH
THE LARGER SYSTEM. IN ANY CASE...CLOUDY AND COOL CONDITIONS WILL
PREVAIL THROUGH THE MIDDLE OF THE WEEK...WITH HIGHS ESPECIALLY
WEDNESDAY A GOOD 10 DEGREES BELOW SEASONAL NORMALS. VERY HARD TO
TELL AT THIS POINT...WITH THE DIFFERENCES IN THE MODELS PLUS LACK OF
RUN-TO-RUN CONTINUITY...WHEN THE PRECIP WILL MOVE OUT. IN GENERAL
HAVE CONTINUED TREND OF MID-RANGE POPS...WITH A FEW LIKELIES SOUTH
ON WEDNESDAY...WITH A SLOW DRYING TREND THURSDAY INTO THURSDAY
EVENING. MORE DIVERGENCE IN EXTENDED GUIDANCE AT THE END OF THE
PERIOD BUT OVERALL EXPECT A DRYING TREND TOWARD THE END OF THE WORK
WEEK WITH TEMPERATURES TRENDING BACK TOWARDS CLIMO.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     MED   75%     MED   73%     MED   73%
KGSP       HIGH 100%     MED   66%     HIGH  86%     HIGH  83%
KAVL       HIGH 100%     MED   75%     MED   74%     HIGH 100%
KHKY       HIGH 100%     MED   69%     MED   73%     HIGH  81%
KGMU       HIGH 100%     MED   69%     MED   74%     HIGH  86%
KAND       HIGH 100%     MED   62%     HIGH  82%     HIGH  98%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 250627
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
227 AM EDT SAT APR 25 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 225 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM THE
SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN MVFR
CEILINGS AND LIGHT SHRA. I WILL ISSUE A QUICK UPDATE TO ADJUST
TEMPERATURES TO OBSERVATIONS...THEN POPULATE TEMPERATURES AND
DEWPOINTS THROUGH TONIGHT WITH A 50/50 BLEND OF PREVIOUS FORECAST
AND NAM.

AS OF 1040 PM EDT FRIDAY...SHIELD OF UPGLIDE INDUCED PRECIP
CONTINUES TO SPREAD ACROSS THE LOWER OHIO AND TENNESSEE VALLEYS THIS
EVENING.  LATEST NAM INDICATES THIS TREND IS STILL EXPECTED TO
CONTINUE ALL THE WHILE ADVECTING EAST OVERNIGHT.  DESPITE LIGHT
RETURNS ON RADAR EXPECTING THE DRY BOUNDARY LAYER TO WIN OVER FOR AT
LEAST A FEW MORE HOURS BEFORE ANY PRECIP FALLS TO THE SFC.
THUS...BACKED POPS DOWN OVER THE NEXT HOUR OR TWO...BUT THEN
CONTINUED WITH THE PREVIOUS TRENDS WITH ONE ADDITIONAL CHANGE.  PER
LATEST CAM GUID BLEND...OPTED TO INCREASE POPS A BIT SOONER
OVERNIGHT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND THE LAKELANDS
REGION.  THIS CHANGE YIELDED LIKELY LEVEL POPS BY DAYBREAK.  POPS
ARE STILL FCST TO EXPAND FURTHER EAST THROUGH MID MORNING WITH
CATEGORICAL POPS PREVAILING ATOP THE ENTIRE REGION BY LATE MORNING.
OTHERWISE...NO SIG CHANGES WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     MED   79%     MED   72%     HIGH  80%
KGSP       HIGH 100%     MED   68%     HIGH  87%     HIGH  83%
KAVL       HIGH 100%     MED   77%     MED   75%     HIGH 100%
KHKY       HIGH 100%     MED   73%     MED   72%     HIGH  85%
KGMU       HIGH 100%     MED   71%     MED   77%     HIGH  83%
KAND       HIGH 100%     MED   68%     MED   78%     HIGH  96%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED




000
FXUS62 KGSP 250627
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
227 AM EDT SAT APR 25 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 225 AM...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE
CWA THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM THE
SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN MVFR
CEILINGS AND LIGHT SHRA. I WILL ISSUE A QUICK UPDATE TO ADJUST
TEMPERATURES TO OBSERVATIONS...THEN POPULATE TEMPERATURES AND
DEWPOINTS THROUGH TONIGHT WITH A 50/50 BLEND OF PREVIOUS FORECAST
AND NAM.

AS OF 1040 PM EDT FRIDAY...SHIELD OF UPGLIDE INDUCED PRECIP
CONTINUES TO SPREAD ACROSS THE LOWER OHIO AND TENNESSEE VALLEYS THIS
EVENING.  LATEST NAM INDICATES THIS TREND IS STILL EXPECTED TO
CONTINUE ALL THE WHILE ADVECTING EAST OVERNIGHT.  DESPITE LIGHT
RETURNS ON RADAR EXPECTING THE DRY BOUNDARY LAYER TO WIN OVER FOR AT
LEAST A FEW MORE HOURS BEFORE ANY PRECIP FALLS TO THE SFC.
THUS...BACKED POPS DOWN OVER THE NEXT HOUR OR TWO...BUT THEN
CONTINUED WITH THE PREVIOUS TRENDS WITH ONE ADDITIONAL CHANGE.  PER
LATEST CAM GUID BLEND...OPTED TO INCREASE POPS A BIT SOONER
OVERNIGHT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND THE LAKELANDS
REGION.  THIS CHANGE YIELDED LIKELY LEVEL POPS BY DAYBREAK.  POPS
ARE STILL FCST TO EXPAND FURTHER EAST THROUGH MID MORNING WITH
CATEGORICAL POPS PREVAILING ATOP THE ENTIRE REGION BY LATE MORNING.
OTHERWISE...NO SIG CHANGES WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...HIGH DEBRIS CLOUDS WILL LIKELY INCREASE ACROSS THE NC
PIEDMONT THROUGH SUNRISE. LLVL MOISTURE SHOULD RAPIDLY INCREASE FROM
THE SOUTHWEST DURING THE MID TO LATE MORNING HOURS...RESULTING IN
MVFR CEILINGS AND LIGHT SHRA. CEILINGS WILL CONTINUE TO LOWER INTO
THE AFTERNOON AS LLVL WINDS INCREASES...DEEPENING THE LLVL FORCING.
BASED ON THE TIMING OF THE NAM...SBCAPE AND STEEPENING LAPSE RATES
WILL DEVELOP DURING THE LATE AFTERNOON AND EARLY EVENING. I WILL
HIGHLIGHT THE 22Z TO 1Z WINDOW WITH A PROB30 FOR TSRA. BY LATE
EVENING...FORECAST SOUNDINGS BECOME MOIST THROUGH A DEEP LAYER AND
MODEL CLOUDS ARE EASILY WITHIN IFR. WINDS DURING THE 6Z TAF WILL
REMAIN FROM THE SOUTH-SOUTHWEST...RESULTING FROM THE APPROACH OF A
WELL ORGANIZED SFC LOW OVER KY/TN.

ELSEWHERE...CONDITIONS WILL GENERALLY FOLLOW THE TREND DISCUSSED FOR
CLT ABOVE. HOWEVER...INCREASES IN MOISTURE AND INSTABILITY WILL
REACH KAND SEVERAL HOURS EARLIER THAN KCLT. THE DEEP MOISTURE AND
FORCING WILL SPREAD SW TO NE...REACHING KHKY AROUND THE SAME PERIOD
AS KCLT. KHKY MAY DEVELOP WINDS FROM THE EAST-NORTHEAST AROUND
SUNRISE...PERSISTING THROUGH THE REST OF THE TAF PERIOD.
ELSEWHERE...WINDS WILL REMAIN FROM THE SOUTH-SOUTHWEST.
THUNDERSTORMS SHOULD DEVELOP OVER THE REGION DURING THE LATE
AFTERNOON TO EARLY EVENING PERIOD. THE GREATEST OVERLAP OF SHEAR AND
INSTABILITY WILL GENERALLY OCCUR ALONG AND WEST OF I-26...SUPPORTING
DAMAGING WINDS AND HAIL. I WILL HIGHLIGHT THE PERIOD OF DEEP
CONVECTION WITH A PROB30.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     MED   79%     MED   72%     HIGH  80%
KGSP       HIGH 100%     MED   68%     HIGH  87%     HIGH  83%
KAVL       HIGH 100%     MED   77%     MED   75%     HIGH 100%
KHKY       HIGH 100%     MED   73%     MED   72%     HIGH  85%
KGMU       HIGH 100%     MED   71%     MED   77%     HIGH  83%
KAND       HIGH 100%     MED   68%     MED   78%     HIGH  96%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED





000
FXUS62 KGSP 250252
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1052 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1040 PM EDT FRIDAY...SHIELD OF UPGLIDE INDUCED PRECIP
CONTINUES TO SPREAD ACROSS THE LOWER OHIO AND TENNESSEE VALLEYS
THIS EVENING. LATEST NAM INDICATES THIS TREND IS STILL EXPECTED TO
CONTINUE ALL THE WHILE ADVECTING EAST OVERNIGHT. DESPITE LIGHT
RETURNS ON RADAR EXPECTING THE DRY BOUNDARY LAYER TO WIN OVER FOR
AT LEAST A FEW MORE HOURS BEFORE ANY PRECIP FALLS TO THE SFC.
THUS...BACKED POPS DOWN OVER THE NEXT HOUR OR TWO...BUT THEN
CONTINUED WITH THE PREVIOUS TRENDS WITH ONE ADDITIONAL CHANGE. PER
LATEST CAM GUID BLEND...OPTED TO INCREASE POPS A BIT SOONER
OVERNIGHT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND THE LAKELANDS
REGION. THIS CHANGE YIELDED LIKELY LEVEL POPS BY DAYBREAK. POPS
ARE STILL FCST TO EXPAND FURTHER EAST THROUGH MID MORNING WITH
CATEGORICAL POPS PREVAILING ATOP THE ENTIRE REGION BY LATE
MORNING. OTHERWISE...NO SIG CHANGES WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            03-09Z        09-15Z        15-21Z        21-00Z
KCLT       HIGH 100%     HIGH 100%     MED   79%     MED   77%
KGSP       HIGH 100%     MED   74%     MED   68%     HIGH  92%
KAVL       HIGH 100%     HIGH 100%     MED   73%     MED   79%
KHKY       HIGH 100%     HIGH 100%     MED   64%     HIGH  90%
KGMU       HIGH 100%     MED   75%     MED   68%     HIGH  92%
KAND       HIGH 100%     HIGH  87%     MED   75%     HIGH  89%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG





000
FXUS62 KGSP 250252
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1052 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 1040 PM EDT FRIDAY...SHIELD OF UPGLIDE INDUCED PRECIP
CONTINUES TO SPREAD ACROSS THE LOWER OHIO AND TENNESSEE VALLEYS
THIS EVENING. LATEST NAM INDICATES THIS TREND IS STILL EXPECTED TO
CONTINUE ALL THE WHILE ADVECTING EAST OVERNIGHT. DESPITE LIGHT
RETURNS ON RADAR EXPECTING THE DRY BOUNDARY LAYER TO WIN OVER FOR
AT LEAST A FEW MORE HOURS BEFORE ANY PRECIP FALLS TO THE SFC.
THUS...BACKED POPS DOWN OVER THE NEXT HOUR OR TWO...BUT THEN
CONTINUED WITH THE PREVIOUS TRENDS WITH ONE ADDITIONAL CHANGE. PER
LATEST CAM GUID BLEND...OPTED TO INCREASE POPS A BIT SOONER
OVERNIGHT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND THE LAKELANDS
REGION. THIS CHANGE YIELDED LIKELY LEVEL POPS BY DAYBREAK. POPS
ARE STILL FCST TO EXPAND FURTHER EAST THROUGH MID MORNING WITH
CATEGORICAL POPS PREVAILING ATOP THE ENTIRE REGION BY LATE
MORNING. OTHERWISE...NO SIG CHANGES WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            03-09Z        09-15Z        15-21Z        21-00Z
KCLT       HIGH 100%     HIGH 100%     MED   79%     MED   77%
KGSP       HIGH 100%     MED   74%     MED   68%     HIGH  92%
KAVL       HIGH 100%     HIGH 100%     MED   73%     MED   79%
KHKY       HIGH 100%     HIGH 100%     MED   64%     HIGH  90%
KGMU       HIGH 100%     MED   75%     MED   68%     HIGH  92%
KAND       HIGH 100%     HIGH  87%     MED   75%     HIGH  89%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG




000
FXUS62 KGSP 242342
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
742 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 740 PM EDT FRIDAY...CONTINUING TO MONITOR DEVELOPING UPGLIDE
REGIME TO THE SW AS IT PERTAINS TO PRECIP ONSET ACROSS NE GEORGIA
AND THE SW NORTH CAROLINA MTNS.  DIDNT OPT FOR ANY CHANGES WITH THIS
UPDATE AS 18Z GFS REMAINS SUPPORTIVE OF CURRENT TRENDS.  WILL DEFER
TO 00Z NAM AND THE EVENING UPDATE TO MAKE ANY POP ADJUSTMENTS IF
NECESSARY.  OTHERWISE...CURRENT FCST REMAIN ON TRACK AND ASIDE FOR
MINOR TWEAKS TO SKY/TEMPS/DEWS...NO CHANGES NEEDED/MADE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     LOW   56%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAND       HIGH 100%     HIGH 100%     LOW   57%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG





000
FXUS62 KGSP 242342
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
742 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 740 PM EDT FRIDAY...CONTINUING TO MONITOR DEVELOPING UPGLIDE
REGIME TO THE SW AS IT PERTAINS TO PRECIP ONSET ACROSS NE GEORGIA
AND THE SW NORTH CAROLINA MTNS.  DIDNT OPT FOR ANY CHANGES WITH THIS
UPDATE AS 18Z GFS REMAINS SUPPORTIVE OF CURRENT TRENDS.  WILL DEFER
TO 00Z NAM AND THE EVENING UPDATE TO MAKE ANY POP ADJUSTMENTS IF
NECESSARY.  OTHERWISE...CURRENT FCST REMAIN ON TRACK AND ASIDE FOR
MINOR TWEAKS TO SKY/TEMPS/DEWS...NO CHANGES NEEDED/MADE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     LOW   56%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAND       HIGH 100%     HIGH 100%     LOW   57%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG




000
FXUS62 KGSP 242342
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
742 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 740 PM EDT FRIDAY...CONTINUING TO MONITOR DEVELOPING UPGLIDE
REGIME TO THE SW AS IT PERTAINS TO PRECIP ONSET ACROSS NE GEORGIA
AND THE SW NORTH CAROLINA MTNS.  DIDNT OPT FOR ANY CHANGES WITH THIS
UPDATE AS 18Z GFS REMAINS SUPPORTIVE OF CURRENT TRENDS.  WILL DEFER
TO 00Z NAM AND THE EVENING UPDATE TO MAKE ANY POP ADJUSTMENTS IF
NECESSARY.  OTHERWISE...CURRENT FCST REMAIN ON TRACK AND ASIDE FOR
MINOR TWEAKS TO SKY/TEMPS/DEWS...NO CHANGES NEEDED/MADE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     LOW   56%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAND       HIGH 100%     HIGH 100%     LOW   57%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG





000
FXUS62 KGSP 242342
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
742 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 740 PM EDT FRIDAY...CONTINUING TO MONITOR DEVELOPING UPGLIDE
REGIME TO THE SW AS IT PERTAINS TO PRECIP ONSET ACROSS NE GEORGIA
AND THE SW NORTH CAROLINA MTNS.  DIDNT OPT FOR ANY CHANGES WITH THIS
UPDATE AS 18Z GFS REMAINS SUPPORTIVE OF CURRENT TRENDS.  WILL DEFER
TO 00Z NAM AND THE EVENING UPDATE TO MAKE ANY POP ADJUSTMENTS IF
NECESSARY.  OTHERWISE...CURRENT FCST REMAIN ON TRACK AND ASIDE FOR
MINOR TWEAKS TO SKY/TEMPS/DEWS...NO CHANGES NEEDED/MADE.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR WILL PREVAIL INITIALLY BEFORE UPGLIDE REGIME DEVELOPS
ATOP INSITU WEDGE LEADING TO MVFR/IFR CONDITIONS.  TAF INITIALIZES
WITH SCT HIGH CIRRUS AHEAD OF MID LEVEL BKN CIGS BY MID MORNING.  AS
REGION OF BEST UPGLIDE SLIDES EAST ACROSS THE AREA NEAR
DAYBREAK...EXPECTING -RA AND SUBSEQUENT VISB/CIG RESTRICITIONS TO
SET IN.  TAF PROGRESSES DOWNWARD FROM MVFR AT APPROX 13Z TO NEAR
LIFR BY 17Z WITH TIMING OF PRECIP BASED ON LATEST CAM GUID.  DURING
THIS TIME MODERATE TO HEAVY RAINFALL COULD OCCUR WITH VISB FALLING
TO AROUND 1.5 SM AND CIGS AS LOW AS 005.  BY MID AFTERNOON EXPECTING
UPGLIDE REGIME TO SUBSIDE AS THE WARM SECTOR DEVELOPS OVER THE
REGION.  WITH THAT...CONTINUED WITH MVFR VISB THROUGH PERIODS END
WITH CIGS AT IFR LEVEL.  WOULD NOT BE SURPRISED IF CIGS IMPROVED
FASTER THAN THESE TRENDS INDICATE AS THE WEDGE LOOKS RATHER
UNIMPRESSIVE...HOWEVER GUIDANCE INSISTS ON IFR THROUGH THE ABOVE
MENTIONED PERIOD.  WINDS WILL REMAIN LIGHT AND SOUTHERLY THROUGH THE
TAF CYCLE.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS UPGLIDE REGIME SETS UP
ATOP THE REGION AS WARM FRONT APPROACHES.  INITIALIZED ALL TAFS WITH
CURRENT SCT/BKN HIGH CLOUDS WITH DETERIORATION EXPECTED BY EARLY
MORNING FROM THE WEST...TO THE EAST.  THUS EXPECTING RESTRICTIONS TO
OCCUR FIRST AT KAVL...THEN MOVE EAST WHERE ALL SITES WILL SEE SOME
FLAVOR OF MVFR/IFR CIGS AND VISB BY MID/LATE MORNING ASSOCIATED WITH
UPGLIDE INDUCED RA.  INSITU WEDGE BOUNDARY LOCATION STILL REMAINS
UNCERTAIN...HOWEVER ITS LOOKING LIKE A TRANSITION TO CONVECTIVE
SHOWERS IS POSSIBLE/LIKELY AT KAVL AND KAND BY THE AFTERNOON HOURS
WHERE TSRA IS MENTIONED AS WELL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     LOW   56%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   26%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAND       HIGH 100%     HIGH 100%     LOW   57%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG




000
FXUS62 KGSP 242030
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
430 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 430 PM EDT FRIDAY...CURRENT FCST REMAINS ON TRACK THEREFORE NO
SIG CHANGES NEEDED/MADE.  CYCLOGENESIS OVER THE SOUTHERN PLAINS
CONTINUES TO PUSH A DEVELOPING WARM FRONT THROUGH THE LOWER
MISSISSIPPI RIVER VALLEY AT THIS TIME...WHILE WESTERLY MID/UPPER
LEVEL FLOW STREAMS CIRRUS ATOP THE TN VALLEY INTO THE SOUTHERN APPS.
FURTHER SKY COVER WILL BUILD IN TONIGHT AS WEAK UPGLIDE REGIME
SLIDES EAST...AND STRENGTHENS.  THUS...DID TWEAK SKY COVER A BIT TO
ACCOUNT FOR MOST RECENT TRENDS.  OTHERWISE TEMPERATURE/DEWPOINT
TRENDS LOOK TO BE IN GOOD AGREEMENT WITH THE CURRENT FCST.  WILL
REEVALUATE POP TIMING WITH NEWER GUIDANCE LATER THIS EVENING.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   44%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   62%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   38%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     LOW   58%
KAND       HIGH 100%     HIGH 100%     HIGH  91%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...JAT





000
FXUS62 KGSP 242030
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
430 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 430 PM EDT FRIDAY...CURRENT FCST REMAINS ON TRACK THEREFORE NO
SIG CHANGES NEEDED/MADE.  CYCLOGENESIS OVER THE SOUTHERN PLAINS
CONTINUES TO PUSH A DEVELOPING WARM FRONT THROUGH THE LOWER
MISSISSIPPI RIVER VALLEY AT THIS TIME...WHILE WESTERLY MID/UPPER
LEVEL FLOW STREAMS CIRRUS ATOP THE TN VALLEY INTO THE SOUTHERN APPS.
FURTHER SKY COVER WILL BUILD IN TONIGHT AS WEAK UPGLIDE REGIME
SLIDES EAST...AND STRENGTHENS.  THUS...DID TWEAK SKY COVER A BIT TO
ACCOUNT FOR MOST RECENT TRENDS.  OTHERWISE TEMPERATURE/DEWPOINT
TRENDS LOOK TO BE IN GOOD AGREEMENT WITH THE CURRENT FCST.  WILL
REEVALUATE POP TIMING WITH NEWER GUIDANCE LATER THIS EVENING.

PREVIOUS DISCUSSION...

AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   44%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   62%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   38%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     LOW   58%
KAND       HIGH 100%     HIGH 100%     HIGH  91%     MED   66%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...JAT




000
FXUS62 KGSP 241831
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
231 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     MED   64%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   69%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   69%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   60%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   71%
KAND       HIGH 100%     HIGH 100%     HIGH  95%     MED   68%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...JAT




000
FXUS62 KGSP 241831
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
231 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AT 230 PM EDT FRIDAY...AN UPPER RIDGE WAS LOCATED OVER THE MS RIVER
VALLEY THIS AFTERNOON...WITH TROUGHS OFF THE EAST COAST AND OVER THE
ROCKIES. SURFACE HIGH PRESSURE CENTERED OVER THE OH RIVER VALLEY
EXTENDED TO THE CAROLINA AND GA COASTS THIS AFTERNOON. MEANWHILE A
COLD FRONT WAS LOCATED OVER CENTRAL FL AND THE NW GULF OF MEXICO.
CLOUDS COVER REMAINED LIMITED MAINLY TO THE MS RIVER VALLEY...WITH
SOME HIGH LEVEL CLOUDS SPILLING OVER THE RIDGE IN SW TN AND N GA.

THE UPPER RIDGE IS EXPECTED TO PROGRESS TO THE SOUTHERN APPALACHIANS
BY SATURDAY MORNING...WHILE AN UPPER LOW CLOSES OFF IN THE TROUGH
UPSTREAM AND CROSSES THE CENTRAL PLAINS. THIS LOW FILLS NEAR THE
SOUTHERN GREAT LAKES LATE SATURDAY...WHILE THE UPPER RIDGE
DEAMPLIFIES...LEADING TO ZONAL FLOW OVER THE SE.

THE SURFACE BOUNDARY IN THE GULF STARTS TO RETURN N AS A WARM FRONT
OVERNIGHT...AND MOIST SOUTHWESTERLY ISENTROPIC UPGLIDE OVER THE
BOUNDARY WILL SUPPORT LOWERING CLOUDS AND PRECIPITATION OVER OUR
AREA. A LIGHT LOW LEVEL SOUTHERLY FLOW WILL ADD SOME UPSLOPE FLOW
INTO THE SOUTHERN APPALACHIANS. UPGLIDE MAXIMIZES BY MIDDAY
SATURDAY...WHEN THE GREATEST PRECIPITATION IS EXPECTED. RAINFALL
AMOUNTS COULD EXCEED ONE INCH IN THE UPPER SAVANNAH RIVER VALLEY AND
THE SOUTH FACING BLUE RIDGE ESCARPMENT ON SATURDAY...BUT AT THIS
TIME FLOODING APPEARS TO BE A LIMITED HAZARD BASED ON THE SOMEWHAT
EXTENDED DURATION OF THE EVENT.

INSTABILITY WILL INCREASE ON SATURDAY...BECOMING INCREASINGLY
SUFFICIENT FOR THUNDERSTORMS IN THE AFTERNOON OVER THE S AND W OF
THE AREA. WITH SHEAR INCREASING...THE CHANCE OF SEVERE THUNDERSTORMS
WILL INCREASE AS WELL. TEMPERATURES WILL EXHIBIT A LIMITED DIURNAL
RANGE...AS CLOUD COVER AND INCREASING MOISTURE LIMIT COOLING AND
HEATING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 205 PM FRIDAY...THE MAIN SHORT TERM CONCERN REVOLVES AROUND
THE CONTINUED POTENTIAL FOR STRONG/SEVERE CONVECTION ACROSS THE AREA
INTO SATURDAY NIGHT. UNFORTUNATELY...CONSIDERING THE RATHER WEAKLY
FORCED NATURE OF THE ENVIRONMENT...CONVECTIVE TRENDS ACROSS OUR AREA
ARE NONE-TOO-OBVIOUS. IT SEEMS A VIRTUAL CERTAINTY THAT ORGANIZED
CONVECTION WILL DEVELOP DURING SAT AFTERNOON/EVENING ACROSS THE OHIO
VALLEY. HOWEVER...THERE WILL BE COMPETITION BETWEEN THE MEAN CLOUD-
BEARING FLOW (DUE WESTERLY) AND THE ORIENTATION OF INSTABILITY AND
LOW LEVEL FORCING (WARM FRONT/CAPE AXIS EXTENDING SOUTHEAST FROM THE
OHIO VALLEY) IN DETERMINING THE TRACK OF ANY ORGANIZED CONVECTIVE
COMPLEX. IN FACT...THERE IS NO CLEAR CONSENSUS AMONG THE LATEST
MESOSCALE AND SHORT TERM MODELS IN THIS REGARD. THE HIGHEST POPS
(PRIMARILY LIKELY) FOR SAT EVENING WILL BE MAINTAINED ACROSS THE
WESTERN MTNS AND OUR FAR NORTHERN ZONES. ASSUMING AN MCS DOES MANAGE
TO DROP INTO THE CWA TOMORROW EVENING...A CONSENSUS OF MODEL
INSTABILITY PROGS INDICATES IT WILL NOT FIND THE MOST ACCOMMODATING
ENVIRONMENT ACROSS OUR NORTHERN ZONES...AS ESSENTIALLY NO MODEL
DEPICTS POSITIVE SURFACE-BASED BUOYANCY DEVELOPING NORTH OF
(ROUGHLY) I-85 IN THE PIEDMONT/FOOTHILLS. (THERE IS HOWEVER A DECENT
AMOUNT OF ELEVATED CAPE DEPICTED). THEREFORE...OUTSIDE OF THE
POTENTIAL FOR A DOWNBURST-PRODUCING MCS TO SLAM INTO THE NC MTNS
BEFORE WEAKENING AND/OR BECOMING LESS ROOTED IN THE BOUNDARY
LAYER...THE SEVERE WEATHER POTENTIAL ACROSS OUR NORTHERN ZONES
APPEARS LESS THAN STELLAR.

THE MORE INTERESTING ACTION TOMORROW NIGHT COULD BE FARTHER SOUTH...
AS WARM FRONT SLOWLY LIFTS NORTH AND SPREADS UNSTABLE AIR INTO OUR
SOUTHERN PIEDMONT/SOUTHWEST MTNS AREA. SOME OF THE MESO-MODELS ARE
HINTING AT THE POTENTIAL FOR SCATTERED DISCRETE CONVECTION TO
DEVELOP WITHIN A DESTABILIZING/RECOVERING AIR MASS ACROSS NORTH
GEORGIA AND THE TENN VALLEY BY LATE AFTERNOON...WHICH COULD MAKE A
RUN INTO THE CWA DURING THE EVENING. AGAIN...THIS IS FAR FROM A SLAM
DUNK IN LIGHT OF A GENERALLY WEAKLY FORCED WARM SECTOR ENVIRONMENT.
HOWEVER...THE POTENTIAL IS CERTAINLY THERE...AND IN LIGHT OF THE
RATHER VOLATILE ENVIRONMENTAL WARM SECTOR CONDITIONS THAT ARE
EXPECTED (SBCAPE 1500-2000 J/KG...DEEP LAYER SHEAR OF 70
KTS)...SUPERCELLS WOULD BE LIKELY...WITH PERHAPS A THREAT FOR AN
ISOLATED TORNADO NEAR THE WARM FRONT.

WEAKENING SURFACE LOW IS EXPECTED TO TRACK NEAR THE NC/VA LINE SAT
NIGHT INTO SUNDAY...WITH TRAILING COLD FRONT MOVING ACROSS THE AREA
DURING THE MORNING INTO THE AFTERNOON. A BIT OF SBCAPE MAY CREEP
INTO THE PIEDMONT AHEAD OF THE FRONT BY EARLY AFTERNOON...WHILE NW
FLOW COULD SUPPORT SHOWER DEVELOPMENT ACROSS THE FAR WESTERN MTNS.
POPS FOR SCATTERED CONVECTION ARE THEREFORE WARRANTED IN MAINLY
THOSE AREAS. THE REMAINDER OF THE PERIOD WILL BE QUIET AND DRY...
WITH TEMPS ABOUT 5 DEGREES BELOW CLIMO.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MODEL GUIDANCE HAS CONTINUED THE TREND OF
DELAYING THE ARRIVAL OF THE NEXT SYSTEM DURING THE MIDDLE OF NEXT
WEEK. THE LATEST GFS KEEPS THE UPPER RIDGE AXIS TO THE WEST MONDAY
NIGHT AND DOES NOT MAKE IT INTO THE WESTERN CAROLINAS UNTIL MAYBE
VERY LATE IN THE DAY ON TUESDAY. THE 00Z RUN OF THE ECMWF WAS
SIMILAR IN SHOWING LITTLE SUPPORT OR MOISTURE FOR PRECIP UNTIL MAYBE
LATE TUESDAY AFTERNOON. WITH THAT IN MIND...WILL IMPOSE YET ANOTHER
DELAY WITH THE ARRIVAL OF PRECIP CHANCES FROM THE SOUTHWEST UNTIL
LATE TUESDAY AFTERNOON...AND WILL SLOW THE INCREASE IN PRECIP
CHANCES TUESDAY NIGHT. NOT MUCH IN THE NEW MODEL GUIDANCE TO SUGGEST
ANY CHANGES TO THE FCST...UNLESS THE 12Z RUN OF THE ECMWF TRENDS
FASTER LIKE THE GFS. HOWEVER...IN SPITE OF THE MODEL DIFFERENCES
WITH THE EVOLUTION OF THE UPPER LOW AND TRACK/STRENGTH OF THE
SURFACE LOW MOVING ACROSS THE DEEP SOUTH ON WEDNESDAY AND
THURSDAY... THE WEAKER/FASTER GFS STILL MANAGES TO HOLD ONTO SOME
LIGHT PRECIP ACROSS THE WESTERN CAROLINAS AS ITS SHEARING/POSITIVELY
TILTED UPPER TROF MOVES OVERHEAD THRU THURSDAY EVENING. THUS...FEW
CHANGES WERE MADE. PRECIP PROB WAS KEPT IN THE CHANCE RANGE AND
TEMPS WERE KEPT SEASONALLY COOL...ABOUT 10 DEG BELOW NORMAL. THE
MODEL SOLUTIONS COME INTO AGREEMENT BY THURSDAY NIGHT WITH MOVING
THE PRECIP OUT. FRIDAY SHOULD BE DRY WITH HIGH PRESSURE BUILDING IN
FROM THE WEST AND TEMPS STARTING A REBOUND TOWARD NORMAL.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     MED   64%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   69%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     MED   69%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   60%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   71%
KAND       HIGH 100%     HIGH 100%     HIGH  95%     MED   68%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...JAT
SHORT TERM...JDL
LONG TERM...PM
AVIATION...JAT





000
FXUS62 KGSP 241713
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1715 UTC UPDATE...SKY COVER WAS REDUCED AGAIN PER SATELLITE IMAGERY.
WINDS WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV...
PRESERVING GUSTS AT HIGHER ELEVATIONS OVERNIGHT AS S FLOW ALOFT
INCREASES AHEAD OF AN APPROACHING MID LEVEL SYSTEM.
TEMPERATURES...DEW POINTS...AND AERAS OF PRECIPITATION WERE
ADJUSTED PER THE LATEST MODEL DATA.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JAT




000
FXUS62 KGSP 241713
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1715 UTC UPDATE...SKY COVER WAS REDUCED AGAIN PER SATELLITE IMAGERY.
WINDS WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV...
PRESERVING GUSTS AT HIGHER ELEVATIONS OVERNIGHT AS S FLOW ALOFT
INCREASES AHEAD OF AN APPROACHING MID LEVEL SYSTEM.
TEMPERATURES...DEW POINTS...AND AERAS OF PRECIPITATION WERE
ADJUSTED PER THE LATEST MODEL DATA.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JAT





000
FXUS62 KGSP 241713
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1715 UTC UPDATE...SKY COVER WAS REDUCED AGAIN PER SATELLITE IMAGERY.
WINDS WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV...
PRESERVING GUSTS AT HIGHER ELEVATIONS OVERNIGHT AS S FLOW ALOFT
INCREASES AHEAD OF AN APPROACHING MID LEVEL SYSTEM.
TEMPERATURES...DEW POINTS...AND AERAS OF PRECIPITATION WERE
ADJUSTED PER THE LATEST MODEL DATA.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JAT




000
FXUS62 KGSP 241713
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 PM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE MOVES OUT OVER THE ATLANTIC
TONIGHT AS LOW PRESSURE MOVES EAST FROM THE CENTRAL PLAINS STATES. A
WARM FRONT WILL LINGER OVER OUR AREA FOR MUCH OF THE WEEKEND
PROVIDING A FOCUS OF SHOWERS AND A FEW STORMS. DRY HIGH PRESSURE
WILL MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM CROSSING THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1715 UTC UPDATE...SKY COVER WAS REDUCED AGAIN PER SATELLITE IMAGERY.
WINDS WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV...
PRESERVING GUSTS AT HIGHER ELEVATIONS OVERNIGHT AS S FLOW ALOFT
INCREASES AHEAD OF AN APPROACHING MID LEVEL SYSTEM.
TEMPERATURES...DEW POINTS...AND AERAS OF PRECIPITATION WERE
ADJUSTED PER THE LATEST MODEL DATA.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
AT KCLT...VFR. GUIDANCE BRINGS THE CIG DOWN TO LOW VFR OVERNIGHT AS
LOW LEVEL MOISTURE INCREASES OVER A WARM FRONT TO THE SOUTH. A
GUIDANCE BLEND DOES NOT SUPPORT A VSBY RESTRICTION OVERNIGHT...BUT
WITH RAIN CHANCES INCREASING...THE WIND EXPECTED TO BE RATHER
LIGHT...IT WOULD NOT BE SURPRISING TO SEE A VSBY RESTRICTION CREEP
INTO LATER FORECASTS. LIGHT WINDS WILL BACK FROM NW TO SW THIS
AFTERNOON...THEN TO S LATE TONIGHT.

