000
FXUS62 KCHS 201146
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
746 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
MID WEEK WHILE ATLANTIC HIGH PRESSURE PREVAILS UNTIL LATE WEEK. A
COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO SATURDAY...
FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHORTWAVE TROUGH ALOFT OVER THE REGION TODAY IS COMPLEX PER
LOOPS OF OVERNIGHT WATER VAPOR SATELLITE IMAGERY. THE MAIN UPPER
WAVE WAS DRIFTING E ALONG THE VA/NC BORDER WHILE A WEAK VORTICITY
AXIS EXTENDED S OVER COASTAL GEORGIA IN NE FLORIDA. AN INTERESTING
FEATURE IS THE IMPULSE OVER THE FLORIDA PANHANDLE...OUR ANALYSIS
DID NOT DETECT THIS FEATURE AT 500 MB...IT MAY BE PART MCV AND IS
FORECAST TO VERTICALLY STRETCH THE MID LEVEL TROUGH TODAY.
THE MAIN FORECAST PROBLEMS OF THE DAY ARE TWOFOLD. THERE APPEARS TO
BE HEAVY RAIN POTENTIAL UNTIL MID AFTERNOON ALONG COASTAL SOUTH
CAROLINA AND THEN AN ISOLATED SEVERE WEATHER RISK W OF I-95 IN SE
GEORGIA AND FAR SOUTHERN SOUTH CAROLINA THIS AFTERNOON.
ADDRESSING THE MORNING POTENTIAL FOR DEVELOPING CONVECTIVE RAINS
ALONG THE SOUTH CAROLINA COAST...VERY DEEP MOISTURE IS IN PLAY.
LATEST ANALYSIS INDICATES MOISTURE TRANSPORT CONVERGENCE AND A
INSTABILITY GRADIENT HAS SETUP ALONG THE COAST. MOST OF THE 00Z
HIGH RESOLUTION MODELS HAVE PERFORMED POORLY THROUGH 12 HOURS BUT
SHORT LINES OF HEAVY SHOWERS WERE DEVELOPING E OF I-95 IN SOUTH
CAROLINA AND IT LOOKS LIKE SOME POTENTIAL FOR TRAINING CELLS. THE
TRENDS ARE WORTH WATCHING GIVEN THE 1.8 INCH PWATS LURKING ON THE
LATEST RUC ANALYSIS. WE CONTINUED LIKELY POPS IN PARTS OF THE
CHARLESTON TRI-COUNTY AREA.
THE SECOND ISSUE OF THE DAY WILL TURN TO DIURNAL CONVECTIVE
DEVELOPMENT DURING THE AFTERNOON ONCE AGAIN. MODELS INDICATE A 35 KT
700 MB WIND MAX DEVELOPING OVER THE INLAND CAROLINAS AROUND MIDDAY
AND PUNCHING DUE S INTO GEORGIA W OF I-95 LATER TODAY. 300 MB FLOW
ACROSS SE GEORGIA RAPIDLY BACKS FROM SW TO SE TODAY AND A POCKET OF
UPPER DIFLUENCE IS PROGGED...EVEN THOUGH THE FLOW IS WEAK AT JET
LEVEL. MORNING LOW CLOUDS ARE LIKELY TO DISSIPATE LEAVING A
POTENTIAL FOR SOME INSOLATION LATE MORNING AND EARLY AFTERNOON.
MODEL INSTABILITY PROGS SHOW PARAMETERS A BIT MORE UNSTABLE THAN
ON SUNDAY BACK OVER OUR INLAND ZONES. MUCH OF THIS SCENARIO WILL
DEPEND ONCE AGAIN ON MESOSCALE BOUNDARIES AND SURFACE HEATING.
CANNOT RULE OUT ISOLATED SEVERE THUNDERSTORMS WITH DAMAGING WIND
MARGINALLY SEVERE HAIL OR SOME VERY SMALL SCALE CONVECTIVE
ORGANIZATION. MANY OF THESE STORMS WILL ALSO PRODUCE VERY HEAVY
DOWNPOURS.
THE CONFIDENCE OF EITHER OF THESE SCENARIOS BECOMING REALITY IN
SPACE AND TIME IS NOT GREAT...THUS WE OPTED TO NOT ADD ANY MENTIONS
IN OUR HAZARDOUS WEATHER OUTLOOK UNTIL RADAR TRENDS BECOME MORE
DEFINITIVE AND A 12Z ANALYSIS IS PERFORMED.
HIGH TEMPS TODAY 80 TO 85 DEGREES MOST AREAS WITH LIGHT SOUTH TO
SOUTHEAST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
UPPER LEVEL TROUGHING OVER THE AREA IS NOT GOING ANYWHERE TONIGHT
BUT WE DO EXPECT CONVECTION TO DECREASE IN COVERAGE AND INTENSITY
DURING THE EVENING. LOW LEVEL COASTAL MOISTURE CONVERGENCE WILL
INCREASE TOWARD DAYBREAK ON TUE ALONG COASTAL SOUTH CAROLINA AND
CONVECTIVE RAINS MAY BREAK OUT ONCE AGAIN THERE. WILL ALSO NEED TO
WATCH TRENDS FOR FOG DEVELOPMENT TONIGHT IF CLOUDS BREAK. WITH
WIDESPREAD CONVECTIVE RAINS EXPECTED TODAY...THERE SEEMS TO BE
INCREASING CHANCES FOR FOG...ESPECIALLY INLAND.
A MOIST AIRMASS WILL PERSIST DURING THE PERIOD ALTHOUGH WE SHOULD
SEE A SLIGHT DECREASE IN PW VALUES BY THURSDAY. THE UPPER
SHORTWAVE WILL SLOWLY DISSOLVE OVERHEAD ON TUESDAY BUT ANOTHER
WAVE WILL APPROACH LATE WEDNESDAY THROUGH THURSDAY. AT THE SURFACE
ATLANTIC HIGH PRESSURE WILL MAINTAIN ITS CONTROL...KEEPING
SOUTHERLY FLOW IN LOW-LEVELS AND ALLOWING DAILY SEABREEZE
CIRCULATIONS TO DEVELOP. CONVECTIVE COVERAGE WILL VARY SOMEWHAT
BETWEEN THE THREE DAYS WITH WEDNESDAY CURRENTLY LOOKING LIKE THE
LEAST ACTIVE DAY DUE TO A LACK OF APPRECIABLE UPPER ENERGY TO WORK
WITH. HIGH TEMPS WILL CLIMB INTO THE MID TO UPPER 80S WITH LOWS IN
THE MIDDLE 60S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
FAIRLY GOOD MODEL CONSISTENCY REGARDING AN UPPER TROUGH SHIFTING
SOUTHEAST AND A COLD FRONTAL PASSAGE FRIDAY OR FRIDAY NIGHT. DRY AND
SLIGHTLY COOLER CANADIAN HIGH PRESSURE LOOKS TO BUILD IN FOR THE
WEEKEND BEFORE SHIFTING OFFSHORE EARLY NEXT WEEK.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
KCHS...A BAND OF SHOWERS WAS DRIFTING TOWARD THE KCHS TERMINAL
THIS MORNING. MODELS CONTINUE TO INDICATE SHOWERS AND ISOLATED
TSTMS INCREASING IN COVERAGE THROUGH MID AFTERNOON WITH THE
SEA BREEZE BECOMING A FOCUS FOR CONVECTION. WE PREVAILED
CONVECTIVE RAINS DURING THE PRIME SEA BREEZE TIME THIS AFTERNOON
WITH VCSH OR TEMPO SHRA UNTIL THEN. TONIGHT...LIKELY VFR BUT
CANNOT RULE OUT MVFR VSBYS LATE IF GROUNDS BECOME WET TODAY.
KSAV...BRIEF MVFR CIGS THIS MORNING BUT CONDITIONS AT DAYBREAK
WERE VFR. THERE COULD BE ADDITIONAL PERIODS OF MVFR CIGS THIS
MORNING OTHERWISE THE MAIN PROBLEM OF THE DAY IS TIMING ANOTHER
BOUT OF DIURNAL CONVECTIVE RAINS. WE MAINTAINED 17Z TO 21Z FROM
PREVIOUS TAFS AS LATEST MODELS ALSO REMAIN CONSISTENT. THERE
COULD BE SOME LOW CLOUDS AND/OR MVFR VSBYS LATE TONIGHT BUT OUR
CONFIDENCE IS LOW AT THIS TIME.
EITHER TERMINAL COULD REPORT THUNDER TODAY AS THE ATMOSPHERE
REMAINS UNSTABLE. WE OPTED TO LEAVE TSRA OUT OF THE PICTURE UNTIL
RADAR TRENDS BECOME BETTER DEFINED.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS TUE THROUGH THU...ALTHOUGH EARLY
MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
THROUGH TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER
THE ATLANTIC WILL EXTEND W ACROSS THE COASTAL WATERS...GENERATING
SE AND S WINDS OF 10-15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THURSDAY
NIGHT WITH SEABREEZE CIRCULATIONS DEVELOPING EACH AFTERNOON. A COLD
FRONT WILL DROP THROUGH FRIDAY EVENING OR SATURDAY MORNING WITH A
NORTHEAST FLOW DEVELOPING AS CANADIAN HIGH PRESSURE BUILDS IN. WINDS
AND SEAS WILL LIKELY INCREASE OVER THE WEEKEND IN RESPONSE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 200813
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
413 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
MID WEEK WHILE ATLANTIC HIGH PRESSURE PREVAILS UNTIL LATE WEEK. A
COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO SATURDAY...
FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PRE-DAWN...THROUGH 4 AM IT HAS BEEN A QUIET OVERNIGHT WITH AREAS OF
LAYERED CLOUDS...SOME INLAND STRATUS AND FOG WAS VERY PATCHY IN
NATURE. SUMMER-LIKE TEMPS IN THE 69 TO 73 DEGREE RANGE...WARMEST
ALONG COASTAL SOUTH CAROLINA WHERE STRONG LOW LEVEL MOISTURE
CONVERGENCE WAS ONGOING.
A SHORTWAVE TROUGH ALOFT OVER THE REGION TODAY IS COMPLEX PER LOOPS
OF OVERNIGHT WATER VAPOR SATELLITE IMAGERY. THE MAIN UPPER WAVE
WAS DRIFTING E ALONG THE VA/NC BORDER WHILE A WEAK VORTICITY AXIS
EXTENDED S OVER COASTAL GEORGIA IN NE FLORIDA. AN INTERESTING
FEATURE IS THE IMPULSE OVER THE FLORIDA PANHANDLE...OUR ANALYSIS
DID NOT DETECT THIS FEATURE AT 500 MB...IT MAY BE PART MCV AND IS
FORECAST TO STRETCH THE MID LEVEL TROUGH TODAY.
THE MAIN FORECAST PROBLEMS OF THE DAY ARE TWOFOLD. THERE APPEARS TO
BE HEAVY RAIN POTENTIAL UNTIL MID AFTERNOON ALONG COASTAL SOUTH
CAROLINA AND THEN AN ISOLATED SEVERE WEATHER RISK W OF I-95 IN SE
GEORGIA AND FAR SOUTHERN SOUTH CAROLINA THIS AFTERNOON.
ADDRESSING THE MORNING POTENTIAL FOR DEVELOPING CONVECTIVE RAINS
ALONG THE SOUTH CAROLINA COAST...VERY DEEP MOISTURE IS IN PLAY.
LATEST ANALYSIS INDICATES MOISTURE TRANSPORT CONVERGENCE AND A
INSTABILITY GRADIENT HAS SETUP ALONG THE COAST. A SLEW OF THE 00Z
HIGH RESOLUTION MODELS ERUPT EXCESSIVE QPF OUTPUT SOMEWHERE
BETWEEN EDISTO BEACH AND THE GRAND STRAND. MOST OF THESE MODELS
APPEAR TO HAVE CONVECTIVE FEEDBACK ISSUES BUT THE TREND IS WORTH
WATCHING GIVEN THE 1.8 INCH PWATS LURKING ON THE LATEST RUC
ANALYSIS. WE HAVE BUMPED POPS TO LIKELY IN PARTS OF THE CHARLESTON
TRI-COUNTY AREA CLOSER TO THE COAST.
THE SECOND ISSUE OF THE DAY WILL TURN TO DIURNAL CONVECTIVE
DEVELOPMENT DURING THE AFTERNOON ONCE AGAIN. MODELS INDICATE A 35 KT
700 MB WIND MAX DEVELOPING OVER THE INLAND CAROLINAS AROUND MIDDAY
AND PUNCHING DUE S INTO GEORGIA W OF I-95 LATER TODAY. 300 MB FLOW
ACROSS SE GEORGIA RAPIDLY BACKS FROM SW TO SE TODAY AND A POCKET OF
UPPER DIFLUENCE IS PROGGED...EVEN THOUGH THE FLOW IS WEAK AT JET
LEVEL. MORNING LOW CLOUDS ARE LIKELY TO DISSIPATE LEAVING A
POTENTIAL FOR SOME INSOLATION LATE MORNING AND EARLY AFTERNOON.
MODEL INSTABILITY PROGS SHOW PARAMETERS A BIT MORE UNSTABLE THAN
ON SUNDAY BACK OVER OUR INLAND ZONES. MUCH OF THIS SCENARIO WILL
DEPEND ONCE AGAIN ON MESOSCALE BOUNDARIES AND SURFACE HEATING.
CANNOT RULE OUT ISOLATED SEVERE THUNDERSTORMS WITH DAMAGING WIND
MARGINALLY SEVERE HAIL OR SOME VERY SMALL SCALE CONVECTIVE
ORGANIZATION. MANY OF THESE STORMS WILL ALSO PRODUCE VERY HEAVY
DOWNPOURS.
THE CONFIDENCE OF EITHER OF THESE SCENARIOS BECOMING REALITY IN
SPACE AND TIME IS NOT GREAT...THUS WE OPTED TO NOT ADD ANY MENTIONS
IN OUR HAZARDOUS WEATHER OUTLOOK UNTIL RADAR TRENDS BECOME MORE
DEFINITIVE AND A 12Z ANALYSIS IS PERFORMED.
HIGH TEMPS TODAY 80 TO 85 DEGREES MOST AREAS WITH LIGHT SOUTH TO
SOUTHEAST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
UPPER LEVEL TROUGHING OVER THE AREA IS NOT GOING ANYWHERE TONIGHT
BUT WE DO EXPECT CONVECTION TO DECREASE IN COVERAGE AND INTENSITY
DURING THE EVENING. LOW LEVEL COASTAL MOISTURE CONVERGENCE WILL
INCREASE TOWARD DAYBREAK ON TUE ALONG COASTAL SOUTH CAROLINA AND
CONVECTIVE RAINS MAY BREAK OUT ONCE AGAIN THERE. WILL ALSO NEED TO
WATCH TRENDS FOR FOG DEVELOPMENT TONIGHT IF CLOUDS BREAK. WITH
WIDESPREAD CONVECTIVE RAINS EXPECTED TODAY...THERE SEEMS TO BE
INCREASING CHANCES FOR FOG...ESPECIALLY INLAND.
A MOIST AIRMASS WILL PERSIST DURING THE PERIOD ALTHOUGH WE SHOULD
SEE A SLIGHT DECREASE IN PW VALUES BY THURSDAY. THE UPPER
SHORTWAVE WILL SLOWLY DISSOLVE OVERHEAD ON TUESDAY BUT ANOTHER
WAVE WILL APPROACH LATE WEDNESDAY THROUGH THURSDAY. AT THE SURFACE
ATLANTIC HIGH PRESSURE WILL MAINTAIN ITS CONTROL...KEEPING
SOUTHERLY FLOW IN LOW-LEVELS AND ALLOWING DAILY SEABREEZE
CIRCULATIONS TO DEVELOP. CONVECTIVE COVERAGE WILL VARY SOMEWHAT
BETWEEN THE THREE DAYS WITH WEDNESDAY CURRENTLY LOOKING LIKE THE
LEAST ACTIVE DAY DUE TO A LACK OF APPRECIABLE UPPER ENERGY TO WORK
WITH. HIGH TEMPS WILL CLIMB INTO THE MID TO UPPER 80S WITH LOWS IN
THE MIDDLE 60S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
FAIRLY GOOD MODEL CONSISTENCY REGARDING AN UPPER TROUGH SHIFTING
SOUTHEAST AND A COLD FRONTAL PASSAGE FRIDAY OR FRIDAY NIGHT. DRY AND
SLIGHTLY COOLER CANADIAN HIGH PRESSURE LOOKS TO BUILD IN FOR THE
WEEKEND BEFORE SHIFTING OFFSHORE EARLY NEXT WEEK.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
KCHS...VFR WEATHER TO PREVAIL OVERNIGHT UNTIL LATE. A FEED OF
ABUNDANT MOISTURE AND ASSOCIATED CONVERGENCE WILL PRODUCE
SCATTERED CONVECTION THIS MORNING. WHILE MUCH OF THIS ACTIVITY LOOKS
TO REMAIN EAST OF THE TERMINAL PRIOR TO DAYBREAK...MODELS DEVELOP
CONVECTIVE RAINS AROUND DAWN AND THEN RAIN CHANCES FOR THE REST OF
TODAY LOOK PRETTY GOOD AS DEEP MOISTURE INTERACTS WITH THE UPPER
TROUGH AND THE SEA BREEZE. SHOWERS/TSTMS SHOULD DECREASE LATE DAY
WITH MAINLY VFR CONDITIONS THIS EVENING.
KSAV...VFR OVERNIGHT WEATHER COULD DROP TO THE MVFR RANGE IN
LIGHT FOG/LOW STRATUS LATE. THERE IS THEN A DECENT CHANCE OF
SHRA AND POSSIBLE TSRA FROM 16-22Z MONDAY WITH SEVERAL MESO-SCALE
BOUNDARIES IN PLACE AIDED BY A SHORT WAVE ALOFT. MVFR WEATHER CAN
CERTAINLY OCCUR PERIODICALLY DURING THIS TIME.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS TUE THROUGH THU...ALTHOUGH EARLY
MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
THROUGH TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER
THE ATLANTIC WILL EXTEND W ACROSS THE COASTAL WATERS...GENERATING
SE AND S WINDS OF 10-15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THURSDAY
NIGHT WITH SEABREEZE CIRCULATIONS DEVELOPING EACH AFTERNOON. A COLD
FRONT WILL DROP THROUGH FRIDAY EVENING OR SATURDAY MORNING WITH A
NORTHEAST FLOW DEVELOPING AS CANADIAN HIGH PRESSURE BUILDS IN. WINDS
AND SEAS WILL LIKELY INCREASE OVER THE WEEKEND IN RESPONSE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 200527
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
127 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
TUESDAY. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL UNTIL LATE WEEK.
A COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO
SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
COMPLICATED PATTERN OVER THE REGION EARLY THIS MORNING WITH A MID
LEVEL TROUGH OVER THE INLAND CAROLINAS AND N GEORGIA. CLOUDS HAVE
DISSIPATED MANY AREAS AND WE WILL LOOK FOR SOME POTENTIAL FOR
PATCHY FOG AND LOW CLOUDS OVERNIGHT...ESPECIALLY INLAND ZONES.
WE HAVE SHOWN LITTLE TO NO POPS THROUGH 2 AM...BEFORE POPS RAMP
UP THEREAFTER...WITH THE GREATEST COVERAGE /40-50 PERCENT/ TO
OCCUR AFTER 3 OR 4 AM AND MAINLY OVER CHARLESTON AND BERKELEY
COUNTIES WHERE THE BEST LIFT/MOISTURE WILL BE FOUND. LOW TEMPS
WILL BE IN THE UPPER 60S AND LOWER 70S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
THE SHORTWAVE TROUGH ALOFT WILL BE SITUATED OVER THE REGION MONDAY
THEN WILL WEAKEN/UNRAVEL AND HIGHER PWATS SHOULD BE SHUNTED INLAND
TUESDAY AS HEIGHTS TEMPORARILY BUILD ALOFT AND ATLANTIC SURFACE HIGH
PRESSURE EXPANDS WESTWARD. THUS...EXPECT GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS MONDAY AS COMPARED TO TUESDAY.
MONDAY...FORECASTS INDICATE HIGH CHANCE/LIKELY POPS AT MANY
LOCATIONS AWAY FROM THE BEACHES AROUND THE TIME OF MAX HEATING
MIDDAY UNTIL LATE AFTERNOON. THEN...CAPPED GREATEST POPS IN CHANCE
CATEGORY AWAY FROM THE BEACHES TUESDAY AFTERNOON. HOWEVER...IF THE
SHORTWAVE TROUGH PERSISTS INTACT LONGER THAN EXPECTED...TUESDAY
COULD BECOME SOMEWHAT MORE ACTIVE THAN INDICATED IN THIS FORECAST.
CANNOT RULE OUT BRIEF/PULSE SEVERE THUNDERSTORMS MONDAY OR TUESDAY
AFTERNOON...ESPECIALLY WHERE MESOSCALE BOUNDARY INTERACTIONS
OCCUR...BUT THE PRIMARY CONCERN WILL REMAIN LOCALLY HEAVY RAIN AS
PWATS REMAIN AROUND 1.75 INCHES ESPECIALLY MONDAY AND MULTICELL
CONVECTION EXHIBITS SLOW/SOMEWHAT ERRATIC PROPAGATION.
TUESDAY...PWATS SHOULD DECREASE TO SOME DEGREE.