ELSEWHERE...GUIDANCE LOWERS CIGS TO LOW VFR OVERNIGHT AS LOW LEVEL
MOISTURE SPREAD NORTH OVER A WARM FRONT TO THE S. SC SITES AND KAVL
ARE EXPECTED TO SEE MVFR CIGS BY DAWN....WHICH PERSIST THROUGH MIDDAY
SATURDAY. WITH RAINFALL EXPECTED TO SET UP TONIGHT...GUIDANCE
SUPPORTS MVFR VSBY AT KAVL BEFORE DAWN...AND THIS TREND MAY SPREAD TO
OTHER SITES IN LATER FORECASTS IF WINDS REMAIN LIGHT AS EXPECTED.
UNDER THE CURRENT SCENARIO...KAVL VSBY WOULD IMPROVE IN THE MORNING.
LIGHT WINDS NW WILL BACK TO SW THIS AFTERNOON...IF THEY HAVE NOT
ALREADY...AND TO S THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE MID ATLANTIC
STATES THIS WEEKEND...AND WIDESPREAD RAINFALL MAY SUPPORT
RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS THE REGION SUNDAY
NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH TUESDAY. ANOTHER LOW
PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     MED   70%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JAT





000
FXUS62 KGSP 241355
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
955 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1400 UTC UPDATE...SKY COVER WAS REDUCED PER SATELLITE IMAGERY. WINDS
WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY WAS RAISED SLIGHTLY PER DEW POINT TRENDS.
THROUGH NOT INCLUDED IN THE PLANNING FORECAST...OVERNIGHT TRANSPORT
WINDS WERE LOWERED PER THE LATEST NAM DATA. ALTHOUGH MIXING HEIGHTS
APPEAR ON TRACK...SMOKE MANAGEMENT PARAMETERS WERE ADJUSTED BASED ON
UPDATED WINDS...TRANSPORT WINDS...AND SKY COVER.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED
FIRE WEATHER...JAT




000
FXUS62 KGSP 241355
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
955 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1400 UTC UPDATE...SKY COVER WAS REDUCED PER SATELLITE IMAGERY. WINDS
WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY WAS RAISED SLIGHTLY PER DEW POINT TRENDS.
THROUGH NOT INCLUDED IN THE PLANNING FORECAST...OVERNIGHT TRANSPORT
WINDS WERE LOWERED PER THE LATEST NAM DATA. ALTHOUGH MIXING HEIGHTS
APPEAR ON TRACK...SMOKE MANAGEMENT PARAMETERS WERE ADJUSTED BASED ON
UPDATED WINDS...TRANSPORT WINDS...AND SKY COVER.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED
FIRE WEATHER...JAT





000
FXUS62 KGSP 241355
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
955 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1400 UTC UPDATE...SKY COVER WAS REDUCED PER SATELLITE IMAGERY. WINDS
WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY WAS RAISED SLIGHTLY PER DEW POINT TRENDS.
THROUGH NOT INCLUDED IN THE PLANNING FORECAST...OVERNIGHT TRANSPORT
WINDS WERE LOWERED PER THE LATEST NAM DATA. ALTHOUGH MIXING HEIGHTS
APPEAR ON TRACK...SMOKE MANAGEMENT PARAMETERS WERE ADJUSTED BASED ON
UPDATED WINDS...TRANSPORT WINDS...AND SKY COVER.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED
FIRE WEATHER...JAT





000
FXUS62 KGSP 241355
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
955 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
1400 UTC UPDATE...SKY COVER WAS REDUCED PER SATELLITE IMAGERY. WINDS
WERE UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV.

AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY WAS RAISED SLIGHTLY PER DEW POINT TRENDS.
THROUGH NOT INCLUDED IN THE PLANNING FORECAST...OVERNIGHT TRANSPORT
WINDS WERE LOWERED PER THE LATEST NAM DATA. ALTHOUGH MIXING HEIGHTS
APPEAR ON TRACK...SMOKE MANAGEMENT PARAMETERS WERE ADJUSTED BASED ON
UPDATED WINDS...TRANSPORT WINDS...AND SKY COVER.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...JAT/NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED
FIRE WEATHER...JAT




000
FXUS62 KGSP 241049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 241049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 241049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 241049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
649 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 640 AM...I WILL ISSUE A QUICK UPDATE TO ADJUST HOURLY
TEMPERATURES AND DEWPOINTS TO OBSERVATIONS. IN ADDITION...LATEST IR
SATELLITE IMAGES INDICATED A BAND OF HIGH CLOUDS LIFTING NORTH OF
THE FORECAST AREA...LEAVING SKY MOSTLY CLEAR. I WILL EDIT SKY GRIDS
TO LOWER SKY VALUES THROUGH MID MORNING.

AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD EAST OF THE MTNS. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION
DURING THE 12Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT
DEPRESSIONS...AND LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS
MORNING. LIGHT NORTH WINDS SHOULD PERSIST THROUGH THE MORNING
HOURS...THEN SOUTH-SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON.
HIGH CLOUDS SHOULD INCREASE TO BKN BY THIS EVENING. FORECAST
SOUNDINGS INDICATE THAT MOISTURE WILL INCREASE RAPIDLY FROM THE TOP-
DOWN LATE TONIGHT. MODELS INDICATE THAT JET DIVERGENCE AND LIFT
ASSOCIATED WITH AN APPROACHING WARM FRONT WILL INCREASE RAPIDLY
AFTER 6Z TONIGHT. I WILL INDICATE LIGHT RA WITH VFR CEILINGS
LATE...MVFR CEILING EXPECTED AT KAVL.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 240753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
353 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED





000
FXUS62 KGSP 240753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
353 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 240753
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
353 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION TODAY.  A
WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL AND A FEW
THUNDERSTORMS TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE WILL
MOVE IN AGAIN FOR THE START OF THE WORK WEEK...WITH ANOTHER LOW
PRESSURE SYSTEM PUSHING THROUGH THE SOUTHEAST BY MIDWEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 315 AM...GUSTY HIGH ELEVATION WINDS SHOULD STEADILY WEAKEN
EARLY THIS MORNING AS THE CENTER OF A LARGE AREA OF LOW PRESSURE
SLIDES OVER THE SOUTHERN APPALACHIANS. BY SUNRISE...TEMPERATURES IN
THE LOW 30S SHOULD BE COMMON ACROSS THE NC MTNS...NO CHANGES TO NPW.

HIGH CLOUDS SHOULD STREAK ACROSS THE REGION THROUGH THE
DAY...ESPECIALLY AS THE CORE OF A 140KT H3 JET PASSES OVER THE NC
ZONES THIS MORNING. OVERALL...CONDITIONS WILL FEATURE SCT TO BKN
HIGH CLOUDS...DRY AFTERNOON HUMIDITY...AND LIGHT WINDS. USING A
BLEND OF MOS...I WILL FORECAST HIGH TEMPERATURES TO RANGE FROM THE
MID 60S WITHIN THE MTN VALLEYS TO NEAR 70 EAST.

TONIGHT...DEEP LOW PRESSURE WILL TRACK FROM THE CENTRAL PLAINS TO
THE CENTRAL CONUS DURING THE NIGHT. AN ASSOCIATED WARM FRONT WILL
LIFT NORTHWARD...BUT SHOULD REMAIN WELL SOUTH OF THE FORECAST AREA
BY 12Z SAT. HOWEVER...A WIDE SWATH OF H3 JET DIVERGENCE WILL DEVELOP
OVER THE REGION LATE TONIGHT. IN ADDITION...MOISTURE AND LIFT
ASSOCIATED WITH THE WARM FRONT WILL LIKELY INCREASE ACROSS THE NC
MTNS AFTER 6Z SATURDAY. I WILL INDICATE A RAPID INCREASE IN POPS
FROM 6Z-12Z SAT. BY SUNRISE SAT...MOST OF THE CWA SHOULD SEE RAIN
DEVELOP. I WILL FORECAST AFTERNOON POPS TO RANGE FROM 80-90 PERCENT
ACROSS THE MTNS TO CHC POPS EAST OF I-77. LOW TEMPERATURES ARE
FORECAST TO RANGE FROM THE MID 50S WITHIN THE SAVANNAH RIVER VALLEY
TO THE U40S NORTH OF I-40..

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 AM FRIDAY...WE HAVE SOME SIGNIFICANT WEATHER POSSIBLE
THROUGH THE SHORT TERM. WE BEGIN AT 12Z SATURDAY WITH INSITU DAMMING
DEVELOPING ACROSS THE PIEDMONT AS A MIDLEVEL LOW TRAVERSES THE UPPER
MIDWEST....DRAGGING A SURFACE LOW AND ATTENDANT FRONT WITH IT. WEAK
MIDLEVEL RIDGING DOMINATES THE SYNOPTIC FIELDS EARLY SATURDAY BUT
WITH WIDESPREAD ISENTROPIC UPGLIDE OVER THE COLD DOME. SHORT-TERM
GUIDANCE IN PRETTY GOOD AGREEMENT WITH THE SURFACE LOW WORKING ITS
WAY ACROSS THE OHIO VALLEY AND EAST SOUTHEAST INTO THE SOUTHERN
APPALACHIANS BY SUNDAY MORNING. THE TRACK OF THE SURFACE LOW
INCREASES THE PRESSURE GRADIENT...ESPECIALLY WITH THE EROSION OF THE
DAMMING...QUITE A BIT. ADD TO THIS THE MEAN UPPER TROUGH PLUS THE
SHORTWAVE WITH A SPLIT FLOW PATTERN ALOFT AND WE HAVE ALL SORTS OF
INGREDIENTS THAT ARE COMING TOGETHER. IN A NUTSHELL...EXPECT SHOWERS
TO DEVELOP AND SPREAD NORTHEAST ACROSS THE AREA SATURDAY
MORNING...WITH HIGHEST POPS AROUND MIDDAY. VERY STABLE LOW LEVEL
AIRMASS IN THE COLD DOME WILL KEEP INSTABILITY DOWN AND TEMPERATURES
BELOW NORMAL...BUT OBVIOUSLY THIS WILL NOT BE THE CASE SOUTH OF THE
WEDGE FRONT. OF COURSE...THIS DOES NOT EVEN BEGIN TO TELL THE WHOLE
STORY FOR THE SHORT TERM. LET US START WITH THE RAIN/QPF SITUATION.

AS THE MOISTURE OVERSPREADS THE AREA FRIDAY NIGHT INTO SATURDAY
MORNING...PRECIPITABLE WATER VALUES INCREASE SIGNIFICANTLY...WELL
ABOVE THE 90TH PERCENTILE FOR CLIMATOLOGY FOR THE AREA AND THIS TIME
OF THE YEAR. NAM IS A LITTLE MORE ROBUST WITH MOISTURE FLUX AND
MOISTURE TRANSPORT VECTORS MAKING IT A LITTLE FARTHER INTO THE NORTH
CAROLINA PIEDMONT...BUT GFS KEEPS BEST MOISTURE FLUX JUST A HAIR
SOUTH OF OUR AREA INTO CENTRAL SOUTH CAROLINA WHERE THE BEST UPPER
DIFFLUENCE REMAINS FROM THE JET STREAK PUSHING ACROSS ALOFT. ONCE
THE CONVECTIVE ELEMENT IS ADDED TO QPF ESPECIALLY SOUTH OF THE WEDGE
FRONT...ABSOLUTELY SEE WHY WPC HAS INCLUDED THE UPSTATE IN A SLIGHT
RISK OF EXCESSIVE RAINFALL FOR DAY2. STORM TOTAL QPF VALUES FOR NOW
RANGE BETWEEN 1-1.5 INCHES BUT WITH THE GROUND FAIRLY MOIST FROM
SUCCESSIVE RAINFALL EVENTS THE PAST WEEK OR SO...COULD BE ENOUGH TO
CAUSE SOME PROBLEMS. AT ANY RATE...WILL INTRODUCE THE POTENTIAL FOR
HEAVY RAIN IN THE HWO.

OTHER SIGNIFICANT ITEM OF NOTE IS POTENTIAL FOR SEVERE CONVECTION
ALONG/SOUTH/WEST OF THE WEDGE FRONT THAT SETS UP. PINPOINTING THE
LOCATION OF THE WEDGE FRONT AT THIS POINT IN THE FORECAST IS
DIFFICULT AT BEST BUT WE CAN AT LEAST GET AN OVERALL IDEA OF THE
EVOLUTION OF CONVECTION DURING THE DAY. SBCAPE VALUES DO NOT START
CREEPING UP INTO THE FORECAST AREA UNTIL SATURDAY AFTERNOON AS THE
APPROACH OF THE SURFACE LOW STARTS PUSHING THE WEDGE FRONT A LITTLE
FARTHER NORTH AND EAST...BUT EVEN THEN THE DIABATIC COOLING
COMPONENT OF THE RAIN FALLING INTO THE SURFACE DRY LAYER SHOULD KEEP
THE WEDGE PRETTY STRONG. GFS IS QUITE A BIT STRONGER WITH THE
DAMMING THAN THE NAM AND HOLDS OFF UNTIL AFTER 18Z SATURDAY TO BRING
ANY SBCAPE IN TO THE REGION...BUT THE MORE BULLISH /AS USUAL/ NAM
BRINGS IN SBCAPE VALUES UPWARDS OF 2000 J/KG INTO EXTREME WESTERN
ZONES BY 00Z SUNDAY. THIS DOES DIMINISH WITH A DIURNAL TREND AS THE
WEDGE TRIES TO REINFORCE ITSELF...DEFLECTING THE HIGHER CAPE VALUES
INTO THE UPSTATE BUT STILL ENOUGH TO BE OF CONCERN. NOT ONLY THE
INSTABILITY HOWEVER BUT THE SHEAR IS QUITE IMPRESSIVE. GFS AND NAM
IN REMARKABLE AGREEMENT BRINGING 70-80KT DEEP LAYER SHEAR ACROSS THE
SOUTHERN APPALACHIANS SATURDAY AFTERNOON AND EVENING...ONLY
WEAKENING VALUES SOMEWHAT OVERNIGHT BUT STILL WIDESPREAD 50-60KT BY
SUNDAY MORNING. LOW LEVEL HELICITY...ENHANCED BY THE AGEOSTROPHIC
ADJUSTMENT OF THE DAMMING...ALSO GETS PRETTY DARN HIGH. PERFECT
PROGGING THE NAM...TAKE SOUTHERN ANDERSON COUNTY 00Z SUNDAY FOR
EXAMPLE...WITH AROUND 800 J/KG SBCAPE...75KT 0-6KM SHEAR...AND OVER
500 M2/S2 0-3KM HELICITY. THIS MIGHT BE AN EXTREME EXAMPLE BUT IT
DOES AT LEAST GIVE SOME IDEA OF WHAT WE ARE LOOKING AT. AS SUCH...
THE DAY2 OUTLOOK FROM SPC TRIES TO DEPICT AN APPROXIMATE LOCATION OF
THE WEDGE FRONT...WITH A GOOD PORTION OF THE FORECAST AREA IN A
SLIGHT RISK AND EVEN EXTREME WESTERN PORTIONS IN ENHANCED. THIS IS
DEFINITELY SOMETHING WE WILL NEED TO NARROW DOWN OVER THE NEXT
COUPLE OF FORECASTS.

DEEP UPPER TROUGH DOMINATES THE EASTERN SEABOARD IN THE WAKE OF THE
SURFACE LOW THAT PUSHES OFF THE CAROLINA COAST ON SUNDAY. DEEP LAYER
CAA CONTINUES THROUGH THE END OF THE SHORT TERM KEEPING TEMPERATURES
BELOW-NORMAL DESPITE THE EROSION OF THE DAMMING. SURFACE GRADIENT
REMAINS STRONG AND WINDS WILL LIKELY PICK UP ON SUNDAY ESPECIALLY IN
THE MOUNTAINS. OF COURSE...WITH THE LOW LEVEL JET AND STRONG
GRADIENT THROUGH THE ENTIRE WEEKEND...ONLY THE STRONG LOW-LEVEL
INVERSION ASSOCIATED WITH THE DAMMING WILL KEEP THAT MOMENTUM FROM
TRANSFERRING TO THE SURFACE ON SATURDAY AND SATURDAY NIGHT. HIGHLY
BUSTABLE TEMPERATURE FORECASTS THROUGH THE WEEKEND AND AS TYPICAL
WILL ENTIRELY DEPEND ON THE LOCATION OF THE WEDGE FRONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 345 AM FRIDAY...LUCKILY THE EXTENDED BEGINS FAIRLY QUIET IN
THE WAKE OF THE MESS OVER THE WEEKEND. SURFACE HIGH PRESSURE
CENTERED ACROSS THE UPPER MIDWEST RIDGES INTO THE SOUTHEAST BY
MONDAY MORNING WITH STRONG NORTHWEST FLOW ALOFT CONTINUING THE CAA
PATTERN. THE NEXT SYSTEM...IN THE FORM OF A CLOSED MIDLEVEL LOW
TRAVERSING THE SOUTHERN PLAINS...IN PHASE WITH BUT NOT ABSORBED BY A
TROUGH DIGGING OUT OF CANADA...BEGINS TO IMPACT OUR AREA BY MIDWEEK.
SURFACE LOW DEVELOPS ACROSS THE NORTHERN GULF AND MOVES INTO THE
DEEP SOUTH LATE TUESDAY AND EARLY WEDNESDAY...AGAIN SPREADING
PRECIPITATION ACROSS THE SOUTHEAST AHEAD OF IT. GFS AND ECMWF IN
FAIRLY DECENT AGREEMENT ON OVERALL MASS FIELDS AT LEAST THROUGH
WEDNESDAY...BUT DIVERGE BY THE END OF THE PERIOD WITH THE GFS
PUSHING THE SURFACE LOW ON OUT INTO THE ATLANTIC WITH THE MIDLEVEL
CLOSED LOW BEING ABSORBED BY THE LONGWAVE TROUGH PUSHING THROUGH THE
EASTERN PART OF THE COUNTRY...PUSHING ALL PRECIP OUT OF THE FORECAST
AREA WEDNESDAY NIGHT. MEANWHILE THE ECMWF KEEPS THE MIDLEVEL LOW AN
ENTITY UNTO ITSELF WHILE DEEPENING THE SURFACE LOW ACROSS THE
COASTAL CAROLINAS. DEFORMATION ZONE SETS UP ACROSS THE SOUTHERN
APPALACHIANS KEEPING PRECIPITATION ACROSS THE AREA INTO LATE
THURSDAY. TRIED TO TAKE A COMPROMISE ESPECIALLY WITH WPC SUGGESTION
OF LEANING TOWARD ENSEMBLES. TEMPERATURES REMAIN BELOW-AVERAGE FOR
THIS TIME OF YEAR ESPECIALLY ON WEDNESDAY WITH HIGHS A GOOD 10
DEGREES OR SO BELOW SEASONAL NORMALS.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...TDP
NEAR TERM...NED
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...NED




000
FXUS62 KGSP 240553
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 150 AM...STRONG WIND GUSTS HAVE BEEN OBSERVED ACROSS THE
HIGHER ELEVATIONS EARLY THIS MORNING. MODELS INDICATE THAT H85 WINDS
WILL WEAKEN THROUGH THE MORNING...I WILL ADJUST TRENDS.
OTHERWISE...I WILL TWEAK HOURLY TEMPERATURE AND DEWPOINT THROUGH
TONIGHT. SKY GRIDS WILL MATCH RECENT SATELLITE IMAGES...THEN BLENDED
SEVERAL HOURS INTO EARLY THIS MORNING.

AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED





000
FXUS62 KGSP 240553
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 150 AM...STRONG WIND GUSTS HAVE BEEN OBSERVED ACROSS THE
HIGHER ELEVATIONS EARLY THIS MORNING. MODELS INDICATE THAT H85 WINDS
WILL WEAKEN THROUGH THE MORNING...I WILL ADJUST TRENDS.
OTHERWISE...I WILL TWEAK HOURLY TEMPERATURE AND DEWPOINT THROUGH
TONIGHT. SKY GRIDS WILL MATCH RECENT SATELLITE IMAGES...THEN BLENDED
SEVERAL HOURS INTO EARLY THIS MORNING.

AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED




000
FXUS62 KGSP 240553
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 150 AM...STRONG WIND GUSTS HAVE BEEN OBSERVED ACROSS THE
HIGHER ELEVATIONS EARLY THIS MORNING. MODELS INDICATE THAT H85 WINDS
WILL WEAKEN THROUGH THE MORNING...I WILL ADJUST TRENDS.
OTHERWISE...I WILL TWEAK HOURLY TEMPERATURE AND DEWPOINT THROUGH
TONIGHT. SKY GRIDS WILL MATCH RECENT SATELLITE IMAGES...THEN BLENDED
SEVERAL HOURS INTO EARLY THIS MORNING.

AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED




000
FXUS62 KGSP 240553
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 AM EDT FRI APR 24 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 150 AM...STRONG WIND GUSTS HAVE BEEN OBSERVED ACROSS THE
HIGHER ELEVATIONS EARLY THIS MORNING. MODELS INDICATE THAT H85 WINDS
WILL WEAKEN THROUGH THE MORNING...I WILL ADJUST TRENDS.
OTHERWISE...I WILL TWEAK HOURLY TEMPERATURE AND DEWPOINT THROUGH
TONIGHT. SKY GRIDS WILL MATCH RECENT SATELLITE IMAGES...THEN BLENDED
SEVERAL HOURS INTO EARLY THIS MORNING.

AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR THROUGH THE PERIOD. THE CENTER OF A
LARGE AREA OF HIGH PRESSURE WILL SLIDE ACROSS THE REGION DURING THE
6Z TAF PERIOD. THIN SKY COVER...WIDE DEWPOINT DEPRESSIONS...AND
LIGHT WINDS WILL RESULT IN COOL TEMPERATURES THIS MORNING. LIGHT
NORTH WINDS SHOULD PERSIST THROUGH THE MORNING HOURS...THEN SOUTH-
SOUTHWEST WINDS EXPECTED DURING THE AFTERNOON. HIGH CLOUDS SHOULD
INCREASE TO BKN BY THIS EVENING.

OUTLOOK...A LOW PRESSURE SYSTEM WILL CROSS THE MIDDLE CONUS EAST
ACROSS THE MID ATLANTIC STATES THIS WEEKEND. WIDESPREAD RAINFALL
WILL LIKELY BECOME MODERATE ACROSS THE REGION ON
SATURDAY...RESULTING IN RESTRICTIONS. A COLD FRONT WILL SWEEP ACROSS
THE REGION SUNDAY NIGHT...FOLLOWED BY DRY HIGH PRESSURE THROUGH
TUESDAY. ANOTHER LOW PRESSURE SYSTEM MAY TRACK ACROSS THE DEEP SOUTH
WEDNESDAY AND THURSDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ033-048>053-
     058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...PM
AVIATION...NED





000
FXUS62 KGSP 240238
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1038 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD AS HIGH PRESSURE PREVAILS.  WINDS THROUGH THE OVERNIGHT WILL
REMAIN LIGHT AND NORTHWESTERLY/NORTHERLY AT ALL SITES AS SFC RIDGE
APPROACHES FROM THE WEST.  UPPER LEVEL JET MAX WILL SLIDE OVERHEAD
WITH FEW/SCT HIGH LEVEL CIRRUS EXPECTED TO INCREASE FROM THE
SOUTH.  WINDS WILL BECOME CALM OR LIGHT/VRB AS THE SFC RIDGE CENTER
MIGRATES TO THE SE EARLY ON FRIDAY WITH WINDS INCREASING/VEERING
SOUTHERLY NEAR PERIODS END AMIDST INCREASING SCT/BKN HIGH CIRRUS.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT FRIDAY FOR NCZ033-048>053-058-
     059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG




000
FXUS62 KGSP 240238
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1038 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 1035 PM EDT THURSDAY...CONSIDERATION HAS BEEN GIVEN ALL NIGHT
TO POSSIBLE FROST ADVISORY ISSUANCE ACROSS THE I40 CORRIDOR OF THE
NC PIEDMONT.  HOWEVER...LATEST GUIDANCE INDICATES THE AIRMASS WILL
BE TOO DRY.  MOSTLY LIKELY BECAUSE IT WILL REMAIN AT LEAST SOMEWHAT
MIXED AS LLV COLD ADVECTIVE FLOW INCREASES PER NAM H85 WINDS.
TEMPERATURES WILL FALL SOMEWHAT OVER THESE REGIONS AS HIGH LEVEL
CIRRUS REMAINS JUST TO THE SOUTH...HOWEVER NAM GUID STILL FAVORS A
NORTHEASTERN MIGRATION OF THE UPPER JET MAX WHICH WOULD SPREAD SAID
CIRRUS INTO THE REGION BY SUNRISE.  THUS...WILL CONTINUE WITH CURRENT
FREEZE WARNING FOR THE MTNS...WITH NO FROST ADVISORY PLANNED.
OTHERWISE...FCST LOOKS GOOD WITH ONLY SLIGHT TWEAKS TO
TEMPS/DEWS/SKY MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD AS HIGH PRESSURE PREVAILS.  WINDS THROUGH THE OVERNIGHT WILL
REMAIN LIGHT AND NORTHWESTERLY/NORTHERLY AT ALL SITES AS SFC RIDGE
APPROACHES FROM THE WEST.  UPPER LEVEL JET MAX WILL SLIDE OVERHEAD
WITH FEW/SCT HIGH LEVEL CIRRUS EXPECTED TO INCREASE FROM THE
SOUTH.  WINDS WILL BECOME CALM OR LIGHT/VRB AS THE SFC RIDGE CENTER
MIGRATES TO THE SE EARLY ON FRIDAY WITH WINDS INCREASING/VEERING
SOUTHERLY NEAR PERIODS END AMIDST INCREASING SCT/BKN HIGH CIRRUS.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING UNTIL 9 AM EDT FRIDAY FOR NCZ033-048>053-058-
     059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG





000
FXUS62 KGSP 232310
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
710 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 710 PM EDT THURSDAY...CURRENT FCST REMAINS ON TRACK THEREFORE
ASIDE FOR MINOR TWEAKS TO TEMPS/DEWS/SKY TO ACCOUNT FOR MOST RECENT
OB TRENDS...NO CHANGES MADE/NEEDED WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD AS HIGH PRESSURE PREVAILS.  WINDS THROUGH THE OVERNIGHT WILL
REMAIN LIGHT AND NORTHWESTERLY/NORTHERLY AT ALL SITES AS SFC RIDGE
APPROACHES FROM THE WEST.  UPPER LEVEL JET MAX WILL SLIDE OVERHEAD
WITH FEW/SCT HIGH LEVEL CIRRUS EXPECTED TO INCREASE FROM THE
SOUTH.  WINDS WILL BECOME CALM OR LIGHT/VRB AS THE SFC RIDGE CENTER
MIGRATES TO THE SE EARLY ON FRIDAY WITH WINDS INCREASING/VEERING
SOUTHERLY NEAR PERIODS END AMIDST INCREASING SCT/BKN HIGH CIRRUS.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG
FIRE WEATHER...JDL




000
FXUS62 KGSP 232310
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
710 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 710 PM EDT THURSDAY...CURRENT FCST REMAINS ON TRACK THEREFORE
ASIDE FOR MINOR TWEAKS TO TEMPS/DEWS/SKY TO ACCOUNT FOR MOST RECENT
OB TRENDS...NO CHANGES MADE/NEEDED WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD AS HIGH PRESSURE PREVAILS.  WINDS THROUGH THE OVERNIGHT WILL
REMAIN LIGHT AND NORTHWESTERLY/NORTHERLY AT ALL SITES AS SFC RIDGE
APPROACHES FROM THE WEST.  UPPER LEVEL JET MAX WILL SLIDE OVERHEAD
WITH FEW/SCT HIGH LEVEL CIRRUS EXPECTED TO INCREASE FROM THE
SOUTH.  WINDS WILL BECOME CALM OR LIGHT/VRB AS THE SFC RIDGE CENTER
MIGRATES TO THE SE EARLY ON FRIDAY WITH WINDS INCREASING/VEERING
SOUTHERLY NEAR PERIODS END AMIDST INCREASING SCT/BKN HIGH CIRRUS.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...CDG
FIRE WEATHER...JDL





000
FXUS62 KGSP 232043
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
443 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 440 PM EDT THURSDAY...RH LEVEL ACROSS THE REGION CONTINUE TO
FALL TOWARDS CRITICAL LEVELS AS MIXING PREVAILS.  MOST SITES REMAIN
IN THE LOWER/MID 20S WHILE A FEW SPORADIC LOCATIONS ARE REPORTING RH
LEVELS IN THE TEENS.  WINDS REMAIN ELEVATED WITH GUSTS IN THE
15-20KTS RANGE FOR THE MOST PART.  HIGH LEVEL CIRRUS CONTINUES TO
PREVAIL ACROSS THE SOUTHERN TIER OF THE FCST AREA AS AFORE MENTIONED
UPPER JET AXIS REMAINS NEARLY STATIONARY...AHEAD OF ITS EVENTUAL
NORTHEAST MIGRATION.  TEMPERATURES REMAIN AT OR JUST BELOW NORMAL
LEVELS REGIONWIDE.  TWEAKED TEMPERATURE/DEWPOINT/RH TRENDS OVER THE
NEXT FEW HOURS TO ACCOUNT FOR MOST RECENT OB TRENDS...AND LEFT THE
REMAINDER OF THE FCST AS IS FOR THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES THIS AFTN...BUT ALL SITES SHOULD TOGGLE BACK TO
NW THEN NRLY THIS EVENING. LOW END LATE AFTN GUSTS WILL
CONTINUE...ESPECIALLY IN WRN NC. THIN CIRRUS WILL RIDE NWD ACROSS
THE TERMINAL FORECAST AREA THROUGH THE PERIOD UNDER A 250 MB JETLET.
WINDS WILL BECOME LIGHTER AND MORE VARIABLE FROM MID MORNING FRIDAY
ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...HG
FIRE WEATHER...JDL





000
FXUS62 KGSP 232043
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
443 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 440 PM EDT THURSDAY...RH LEVEL ACROSS THE REGION CONTINUE TO
FALL TOWARDS CRITICAL LEVELS AS MIXING PREVAILS.  MOST SITES REMAIN
IN THE LOWER/MID 20S WHILE A FEW SPORADIC LOCATIONS ARE REPORTING RH
LEVELS IN THE TEENS.  WINDS REMAIN ELEVATED WITH GUSTS IN THE
15-20KTS RANGE FOR THE MOST PART.  HIGH LEVEL CIRRUS CONTINUES TO
PREVAIL ACROSS THE SOUTHERN TIER OF THE FCST AREA AS AFORE MENTIONED
UPPER JET AXIS REMAINS NEARLY STATIONARY...AHEAD OF ITS EVENTUAL
NORTHEAST MIGRATION.  TEMPERATURES REMAIN AT OR JUST BELOW NORMAL
LEVELS REGIONWIDE.  TWEAKED TEMPERATURE/DEWPOINT/RH TRENDS OVER THE
NEXT FEW HOURS TO ACCOUNT FOR MOST RECENT OB TRENDS...AND LEFT THE
REMAINDER OF THE FCST AS IS FOR THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES THIS AFTN...BUT ALL SITES SHOULD TOGGLE BACK TO
NW THEN NRLY THIS EVENING. LOW END LATE AFTN GUSTS WILL
CONTINUE...ESPECIALLY IN WRN NC. THIN CIRRUS WILL RIDE NWD ACROSS
THE TERMINAL FORECAST AREA THROUGH THE PERIOD UNDER A 250 MB JETLET.
WINDS WILL BECOME LIGHTER AND MORE VARIABLE FROM MID MORNING FRIDAY
ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...HG
FIRE WEATHER...JDL




000
FXUS62 KGSP 231848
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
248 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES THIS AFTN...BUT ALL SITES SHOULD TOGGLE BACK TO
NW THEN NRLY THIS EVENING. LOW END LATE AFTN GUSTS WILL
CONTINUE...ESPECIALLY IN WRN NC. THIN CIRRUS WILL RIDE NWD ACROSS
THE TERMINAL FORECAST AREA THROUGH THE PERIOD UNDER A 250 MB JETLET.
WINDS WILL BECOME LIGHTER AND MORE VARIABLE FROM MID MORNING FRIDAY
ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...HG
FIRE WEATHER...HG




000
FXUS62 KGSP 231848
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
248 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES THIS AFTN...BUT ALL SITES SHOULD TOGGLE BACK TO
NW THEN NRLY THIS EVENING. LOW END LATE AFTN GUSTS WILL
CONTINUE...ESPECIALLY IN WRN NC. THIN CIRRUS WILL RIDE NWD ACROSS
THE TERMINAL FORECAST AREA THROUGH THE PERIOD UNDER A 250 MB JETLET.
WINDS WILL BECOME LIGHTER AND MORE VARIABLE FROM MID MORNING FRIDAY
ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...HG
FIRE WEATHER...HG





000
FXUS62 KGSP 231848
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
248 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 225 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA TONIGHT...WITH ACCOMPANYING THIN CIRRUS THROUGHOUT. AN
UPPER LEVEL RIDGE WILL ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS
LOW PRESSURE COVERS THE PLAINS AND NEW ENGLAND. UNDER THE
RIDGE...THE SFC HIGH CENTER WILL APPROACH THE SRN/CENTRAL
APPALACHIANS OVERNIGHT. THIS SETUP WILL MAKE FOR A VERY CHALLENGING
FROST/FREEZE FORECAST. COOP MOS AND THE LATEST GUIDANCE SOURCES ARE
A TOUCH COLDER THAN PREVIOUSLY FOR THE MTNS...SO THE CURRENT FREEZE
WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE INTERSTATE
40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY COLDER...BUT THE
DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL MAKE FROST
FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE LOW LEVEL
COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE MODEST TO
MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST AREAS. PATCHY
FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT SECTIONS
OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 220 PM THURSDAY...WARM CONVEYOR BELT MOISTURE/FORCING IN
ADVANCE OF INTENSIFYING GREAT PLAINS CYCLONE WILL TRANSLATE ACROSS
THE AREA LATE SAT NIGHT INTO SUNDAY...WITH PRECIP LIKELY SPREADING
INTO THE WESTERN CWA WITHIN A COUPLE OF HOURS OF MIDNIGHT. POPS WILL
THEREFORE RAMP UP QUICKLY TO CATEGORICAL IN THOSE AREAS BY DAYBREAK
SUNDAY...OVERSPREADING THE REMAINDER OF THE FORECAST AREA THROUGHOUT
SUNDAY MORNING. WITH A LINGERING DRY AIR MASS IN PLACE IN ADVANCE OF
THE PRECIP SHIELD...AGEOSTROPHIC ADJUSTMENT/IN SITU COLD AIR DAMMING
WILL LIKELY OCCUR AS WET BULB EFFECTS RESULT IN ESTABLISHMENT OF
SHALLOW COLD POOL IN RESPONSE TO FALLING PRECIP.

WESTERLY FLOW THROUGH A DEEP LAYER ABOVE THE SURFACE IS GENERALLY
NOT INDICATIVE OF STRONG LOW LEVEL FORCING/HEAVY RAIN THREAT...AND
FORECAST PWATS ARE ONLY 1-2 STANDARD DEVIATION ABOVE CLIMO.
INDEED...A CONSENSUS OF MODEL/ENSEMBLE GUIDANCE ALONG WITH WPC
FORECASTS INDICATES MAYBE UP TO 1.5 INCHES OF RAIN WILL FALL
THROUGHOUT THE EVENT...AND THIS SEEMS REASONABLE. HOWEVER...A
CONSENSUS OF SHORT TERM GUIDANCE INDICATES THAT THERE WILL BE
CONSIDERABLE DESTABILIZATION SATURDAY AFTERNOON IN THE WARM SECTOR
ACROSS THE TENN VALLEY/GEORGIA. WITH DEEP LAYER WESTERLY FLOW
ORIENTED MORE OR LESS PARALLEL TO CAD BOUNDARY/WARM FRONT...THE
POTENTIAL WILL EXIST FOR TRAINING CELLS AND POSSIBLY LOCALIZED FLASH
FLOODING ALONG THE FRONT...THE BIG QUESTION (AS USUAL) BEING EXACTLY
WHERE THAT BOUNDARY WILL SET UP. THERE WILL ALSO BE VERY ROBUST
SHEAR WITHIN THE WARM SECTOR...AS MUCH AS 70 KTS IN THE 0-6KM LAYER
ACROSS THE TENN VALLEY. THEREFORE...SEVERE CONVECTION APPEARS TO BE
A GOOD BET IN THE WARM SECTOR SAT AFTERNOON...WHICH COULD POSSIBLY
AFFECT OUR SOUTHERN PIEDMONT ZONES...DEPENDING UPON THE POSITION OF
THE CAD FRONT...BUT PERHAPS MORE LIKELY ACROSS THE WESTERN NC MTNS
WHICH SHOULD SEE WARM SECTOR AIR BY AT LEAST THE END OF THE DAY.