WEDNESDAY...TEMPERATURES IN THE UPPER 80S TO AROUND 90F WILL BECOME
MORE COMMON AS THE ATLANTIC RIDGE PREVAILS. HOWEVER...THE SYNOPTIC
SCALE UPPER TROUGH APPROACHING FROM THE WEST WILL BEGIN TO IMPACT
THE REGION...SO AT LEAST SLIGHT CHANCE/CHANCE POPS FOR DIURNAL
SHOWERS/THUNDERSTORMS ARE JUSTIFIED DUE TO THE INFLUENCE OF THE SEA
BREEZE AND THE UPPER TROUGH.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
KCHS...VFR WEATHER TO PREVAIL OVERNIGHT UNTIL LATE. A FEED OF
ABUNDANT MOISTURE AND ASSOCIATED CONVERGENCE WILL PRODUCE
SCATTERED CONVECTION THIS MORNING. WHILE MUCH OF THIS ACTIVITY LOOKS
TO REMAIN EAST OF THE TERMINAL PRIOR TO DAYBREAK...MODELS DEVELOP
CONVECTIVE RAINS AROUND DAWN AND THEN RAIN CHANCES FOR THE REST OF
TODAY LOOK PRETTY GOOD AS DEEP MOISTURE INTERACTS WITH THE UPPER
TROUGH AND THE SEA BREEZE. SHOWERS/TSTMS SHOULD DECREASE LATE DAY
WITH MAINLY VFR CONDITIONS THIS EVENING.
KSAV...VFR OVERNIGHT WEATHER COULD DROP TO THE MVFR RANGE IN
LIGHT FOG/LOW STRATUS LATE. THERE IS THEN A DECENT CHANCE OF
SHRA AND POSSIBLE TSRA FROM 16-22Z MONDAY WITH SEVERAL MESO-SCALE
BOUNDARIES IN PLACE AIDED BY A SHORT WAVE ALOFT. MVFR WEATHER CAN
CERTAINLY OCCUR PERIODICALLY DURING THIS TIME.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY...ALTHOUGH
EARLY MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER THE NW
ATLANTIC WILL EXTEND ACROSS THE COASTAL WATERS...GENERATING SE AND
SOUTH WINDS OF 10-15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
ISOLATED TO SCATTERED SHOWERS AND T-STORMS ARE EXPECTED TO DEVELOP
ALONG THE SOUTH CAROLINA COAST LATER TONIGHT.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH LATE WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4
FEET MUCH OF THE TIME. AHEAD OF AN APPROACHING COLD FRONT LATE IN
THE PERIOD...A TIGHTENING SURFACE PRESSURE GRADIENT COULD CONTRIBUTE
TO STRONGER WINDS AND BUILDING SEAS...AND THE PROBABILITY FOR LOW
END SMALL CRAFT ADVISORY CONDITIONS WILL INCREASE SOMEWHAT MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...
MARINE...
000
FXUS62 KCHS 200210
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1010 PM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
TUESDAY. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL UNTIL LATE WEEK.
A COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO
SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
DEEP RIDGING IN THE ATLANTIC AND STRETCHING FROM THE GULF OF
MEXICO INTO CANADA IS INTERRUPTED BY A SHORT WAVE FOUND NEARBY
TONIGHT. AT THE SURFACE THE FORECAST REGION WILL LIE UNDER THE
WESTERN EXTENSION OF STRONG ATLANTIC HIGH PRESSURE...AS MESO-SCALE
BOUNDARIES FROM EARLIER CONVECTION CONTINUE TO DISSIPATE.
WHILE WE CAN/T ENTIRELY RULE OUT A STRAY SHOWER OR TWO PRIOR TO
MIDNIGHT FROM ANY LEFT OUTFLOWS...OUR ATTENTION TRANSFERS OVER
THE ATLANTIC AFTER MIDNIGHT...WITH A SOUTHERLY FLOW OF RICH
TROPICAL-LIKE MOISTURE TO PREVAIL. PWATS WILL BE NEAR 1.75
INCHES...OR JUST A TAD BELOW 2 STANDARD DEVIATIONS ABOVE NORMAL.
CONVERGENCE WILL BECOME ENHANCED WITH A SOUTH TO SW FLOW WITHIN
THE FIRST MILE OF SO OF THE TROPOSPHERE. THUS WE LOOK FOR THE
POTENTIAL OF TRAINING OF ECHOES TO OCCUR AND A LOCALIZED HEAVY
RAIN RISK LATE.
WE HAVE SHOWN LITTLE TO NO POPS THROUGH 2 AM...BEFORE POPS RAMP
UP THEREAFTER...WITH THE GREATEST COVERAGE /40-50 PERCENT/ TO
OCCUR AFTER 3 OR 4 AM AND MAINLY OVER CHARLESTON AND BERKELEY
COUNTIES WHERE THE BEST LIFT/MOISTURE WILL BE FOUND.
IT/LL BE ANOTHER UNUSUALLY WARM AND MUGGY NIGHT WITH WEAK WARM
ADVECTION...PLENTIFUL CLOUD COVER AND ELEVATED DEW POINTS. LOWEST
TEMPS WILL BE IN THE UPPER 60S AND LOWER 70S...ABOUT 4-8 DEGREES
ABOVE NORMS.
GIVEN THE RAINFALL IN MANY LOCATIONS EARLIER...AND WITH SATELLITE
IMAGES SHOWING A LITTLE CLEARING ATTEMPTING TO SET IN...WE COULD
EXPERIENCE SOME LOW STRATUS AND FOG FORMATION. BUT PROBABILITIES
STILL REMAIN TOO LOW TO INCLUDE IN THE GRIDDED WEATHER ELEMENTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE SHORTWAVE TROUGH ALOFT WILL BE SITUATED OVER THE REGION MONDAY
THEN WILL WEAKEN/UNRAVEL AND HIGHER PWATS SHOULD BE SHUNTED INLAND
TUESDAY AS HEIGHTS TEMPORARILY BUILD ALOFT AND ATLANTIC SURFACE HIGH
PRESSURE EXPANDS WESTWARD. THUS...EXPECT GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS MONDAY AS COMPARED TO TUESDAY.
MONDAY...FORECASTS INDICATE HIGH CHANCE/LIKELY POPS AT MANY
LOCATIONS AWAY FROM THE BEACHES AROUND THE TIME OF MAX HEATING
MIDDAY UNTIL LATE AFTERNOON. THEN...CAPPED GREATEST POPS IN CHANCE
CATEGORY AWAY FROM THE BEACHES TUESDAY AFTERNOON. HOWEVER...IF THE
SHORTWAVE TROUGH PERSISTS INTACT LONGER THAN EXPECTED...TUESDAY
COULD BECOME SOMEWHAT MORE ACTIVE THAN INDICATED IN THIS FORECAST.
CANNOT RULE OUT BRIEF/PULSE SEVERE THUNDERSTORMS MONDAY OR TUESDAY
AFTERNOON...ESPECIALLY WHERE MESOSCALE BOUNDARY INTERACTIONS
OCCUR...BUT THE PRIMARY CONCERN WILL REMAIN LOCALLY HEAVY RAIN AS
PWATS REMAIN AROUND 1.75 INCHES ESPECIALLY MONDAY AND MULTICELL
CONVECTION EXHIBITS SLOW/SOMEWHAT ERRATIC PROPAGATION.
TUESDAY...PWATS SHOULD DECREASE TO SOME DEGREE.
WEDNESDAY...TEMPERATURES IN THE UPPER 80S TO AROUND 90F WILL BECOME
MORE COMMON AS THE ATLANTIC RIDGE PREVAILS. HOWEVER...THE SYNOPTIC
SCALE UPPER TROUGH APPROACHING FROM THE WEST WILL BEGIN TO IMPACT
THE REGION...SO AT LEAST SLIGHT CHANCE/CHANCE POPS FOR DIURNAL
SHOWERS/THUNDERSTORMS ARE JUSTIFIED DUE TO THE INFLUENCE OF THE SEA
BREEZE AND THE UPPER TROUGH.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
KCHS...VFR WEATHER TO PREVAIL AT LEAST THROUGH THE FIRST PART OF
TONIGHT. WE THEN LOOK INTO THE ATLANTIC OVERNIGHT AS A FEED OF
ABUNDANT MOISTURE AND ITS ASSOCIATED CONVERGENCE WILL PRODUCE
SCATTERED CONVECTION OVERNIGHT INTO MONDAY MORNING. WHILE MUCH OF
THIS ACTIVITY LOOKS TO REMAIN EAST OF THE TERMINAL...CHANCES ARE
SUFFICIENT ENOUGH TO MENTION VCSH AND MIST FROM 07-15Z WITH
BORDERLINE MVFR CONDITIONS TO OCCUR. A GREATER RISK OF SHRA AND
POSSIBLE TSRA WITH PERIODIC FLIGHT RESTRICTIONS THEN EXISTS FROM
15-21Z AS THE SEA BREEZE MOVES THROUGH AND INTERACTS WITH A SHORT
WAVE ALOFT AND VARIOUS OTHER MESO-SCALE BOUNDARIES.
KSAV...VFR OVERNIGHT WEATHER COULD DROP TO THE MVFR RANGE IN
LIGHT FOG/LOW STRATUS LATE TONIGHT INTO MONDAY MORNING. THERE IS
THEN A HIGH END CHANCE OF SHRA AND POSSIBLE TSRA FROM 16-22Z
MONDAY WITH SEVERAL MESO-SCALE BOUNDARIES IN PLACE AIDED BY A
SHORT WAVE ALOFT. MVFR WEATHER CAN CERTAINLY OCCUR PERIODICALLY
DURING THIS TIME.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY...ALTHOUGH
EARLY MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER THE NW
ATLANTIC WILL EXTEND ACROSS THE COASTAL WATERS...GENERATING SE AND
SOUTH WINDS OF 10-15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
MARINERS SHOULD BE ALERT FOR ISOLATED TO SCATTERED
T-STORMS...MAINLY AFTER MIDNIGHT WHICH WILL PRODUCE GUSTY
WINDS...FREQUENT LIGHTNING AND VERY HEAVY RAINS REDUCING
VISIBILITY TO NEAR ZERO AT TIMES.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH LATE WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4
FEET MUCH OF THE TIME. AHEAD OF AN APPROACHING COLD FRONT LATE IN
THE PERIOD...A TIGHTENING SURFACE PRESSURE GRADIENT COULD CONTRIBUTE
TO STRONGER WINDS AND BUILDING SEAS...AND THE PROBABILITY FOR LOW
END SMALL CRAFT ADVISORY CONDITIONS WILL INCREASE SOMEWHAT MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...
MARINE...
000
FXUS62 KCHS 192335
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
735 PM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
TUESDAY. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL UNTIL LATE WEEK.
A COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO
SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
DEEP RIDGING IN THE ATLANTIC AND STRETCHING FROM THE GULF OF
MEXICO INTO CANADA IS INTERRUPTED BY A SHORT WAVE FOUND NEARBY
TONIGHT. AT THE SURFACE THE FORECAST REGION WILL LIE UNDER THE
WESTERN EXTENSION OF STRONG ATLANTIC HIGH PRESSURE...WITH A WEAK
TROUGH AND ITS ASSOCIATED COLD POOLING JUST WEST AND SW OF THE
ALTAMAHA RIVER THIS EVENING. THIS FEATURE WILL DISSIPATE...AS WILL
OTHER LINGERING MESO-SCALE BOUNDARIES FROM EARLIER CONVECTION. BUT
WITHIN THE NOCTURNAL ENVIRONMENT MUCH OF THE ACTIVITY WILL BE IN A
DISSIPATING TREND EARLY ON. OUR ATTENTION THEN TRANSFERS OVER THE
ATLANTIC AFTER MIDNIGHT...WITH A SOUTHERLY FLOW OF RICH TROPICAL-
LIKE MOISTURE TO PREVAIL. CONVERGENCE WILL BECOME ENHANCED WITH A
SOUTH TO SW FLOW WITHIN THE FIRST MILE OF SO OF THE TROPOSPHERE.
WE LOOK FOR POTENTIAL TRAINING OF ECHOES TO OCCUR AND A LOCALIZED
HEAVY RAIN RISK LATE.
WE HAVE SHOWN SLIGHT CHANCE AND CHANCE POPS THROUGH THE
NIGHT...BUT THE BEST COVERAGE WILL OCCUR AFTER 3 OR 4 AM AND
MAINLY OVER CHARLESTON AND BERKELEY COUNTIES WHERE THE BEST
LIFT/MOISTURE WILL BE FOUND.
IT/LL BE ANOTHER UNUSUALLY WARM AND MUGGY NIGHT WITH WEAK WARM
ADVECTION...PLENTIFUL CLOUD COVER AND ELEVATED DEW POINTS. LOWEST
TEMPS WILL BE IN THE UPPER 60S AND LOWER 70S...ABOUT 4-8 DEGREES
ABOVE NORMS.
GIVEN THE RAINFALL IN MANY LOCATIONS EARLIER TODAY...SHOULD ANY
CLEARING ATTEMPT TO SET IN WE WOULD EXPERIENCE SOME FOG FORMATION.
PROBABILITIES THOUGH ARE TOO LOW TO INCLUDE IN THE GRIDDED WEATHER
ELEMENTS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE SHORTWAVE TROUGH ALOFT WILL BE SITUATED OVER THE REGION MONDAY
THEN WILL WEAKEN/UNRAVEL AND HIGHER PWATS SHOULD BE SHUNTED INLAND
TUESDAY AS HEIGHTS TEMPORARILY BUILD ALOFT AND ATLANTIC SURFACE HIGH
PRESSURE EXPANDS WESTWARD. THUS...EXPECT GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS MONDAY AS COMPARED TO TUESDAY.
MONDAY...FORECASTS INDICATE HIGH CHANCE/LIKELY POPS AT MANY
LOCATIONS AWAY FROM THE BEACHES AROUND THE TIME OF MAX HEATING
MIDDAY UNTIL LATE AFTERNOON. THEN...CAPPED GREATEST POPS IN CHANCE
CATEGORY AWAY FROM THE BEACHES TUESDAY AFTERNOON. HOWEVER...IF THE
SHORTWAVE TROUGH PERSISTS INTACT LONGER THAN EXPECTED...TUESDAY
COULD BECOME SOMEWHAT MORE ACTIVE THAN INDICATED IN THIS FORECAST.
CANNOT RULE OUT BRIEF/PULSE SEVERE THUNDERSTORMS MONDAY OR TUESDAY
AFTERNOON...ESPECIALLY WHERE MESOSCALE BOUNDARY INTERACTIONS
OCCUR...BUT THE PRIMARY CONCERN WILL REMAIN LOCALLY HEAVY RAIN AS
PWATS REMAIN AROUND 1.75 INCHES ESPECIALLY MONDAY AND MULTICELL
CONVECTION EXHIBITS SLOW/SOMEWHAT ERRATIC PROPAGATION.
TUESDAY...PWATS SHOULD DECREASE TO SOME DEGREE.
WEDNESDAY...TEMPERATURES IN THE UPPER 80S TO AROUND 90F WILL BECOME
MORE COMMON AS THE ATLANTIC RIDGE PREVAILS. HOWEVER...THE SYNOPTIC
SCALE UPPER TROUGH APPROACHING FROM THE WEST WILL BEGIN TO IMPACT
THE REGION...SO AT LEAST SLIGHT CHANCE/CHANCE POPS FOR DIURNAL
SHOWERS/THUNDERSTORMS ARE JUSTIFIED DUE TO THE INFLUENCE OF THE SEA
BREEZE AND THE UPPER TROUGH.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
KCHS...LATEST PROGNOSIS SUGGESTS THAT CONVECTION WEST OF THE
TERMINAL WILL NOT MAKE IT BEFORE IT DISSIPATES THIS EVENING...WITH
OUR ATTENTION TO THEN SHIFT TO THE ATLANTIC. A FEED OF MOISTURE
AND ITS ASSOCIATED CONVERGENCE WILL PRODUCE SCATTERED CONVECTION
OVERNIGHT INTO MONDAY MORNING. WHILE MUCH OF THIS ACTIVITY LOOKS
TO REMAIN EAST OF THE TERMINAL...CHANCES ARE SUFFICIENT ENOUGH TO
MENTION VCSH AND MIST FROM 07-15Z WITH BORDERLINE MVFR CONDITIONS
TO OCCUR. A GREATER RISK OF SHRA AND POSSIBLE TSRA WITH PERIODIC
FLIGHT RESTRICTIONS THEN EXISTS FROM 15-21Z AS THE SEA BREEZE
MOVES THROUGH AND INTERACTS WITH A SHORT WAVE ALOFT AND VARIOUS
OTHER MESO-SCALE BOUNDARIES.
KSAV...VERY LOW CHANCE THAT CONVECTION TO THE NORTH AND NW WILL
SKIRT THE AIRFIELD BEFORE DISSIPATING. OTHERWISE...VFR WEATHER
COULD DROP TO THE MVFR RANGE IN LIGHT FOG/LOW STRATUS LATE TONIGHT
INTO MONDAY MORNING. BETTER CHANCES OF SHRA AND POSSIBLE TSRA FROM
16-22Z MONDAY WITH SEVERAL MESO-SCALE BOUNDARIES IN PLACE AIDED BY
A SHORT WAVE ALOFT. MVFR WEATHER CAN CERTAINLY OCCUR PERIODICALLY
DURING THIS TIME.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY...ALTHOUGH
EARLY MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER THE NW
ATLANTIC WILL EXTEND ACROSS THE COASTAL WATERS...GENERATING SE AND
SOUTH WINDS OF 15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
MARINERS SHOULD BE ALERT FOR ISOLATED TO SCATTERED
T-STORMS...MAINLY AFTER MIDNIGHT WHICH WILL PRODUCE GUSTY
WINDS...FREQUENT LIGHTNING AND VERY HEAVY RAINS REDUCING
VISIBILITY TO NEAR ZERO AT TIMES.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH LATE WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4
FEET MUCH OF THE TIME. AHEAD OF AN APPROACHING COLD FRONT LATE IN
THE PERIOD...A TIGHTENING SURFACE PRESSURE GRADIENT COULD CONTRIBUTE
TO STRONGER WINDS AND BUILDING SEAS...AND THE PROBABILITY FOR LOW
END SMALL CRAFT ADVISORY CONDITIONS WILL INCREASE SOMEWHAT MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...
MARINE...
000
FXUS62 KCHS 192014
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
414 PM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
TUESDAY. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL UNTIL LATE WEEK.
A COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO
SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
THIS AFTERNOON...ONGOING SHOWERS/THUNDERSTORMS CONTINUE WITH THE
BULK OF THE ACTIVITY ACROSS SOUTHEAST GA AND INTO SOUTHEAST SC ALONG
THE SAVANNAH RIVER. THE FOCUS FOR THE STRONGEST CONVECTION WILL
CONTINUE TO BE LOCATIONS CLOSER TO THE ALTAMAHA NEAR THE AXIS OF
BEST INSTABILITY AND WHERE THE BEST INSOLATION TOOK PLACE OVER THE
LAST FEW HOURS. STORMS ROUGHLY ALONG AND SOUTH OF I-16 MAY BRIEFLY
BECOME SEVERE WITH HAIL TO THE SIZE OF QUARTERS AND STRONG DAMAGING
WIND GUSTS. THE OVERALL SEVERE THREAT IS STILL LOW HOWEVER AND WILL
BE ISOLATED AT BEST.
TONIGHT...THE OVERALL SYNOPTIC SETUP WILL BE SIMILAR TO LAST NIGHT
WITH THE BAGGY MID-LEVEL DISTURBANCE POSITIONED TO THE NORTH AND
MOIST SOUTHERLY/SOUTHEASTERLY FLOW AROUND ATLANTIC HIGH PRESSURE AT
THE SURFACE. ONCE THE LINGERING EVENING STORMS DIMINISH WITH THE
LOSS OF AFTERNOON HEATING...THERE WILL BE A PERIOD OF MINIMAL PRECIP
COVERAGE UNTIL LATE TONIGHT. IN THE LATE NIGHT PERIOD...THE VARIOUS
HI-RES MODELS SHOW ANOTHER ROUND OF PRECIP MOVING ONSHORE FROM THE
ATLANTIC AND AFFECTING MAINLY THE SC COASTLINE. DEEP MOISTURE WITH
PWATS AROUND 1.7 INCHES AND SUBTLE CONVERGENCE WITHIN THE ONSHORE
SOUTHERLY FLOW WILL BE THE PRIMARY DRIVER. POPS FEATURE A WEST TO
EAST GRADIENT WITH SLIGHT CHANCES TO THE WEST AND HIGH CHANCES TO
THE EAST ACROSS CHARLESTON COUNTY. THE PRESENCE OF ELEVATED
INSTABILITY ABOVE THE NOCTURNAL INVERSION WILL KEEP THUNDER IN THE
FORECAST...BUT THE THREAT OF SEVERE WEATHER IS LOW. MORE OF A
CONCERN IS LOCALLY HEAVY RAINFALL...ESPECIALLY SINCE MANY LOCATIONS
ACROSS EASTERN CHARLESTON COUNTY SAW OVER 2 INCHES OF RAIN OVERNIGHT
LAST NIGHT. TEMPS WILL CONTINUE TO BE VERY MILD...ONLY FALLING INTO
THE UPPER 60S TO LOW 70S.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE SHORTWAVE TROUGH ALOFT WILL BE SITUATED OVER THE REGION MONDAY
THEN WILL WEAKEN/UNRAVEL AND HIGHER PWATS SHOULD BE SHUNTED INLAND
TUESDAY AS HEIGHTS TEMPORARILY BUILD ALOFT AND ATLANTIC SURFACE HIGH
PRESSURE EXPANDS WESTWARD. THUS...EXPECT GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS MONDAY AS COMPARED TO TUESDAY.
MONDAY...FORECASTS INDICATE HIGH CHANCE/LIKELY POPS AT MANY
LOCATIONS AWAY FROM THE BEACHES AROUND THE TIME OF MAX HEATING
MIDDAY UNTIL LATE AFTERNOON. THEN...CAPPED GREATEST POPS IN CHANCE
CATEGORY AWAY FROM THE BEACHES TUESDAY AFTERNOON. HOWEVER...IF THE
SHORTWAVE TROUGH PERSISTS INTACT LONGER THAN EXPECTED...TUESDAY
COULD BECOME SOMEWHAT MORE ACTIVE THAN INDICATED IN THIS FORECAST.
CANNOT RULE OUT BRIEF/PULSE SEVERE THUNDERSTORMS MONDAY OR TUESDAY
AFTERNOON...ESPECIALLY WHERE MESOSCALE BOUNDARY INTERACTIONS
OCCUR...BUT THE PRIMARY CONCERN WILL REMAIN LOCALLY HEAVY RAIN AS
PWATS REMAIN AROUND 1.75 INCHES ESPECIALLY MONDAY AND MULTICELL
CONVECTION EXHIBITS SLOW/SOMEWHAT ERRATIC PROPAGATION.