IN FACT...SOME OF THE SHORT TERM GUIDANCE IS SUGGESTING THAT
ORGANIZED CONVECTION WILL DEVELOP NEAR THE SURFACE LOW ACROSS THE
OHIO VALLEY DURING THE AFTERNOON...AND DROP SOUTHEAST ALONG THE WARM
FRONT INTO THE SOUTHERN APPALACHIANS DURING THE EVENING...WHICH
COULD POSE A MORE ORGANIZED RISK FOR SEVERE WEATHER. THEREFORE...
WHILE POPS WILL LOWER DURING SAT AFTERNOON AS THE WARM CONVEYOR BELT
ZONE SHIFTS EAST...POPS WILL RAMP UP AGAIN FROM THE WEST DURING THE
EVENING.

SURFACE LOW IS EXPECTED TO PASS OVER THE VIRGINIA/NC REGION SAT
NIGHT INTO SUNDAY...WITH ASSOCIATED COLD FRONT EXPECTED TO SWEEP
ACROSS THE AREA DURING THE AFTERNOON. SECONDARY SURFACE LOW
DEVELOPMENT IS ANTICIPATED OFF THE MID-ATLANTIC COAST DURING THIS
TIME...WHICH IS EXPECTED TO RESULT IN VEERING NW/DOWNSLOPE LOW LEVEL
FLOW. THERE IS ENOUGH INSTABILITY INDICATED IN ADVANCE OF THE COLD
FRONT TO SUPPORT LOW POPS THROUGH SUNDAY...BUT OVERALL COVERAGE OF
CONVECTION IS QUITE UNCERTAIN CONSIDERING THE DOWNSLOPE FLOW AND
OVERALL WEAKLY FORCED ENVIRONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS APPEARS TO HAVE A TREND TOWARD THE
00Z ECMWF WITH ITS SURFACE LOW MOVING ACROSS THE DEEP SOUTH DURING
THE MIDDLE OF THE WEEK. AT THE START OF THE PERIOD...SUNDAY NIGHT...
THINK THAT ANY LINGERING LIGHT PRECIP OVER THE NC MOUNTAINS WILL
QUICKLY DRY UP...SO THAT PERIOD WAS KEPT DRY. THE NEW GUIDANCE SHOWS
A SLOWLY PROGRESSIVE UPPER PATTERN FOR EARLY NEXT WEEK. AN UPPER
RIDGE IS EXPECTED TO BUILD IN FROM THE WEST ON MONDAY WITH THE RIDGE
AXIS REMAINING WEST OF THE FCST AREA THRU DAYBREAK ON TUESDAY. THAT
WILL SUPPORT DRY HIGH PRESSURE RIDGING DOWN AT THE SURFACE INTO
MONDAY NIGHT. WITH THIS PATTERN...IT SEEMS UNLIKELY THAT ANY
APPRECIABLE MOISTURE WILL CROSS OVER THE TOP OF THE RIDGE AND BRING
PRECIP INTO THE FCST AREA UNTIL SOMETIME PERHAPS AFTER SUNRISE ON
TUESDAY. WILL ELIMINATE THE LOW PRECIP CHANCE FOR MONDAY NIGHT AS A
RESULT. THE GFS SOLUTION IS SOMEWHAT SUSPECT FOR MONDAY NIGHT AND
TUESDAY AS IT BLOWS UP A LOW LEVEL PV ANOMALY WHICH KEEPS A
PERSISTENT MCS ALONG THE GULF COAST. ASSUMING THAT IS OVERDONE...
THEN PERHAPS AS THE UPPER RIDGE AXIS MOVES OVERHEAD ON TUESDAY...WE
WILL SEE THE ARRIVAL OF GULF MOISTURE IN THE AFTERNOON WHICH SHOULD
FUEL A CHANCE OF SHOWERS. SO...THE NEW FCST CATCHES UP TO THE OLD
FCST BY AFTERNOON WITH A CHANCE OF PRECIP ACROSS THE ENTIRE AREA BY
THE END OF THE DAY. FROM THAT POINT ONWARD...THE MEDIUM RANGE LOOKS
UNSETTLED AS AN UPPER LOW SLOWLY MOVES EAST ACROSS THE DEEP SOUTH.
THE SOUTHERLY TRACK OF THE SFC LOW SHOULD MAINTAIN A MOIST E/SE FLOW
THAT WILL ENHANCE PRECIP POTENTIAL OVER THE MTNS AND FOOTHILLS
WEDNESDAY AND THURSDAY AND KEEP TEMPS ON THE COOL SIDE OF NORMAL.
PRECIP PROBABILITY WAS LIMITED TO THE CHANCE RANGE FOR NOW BECAUSE
OF RUN-TO-RUN CONSISTENCY ISSUES WITH THE LOW TRACK IN THE GFS.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES THIS AFTN...BUT ALL SITES SHOULD TOGGLE BACK TO
NW THEN NRLY THIS EVENING. LOW END LATE AFTN GUSTS WILL
CONTINUE...ESPECIALLY IN WRN NC. THIN CIRRUS WILL RIDE NWD ACROSS
THE TERMINAL FORECAST AREA THROUGH THE PERIOD UNDER A 250 MB JETLET.
WINDS WILL BECOME LIGHTER AND MORE VARIABLE FROM MID MORNING FRIDAY
ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...PM
AVIATION...HG
FIRE WEATHER...HG




000
FXUS62 KGSP 231805
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 155 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA THROUGH TONIGHT. ATTENDANT CIRRUS SHOULD FOLLOW...BUT
WILL BE MAINLY THIN SKY COVER THROUGHOUT. AN UPPER LEVEL RIDGE WILL
ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS LOW PRESSURE COVERS
THE PLAINS AND NEW ENGLAND. UNDER THE RIDGE...THE SFC HIGH CENTER
WILL APPROACH THE SRN/CENTRAL APPALACHIANS OVERNIGHT. THIS SETUP
WILL MAKE FOR A VERY CHALLENGING FROST/FREEZE FORECAST. COOP MOS AND
THE LATEST GUIDANCE ARE A TOUCH COLDER FOR THE MTNS...SO THE CURRENT
FREEZE WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE
INTERSTATE 40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY
COLDER...BUT THE DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL
MAKE FROST FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE
LOW LEVEL COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE
MODEST TO MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST
AREAS. PATCHY FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT
SECTIONS OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES...BUT ALL SITES TOGGLE BACK TO NW THEN NRLY
THIS EVENING. LOW END LATE AFTN GUSTS WILL CONTINUE. THIN CIRRUS
WILL RIDE NWD ACROSS THE TERMINAL FORECAST AREA THROUGH THE PERIOD
UNDER A 250 MB JETLET. WINDS WILL BECOME LIGHTER AND MORE VARIABLE
FROM MID MORNING FRIDAY ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...MOISTURE...PRECIPTATION...AND RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...HG
FIRE WEATHER...HG




000
FXUS62 KGSP 231805
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 155 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA THROUGH TONIGHT. ATTENDANT CIRRUS SHOULD FOLLOW...BUT
WILL BE MAINLY THIN SKY COVER THROUGHOUT. AN UPPER LEVEL RIDGE WILL
ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS LOW PRESSURE COVERS
THE PLAINS AND NEW ENGLAND. UNDER THE RIDGE...THE SFC HIGH CENTER
WILL APPROACH THE SRN/CENTRAL APPALACHIANS OVERNIGHT. THIS SETUP
WILL MAKE FOR A VERY CHALLENGING FROST/FREEZE FORECAST. COOP MOS AND
THE LATEST GUIDANCE ARE A TOUCH COLDER FOR THE MTNS...SO THE CURRENT
FREEZE WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE
INTERSTATE 40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY
COLDER...BUT THE DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL
MAKE FROST FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE
LOW LEVEL COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE
MODEST TO MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST
AREAS. PATCHY FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT
SECTIONS OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES...BUT ALL SITES TOGGLE BACK TO NW THEN NRLY
THIS EVENING. LOW END LATE AFTN GUSTS WILL CONTINUE. THIN CIRRUS
WILL RIDE NWD ACROSS THE TERMINAL FORECAST AREA THROUGH THE PERIOD
UNDER A 250 MB JETLET. WINDS WILL BECOME LIGHTER AND MORE VARIABLE
FROM MID MORNING FRIDAY ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...MOISTURE...PRECIPTATION...AND RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...HG
FIRE WEATHER...HG





000
FXUS62 KGSP 231805
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 155 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA THROUGH TONIGHT. ATTENDANT CIRRUS SHOULD FOLLOW...BUT
WILL BE MAINLY THIN SKY COVER THROUGHOUT. AN UPPER LEVEL RIDGE WILL
ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS LOW PRESSURE COVERS
THE PLAINS AND NEW ENGLAND. UNDER THE RIDGE...THE SFC HIGH CENTER
WILL APPROACH THE SRN/CENTRAL APPALACHIANS OVERNIGHT. THIS SETUP
WILL MAKE FOR A VERY CHALLENGING FROST/FREEZE FORECAST. COOP MOS AND
THE LATEST GUIDANCE ARE A TOUCH COLDER FOR THE MTNS...SO THE CURRENT
FREEZE WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE
INTERSTATE 40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY
COLDER...BUT THE DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL
MAKE FROST FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE
LOW LEVEL COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE
MODEST TO MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST
AREAS. PATCHY FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT
SECTIONS OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES...BUT ALL SITES TOGGLE BACK TO NW THEN NRLY
THIS EVENING. LOW END LATE AFTN GUSTS WILL CONTINUE. THIN CIRRUS
WILL RIDE NWD ACROSS THE TERMINAL FORECAST AREA THROUGH THE PERIOD
UNDER A 250 MB JETLET. WINDS WILL BECOME LIGHTER AND MORE VARIABLE
FROM MID MORNING FRIDAY ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...MOISTURE...PRECIPTATION...AND RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...HG
FIRE WEATHER...HG





000
FXUS62 KGSP 231805
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 PM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE CONTINUES ACROSS OUR REGION THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR WIDESPREAD RAINFALL
TO OUR AREA OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT
THE START OF NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST
MIDWEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 155 PM EDT...AN UPPER LEVEL JET AXIS WILL LIFT NE ACROSS THE
FORECAST AREA THROUGH TONIGHT. ATTENDANT CIRRUS SHOULD FOLLOW...BUT
WILL BE MAINLY THIN SKY COVER THROUGHOUT. AN UPPER LEVEL RIDGE WILL
ALSO BUILD OVER THE SE TONIGHT THROUGH FRI AS LOW PRESSURE COVERS
THE PLAINS AND NEW ENGLAND. UNDER THE RIDGE...THE SFC HIGH CENTER
WILL APPROACH THE SRN/CENTRAL APPALACHIANS OVERNIGHT. THIS SETUP
WILL MAKE FOR A VERY CHALLENGING FROST/FREEZE FORECAST. COOP MOS AND
THE LATEST GUIDANCE ARE A TOUCH COLDER FOR THE MTNS...SO THE CURRENT
FREEZE WARNING SEEMS WELL PLACED THERE. FARTHER EAST...ALONG THE
INTERSTATE 40 CORRIDOR...OVERNIGHT MINS HAVE TRENDED SLIGHTLY
COLDER...BUT THE DRY SFC AIR AND LIGHT WINDS/MIXING OVERNIGHT WILL
MAKE FROST FORMATION PROBLEMATIC. ANTICIPATE SOME RESURGENCE IN THE
LOW LEVEL COLD ADVECTION OVERNIGHT...AND DEWPOINT RECOVERY WILL BE
MODEST TO MAINTAIN DEPRESSIONS OF ABOUT 4 OR 5 DEGREES IN MOST
AREAS. PATCHY FROST HAS BEEN ADDED ACROSS NC FOOTHILL AND PIEDMONT
SECTIONS OVERNIGHT...BUT NO FROST ADVISORY WILL BE ISSUED AT PRESENT.

THE SFC HIGH WILL MIGRATE EASTWARD ACROSS THE FORECAST AREA ON
FRIDAY. PROFILES WILL REMAIN GENERALLY DRY...BUT SOME DEGREE OF MID
LEVEL MOISTURE WILL START TO ARRIVE OVER THE RIDGE AXIS INTO THE SRN
APPALACHIANS LATE FRIDAY. TEMPERATURES SHOULD REMAIN 5 DEGREES OR
MORE BELOW CLIMO THROUGHOUT.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...NW FLOW WILL CONTINUE ACROSS THE REGION THIS
AFTERNOON THROUGH TONIGHT AS SFC HIGH PRESSURE SLOWLY BUILDS INTO
THE SRN APPALACHIANS FROM THE W. WRN UPSTATE TAF SITE WINDS WILL BE
BRIEFLY WSW AT TIMES...BUT ALL SITES TOGGLE BACK TO NW THEN NRLY
THIS EVENING. LOW END LATE AFTN GUSTS WILL CONTINUE. THIN CIRRUS
WILL RIDE NWD ACROSS THE TERMINAL FORECAST AREA THROUGH THE PERIOD
UNDER A 250 MB JETLET. WINDS WILL BECOME LIGHTER AND MORE VARIABLE
FROM MID MORNING FRIDAY ONWARD AS THE SFC HIGH BUILDS OVERHEAD.

OUTLOOK...MOISTURE...PRECIPTATION...AND RESTRICTIONS WILL RETURN FRI
NIGHT THROUGH SAT AS A LOW PRES SYSTEM MOVES EAST FROM THE PLAINS
STATES. A TRAILING COLD FRONT WILL CROSS THE REGION ON SUNDAY...WITH
BRIEF DRY HIGH PRESSURE RETURNING EARLY NEXT WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...HG
FIRE WEATHER...HG




000
FXUS62 KGSP 231456
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1056 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM EDT...A BIT MORE CLOUDINESS HAS BEEN ADDED TO THE
SOUTHERN TIER FOR THE AFTERNOON HOURS AS THE CIRRUS COULD BE A BIT
MORE OPAQUE FROM TIME TO TIME. THIS NECESSITATED A SLIGHT TRIM OF A
DEGREE OR SO TO MAX TEMPS...WITH WITH SLIGHT BOOST IN THE SUNNIER NW
PIEDMONT WHERE TEMP TRENDS ARE AT OR ABOVE FORECAST VALUES.

OTHERWISE...THE FORECAST REMAINS ON TRACK...WITH AN UPPER LOW
STARTING TO DRIFT EAST FROM THE GREAT LAKES...AND RISING HEIGHTS AND
SUBSIDENCE ATOP THE CWFA THIS AFTN THROUGH TONIGHT. AT THE SFC...DRY
HIGH PRES WILL CONTINUE TO NOSE SOUTH INTO THE AREA...WITH THE
CENTER OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. EXPECT
CONTINUED BREEZY CONDITIONS IN THE MTNS WITH HIGHS WILL IN THE 50S
TO LWR 60S IN THE MTNS... AND UPR 60S IN THE NW NC PIEDMONT TO 70 TO
75 ACROSS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO A FREEZE WARNING HAS
BEEN ISSUED FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS
AND NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY
FROST. HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING
TO LIMIT MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...MAINLY JUST A WIND FCST CONTINUES...WITH VFR
CONDITIONS EXPECTED THRU THE 12Z TAF PERIOD. JUST OCCASIONAL FEW-SCT
CIRRUS EXPECTED THRU THE PERIOD. WINDS WILL FAVOR A WEST-SOUTHWEST
TO WEST-NORTHWEST DIRECTION ACRS THE PIEDMONT. GUIDANCE HAS TRENDED
WEAKER WITH A LEE TROF...SO KCLT MAY STAY JUST NORTH OF DUE WEST
THIS AFTN. OCCASIONAL SHIFTS TO WEST-SOUTHWEST MAY OCCUR. A FEW
LOW-END GUSTS ARE POSSIBLE OUTSIDE THE MTNS OF 15-19 KTS. A NW WIND
WILL CONTINUE AT KAVL THRU THE PERIOD MAY SEE OCCASIONAL LOW-END
GUSTS IN THE 15-19 KT RANGE. AT KAVL...THE NW WIND WILL BE A LITTLE
STRONGER WITH GUSTS AROUND 20 TO 25 KTS. WINDS WILL SUBSIDE THIS
EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK/HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK/HG
FIRE WEATHER...HG





000
FXUS62 KGSP 231456
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1056 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM EDT...A BIT MORE CLOUDINESS HAS BEEN ADDED TO THE
SOUTHERN TIER FOR THE AFTERNOON HOURS AS THE CIRRUS COULD BE A BIT
MORE OPAQUE FROM TIME TO TIME. THIS NECESSITATED A SLIGHT TRIM OF A
DEGREE OR SO TO MAX TEMPS...WITH WITH SLIGHT BOOST IN THE SUNNIER NW
PIEDMONT WHERE TEMP TRENDS ARE AT OR ABOVE FORECAST VALUES.