TUESDAY...PWATS SHOULD DECREASE TO SOME DEGREE.
WEDNESDAY...TEMPERATURES IN THE UPPER 80S TO AROUND 90F WILL BECOME
MORE COMMON AS THE ATLANTIC RIDGE PREVAILS. HOWEVER...THE SYNOPTIC
SCALE UPPER TROUGH APPROACHING FROM THE WEST WILL BEGIN TO IMPACT
THE REGION...SO AT LEAST SLIGHT CHANCE/CHANCE POPS FOR DIURNAL
SHOWERS/THUNDERSTORMS ARE JUSTIFIED DUE TO THE INFLUENCE OF THE SEA
BREEZE AND THE UPPER TROUGH.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
AT KSAV...THE MOST IMMEDIATE CONCERN IS DIRECT IMPACTS FROM
THUNDERSTORMS OVER THE NEXT 4-5 HOURS. CURRENTLY NUMEROUS SHOWERS
ARE DEVELOPING IN THE VICINITY AND A PREVAILING VCTS IS BEING
CARRIED IN THE FORECAST. STILL CAN/T SAY WITH TOTAL CONFIDENCE
THAT A THUNDERSTORM WILL MOVE DIRECTLY OVER THE AIRFIELD BUT I
HAVE ADDED A TEMPO FOR MVFR TSRA BETWEEN 20-22Z. THE MAIN IMPACT
WILL BE REDUCED VISIBILITIES IN HEAVY CONVECTIVE RAINS...BUT GUSTY
WINDS CANNOT BE RULED OUT. THEN OVERNIGHT...THE MAIN FORECAST
PROBLEM WILL BE THE DEVELOPMENT OF MVFR CEILINGS. I HAVE KEPT THE
FORECAST SCATTERED AT THE MVFR LEVEL...BUT SUBSEQUENT TAF
ISSUANCES MAY NEED TO GO PREVAILING MVFR.
AT KCHS...AFTERNOON SHOWER/THUNDERSTORM DEVELOPMENT OCCURRED NEAR
THE AIRFIELD AND THEN PUSHED INLAND. BASED ON EXTENSIVE CLOUD
COVER...THIS AREA SHOULD REMAIN MAINLY PRECIP FREE FOR THE
REMAINDER OF THE AFTERNOON SO I HAVE KEPT ANY MENTION OF
SHOWERS/STORMS OUT OF THE FORECAST. THE MAIN FORECAST ISSUE FOR
CHS OVERNIGHT IS THE DEVELOPMENT OF MVFR LEVEL CEILINGS AND
SHOWERS LATE. MODELS ONCE AGAIN HINT AT AN AXIS OF SHOWERS
STREAMING IN FROM OFFSHORE AND INTO MUCH OF CHARLESTON COUNTY LATE
TONIGHT. CONFIDENCE IN THE EXACT PLACEMENT OF THESE SHOWERS ISN/T
HIGH BUT COVERAGE SHOULD BE HIGH ENOUGH SUCH THAT A SHRA MENTION
IS WARRANTED. ALSO...THE FORECAST FEATURES PREVAILING MVFR
CEILINGS STARTING AT 10Z.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED SHOWERS
AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE
IN THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY...ALTHOUGH EARLY
MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH LATE WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4
FEET MUCH OF THE TIME. AHEAD OF AN APPROACHING COLD FRONT LATE IN
THE PERIOD...A TIGHTENING SURFACE PRESSURE GRADIENT COULD CONTRIBUTE
TO STRONGER WINDS AND BUILDING SEAS...AND THE PROBABILITY FOR LOW
END SMALL CRAFT ADVISORY CONDITIONS WILL INCREASE SOMEWHAT MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BSH
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...BSH/SPR
MARINE...BSH/SPR
000
FXUS62 KCHS 191807
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
207 PM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL DISSIPATE OVER THE AREA THROUGH TUESDAY.
OTHERWISE ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE
THROUGH FRIDAY WHEN A COLD FRONT DROPS INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS AFTERNOON...AS EXPECTED SHOWERS AND THUNDERSTORMS HAVE
BLOSSOMED WITHIN THIS UNCAPPED AND MOIST ATMOSPHERE. THE ACTIVITY
HAS BEEN CONCENTRATED MAINLY ALONG I-95 AND AREAS JUST TO THE EAST
ACROSS THE TRI-COUNTY. LOCATIONS FURTHER WEST ACROSS INLAND
SOUTHEAST GA HAVE REMAINED NEARLY PRECIP FREE MOSTLY THANKS TO THE
THICK CLOUD COVER OVERHEAD. SO FAR THESE THUNDERSTORMS HAVE BEEN
PRETTY TAME DUE TO UNIMPRESSIVE MID LEVELS WHICH HAS KEPT UPDRAFTS
FROM BECOMING TOO ROBUST. THIS OVERALL TREND WILL CONTINUE WITH
LOTS OF COVERAGE BUT NONE BECOMING TOO STRONG. IF THERE IS AN AREA
WITH A HIGHER THREAT OF SEVERE THUNDERSTORMS IT IS THE NORTHWEST
TO SOUTHEAST ORIENTED CORRIDOR OF TATTNALL...LONG...AND MCINTOSH
COUNTIES. VISIBLE SATELLITE IMAGERY SHOWS MUCH MORE INSOLATION AND
IT IS MUCH CLOSER TO THE AXIS OF HIGHER MLCAPES. THE MAIN THREAT
WILL BE FROM WINDS WHERE MULTICELL CLUSTERS ARE ABLE TO ORGANIZE
AND INITIATE A COLD POOL.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
THE MID LEVEL DISTURBANCE TO THE N WILL DRIFT TOWARD THE FOOTHILLS
OF VIRGINIA/NORTH CAROLINA BY LATE TONIGHT. CONVECTIVE RAINS WILL
LINGER THROUGH THE EVENING OVER INLAND AREAS WITH A GRADUAL TREND
TOWARD DECREASING COVERAGE/INTENSITY OF CONVECTION AFTER SUNSET...
ESPECIALLY OVER INLAND SE GEORGIA. IN SOUTH CAROLINA ADJACENT TO THE
MIDLANDS AND PEE DEE REGIONS...WE MAY SEE CONVECTIVE RAINS HANG
ON INTO THE NIGHT. LATE NIGHT SHOWERS/ISOLATED TSTMS ALSO POSSIBLE
ALONG COASTAL SOUTH CAROLINA WHERE SPEED/MOISTURE CONVERGENCE
INCREASE AFTER MIDNIGHT.
A JUICY AIRMASS WILL RESIDE ACROSS THE FORECAST AREA MONDAY INTO
TUESDAY WITH PW VALUES HOVERING AROUND 1.8 INCHES. UPPER SHORTWAVE
ENERGY WILL BE OVER THE AREA ON MONDAY BEFORE DISSIPATING MONDAY
NIGHT AND TUESDAY AS WEAK UPPER RIDGING OCCURS. THE BEST COVERAGE OF
SHOWERS AND TSTMS IS EXPECTED MONDAY WITH DIMINISHING COVERAGE EACH
DAY THEREAFTER. THE INCREASING UPPER HEIGHTS WILL ALSO RESULT IN A
GRADUAL WARMING TREND WITH INLAND HIGHS CLIMBING BACK TO NEAR 90 BY
WEDNESDAY. SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ON MONDAY
GIVEN DECENT INSTABILITY COMBINED WITH THE UPPER FORCING...
UNSEASONABLY HIGH PRECIPITABLE WATER VALUES AND STEERING FLOW LESS
THAN 10 KT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AT KSAV...THE MOST IMMEDIATE CONCERN IS DIRECT IMPACTS FROM
THUNDERSTORMS OVER THE NEXT 4-5 HOURS. CURRENTLY NUMEROUS SHOWERS
ARE DEVELOPING IN THE VICINITY AND A PREVAILING VCTS IS BEING
CARRIED IN THE FORECAST. STILL CAN/T SAY WITH TOTAL CONFIDENCE
THAT A THUNDERSTORM WILL MOVE DIRECTLY OVER THE AIRFIELD BUT I
HAVE ADDED A TEMPO FOR MVFR TSRA BETWEEN 20-22Z. THE MAIN IMPACT
WILL BE REDUCED VISIBILITIES IN HEAVY CONVECTIVE RAINS...BUT GUSTY
WINDS CANNOT BE RULED OUT. THEN OVERNIGHT...THE MAIN FORECAST
PROBLEM WILL BE THE DEVELOPMENT OF MVFR CEILINGS. I HAVE KEPT THE
FORECAST SCATTERED AT THE MVFR LEVEL...BUT SUBSEQUENT TAF
ISSUANCES MAY NEED TO GO PREVAILING MVFR.
AT KCHS...AFTERNOON SHOWER/THUNDERSTORM DEVELOPMENT OCCURRED NEAR
THE AIRFIELD AND THEN PUSHED INLAND. BASED ON EXTENSIVE CLOUD
COVER...THIS AREA SHOULD REMAIN MAINLY PRECIP FREE FOR THE
REMAINDER OF THE AFTERNOON SO I HAVE KEPT ANY MENTION OF
SHOWERS/STORMS OUT OF THE FORECAST. THE MAIN FORECAST ISSUE FOR
CHS OVERNIGHT IS THE DEVELOPMENT OF MVFR LEVEL CEILINGS AND
SHOWERS LATE. MODELS ONCE AGAIN HINT AT AN AXIS OF SHOWERS
STREAMING IN FROM OFFSHORE AND INTO MUCH OF CHARLESTON COUNTY LATE
TONIGHT. CONFIDENCE IN THE EXACT PLACEMENT OF THESE SHOWERS ISN/T
HIGH BUT COVERAGE SHOULD BE HIGH ENOUGH SUCH THAT A SHRA MENTION
IS WARRANTED. ALSO...THE FORECAST FEATURES PREVAILING MVFR
CEILINGS STARTING AT 10Z.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES ASSOCIATED WITH SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE IN
THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY.
&&
.MARINE...
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS AVERAGING LESS THAN 15 KNOTS THROUGH TONIGHT. SEAS THIS MORNING
MAINLY IN THE 2 FT RANGE BUT GRADUALLY EDGING INTO THE 2 TO 4 FEET
RANGE THROUGH TONIGHT. THE 4 FT SEAS SHOULD BE RELEGATED TO OUTER
GEORGIA WATERS SEAWARD FROM GRAYS REEF.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH NEXT WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY NEXT WEEK. SEAS WILL
AVERAGE 2 TO 4 FEET MUCH OF THE TIME...ALTHOUGH SEAS AS HIGH AS
5-6 FT COULD BEGIN TO IMPINGE UPON WATERS BEYOND 20 NM BY MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH
MARINE...JRL
000
FXUS62 KCHS 191457
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1057 AM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL DISSIPATE OVER THE AREA THROUGH TUESDAY.
OTHERWISE ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE
THROUGH FRIDAY WHEN A COLD FRONT DROPS INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...LINGERING SHOWER ACTIVITY FROM THE OVERNIGHT
PERIOD HAS WRAPPED UP AND MUCH OF THE FORECAST AREA IS CURRENTLY
PRECIP FREE. THIS WON/T LAST LONG AS VISIBLE SATELLITE SHOWS CU
ALREADY FORMING UNDER THE THIN HIGH CLOUDS ACROSS SOUTHEAST GA AND
THE FIRST HINTS OF DIURNAL SHOWERS ARE SHOWING UP ON RADAR
IMAGERY. FOR TODAY...THERE ARE A LOT OF SIMILARITIES TO YESTERDAY.
THE BAGGY MID-LEVEL TROUGH PERSISTS TO THE NORTHWEST...AN ONGOING
AND LEFTOVER CONVECTIVE COMPLEX IS UPSTREAM ACROSS NORTH/CENTRAL
GA...AND MID/HIGH LEVEL CLOUDS ASSOCIATED WITH IT ARE SPREADING
ACROSS INLAND COUNTIES. SOME DIFFERENCES TO YESTERDAY INCLUDE
WARMER 500 MB TEMPS...BUT ALSO COOLER 850 MB TEMPS WHICH WILL
RESULT IN LITTLE TO NO CAP THROUGH THE DAY. IN SUMMARY...WE ARE
LEFT WITH AN INCREASINGLY MOIST AIRMASS WITH NO
CAP...WEAK/MODERATE INSTABILITY. CONVECTIVE INITIATION AND
COVERAGE WILL LARGELY BE DETERMINED BY MESOSCALE BOUNDARY
INTERACTIONS FROM OUTFLOW ORIGINATING FROM THE UPSTREAM
CONVECTION...AND THE INLAND PENETRATING SEABREEZE. RECENT RUNS OF
HI-RES MODELS SHOW A CONVECTION DISTRIBUTION SIMILAR TO
YESTERDAY...FAVORING AREAS ALONG AND WEST OF I-95. FOR POPS I HAVE
MORE CLOSELY FOLLOWED THE HRRR WHICH HAD THE BEST REPRESENTATION
OF THE MORNING SHOWERS. I HAVE INCREASED POPS TO LIKELY FOR THE
REGION ALONG AND WEST OF I-95. REGARDING THE SEVERE THREAT...NO
PARAMETERS REALLY JUMP OFF THE PAGE AND THE BEST CHANCE FOR AN
ISOLATED SEVERE STORM WILL BE WHERE THE STRONGEST BOUNDARY
INTERACTIONS OCCUR. IF A STORM WERE TO BECOME SEVERE IT WILL
LIKELY ONLY BE SO FOR A VERY SHORT PERIOD OF TIME DUE TO THE PULSE
NATURE OF THE CONVECTION. OF SLIGHTLY MORE CONCERN IS THE HEAVY
RAIN POTENTIAL. PWATS WILL BE QUITE HIGH...MAXING OUT AROUND 2
STANDARD DEVIATIONS ABOVE NORMAL...AND RAINFALL PRODUCTION WILL BE
QUITE EFFICIENT. SINCE THE AREAS WHERE POPS ARE THE HIGHEST
RECEIVED THE MOST RAIN YESTERDAY...LOCALLY EXCESSIVE RAINFALL
COULD RESULT IN MINOR FLOODING OF LOW LYING AND POOR DRAINAGE
AREAS. TEMPS WILL REACH THE LOW TO MID 80S...WITH SOME POTENTIAL
TO BE HIGHER IN AREAS THAT SEE MORE BREAKS IN CLOUD COVER THIS
AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
THE MID LEVEL DISTURBANCE TO THE N WILL DRIFT TOWARD THE FOOTHILLS
OF VIRGINIA/NORTH CAROLINA BY LATE TONIGHT. CONVECTIVE RAINS WILL
LINGER THROUGH THE EVENING OVER INLAND AREAS WITH A GRADUAL TREND
TOWARD DECREASING COVERAGE/INTENSITY OF CONVECTION AFTER SUNSET...
ESPECIALLY OVER INLAND SE GEORGIA. IN SOUTH CAROLINA ADJACENT TO THE
MIDLANDS AND PEE DEE REGIONS...WE MAY SEE CONVECTIVE RAINS HANG
ON INTO THE NIGHT. LATE NIGHT SHOWERS/ISOLATED TSTMS ALSO POSSIBLE
ALONG COASTAL SOUTH CAROLINA WHERE SPEED/MOISTURE CONVERGENCE
INCREASE AFTER MIDNIGHT.
A JUICY AIRMASS WILL RESIDE ACROSS THE FORECAST AREA MONDAY INTO
TUESDAY WITH PW VALUES HOVERING AROUND 1.8 INCHES. UPPER SHORTWAVE
ENERGY WILL BE OVER THE AREA ON MONDAY BEFORE DISSIPATING MONDAY
NIGHT AND TUESDAY AS WEAK UPPER RIDGING OCCURS. THE BEST COVERAGE OF
SHOWERS AND TSTMS IS EXPECTED MONDAY WITH DIMINISHING COVERAGE EACH
DAY THEREAFTER. THE INCREASING UPPER HEIGHTS WILL ALSO RESULT IN A
GRADUAL WARMING TREND WITH INLAND HIGHS CLIMBING BACK TO NEAR 90 BY
WEDNESDAY. SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ON MONDAY
GIVEN DECENT INSTABILITY COMBINED WITH THE UPPER FORCING...
UNSEASONABLY HIGH PRECIPITABLE WATER VALUES AND STEERING FLOW LESS
THAN 10 KT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
AT KSAV...CONSENSUS OF 00Z AND 06Z HIGH RESOLUTION GUIDANCE
SUGGESTS THE TERMINAL WILL BE IMPACTED BY AT LEAST TSTMS IN THE
VICINITY OF THE I-95 CORRIDOR THIS AFTERNOON. WE HAVE INTRODUCED
TEMPO TSRA FROM 18Z-22Z BUT SUSPECT TIMING/COVERAGE WILL NEED
ADJUSTMENTS AS RADAR TRENDS BECOME BETTER DEFINED. THERE IS A RISK
FOR ADDITIONAL CONVECTIVE RAINS TONIGHT BUT CONFIDENCE IS GREATER
FOR AREAS TO THE NORTH AND WE HAVE LEANED TOWARD A VFR FORECAST
TONIGHT.
AT KCHS...THERE HAS BEEN VCSH THIS MORNING BUT THE BRUNT OF THE
OVERNIGHT CONVECTIVE RAINS DEVELOPED SLIGHTLY UP THE COAST FROM
THE TERMINAL. WE THINK SHOWERS OR EVEN AN ISOLATED TSTM COULD
DEVELOP THIS MORNING BUT CONFIDENCE IS LOW FOR ANY SIGNIFICANT
COVERAGE...SO MORNING VCSH FOR NOW. MODELS FAIRLY EMPHATIC KEEPING
WIDESPREAD AFTERNOON CONVECTION MAINLY W AND SW OF THE TERMINAL.
TONIGHT COULD BE A DIFFERENT STORY AS MOISTURE CONVERGENCE AND AN
UPPER DISTURBANCE EXPECTED TO ADDITIONAL SHOWERS AND A FEW TSTMS.
A BIT EARLY FOR ANYTHING PREVAILING BUT WE HAVE A VCSH FOR AFTER
MIDNIGHT.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES ASSOCIATED WITH SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE IN
THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY.
&&
.MARINE...
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS AVERAGING LESS THAN 15 KNOTS THROUGH TONIGHT. SEAS THIS MORNING
MAINLY IN THE 2 FT RANGE BUT GRADUALLY EDGING INTO THE 2 TO 4 FEET
RANGE THROUGH TONIGHT. THE 4 FT SEAS SHOULD BE RELEGATED TO OUTER
GEORGIA WATERS SEAWARD FROM GRAYS REEF.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH NEXT WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY NEXT WEEK. SEAS WILL
AVERAGE 2 TO 4 FEET MUCH OF THE TIME...ALTHOUGH SEAS AS HIGH AS
5-6 FT COULD BEGIN TO IMPINGE UPON WATERS BEYOND 20 NM BY MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 191137
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
737 AM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL DISSIPATE OVER THE AREA THROUGH TUESDAY.
OTHERWISE ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE
THROUGH FRIDAY WHEN A COLD FRONT DROPS INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE MAIN MID LEVEL DISTURBANCE IS FORECAST TO SAG ESE INTO THE
MOUNTAINS OF NORTH CAROLINA WHILE A BAGGY UPPER TROUGH TAKES SHAPE
OVER OUR FORECAST REGION. UNSETTLED WEATHER CONDITIONS ARE EXPECTED
TO EXPAND IN COVERAGE BY THIS AFTERNOON...ESPECIALLY ALONG AND W
OF INTERSTATE 95. DIURNAL CONVECTION WILL DEVELOP IN A REGIME
MARKED BY DEEP MOISTURE AND LOW LEVEL CONVERGENCE ENHANCED BY THE
LATE SEA BREEZE OSCILLATION. THE BIG FORECAST QUESTION AT DAYBREAK
IS HOW BOUNDARIES FROM UPSTREAM CONVECTION OVER NE GEORGIA PLAY
INTO THE MIX OVER OUR WESTERN ZONES TODAY. MODELS HAVE COME AROUND
TO INDICATE THE BETTER INSTABILITY WILL DEVELOP ACROSS OUR INLAND
AREAS AND OUR POP SCHEME TRENDED TOWARD LIKELY POPS ALONG AND W OF
I-95 THIS AFTERNOON WITH CHANCE POPS TOWARD THE IMMEDIATE COAST.
SKY COVER IS TRICKY TODAY BUT TRENDS FROM OVERNIGHT SUGGEST THE
BETTER CHANCES FOR ANY SUBSTANTIAL INSOLATION WOULD BE ALONG AND
S OF I-16 IN GEORGIA. MOSTLY CLOUDY CONDITIONS SHOULD BE THE
STORY FOR MOST AREAS WITH PLENTIFUL MID AND HIGH CLOUDS. WITH VARIOUS
MODELS INDICATING 2500 J/KG OF SB CAPE OVER CENTRAL/WESTERN
AREAS...THERE BE COULD BE ISOLATED STRONG TO SEVERE TSTMS MAINLY
ALONG/W OF I-95 WHERE BOUNDARIES INTERACT. MID LEVEL INSTABILITY
IS MARGINAL WITH WEAK LAPSE RATES BUT CANNOT RULE OUT SOME
POTENTIAL FOR WET MICROBURSTS AND MOSTLY SMALL HAIL. LOCALLY HEAVY
RAINFALL IS ALSO POSSIBLE GIVEN PWATS BETWEEN 1.5 AND 1.8 INCHES
WITHIN A RELATIVELY WEAK STEERING FLOW REGIME.
WE MADE VERY FEW CHANGES TO MAX TEMPS AND SURFACE WINDS TODAY...