OTHERWISE...THE FORECAST REMAINS ON TRACK...WITH AN UPPER LOW
STARTING TO DRIFT EAST FROM THE GREAT LAKES...AND RISING HEIGHTS AND
SUBSIDENCE ATOP THE CWFA THIS AFTN THROUGH TONIGHT. AT THE SFC...DRY
HIGH PRES WILL CONTINUE TO NOSE SOUTH INTO THE AREA...WITH THE
CENTER OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. EXPECT
CONTINUED BREEZY CONDITIONS IN THE MTNS WITH HIGHS WILL IN THE 50S
TO LWR 60S IN THE MTNS... AND UPR 60S IN THE NW NC PIEDMONT TO 70 TO
75 ACROSS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO A FREEZE WARNING HAS
BEEN ISSUED FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS
AND NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY
FROST. HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING
TO LIMIT MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...MAINLY JUST A WIND FCST CONTINUES...WITH VFR
CONDITIONS EXPECTED THRU THE 12Z TAF PERIOD. JUST OCCASIONAL FEW-SCT
CIRRUS EXPECTED THRU THE PERIOD. WINDS WILL FAVOR A WEST-SOUTHWEST
TO WEST-NORTHWEST DIRECTION ACRS THE PIEDMONT. GUIDANCE HAS TRENDED
WEAKER WITH A LEE TROF...SO KCLT MAY STAY JUST NORTH OF DUE WEST
THIS AFTN. OCCASIONAL SHIFTS TO WEST-SOUTHWEST MAY OCCUR. A FEW
LOW-END GUSTS ARE POSSIBLE OUTSIDE THE MTNS OF 15-19 KTS. A NW WIND
WILL CONTINUE AT KAVL THRU THE PERIOD MAY SEE OCCASIONAL LOW-END
GUSTS IN THE 15-19 KT RANGE. AT KAVL...THE NW WIND WILL BE A LITTLE
STRONGER WITH GUSTS AROUND 20 TO 25 KTS. WINDS WILL SUBSIDE THIS
EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
DRY HIGH PRES CONTINUES TO BUILD INTO THE REGION FROM THE NW. A
DECENT GRADIENT PERSISTS IN THE NW FLOW AND LOW END GUSTS OF 20 TO
25 KT IN THE MTNS AND UPPER TEENS ACROSS THE PIEDMONT WILL CONTINUE
WITH MIXING THIS AFTERNOON. IN ADDITION...DEW POINT MIXING WILL
PROVIDE RH VALUES IN THE LOWER TO MIDDLE 20S FOR A GOOD CHUNK OF THE
AREA. GIVEN THE LINGERING FUEL MOISTURE...WILL JUST HEADLINE DRY AND
BREEZY CONDITIONS IN THE FWF...BUT A FEW SPOTS COULD SEE HEIGHTENED
FIRE DANGER THIS AFTN.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK/HG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK/HG
FIRE WEATHER...HG




000
FXUS62 KGSP 231053
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
653 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...NO CHANGES NEEDED WITH THIS UPDATE AS FCST IS ON
TRACK.

AS OF 300 AM...THE UPPER LOW THAT HAS BEEN SPINNING OVER THE GREAT
LAKES THE LAST FEW DAYS WILL FINALLY START TO DRIFT EAST...WITH
RISING HEIGHTS AND SUBSIDENCE ATOP THE CWFA TODAY THRU TONIGHT. AT
THE SFC...DRY HIGH PRES NOSE SOUTH INTO THE AREA...WITH THE CENTER
OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. IT WILL BE A NICE
DAY...WITH BREEZY CONDITIONS IN THE MTNS. HIGHS WILL BE IN THE 50S
TO LWR 60S IN THE MTNS AND UPR 60S IN THE NW NC PIEDMONT TO MID 70S
ACRS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO WILL ISSUE A FREEZE
WARNING FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS AND
NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY FROST.
HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING TO LIMIT
MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...MAINLY JUST A WIND FCST...WITH VFR
CONDITIONS EXPECTED THRU THE 12Z TAF PERIOD. JUST OCCASIONAL FEW-SCT
CIRRUS EXPECTED THRU THE PERIOD. WINDS WILL FAVOR A WEST-SOUTHWEST
TO WEST-NORTHWEST DIRECTION ACRS THE PIEDMONT. GUIDANCE HAS TRENDED
WEAKER WITH A LEE TROF...SO KCLT MAY STAY JUST NORTH OF DUE WEST
THIS AFTN. OCCASIONAL SHIFT TO WEST-SOUTHWEST MAY OCCUR. A FEW LOW-
END GUSTS ARE POSSIBLE OUTSIDE THE MTNS OF 15-19 KTS. A NW WIND WILL
CONTINUE AT KAVL THRU THE PERIOD MAY SEE OCCASIONAL LOW-END GUSTS IN
THE 15-19 KT RANGE. AT KAVL...THE NW WIND WILL BE A LITTLE
STRONGER WITH GUSTS AROUND 20 KTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK




000
FXUS62 KGSP 231053
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
653 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...NO CHANGES NEEDED WITH THIS UPDATE AS FCST IS ON
TRACK.

AS OF 300 AM...THE UPPER LOW THAT HAS BEEN SPINNING OVER THE GREAT
LAKES THE LAST FEW DAYS WILL FINALLY START TO DRIFT EAST...WITH
RISING HEIGHTS AND SUBSIDENCE ATOP THE CWFA TODAY THRU TONIGHT. AT
THE SFC...DRY HIGH PRES NOSE SOUTH INTO THE AREA...WITH THE CENTER
OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. IT WILL BE A NICE
DAY...WITH BREEZY CONDITIONS IN THE MTNS. HIGHS WILL BE IN THE 50S
TO LWR 60S IN THE MTNS AND UPR 60S IN THE NW NC PIEDMONT TO MID 70S
ACRS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO WILL ISSUE A FREEZE
WARNING FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS AND
NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY FROST.
HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING TO LIMIT
MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...MAINLY JUST A WIND FCST...WITH VFR
CONDITIONS EXPECTED THRU THE 12Z TAF PERIOD. JUST OCCASIONAL FEW-SCT
CIRRUS EXPECTED THRU THE PERIOD. WINDS WILL FAVOR A WEST-SOUTHWEST
TO WEST-NORTHWEST DIRECTION ACRS THE PIEDMONT. GUIDANCE HAS TRENDED
WEAKER WITH A LEE TROF...SO KCLT MAY STAY JUST NORTH OF DUE WEST
THIS AFTN. OCCASIONAL SHIFT TO WEST-SOUTHWEST MAY OCCUR. A FEW LOW-
END GUSTS ARE POSSIBLE OUTSIDE THE MTNS OF 15-19 KTS. A NW WIND WILL
CONTINUE AT KAVL THRU THE PERIOD MAY SEE OCCASIONAL LOW-END GUSTS IN
THE 15-19 KT RANGE. AT KAVL...THE NW WIND WILL BE A LITTLE
STRONGER WITH GUSTS AROUND 20 KTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK





000
FXUS62 KGSP 231053
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
653 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...NO CHANGES NEEDED WITH THIS UPDATE AS FCST IS ON
TRACK.

AS OF 300 AM...THE UPPER LOW THAT HAS BEEN SPINNING OVER THE GREAT
LAKES THE LAST FEW DAYS WILL FINALLY START TO DRIFT EAST...WITH
RISING HEIGHTS AND SUBSIDENCE ATOP THE CWFA TODAY THRU TONIGHT. AT
THE SFC...DRY HIGH PRES NOSE SOUTH INTO THE AREA...WITH THE CENTER
OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. IT WILL BE A NICE
DAY...WITH BREEZY CONDITIONS IN THE MTNS. HIGHS WILL BE IN THE 50S
TO LWR 60S IN THE MTNS AND UPR 60S IN THE NW NC PIEDMONT TO MID 70S
ACRS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO WILL ISSUE A FREEZE
WARNING FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS AND
NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY FROST.
HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING TO LIMIT
MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...MAINLY JUST A WIND FCST...WITH VFR
CONDITIONS EXPECTED THRU THE 12Z TAF PERIOD. JUST OCCASIONAL FEW-SCT
CIRRUS EXPECTED THRU THE PERIOD. WINDS WILL FAVOR A WEST-SOUTHWEST
TO WEST-NORTHWEST DIRECTION ACRS THE PIEDMONT. GUIDANCE HAS TRENDED
WEAKER WITH A LEE TROF...SO KCLT MAY STAY JUST NORTH OF DUE WEST
THIS AFTN. OCCASIONAL SHIFT TO WEST-SOUTHWEST MAY OCCUR. A FEW LOW-
END GUSTS ARE POSSIBLE OUTSIDE THE MTNS OF 15-19 KTS. A NW WIND WILL
CONTINUE AT KAVL THRU THE PERIOD MAY SEE OCCASIONAL LOW-END GUSTS IN
THE 15-19 KT RANGE. AT KAVL...THE NW WIND WILL BE A LITTLE
STRONGER WITH GUSTS AROUND 20 KTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK




000
FXUS62 KGSP 230803
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
403 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM...THE UPPER LOW THAT HAS BEEN SPINNING OVER THE GREAT
LAKES THE LAST FEW DAYS WILL FINALLY START TO DRIFT EAST...WITH
RISING HEIGHTS AND SUBSIDENCE ATOP THE CWFA TODAY THRU TONIGHT. AT
THE SFC...DRY HIGH PRES NOSE SOUTH INTO THE AREA...WITH THE CENTER
OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. IT WILL BE A NICE
DAY...WITH BREEZY CONDITIONS IN THE MTNS. HIGHS WILL BE IN THE 50S
TO LWR 60S IN THE MTNS AND UPR 60S IN THE NW NC PIEDMONT TO MID 70S
ACRS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO WILL ISSUE A FREEZE
WARNING FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS AND
NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY FROST.
HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING TO LIMIT
MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK




000
FXUS62 KGSP 230803
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
403 AM EDT THU APR 23 2015

.SYNOPSIS...
COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE NORTH TODAY THROUGH
FRIDAY.  A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO OUR
REGION OVER THE WEEKEND. DRY HIGH PRESSURE PREVAILS AT THE START OF
NEXT WEEK...THEN A LOW WILL MOVE ALONG THE GULF COAST MIDWEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM...THE UPPER LOW THAT HAS BEEN SPINNING OVER THE GREAT
LAKES THE LAST FEW DAYS WILL FINALLY START TO DRIFT EAST...WITH
RISING HEIGHTS AND SUBSIDENCE ATOP THE CWFA TODAY THRU TONIGHT. AT
THE SFC...DRY HIGH PRES NOSE SOUTH INTO THE AREA...WITH THE CENTER
OF THE HIGH SETTLING INTO THE OHIO VALLEY TONIGHT. IT WILL BE A NICE
DAY...WITH BREEZY CONDITIONS IN THE MTNS. HIGHS WILL BE IN THE 50S
TO LWR 60S IN THE MTNS AND UPR 60S IN THE NW NC PIEDMONT TO MID 70S
ACRS THE UPPER SAVANNAH VALLEY.

TONIGHT...THE NAM AND GFS AGREE ON ANOTHER SURGE OF 850 MB CAA
WITHIN NWLY FLOW OF 20 TO 35 KTS. THE MOS BLEND HAS LOWS DIPPING
INTO THE UPR 20S TO MID 30S IN THE MTNS...AND MID 30S TO LWR 40S
ACRS THE PIEDMONT. THIS SEEMS REASONABLE...SO WILL ISSUE A FREEZE
WARNING FOR THE NC MTNS. THE I-40 CORRIDOR OF THE NC FOOTHILLS AND
NW PIEDMONT HAVE SOME MID 30S...WHICH MAY RESULT IN PATCHY FROST.
HOWEVER...GIVEN THE LLVL CAA OVERNIGHT...EXPECT ENUF MIXING TO LIMIT
MORE WIDESPREAD FROST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THU...AS AN UPPER RIDGE BUILDS INTO THE AREA FRI AND
FRI NITE...SHORT WAVES UNDERCUT THE RIDGE AND MOVE ACROSS THE AREA.
A DAMPENING UPPER LOW KNOCKS DOWN THE RIDGE AND BRINGS A TROF ACROSS
THE AREA SAT AND SAT NITE. AT THE SFC...HIGH PRESSURE OVER THE AREA
SLIDES EAST FRI NITE AS A WARM FRONT APPROACHES FROM THE WEST. THE
WARM FRONT MOVES INTO THE AREA FRI NITE AND ACROSS THE AREA SAT. A
WAVE OF LOW PRESSURE FORMS ALONG THE FRONT NEAR THE COAST SAT NITE
AND MOVES EAST PULLING A BOUNDARY ACROSS THE AREA ALONG WITH ANOTHER
WAVE FORMING ALONG THE FRONT. DEEP MOISTURE AND ISENTROPIC LIFT
DEVELOP AS THE FRONT MOVES THRU LEADING TO CAT POP FOR SAT. THE LIFT
WEAKENS SAT NITE...BUT MOISTURE REMAINS HIGH. THIS WILL COMBINE WITH
THE FORCING TO KEEP LIKELY POP ACROSS THE AREA. ALTHOUGH WIDESPREAD
PRECIP IS EXPECTED...QPF AMOUNTS REMAIN IN QUESTION. PW VALUES WILL
BE QUITE HIGH AND A GOOD LOW LEVEL JET DEVELOPS. HOWEVER...THE GFS
CONTINUES TO HINT THAT CONVECTION COULD DEVELOP SOUTH OF THE AREA
LIMITING NORTHWARD MOISTURE FLUX...AND RESULTANT QPF. WILL HAVE TO
KEEP AN EYE ON THIS SYSTEM AS SOME HEAVY RAIN IS POSSIBLE BUT
UNCERTAIN. IN ADDITION...INSTABILITY DOES INCREASE OVER THE WRN
PORTIONS OF THE CWFA WHERE SOME HEATING CAN DEVELOP. WIND SHEAR WILL
INCREASE WITH THE INCREASING LOW LEVEL JET AS WELL. WITH THE
POTENTIAL FOR A BOUNDARY SETTING UP IN THAT AREA...WILL HAVE TO KEEP
AN EYE OUT FOR SVR STORM POTENTIAL AS WELL. BELOW NORMAL HIGHS FRI
COOL MOST AREAS SAT WITH PRECIP MOVING IN...BUT REMAIN NEARLY STEADY
ACROSS THE MTNS AND WRN UPSTATE/NE GA. ABOVE NORMAL LOWS FRI NITE
RISE SEVERAL DEGREES SAT NITE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 400 AM THURSDAY...SCT SHRA WILL LINGER ACROSS THE AREA SUNDAY
AS THE BOUNDARY SLIDES ACROSS THE AREA AND A LOW PRESSURE WAVE MOVES
ALONG THE BOUNDARY. HIGHS WILL BE NEAR TO A LITTLE ABOVE NORMAL.

GUIDANCE IS NOW DRY FOR MONDAY AS WEAK SFC HIGH MOVES IN UNDER A
DEEP UPPER LOW SETTING UP OVER NEW ENGLAND. THE UPPER LOW WEAKENS
ALLOWING SYSTEMS TO THE WEST TO MOVE TOWARD THE AREA. THE ECMWF
RETAINS ITS FORECAST OF A SRN STREAM UPPER LOW MOVING TOWARD THE
AREA TUE AND ACROSS THE AREA WED. HOWEVER...IT NOW HAS ITS MILLER-A
LOW MUCH FARTHER SOUTH IN THE GULF KEEPING THE BULK OF THE
ASSOCIATED PRECIP SOUTH OF THE CWFA AS WELL. THE GFS STILL SHOWS
SEPARATE NRN AND SRN STREAM WAVES MOVING EAST AND MERGING OVER THE
MID MS VALLEY BEFORE MOVING INTO THE AREA LATE WED. THE SFC PATTERN
STARTS WITH WHAT LOOKS LIKE A MILLER-A THEN DEVELOPS INTO A HYBRID
MILLER-B WITH A LOW MOVING UP WEST OF THE APPALACHIANS AND ANOTHER
UP THE ATLANTIC COAST. THE GFS IS ALSO MUCH WETTER AND BRINGS THE
PRECIP IN SOONER. HAVE GONE WITH A MDL BLEND WHICH TONES DOWN THE
POP...KEEPING IT IN THE CHC RANGE...AND SLOWING THE ONSET. HIGHS
START OUT NEAR NORMAL MONDAY AND FALL AROUND 10 DEGREES BELOW NORMAL
BY WED. LOWS REMAIN NEARLY STEADY A LITTLE BELOW NORMAL. THE GFS
WOULD INDICATE THE POTENTIAL FOR HEAVY RAIN...BUT THIS IS HIGHLY
UNCERTAIN GIVEN THE GUIDANCE DIFFERENCES.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR
     NCZ033-048>053-058-059-062>065-501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...ARK
NEAR TERM...ARK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK





000
FXUS62 KGSP 230513
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 AM EDT THU APR 23 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM...UPDATED THE POPS TO MATCH UP WITH A WEAKENING CLUSTER
OF SHWRS AS IT CROSSES THE UPSTATE. THE PRECIP SHUD END OR EXIT TO
THE EAST WITHIN THE NEXT HOUR OR SO. ALSO UPDATED THE SKY AND WIND
GRIDS FOR THE 06Z TAFS.

AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...ARK/CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...ARK




000
FXUS62 KGSP 230513
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 AM EDT THU APR 23 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM...UPDATED THE POPS TO MATCH UP WITH A WEAKENING CLUSTER
OF SHWRS AS IT CROSSES THE UPSTATE. THE PRECIP SHUD END OR EXIT TO
THE EAST WITHIN THE NEXT HOUR OR SO. ALSO UPDATED THE SKY AND WIND
GRIDS FOR THE 06Z TAFS.

AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...ARK/CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...ARK





000
FXUS62 KGSP 230513
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 AM EDT THU APR 23 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM...UPDATED THE POPS TO MATCH UP WITH A WEAKENING CLUSTER
OF SHWRS AS IT CROSSES THE UPSTATE. THE PRECIP SHUD END OR EXIT TO
THE EAST WITHIN THE NEXT HOUR OR SO. ALSO UPDATED THE SKY AND WIND
GRIDS FOR THE 06Z TAFS.

AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...ARK/CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...ARK





000
FXUS62 KGSP 230513
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 AM EDT THU APR 23 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 100 AM...UPDATED THE POPS TO MATCH UP WITH A WEAKENING CLUSTER
OF SHWRS AS IT CROSSES THE UPSTATE. THE PRECIP SHUD END OR EXIT TO
THE EAST WITHIN THE NEXT HOUR OR SO. ALSO UPDATED THE SKY AND WIND
GRIDS FOR THE 06Z TAFS.

AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS EXPECTED THRU THE TAF 06Z
TAF PERIOD. A BATCH OF MID LVL CLOUDS WILL EXIT TO THE EAST DURING
THE OVERNIGHT HOURS...WITH JUST FEW-SCT CIRRUS EXPECTED FROM THEN
ON. WINDS WILL SHIFT FROM WEST-SOUTHWEST TO NORTHWEST OUTSIDE THE
MTNS...WHILE THE NW WIND WILL CONTINUE AT KAVL THRU THIS MORNING. A
LEE TROF WILL SET UP THIS AFTN...SHIFTING WINDS BACK TO SW ACRS THE
PIEDMONT SITES. MAY SEE OCCASIONAL LOW-END GUSTS IN THE 15-19 KT
RANGE. AT KAVL...THE NW WIND WILL PICK UP AND SHUD SEE LOW-END
GUSTS. WINDS WILL SUBSIDE THIS EVENING.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD IN ACRS THE REGION THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...ARK/CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...ARK




000
FXUS62 KGSP 230237
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1037 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
CYCLE.  WINDS ARE INITIALIZED AT...OR WILL VEER NORTH OF WEST AT ALL
SITES THROUGH THE EVENING AS A COLD FRONT SLIDES THROUGH THE
REGION.  KEPT ALL TAF SITES DRY WITH THE EXCEPTION OF BRIEF VCSH
MENTION AMONGST MID LEVEL VFR BKN CIGS.  WNW WINDS WILL SUBSIDE
OVERNIGHT AS THE PGF WEAKENS...WITH ALL SITES DUE NNW BY MORNING
UNDER FEW/SCT HIGH LEVEL CIRRUS.  LEE TROF WILL ALLOW FOR WINDS TO
BACK WESTERLY DURING THE LATE MORNING TO EARLY AFTERNOON ON THURSDAY
WITH SOME LIGHT GUSTING POSSIBLE AS THE MIXED LAYER DEEPENS...THUS
ALL SITES FEATURE SUCH IN THE TAF THROUGH PERIODS END.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD THROUGH FRIDAY...BEFORE
ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM THE WEST OVER THE
WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...CDG





000
FXUS62 KGSP 230237
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1037 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
CYCLE.  WINDS ARE INITIALIZED AT...OR WILL VEER NORTH OF WEST AT ALL
SITES THROUGH THE EVENING AS A COLD FRONT SLIDES THROUGH THE
REGION.  KEPT ALL TAF SITES DRY WITH THE EXCEPTION OF BRIEF VCSH
MENTION AMONGST MID LEVEL VFR BKN CIGS.  WNW WINDS WILL SUBSIDE
OVERNIGHT AS THE PGF WEAKENS...WITH ALL SITES DUE NNW BY MORNING
UNDER FEW/SCT HIGH LEVEL CIRRUS.  LEE TROF WILL ALLOW FOR WINDS TO
BACK WESTERLY DURING THE LATE MORNING TO EARLY AFTERNOON ON THURSDAY
WITH SOME LIGHT GUSTING POSSIBLE AS THE MIXED LAYER DEEPENS...THUS
ALL SITES FEATURE SUCH IN THE TAF THROUGH PERIODS END.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD THROUGH FRIDAY...BEFORE
ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM THE WEST OVER THE
WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...CDG




000
FXUS62 KGSP 230237
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1037 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
CYCLE.  WINDS ARE INITIALIZED AT...OR WILL VEER NORTH OF WEST AT ALL
SITES THROUGH THE EVENING AS A COLD FRONT SLIDES THROUGH THE
REGION.  KEPT ALL TAF SITES DRY WITH THE EXCEPTION OF BRIEF VCSH
MENTION AMONGST MID LEVEL VFR BKN CIGS.  WNW WINDS WILL SUBSIDE
OVERNIGHT AS THE PGF WEAKENS...WITH ALL SITES DUE NNW BY MORNING
UNDER FEW/SCT HIGH LEVEL CIRRUS.  LEE TROF WILL ALLOW FOR WINDS TO
BACK WESTERLY DURING THE LATE MORNING TO EARLY AFTERNOON ON THURSDAY
WITH SOME LIGHT GUSTING POSSIBLE AS THE MIXED LAYER DEEPENS...THUS
ALL SITES FEATURE SUCH IN THE TAF THROUGH PERIODS END.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD THROUGH FRIDAY...BEFORE
ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM THE WEST OVER THE
WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...CDG




000
FXUS62 KGSP 230237
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1037 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1030 PM EDT WEDNESDAY...EXPECTING LINE OF CONVECTION SLIDING
OUT OF NORTHEAST GA TO MOVE UP THE I85 CORRIDOR AS IT WEAKENS.
LATEST GUIDANCE FAVORS SURVIVAL OF SAID SHRA/TSRA AT LEAST THROUGH
THE I26 CORRIDOR...WITH SOME WEAKENING PROGGED FURTHER EAST.  02Z
SPC MESO ANALYSIS INDICATES LITTLE INSTABILITY TO FUEL THE LINE AS IT
MOVES EAST THUS EXPECTING THUNDER CHANCES TO DIMINISH LEAVING
NOTHING MORE THAN A BAND OF SHRA WITHIN AN HOUR OR SO.
NEVERTHELESS...MODEST LLV WINDS COULD MIX TO THE SURFACE TO PRODUCE
ISOLATED GUSTS OF UP TO 30-40MPH INITIALLY.  MEANWHILE...THE COLD
FRONT IS PUSHING THROUGH THE HIGH TERRAIN ATM...AND SHOULD SWEEP
THROUGH THE REMAINDER OF THE FCST AREA WITHIN THE NEXT FEW HOURS AS
PREVIOUSLY FCST.  TWEAKED POPS/QPF IN THE EXTREME NEAR TERM TO
BETTER REFLECT MOST RECENT RADAR TRENDS.  NO OTHER SIG CHANGES
NEEDED/MADE TO THE FCST WITH THIS UPDATE.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICEABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER ESPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
CYCLE.  WINDS ARE INITIALIZED AT...OR WILL VEER NORTH OF WEST AT ALL
SITES THROUGH THE EVENING AS A COLD FRONT SLIDES THROUGH THE
REGION.  KEPT ALL TAF SITES DRY WITH THE EXCEPTION OF BRIEF VCSH
MENTION AMONGST MID LEVEL VFR BKN CIGS.  WNW WINDS WILL SUBSIDE
OVERNIGHT AS THE PGF WEAKENS...WITH ALL SITES DUE NNW BY MORNING
UNDER FEW/SCT HIGH LEVEL CIRRUS.  LEE TROF WILL ALLOW FOR WINDS TO
BACK WESTERLY DURING THE LATE MORNING TO EARLY AFTERNOON ON THURSDAY
WITH SOME LIGHT GUSTING POSSIBLE AS THE MIXED LAYER DEEPENS...THUS
ALL SITES FEATURE SUCH IN THE TAF THROUGH PERIODS END.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD THROUGH FRIDAY...BEFORE
ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM THE WEST OVER THE
WEEKEND ALONG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...CDG





000
FXUS62 KGSP 222049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
449 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 445 PM EDT WEDNESDAY...NO SIG CHANGES NEEDED/MADE TO THE FCST
WITH THIS UPDATE.  DID MAKE SLIGHT TWEAKS TO POPS THROUGH THE
EVENING TO ACCOUNT FOR MOST RECENT CAM GUID AS IT PERTAINS TO
SHOWERS ASSOCIATED WITH WEAK COLD FROPA NOW SLIDING THROUGH EAST TN.
WINDS ACROSS THE NORTHERN MOUNTAINS LOOK TO BE ON A DOWNWARD TREND
THUS CURRENT PLAN IS TO ALLOW WIND ADVISORY TO EXPIRE ON SCHEDULE AT
7PM.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEMDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER EZXPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  89%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...LG





000
FXUS62 KGSP 222049
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
449 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 445 PM EDT WEDNESDAY...NO SIG CHANGES NEEDED/MADE TO THE FCST
WITH THIS UPDATE.  DID MAKE SLIGHT TWEAKS TO POPS THROUGH THE
EVENING TO ACCOUNT FOR MOST RECENT CAM GUID AS IT PERTAINS TO
SHOWERS ASSOCIATED WITH WEAK COLD FROPA NOW SLIDING THROUGH EAST TN.
WINDS ACROSS THE NORTHERN MOUNTAINS LOOK TO BE ON A DOWNWARD TREND
THUS CURRENT PLAN IS TO ALLOW WIND ADVISORY TO EXPIRE ON SCHEDULE AT
7PM.

PREVIOUS DISCUSSION...

AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVELOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEMDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER EZXPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  89%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...CDG/LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...LG




000
FXUS62 KGSP 221846
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
246 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVLOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEMDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER EZXPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  92%     HIGH  94%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...LG




000
FXUS62 KGSP 221846
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
246 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVLOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEMDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER EZXPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  92%     HIGH  94%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...LG





000
FXUS62 KGSP 221846
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
246 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES SOUTH OF OUR AREA TONIGHT AND COOL...DRY HIGH
PRESSURE BUILDS IN FROM THE NORTH ON FRIDAY.  A WARM FRONT BRINGS
BETTER CHANCES FOR RAINFALL TO OUR REGION OVER THE WEEKEND. DRY HIGH
PRESSURE PREVAILS AT THE START OF NEXT WEEK...THEN A LOW MOVING
ALONG THE GULF COAST INFLUENCES OUR WEATHER IN MID WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 2 PM WED...LATEST VISIBLE SAT IMAGE SHOWS SCT CUMULUS
DEVLOPING OUTSIDE THE MOUNTAINS...WITH CONSIDERABLE CLOUDINESS OVER
THE MOUNTAINS AS A COLD FRONT APPROACHES FROM THE NW. REGIONAL RADAR
SHOWS A FEW LIGHT RETURNS OVER THE MOUNTAINS. CAM MODELS STILL
INDICATE THAT CT SHOWERS WILL DEVELOP MAINLY OVER THE BORDER
COUNTIES OF WESTERN NC CIRCA 20Z AND MOVE SE. ISOLATED THUNDERSTORMS
REMAIN POSSIBLE AS SEVERAL HUNDRED JOULES OF CAPE POOL AHEAD OF THE
FRONT. AIRMASS IS QUITE DRY AND WITH A DEEP LAYER WESTERLY COMPONENT
THROUGH THE COLUMN EXPECT THAT DOWNSLOPE SHOULD ESSENTIALLY KILL
MOST...IF NOT ALL OF THE SHOWERS AS THEY TRY TO MOVE OUT OF THE
MOUNTAINS THIS EVENING. HENCE...MOST AREAS EAST OF THE MOUNTAINS
WILL JUST SEE AN INCREASE IN CLOUDS AND SCT SPRINKLES AT BEST.
GRADIENT WINDS WILL REMAIN STRONG WITH SOME GUSTS TO AROUND 30
MPH...EXCEPT 40-50 MPH IN THE NORTHERN MOUNTAINS. HENCE...WILL
CONTINUE THE WIND ADVISORY IN THE NORTHERN MOUNTAINS. A FEW HIGHER
WIND GUSTS MAY OCCUR WHERE SHOWERS MIX DOWN HIGHER WINDS.

COLD ADVECTION BEHIND THE FRONT WILL BE NOTICABLE OVER THE MOUNTAINS
TONIGHT. TEMPERATURES ARE FORECAST TO FALL INTO THE MIDDLE 30S TO
LOWER 40S. CLOUDS AND WINDS SHOULD PRECLUDE ANY FROST FORMATION
OVERNIGHT. MINIMUM TEMPS OUTSIDE THE MOUNTAINS WILL RANGE FROM THE
MIDDLE 40S OVER THE NORTHERN FOOTHILLS TO THE MIDDLE 50S IN THE
LOWER PIEMDMONT.

THE FRONT WILL MOVE ACROSS THE ENTIRE AREA BY EARLY THU. HIGH
PRESSURE WILL THEN RIDGE SE OVER THE AREA ON THURSDAY. A FEW CLOUDS
MAY LINGER EZXPECIALLY OVER SOUTHERN SECTIONS EARLY TOMORROW...BUT
CONSIDERABLE SUNSHINE SHOULD BE THE RULE. MAX TEMPS WILL BE WELL
BELOW CLIMO IN THE MOUNTAINS AND A CATEGORY OR SO BELOW NORMAL
OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM WED...UPPER TROUGH AXIS MOVES EWD AND OFFSHORE THU
NIGHT AND FRI ALLOWING HEIGHTS TO RISE OVER THE CWFA...AND DRY HIGH
PRESSURE TO CENTER OVER THE SRN APPALACHIANS BY FRI MRNG. THE
AIRMASS IS CANADIAN IN ORIGIN THOUGH IS LIKELY HAVE MODIFIED TO SOME
EXTENT BY THE TIME IT SETTLES IN. THE SFC HIGH IS NOT THAT
EXPANSIVE...AND FURTHERMORE THE RELATIVELY TIGHT HEIGHT GRADIENT
ALOFT MAY KEEP THE HIGHER ELEVATIONS UNDER SLIGHT FLOW THRU THE
NIGHT. MOS GUIDANCE BASICALLY SUPPORTS A HARD FREEZE OVER THE NRN
MTN ZONES AND VICINITY. THIS SEEMS A BIT TOO LOW. FOR NOW WILL
FEATURE MINS WITHIN A DEGREE OR TWO OF FREEZING AT THE COOLEST
SPOTS. HIGH VALLEYS MAY END UP THE COLDEST. FROST APPEARS TO BE OF
LITTLE CONCERN DUE TO DRY DEWPOINTS THAT WILL ACCOMPANY THE AIRMASS.
CAN/T RULE OUT THE EVENTUAL ISSUANCE OF A FREEZE WARNING...BUT FOR
NOW WILL JUST CONTINUE MENTION IN HWO.

THE HIGH SHIFTS OFF TO THE SOUTHEAST AS THE RIDGE AXIS APPROACHES
LATER FRIDAY. SKIES WILL INITIALLY BE MOSTLY CLEAR AND TEMPS SHOULD
BE ABLE TO REBOUND TO ABOUT A CATEGORY BELOW NORMAL FOR MAXES.
HOWEVER...A SHORTWAVE MOVING FROM THE SRN ROCKIES INTO THE PLAINS AND
ASSOCIATED SFC LOW WILL ADVECT GULF MOISTURE INTO THE SERN STATES.
CLOUDS WILL INCREASE AS ISENTROPIC LIFT RAMPS UP OVER THE AREA DURING
THE SECOND HALF OF THE DAY...WITH POPS FOLLOWING SUIT. CLOUDY SKIES
FRI NIGHT WILL KEEP TEMPS ABOVE FREEZING. MOISTURE AND DEEP FORCING
PEAK DURING THE DAY SATURDAY...WITH AT LEAST MODEST CONVECTIVE
ENHANCEMENT POSSIBLE. PWAT VALUES ARE PROGGED BY THE GFS TO REACH
NEAR RECORD VALUES OVER AT LEAST THE SRN PORTION OF THE AREA. USED
SREF PLUMES TO GET A FEEL FOR QPF...WITH A FAIRLY WIDE RANGE AND
SPATIAL DISTRIBUTION NOTED BETWEEN DIFFERENT MODELS. LOCALLY HEAVY
RAIN IS OF SOME CONCERN SATURDAY ESP IF CONVECTIVE ELEMENTS GET
INVOLVED. HOWEVER WIND PROFILES WILL LIKELY KEEP CELLS MOVING...AND
SOIL CAPACITY LIKELY WILL HAVE RECOVERED SOMEWHAT FROM THE RECENT
RAINFALL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
SUNDAY WITH FLATTENING UPPER RIDGING OVER THE SE CONUS AND AN H5
SHORTWAVE MOVING INTO THE FCST AREA FROM THE WEST. AT THE SAME
TIME...A LARGE AND PERSISTENT CLOSED UPPER LOW IS SPINNING AND
REMAINS NEARLY STATIONARY OVER NEW ENGLAND. THE OVERALL AGREEMENT
BETWEEN THE LONG RANGE MODELS WRT TO THE SYNOPTIC PATTERN EVOLUTION
DOES NOT LOOK VERY GOOD AT THIS TIME. THE 00Z ECMWF HAS THE H5
SHORTWAVE BEING ABSORBED BACK INTO THE CLOSED LOW LATE SUN AND THE
CENTER OF THE LOW SLIDING GRADUALLY SW ON MON AND TUES. THE GFS
KEEPS THE UPPER LOW FARTHER TO THE NE AND BRINGS ANOTHER ROUND OF
UPPER RIDGING OVER THE FCST AREA ON MON. BOTH MODELS SPIN OFF A
SOUTHERN STREAM CLOSED H5 LOW OVER ARIZONA/NEW MEXICO EARLY IN THE
WEEK AND MOVE THE LOW TO OUR REGION BY MID WEEK. THE GFS MAINTAINS A
DEEPER AND MORE WELL DEFINED LOW COMPARED TO THE ECWMF WHICH TRIES
TO REABSORB THE LOW BACK INTO THE NORTHERN FLOW. REGARDLESS OF THE
SOLUTION YOU USE...BOTH HAVE THE UPPER TROF/LOW MOVING OVER THE CWFA
BY NEW DAY 7 ON WED.