CONSIDERABLE CLOUD COVERAGE IS EXPECTED TO KEEP MOST AREAS IN THE MID
80S OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
THE MID LEVEL DISTURBANCE TO THE N WILL DRIFT TOWARD THE FOOTHILLS
OF VIRGINIA/NORTH CAROLINA BY LATE TONIGHT. CONVECTIVE RAINS WILL
LINGER THROUGH THE EVENING OVER INLAND AREAS WITH A GRADUAL TREND
TOWARD DECREASING COVERAGE/INTENSITY OF CONVECTION AFTER SUNSET...
ESPECIALLY OVER INLAND SE GEORGIA. IN SOUTH CAROLINA ADJACENT TO THE
MIDLANDS AND PEE DEE REGIONS...WE MAY SEE CONVECTIVE RAINS HANG
ON INTO THE NIGHT. LATE NIGHT SHOWERS/ISOLATED TSTMS ALSO POSSIBLE
ALONG COASTAL SOUTH CAROLINA WHERE SPEED/MOISTURE CONVERGENCE
INCREASE AFTER MIDNIGHT.
A JUICY AIRMASS WILL RESIDE ACROSS THE FORECAST AREA MONDAY INTO
TUESDAY WITH PW VALUES HOVERING AROUND 1.8 INCHES. UPPER SHORTWAVE
ENERGY WILL BE OVER THE AREA ON MONDAY BEFORE DISSIPATING MONDAY
NIGHT AND TUESDAY AS WEAK UPPER RIDGING OCCURS. THE BEST COVERAGE OF
SHOWERS AND TSTMS IS EXPECTED MONDAY WITH DIMINISHING COVERAGE EACH
DAY THEREAFTER. THE INCREASING UPPER HEIGHTS WILL ALSO RESULT IN A
GRADUAL WARMING TREND WITH INLAND HIGHS CLIMBING BACK TO NEAR 90 BY
WEDNESDAY. SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ON MONDAY
GIVEN DECENT INSTABILITY COMBINED WITH THE UPPER FORCING...
UNSEASONABLY HIGH PRECIPITABLE WATER VALUES AND STEERING FLOW LESS
THAN 10 KT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
AT KSAV...CONSENSUS OF 00Z AND 06Z HIGH RESOLUTION GUIDANCE
SUGGESTS THE TERMINAL WILL BE IMPACTED BY AT LEAST TSTMS IN THE
VICINITY OF THE I-95 CORRIDOR THIS AFTERNOON. WE HAVE INTRODUCED
TEMPO TSRA FROM 18Z-22Z BUT SUSPECT TIMING/COVERAGE WILL NEED
ADJUSTMENTS AS RADAR TRENDS BECOME BETTER DEFINED. THERE IS A RISK
FOR ADDITIONAL CONVECTIVE RAINS TONIGHT BUT CONFIDENCE IS GREATER
FOR AREAS TO THE NORTH AND WE HAVE LEANED TOWARD A VFR FORECAST
TONIGHT.
AT KCHS...THERE HAS BEEN VCSH THIS MORNING BUT THE BRUNT OF THE
OVERNIGHT CONVECTIVE RAINS DEVELOPED SLIGHTLY UP THE COAST FROM
THE TERMINAL. WE THINK SHOWERS OR EVEN AN ISOLATED TSTM COULD
DEVELOP THIS MORNING BUT CONFIDENCE IS LOW FOR ANY SIGNIFICANT
COVERAGE...SO MORNING VCSH FOR NOW. MODELS FAIRLY EMPHATIC KEEPING
WIDESPREAD AFTERNOON CONVECTION MAINLY W AND SW OF THE TERMINAL.
TONIGHT COULD BE A DIFFERENT STORY AS MOISTURE CONVERGENCE AND AN
UPPER DISTURBANCE EXPECTED TO ADDITIONAL SHOWERS AND A FEW TSTMS.
A BIT EARLY FOR ANYTHING PREVAILING BUT WE HAVE A VCSH FOR AFTER
MIDNIGHT.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES ASSOCIATED WITH SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE IN
THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY.
&&
.MARINE...
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS AVERAGING LESS THAN 15 KNOTS THROUGH TONIGHT. SEAS THIS MORNING
MAINLY IN THE 2 FT RANGE BUT GRADUALLY EDGING INTO THE 2 TO 4 FEET
RANGE THROUGH TONIGHT. THE 4 FT SEAS SHOULD BE RELEGATED TO OUTER
GEORGIA WATERS SEAWARD FROM GRAYS REEF.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH NEXT WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY NEXT WEEK. SEAS WILL
AVERAGE 2 TO 4 FEET MUCH OF THE TIME...ALTHOUGH SEAS AS HIGH AS
5-6 FT COULD BEGIN TO IMPINGE UPON WATERS BEYOND 20 NM BY MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 190814
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
414 AM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL DISSIPATE OVER THE AREA THROUGH TUESDAY.
OTHERWISE ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT WEATHER FEATURE
THROUGH FRIDAY WHEN A COLD FRONT DROPS INTO THE AREA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PRE-DAWN...AN 850 MB THERMAL RIDGE EXTENDED N THROUGH THE FORECAST
AREA OVERNIGHT AND CONVECTION WAS STARTING TO REDEVELOP AT IT/S NOSE
ALONG COASTAL CHARLESTON COUNTY AT 4 AM. CLOUDS HAVE BEEN PREVALENT
MANY AREAS ALTHOUGH SOME CLEARING WAS NOTED TO THE S OF I-16 IN
GEORGIA. WE ADDED SOME PATCHY FOG TO THE FORECAST IN SOME OF
GEORGIA ZONES WHERE THE CLOUDS SCATTERED OUT OVERNIGHT. TEMPS
INLAND 65-69 DEGREES...BUT STILL VERY MILD ALONG COASTAL SOUTH
CAROLINA WITH READINGS IN THE LOWER 70S.
TODAY...THE MAIN MID LEVEL DISTURBANCE IS FORECAST TO SAG ESE
INTO THE MOUNTAINS OF NORTH CAROLINA WHILE A BAGGY UPPER TROUGH
TAKES SHAPE OVER OUR FORECAST REGION. UNSETTLED WEATHER CONDITIONS
ARE EXPECTED TO EXPAND IN COVERAGE BY THIS AFTERNOON...ESPECIALLY
ALONG AND W OF INTERSTATE 95. DIURNAL CONVECTION WILL DEVELOP IN A
REGIME MARKED BY DEEP MOISTURE AND LOW LEVEL CONVERGENCE ENHANCED
BY THE LATE SEA BREEZE OSCILLATION. MODELS HAVE COME AROUND TO
INDICATE THE BETTER INSTABILITY WILL DEVELOP ACROSS OUR INLAND
AREAS AND OUR POP SCHEME TRENDED TOWARD LIKELY POPS ALONG AND W OF
I-95 THIS AFTERNOON WITH CHANCE POPS TOWARD THE IMMEDIATE COAST.
SKY COVER IS TRICKY TODAY BUT TRENDS FROM OVERNIGHT SUGGEST THE
BETTER CHANCES FOR ANY SUBSTANTIAL INSOLATION WOULD BE ALONG AND
S OF I-16 IN GEORGIA. MOSTLY CLOUDY CONDITIONS SHOULD BE THE
STORY FOR MOST AREAS. WITH VARIOUS MODELS INDICATING 2500 J/KG OF
SB CAPE OVER CENTRAL/WESTERN AREAS...THERE BE COULD BE ISOLATED
STRONG TO SEVERE TSTMS MAINLY ALONG/W OF I-95 WHERE BOUNDARIES
INTERACT. MID LEVEL INSTABILITY IS MARGINAL WITH WEAK LAPSE RATES
BUT CANNOT RULE OUT SOME POTENTIAL FOR WET MICROBURSTS AND MOSTLY
SMALL HAIL. LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE GIVEN PWATS
BETWEEN 1.5 AND 1.8 INCHES WITHIN A RELATIVELY WEAK STEERING FLOW
REGIME.
WE MADE VERY FEW CHANGES TO MAX TEMPS AND SURFACE WINDS
TODAY...CLOUDS EXPECTED TO KEEP MOST AREAS IN THE MID 80S OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
THE MID LEVEL DISTURBANCE TO THE N WILL DRIFT TOWARD THE FOOTHILLS
OF VIRGINIA/NORTH CAROLINA BY LATE TONIGHT. CONVECTIVE RAINS WILL
LINGER THROUGH THE EVENING OVER INLAND AREAS WITH A GRADUAL TREND
TOWARD DECREASING COVERAGE/INTENSITY OF CONVECTION AFTER SUNSET...
ESPECIALLY OVER INLAND SE GEORGIA. IN SOUTH CAROLINA ADJACENT TO THE
MIDLANDS AND PEE DEE REGIONS...WE MAY SEE CONVECTIVE RAINS HANG
ON INTO THE NIGHT. LATE NIGHT SHOWERS/ISOLATED TSTMS ALSO POSSIBLE
ALONG COASTAL SOUTH CAROLINA WHERE SPEED/MOISTURE CONVERGENCE
INCREASE AFTER MIDNIGHT.
A JUICY AIRMASS WILL RESIDE ACROSS THE FORECAST AREA MONDAY INTO
TUESDAY WITH PW VALUES HOVERING AROUND 1.8 INCHES. UPPER SHORTWAVE
ENERGY WILL BE OVER THE AREA ON MONDAY BEFORE DISSIPATING MONDAY
NIGHT AND TUESDAY AS WEAK UPPER RIDGING OCCURS. THE BEST COVERAGE OF
SHOWERS AND TSTMS IS EXPECTED MONDAY WITH DIMINISHING COVERAGE EACH
DAY THEREAFTER. THE INCREASING UPPER HEIGHTS WILL ALSO RESULT IN A
GRADUAL WARMING TREND WITH INLAND HIGHS CLIMBING BACK TO NEAR 90 BY
WEDNESDAY. SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ON MONDAY
GIVEN DECENT INSTABILITY COMBINED WITH THE UPPER FORCING...
UNSEASONABLY HIGH PRECIPITABLE WATER VALUES AND STEERING FLOW LESS
THAN 10 KT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
SIGNIFICANT MODEL DIFFERENCES APPEAR IN THE LONG TERM...MAINLY
REGARDING THE NEXT UPPER TROUGH THAT SHIFTS INTO THE EASTERN UNITED
STATES LATE IN THE WEEK. WE ARE TRENDING TOWARD THE ECMWF WHICH
MOVES THE UPPER TROUGH AND A COLD FRONT THROUGH THE AREA ON SATURDAY
WITH A DRY AND COOLER CANADIAN HIGH PRESSURE SYSTEM BUILDING IN
THEREAFTER. THUS WE ARE SHOWING DIURNAL...MAINLY SEABREEZE-DRIVEN
POPS THURSDAY AND FRIDAY...THEN DRY OVER THE WEEKEND.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
AT KSAV...VFR CONDITIONS OVERNIGHT BUT THERE ARE CHANCES THAT SOME
CLEARING MAY LEAD TO AREAS OF FOG TOWARD DAYBREAK. WE MAINTAINED
A TEMPO FOR MVFR VSBYS IN THE 06Z TAF. WE ALSO INTRODUCED PROBABILITIES
FOR TSTMS 17Z-21Z AS THE SEA BREEZE INTERACTS WITH DEEP MOISTURE
AND MODERATE INSTABILITY.