AT THE SFC...A WARM FRONT WILL BE MOVING NORTH OF THE CWFA LATE
SAT/EARLY SUN AS THE PARENT LOW APPROACHES THE CAROLINAS FROM THE
WEST. AS THE CENTER OF THE LOW MOVES TOWARDS THE COAST...LOW LVL
WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND THE DEEPER LYR
MOISTURE SHOULD DWINDLE. BY MON MORNING...CANADIAN HIGH PRESSURE
WILL SPREAD BACK OVER THE REGION FROM THE NORTH AND DRY THINGS OUT.
ON TUES...A GREAT PLAINS LOW WILL DEEPEN AND MAKES ITS WAY TOWARDS
THE FCST AREA. AT THIS POINT...MODEL DIFFERENCE BECOME MORE
SIGNIFICANT WITH THE ECMWF KEEPING THE LOW ON A MORE SLY PATH AND
NOT HAVING IT REACH THE CWFA UNTIL EARLY WED...WHILE THE GFS
DEVELOPS A DEEPER LOW AND KEEPS IT ON A MORE NLY TRACK AS IT
APPROACHES THE CWFA ON TUES. EITHER WAY...THE END OF THE FCST PERIOD
SHOULD BE THE WETTEST AND MOST ACTIVE. TEMPS START OUT AROUND CLIMO
ON SUN AND STEADILY DROP THRU THE PERIOD WITH HIGHS ON DAYS 6 AND 7
ABOUT 7 TO 10 DEGREES BELOW NORMAL.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  92%     HIGH  94%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...LG
SHORT TERM...WIMBERLEY
LONG TERM...JPT
AVIATION...LG





000
FXUS62 KGSP 221719
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
119 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1 PM...GOING FORECAST ON TRACK. SOME LIGHT RETURNS SHOWING UP
ON RADAR ALONG THE TN BORDER IN WESTERN NC. HENCE...SCT TYPE POPS
LOOK GOOD FOR THE BORDER COUNTIES THIS AFTERNOON. MADE SOME MINOR
ADJUSTMENTS TO TEMP/DEWPOINTS. WINDS ARE GUSTY AS EXPECTED.

AS OF 815 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED TEMP
GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR TEMP/DEWPOINTS
TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST CONSHORT POPS
WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS CIRCA 18Z
MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS REASONABLE BASED ON
REGIONAL RADARS TO THE NW. GUSTY WINDS ARE STILL EXPECTED IN ADVANCE
OF THE COLD FRONT AS PRESSURE GRADIENT TIGHTENS. WIND ADVISORY LOOKS
WELL PLACED FOR THE NORTHERN MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     MED   62%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...LG




000
FXUS62 KGSP 221719
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
119 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1 PM...GOING FORECAST ON TRACK. SOME LIGHT RETURNS SHOWING UP
ON RADAR ALONG THE TN BORDER IN WESTERN NC. HENCE...SCT TYPE POPS
LOOK GOOD FOR THE BORDER COUNTIES THIS AFTERNOON. MADE SOME MINOR
ADJUSTMENTS TO TEMP/DEWPOINTS. WINDS ARE GUSTY AS EXPECTED.

AS OF 815 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED TEMP
GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR TEMP/DEWPOINTS
TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST CONSHORT POPS
WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS CIRCA 18Z
MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS REASONABLE BASED ON
REGIONAL RADARS TO THE NW. GUSTY WINDS ARE STILL EXPECTED IN ADVANCE
OF THE COLD FRONT AS PRESSURE GRADIENT TIGHTENS. WIND ADVISORY LOOKS
WELL PLACED FOR THE NORTHERN MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     MED   62%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...LG





000
FXUS62 KGSP 221719
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
119 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1 PM...GOING FORECAST ON TRACK. SOME LIGHT RETURNS SHOWING UP
ON RADAR ALONG THE TN BORDER IN WESTERN NC. HENCE...SCT TYPE POPS
LOOK GOOD FOR THE BORDER COUNTIES THIS AFTERNOON. MADE SOME MINOR
ADJUSTMENTS TO TEMP/DEWPOINTS. WINDS ARE GUSTY AS EXPECTED.

AS OF 815 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED TEMP
GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR TEMP/DEWPOINTS
TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST CONSHORT POPS
WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS CIRCA 18Z
MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS REASONABLE BASED ON
REGIONAL RADARS TO THE NW. GUSTY WINDS ARE STILL EXPECTED IN ADVANCE
OF THE COLD FRONT AS PRESSURE GRADIENT TIGHTENS. WIND ADVISORY LOOKS
WELL PLACED FOR THE NORTHERN MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     MED   62%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...LG




000
FXUS62 KGSP 221719
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
119 PM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 1 PM...GOING FORECAST ON TRACK. SOME LIGHT RETURNS SHOWING UP
ON RADAR ALONG THE TN BORDER IN WESTERN NC. HENCE...SCT TYPE POPS
LOOK GOOD FOR THE BORDER COUNTIES THIS AFTERNOON. MADE SOME MINOR
ADJUSTMENTS TO TEMP/DEWPOINTS. WINDS ARE GUSTY AS EXPECTED.

AS OF 815 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED TEMP
GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR TEMP/DEWPOINTS
TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST CONSHORT POPS
WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS CIRCA 18Z
MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS REASONABLE BASED ON
REGIONAL RADARS TO THE NW. GUSTY WINDS ARE STILL EXPECTED IN ADVANCE
OF THE COLD FRONT AS PRESSURE GRADIENT TIGHTENS. WIND ADVISORY LOOKS
WELL PLACED FOR THE NORTHERN MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (NORTHWEST AT KAVL)
WINDS WILL CONTINUE THIS AFTERNOON...WITH POTENTIAL FOR 25-30 KT
GUSTS AT TIMES. A COLD FRONT WILL PUSH INTO THE AREA LATE THIS AFTN
AND MOVE ACRSOSS THE REGION OVERNIGHT. MAINLY MID AND UPR LVL
MOISTURE WILL ACCOMPANY THE FRONT. A ISOLD TO SCATTERED SHRA ARE
EXPECTED O MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE NORTH.
CAN`T RULE OUT ISOLATED THUNDERSTORMS DUE TO SOME ELEVATED CAPE.
HOWEVER...WILL REMOVE MENTION OF VCTS AT KAVL AND KHKY AS 12Z
GUIDANCE KEEPS MOST CONVECTION TO THEIR WEST. WINDS WILL SUBSIDE
AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS MOVING ACROSS
THE AREA OVERNIGHT. HOWEVER...VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND ALONMG WITH RESTRICTIONS.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     MED   62%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...LG





000
FXUS62 KGSP 221213
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
813 AM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 810 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED
TEMP GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR
TEMP/DEWPOINTS TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST
CONSHORT POPS WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS
CIRCA 18Z MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS
REASONABLE BASED ON REGIONAL RADARS TO THE NW. GUSTY WINDS ARE
STILL EXPECTED IN ADVANCE OF THE COLD FRONT AS PRESSURE GRADIENT
TIGHTENS. WIND ADVISORY LOOKS WELL PLACED FOR THE NORTHERN
MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (WEST-NORTHWEST AT
KAVL) WINDS BY 15-16Z...WITH POTENTIAL FOR 25-30 KT GUSTS AT TIMES
THIS AFTN. A COLD FRONT WILL PUSH INTO THE AREA THIS AFTN...BRINGING
MAINLY MID AND UPR LVL MOISTURE. A ISOLD TO SCATTERED SHRA AND TSRA
ARE EXPECTED TO MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE
NORTH. WILL MENTION VCTS AT KAVL AND KHKY...WHERE THE HIGHEST CHC OF
IMPACT WILL BE. COVERAGE LOOKS TOO LIMITED AT THE OTHER SITES. WINDS
WILL SUBSIDE AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS
LINGERING THRU THE EVENING.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND.

CONFIDENCE TABLE...

            12-18Z        18-24Z        00-06Z        06-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...ARK/LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK/LG





000
FXUS62 KGSP 221213
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
813 AM EDT WED APR 22 2015

.SYNOPSIS...
A COLD FRONT MOVES INTO THE AREA FROM THE NORTHWEST TODAY WITH GUSTY
WINDS AND LOW PRECIPITATION CHANCES. THE FRONT MOVES SOUTH OF THE
AREA TONIGHT WITH DRY HIGH PRESSURE PREVAILING BRIEFLY IN ITS WAKE.
A WARM FRONT BRINGS BETTER CHANCES FOR RAINFALL TO THE AREA OVER THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 810 AM...TEMPS A LITTLE COOLER THAN EXPECTED SO ADJUSTED
TEMP GRID USING OBSERVATIONS AND USED LATEST CONSHORT FOR
TEMP/DEWPOINTS TREND THROUGH TODAY. ALSO...BLENDED IN THE LATEST
CONSHORT POPS WHICH BRINGS SCT SHOWERS/STORMS IN THE MOUNTAINS
CIRCA 18Z MAXIMIZING DURING THE LATE AFTERNOON. THIS LOOKS
REASONABLE BASED ON REGIONAL RADARS TO THE NW. GUSTY WINDS ARE
STILL EXPECTED IN ADVANCE OF THE COLD FRONT AS PRESSURE GRADIENT
TIGHTENS. WIND ADVISORY LOOKS WELL PLACED FOR THE NORTHERN
MOUNTAINS.

AS OF 645 AM...NO SIGNIFICANT CHANGES NEEDED FOR THIS UPDATE...AS
LATEST GUIDANCE IN LINE WITH THE CURRENT FCST.

AS OF 315 AM...A MID LVL WESTERLY JET WILL STRENGTHEN AROUND THE
BASE OF A BROAD UPPER LOW SPINNING OVER THE GREAT LAKES TODAY. AT
THE SFC...A RELATIVELY DRY COLD FRONT WILL CROSS THE OHIO VALLEY
THIS MORNING...THEN PUSH ACRS THE APPALACHIANS THIS AFTN. THE MAIN
CONCERN FOR TODAY LOOKS TO BE GUSTY WIND POTENTIAL...ESP IN THE NRN
MTNS WHERE THE WESTERLY LLVL FLOW WILL BE STRONGEST. THE 00Z GFS IS
STRONGER WITH WINDS AND GUSTS THAN THE NAM. BOTH SHOW DEEP MIXING OF
7-10 KFT AGL. TAKING A BLEND OF THE TWO RESULTS IN WINDS JUST BELOW
WIND ADVISORY CRITERIA. HOWEVER...PORTIONS OF THE NRN MTNS WILL BE
CLOSE...AND GIVEN THE WET SOILS FROM RECENT HEAVY RAINS...THINK EVEN
20-30 MPH WINDS WITH 35-45 MPH GUSTS MAY DOWN A FEW TREES. SO AFTER
COLLABORATION WITH RNK...WILL HOIST A WIND ADVISORY FOR THE NRN MTNS
FOR TODAY.

THE OTHER FCST CHALLENGE FOR TODAY WILL BE CONVECTION...WHICH WHAT
DOES DEVELOP WILL HAVE POTENTIAL TO TAP INTO VERY STRONG WINDS. THE
NEW DAY 1 SPC CONVECTIVE OUTLOOK HAS PAINTED A MRGL RISK FOR MAINLY
DAMAGING WIND GUSTS ACRS THE NC MTNS. THE MAJORITY OF HIGH-RES/CAMS
DO SHOW SCATTERED CONVECTION DEVELOPING ALONG AND AHEAD OF THE
COLD FRONT THIS AFTN...PUSHING INTO WESTERN NC. I THINK THE SLGT CHC
TO LOW-END CHC POPS LOOKS GOOD...WITH AN ISOLD CHC OF SEVERE TSTMS.
THE WESTERLY DOWNSLOPE FLOW ACRS THE PIEDMONT SHUD LIMIT MOISTURE
CONVERGENCE FOR ANYTHING MORE THAN ISOLD CONVECTION. SO THERE IS A
GRADIENT OF POP TAPERING TO SLGT CHC POP ACRS NE GA AND THE UPSTATE.
UNDER GRADUALLY INCREASING CLOUDINESS...TEMPS SHUD BE ABLE TO WARM
INTO THE 60S IN THE MTNS AND MID-UPR 70S ACRS THE PIEDMONT.

TONIGHT...THE LLVL CAA AND DRYING SHUD RAMP UP THIS EVENING...SO
POPS WILL TAPER OFF. WINDS SHUD ALSO SUBSIDE AND LOSE GUSTINESS BY
LATE EVENING AS WE LOSE THE DEEP MIXING. TEMPS WILL DIP BACK INTO
THE UPR 30S TO LWR 40S IN THE MTNS...AND MID 40S TO MID 50 ACRS THE
PIEDMONT.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 210 AM WED...A BROAD LOW AMPLITUDE UPPER TROF MOVES EAST OF
THE AREA THU WITH SHORT WAVE RIDGING MOVING ON ON FRI. A SHORT WAVE
UNDERCUTS THE RIDGE AND MOVES INTO THE AREA FRI NITE ALONG WITH THE
RIDGE AXIS. CLOUDS WILL DIMINISH THU AS A COLD FRONT MOVES SOUTH OF
THE AREA AND HIGH PRESSURE BUILDS IN FROM THE NW. ALTHOUGH LIGHTER
THAN WED...WILL STILL SEE SOME GUSTY WINDS THRU THE DAY AS WELL.
HIGH PRESSURE REMAINS OVER THE AREA FRI. DEEP MOISTURE AND LOW LEVEL
ISENTROPIC LIFT MOVE IN FROM THE WEST BRINGING CLOUDS AND EVENTUALLY
PRECIP. KEPT POP IN THE CHC RANGE AS THERE IS STILL SOME
DISAGREEMENT ON TIMING...WITH HIGHEST POP OVER THE SWRN MTNS INTO
THE UPPER SAVANNAH RIVER VALLEY. THE AIR MASS MOVING IN WITH THE
HIGH IS QUITE COOL. TEMPS THU AND THU NITE WILL BE AROUND 5 DEGREES
BELOW NORMAL...BUT COULD BE EVEN COOLER THU NITE IF RADIATIONAL
COOLING CONDITIONS IMPROVE. THIS COULD BRING FROSTY CONDITIONS OT
THE I-40 CORRIDOR...AND FROST/FREEZE CONCERNS TO THE CENTRAL AND SRN
NC MTNS. HIGHS RISE A FEW DEGREES FRI...WITH LOWS RISING UP TO 5
DEGREES ABOVE NORMAL FRI NITE WITH WAA AND INCREASING CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 400 AM WED...GUIDANCE IN PRETTY GOOD AGREEMENT FOR THE FIRST
HALF OF THE MEDIUM RANGE...BUT DIVERGES FOR THE LATTER HALF. A SHORT
WAVE MOVES INTO THE AREA SAT NITE THEN BECOMES ENVELOPED INTO THE
UPPER LOW CIRCULATION NEAR THE NEW ENGLAND COAST. THIS LOW KEEPS
CYCLONIC FLOW ACROSS MUCH OF THE EAST COAST UNTIL MONDAY. THE GFS
AND ECMWF BRING A LOW PRESSURE SYSTEM INTO THE AREA SAT THEN OFF
SHORE SAT NITE. THIS KEEPS DEEP MOISTURE AND LOW LEVEL ISENTROPIC
LIFT ACROSS THE AREA SAT WITH THE LIFT DIMINISHING SAT NITE.
HOWEVER...A BOUNDARY REMAINS ACROSS THE AREA SUN AND A WAVE MAY FORM
ALONG THE BOUNDARY AND MOVE ACROSS THE AREA. THIS WILL KEEP A THREAT
OF PRECIP OVER THE CWFA DURING THE DAY. COULD SEE UP TO 1.5 INCHES
OF RAIN WITH THIS SYSTEM. WILL HAVE TO SEE HOW THE GROUND AND
STREAMS RESPOND THE THE DRY DAYS BEFORE THIS EVENT DEVELOPS TO SEE
IF THIS WOULD BE ENOUGH QPF TO CAUSE A SIGNIFICANT RESPONSE. HIGHS
AROUND 5 DEGREES BELOW NORMAL SAT RISE TO NEAR NORMAL SUN. LOWS WILL
START AROUND 5 DEGREES ABOVE NORMAL THEN FALL TO NEAR NORMAL.

DRY WX FORECAST MONDAY EVEN WITH THE MDL DIFFERENCES AS GFS HAS HIGH
PRESSURE MOVING IN...AND THE ECMWF HAS CYCLONIC BUT DRY FLOW OVER
THE AREA. HIGHS WILL BE NEAR NORMAL WHILE LOWS WILL BE AROUND 5
DEGREES ABOVE NORMAL.

THE ECMWF DAMPENS A SRN STREAM UPPER LOW AS IT MOVES INTO THE AREA
AND INTERACTS WITH THE CYCLONIC FLOW ACROSS THE EAST COAST. THE GFS
THE GFS MOVES SHORT WAVE RIDGING OVER THE AREA AS STRONG NRN AND SRN
STREAM LOWS MERGE OVER THE MID MS VALLEY. AT THE SFC...THE ECMWF HAS
A MILLER-A LOW MOVING IT ALONG THE GULF COAST TO THE SERN ATLANTIC
COAST. THE GFS HAS MORE OF A MILLER-B LOW AND BRINGS IT IN FASTER.
EITHER WAY...PRECIP CHC WILL BE ON THE INCREASE THRU THE DAY AND
CONTINUING INTO THE EVENING. HOWEVER...QPF WOULD BE DRAMATICALLY
DIFFERENT. HIGHS TUE WILL BE AROUND 5 DEGREES BELOW NORMAL.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE... GUSTY WEST-SOUTHWEST (WEST-NORTHWEST AT
KAVL) WINDS BY 15-16Z...WITH POTENTIAL FOR 25-30 KT GUSTS AT TIMES
THIS AFTN. A COLD FRONT WILL PUSH INTO THE AREA THIS AFTN...BRINGING
MAINLY MID AND UPR LVL MOISTURE. A ISOLD TO SCATTERED SHRA AND TSRA
ARE EXPECTED TO MOVE INTO THE NC MTNS TO THE FOOTHILLS FROM THE
NORTH. WILL MENTION VCTS AT KAVL AND KHKY...WHERE THE HIGHEST CHC OF
IMPACT WILL BE. COVERAGE LOOKS TOO LIMITED AT THE OTHER SITES. WINDS
WILL SUBSIDE AFTER SUNSET THIS EVENING WITH MID TO HIGH CLOUD CIGS
LINGERING THRU THE EVENING.

OUTLOOK...A DRY HIGH PRES SYSTEM WILL BUILD IN THURSDAY THROUGH
FRIDAY...BEFORE ANOTHER WET STORM SYSTEM APPROACHES THE AREA FROM
THE WEST OVER THE WEEKEND.

CONFIDENCE TABLE...

            12-18Z        18-24Z        00-06Z        06-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ033-049-050.
SC...NONE.

&&

$$
SYNOPSIS...RWH
NEAR TERM...ARK/LG
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...ARK/LG




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