AT KCHS...WE HAVE INTRODUCED VCSH FOR THE MORNING HOURS NEARING DAYBREAK
UNTIL MIDDAY THEN INTRODUCED PROBABILITIES OF SHOWERS 16Z-20Z AS THE
SEA BREEZE INTERACTS WITH DEEP MOISTURE. INSTABILITY APPEARS WEAKER
THAN AREAS TO THE SW AND S OF THE TERMINAL AND WE HAVE OPTED TO
LEAVE THUNDER OUT EVEN THOUGH TSTMS ARE CERTAINLY POSSIBLE.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS IN
CEILINGS AND VISIBILITIES ASSOCIATED WITH SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES WILL BE IN
THE AFTERNOON HOURS SUNDAY THROUGH TUESDAY.
&&
.MARINE...
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS AVERAGING LESS THAN 15 KNOTS THROUGH TONIGHT. SEAS THIS MORNING
MAINLY IN THE 2 FT RANGE BUT GRADUALLY EDGING INTO THE 2 TO 4 FEET
RANGE THROUGH TONIGHT. THE 4 FT SEAS SHOULD BE RELEGATED TO OUTER
GEORGIA WATERS SEAWARD FROM GRAYS REEF.
OFFSHORE HIGH PRESSURE WILL PERSIST THROUGH NEXT WEEK...WITH
LOCALLY/BRIEFLY STRONGER ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE
DIURNAL SEA BREEZE CIRCULATION EACH DAY NEXT WEEK. SEAS WILL
AVERAGE 2 TO 4 FEET MUCH OF THE TIME...ALTHOUGH SEAS AS HIGH AS
5-6 FT COULD BEGIN TO IMPINGE UPON WATERS BEYOND 20 NM BY MID TO
LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 190540
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
140 AM EDT SUN MAY 19 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ADDITIONAL SHOWERS UPSTREAM CONTINUE TO SLOWLY PUSH TOWARD THE
FORECAST AREA TO THE W OF I-95 AND MAINLY N OF I-16 OVERNIGHT.
CERTAIN MODELS CONTINUE TO INDICATE ISOLATED TO SCATTERED
CONVECTIVE RAINS DEVELOPING ALONG COASTAL SOUTH CAROLINA LATE
TONIGHT BUT CONSENSUS WITH THE 00Z MODEL RUN IS POOR. MAINLY
SLIGHT CHANCE POPS RETAINED OVERNIGHT. SKIES HAD CLEARED A BIT TO
THE S OF I-16 IN GEORGIA AND THERE COULD BE PATCHY FOG IN THAT
REGION. LOWS IN THE 60S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KSAV...VFR CONDITIONS OVERNIGHT BUT THERE ARE CHANCES THAT SOME
CLEARING MAY LEAD TO AREAS OF FOG TOWARD DAYBREAK. WE MAINTAINED
A TEMPO FOR MVFR VSBYS IN THE 06Z TAF. WE ALSO INTRODUCED PROBABILITIES
FOR TSTMS 17Z-21Z AS THE SEA BREEZE INTERACTS WITH DEEP MOISTURE
AND MODERATE INSTABILITY.
AT KCHS...WE HAVE INTRODUCED VCSH FOR THE MORNING HOURS NEARING DAYBREAK
UNTIL MIDDAY THEN INTRODUCED PROBABILITIES OF SHOWERS 16Z-20Z AS THE
SEA BREEZE INTERACTS WITH DEEP MOISTURE. INSTABILITY APPEARS WEAKER
THAN AREAS TO THE SW AND S OF THE TERMINAL AND WE HAVE OPTED TO
LEAVE THUNDER OUT EVEN THOUGH TSTMS ARE CERTAINLY POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
OVERNIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KT
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...
MARINE...
000
FXUS62 KCHS 190108
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
908 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A FEW ISOLATED SHOWERS REMAIN...AND WHILE THESE ARE EXPECTED TO
DISSIPATE OVER THE NEXT COUPLE HOURS...ADDITIONAL SHOWERS
UPSTREAM WILL HEAD TOWARD THE NORTHERN HALF OF THE CWA
OVERNIGHT...SO I LEFT IN A LOW END CHANCE OVERNIGHT THERE...WITH
ONLY A SLIGHT CHANCE ELSEWHERE. TEMPS AND DEW POINTS ARE ON
TARGET...SO NO OTHER CHANGES WERE MADE WITH THE EVENING UPDATE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
AT KSAV...VFR CONDITIONS ARE EXPECTED THE REMAINDER OF THE
EVENING. IN THE PRE DAWN HOURS...HOWEVER...I DO HAVE THE
POTENTIAL FOR SOME MVFR VSBYS. WINDS WILL BE FAIRLY LIGHT...AND
THERE WAS SOME PRETTY HEAVY RAIN FROM THE AIRPORT WESTWARD INTO
SOUTHERN EFFINGHAM COUNTY EARLIER TODAY...SO THE INCREASE IN LOW
LEVEL AVAILABLE MOISTURE HAS LED ME TO BE MORE CONCERNED WITH FOG
DESPITE THE PLENTIFUL HIGH CLOUDS EXPECTED OVERNIGHT.
AT KCHS...OTHER THAN THICK ANVIL CLOUDS PASSING OVERHEAD...I DONT
EXPECT MUCH IN THE WAY OF WEATHER OVERNIGHT. I DO THINK THAT
THUNDERSTORMS WILL BE IN THE VICINITY OF THE TERMINAL AT SOME POINT
TOMORROW...ESPECIALLY IN THE LATER AFTERNOON...BUT I AM NOT
CONFIDENT ENOUGH IN THE TIMING OF THOSE STORMS AT THIS TIME TO
EXPLICITLY INTRODUCE THEM INTO THE TAF.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...FWA
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...FWA
MARINE...BSH/FWA/SPR
000
FXUS62 KCHS 182335
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
735 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THE CAPE HAS BEEN MOSTLY USED UP NOW...WITH THE EXCEPTION OF THE
FAR SOUTHERN PORTIONS OF THE CWA DOWN BY THE ALTAMAHA RIVER...SO
THE MAJORITY OF THE CONVECTIVE ACTIVITY IS OVER FOR THE EVENING.
HOWEVER...WITH THE SHORTWAVE STILL IN THE VICINITY...THERE REMAINS
A CHANCE OF SHOWERS FOR THE NEXT FEW HOURS. NO SHORT TERM CHANGES
TO THE GRIDS...BUT WILL UPDATE BY 930 OR SO TO ACCOUNT FOR TRENDS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AT KSAV...THE THUNDERSTORMS HAVE MOVED EAST OF THE FIELD AND
DISSIPATED...ALTHOUGH THERE ARE STILL A FEW SHOWERS UPSTREAM THAT
MAY DRIFT ACROSS THE TERMINAL FOR THE NEXT COUPLE OF HOURS. THEY
SHOULD NOT MAKE MUCH OF AN IMPACT IN TERMS OF VSBYS OR
CIGS...SO VFR CONDITIONS ARE EXPECTED THE REMAINDER OF THE EVENING.
IN THE PRE DAWN HOURS...HOWEVER...I DID ADD IN THE POTENTIAL FOR
SOME MVFR VSBYS. WINDS WILL BE FAIRLY LIGHT...AND THERE WAS SOME
PRETTY HEAVY RAIN FROM THE AIRPORT WESTWARD INTO SOUTHERN
EFFINGHAM COUNTY EARLIER TODAY...SO THE INCREASE IN LOW LEVEL
AVAILABLE MOISTURE HAS LED ME TO BE MORE CONCERNED WITH FOG
DESPITE THE PLENTIFUL HIGH CLOUDS EXPECTED OVERNIGHT.
AT KCHS...OTHER THAN THICK ANVIL CLOUDS PASSING OVERHEAD...I DONT
EXPECT MUCH IN THE WAY OF WEATHER OVERNIGHT. I DO THINK THAT
THUNDERSTORMS WILL BE IN THE VICINITY OF THE TERMINAL AT SOME POINT
TOMORROW...ESPECIALLY IN THE LATER AFTERNOON...BUT I AM NOT
CONFIDENT ENOUGH IN THE TIMING OF THOSE STORMS AT THIS TIME TO
EXPLICITLY INTRODUCE THEM INTO THE TAF.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...FWA
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...FWA
MARINE...BSH/SPR
000
FXUS62 KCHS 182135
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
535 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LATE THIS AFTERNOON...CONVECTION HAS DRIFTED SLOWLY TO THE EAST
OVER THE PAST HOUR OR TWO AND HAS NOTICEABLY WEAKENED. MUCH OF THIS
IS DUE TO DWINDLING MLCAPE AND THE HIGH CLOUDS SPAWNED BY THESE
THUNDERSTORMS WILL CONTINUE TO INHIBIT DESTABILIZATION DOWNSTREAM.
THE UPDATED POPS FAVOR THE 18/19Z HRRR WHICH SHOWS THE CURRENT
CONVECTION DISSIPATING IN PLACE. ALSO UPDATED HOURLY TEMPS WHICH
SHOW SIGNIFICANT SPATIAL VARIABILITY THANKS TO RAIN COOLED AIR AND
THUNDERSTORM OUTFLOW.
TONIGHT...WITH THE LOSS OF AFTERNOON HEATING ANY REMAINING
SHOWER/STORM ACTIVITY WILL DECREASE THIS EVENING. THROUGH THE
OVERNIGHT...THE BAGGY UPPER TROUGH ALOFT WILL CONTINUE TO MEANDER
AROUND JUST TO THE NORTH AND NORTHWEST OF THE FORECAST AREA. A
PERUSAL OF MODEL SOUNDINGS SHOWS CONTINUED MOISTENING AND THE
PRESENCE OF ELEVATED INSTABILITY THROUGH DAYBREAK. IN
FACT...SHOWALTERS GO TO AROUND -1 OR -2. MANY OF THE SUITE OF
MODELS DEPICTS SHOWER/STORM COVERAGE INCREASING LATE ACROSS MUCH
OF THE AREA AND STREAMING IN FROM OFFSHORE. POPS SHOW A DECREASING
TREND THROUGH THE EVENING AND THEN RAMP BACK UP TO CHANCE TOWARDS
SUNRISE. PLENTIFUL CLOUD COVER AND WARM SOUTHERLY FLOW WILL KEEP
LOWS IN THE MID/UPPER 60S IN MOST AREAS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AT KSAV...THE AIRFIELD DID RECEIVE A GLANCING BLOW FROM A
WEAKENING THUNDERSTORM WHICH BRIEFLY CAUSED VISIBILITY REDUCTIONS.
BASED ON CURRENT RADAR IT APPEARS THAT THUNDERSTORMS WILL REMAIN
IN THE VICINITY OF THE AIRFIELD THROUGH ABOUT 23Z BEFORE
COMPLETELY DISSIPATING. THEN OVERNIGHT...MODEL GUIDANCE SHOWS THE
POTENTIAL FOR DEVELOPING MVFR CEILINGS LATE WHICH THEN CONTINUES
THROUGH MUCH OF THE MORNING. STILL NOT CONFIDENT ENOUGH TO
ADVERTISE PREVAILING MVFR CONDITIONS SO I HAVE JUST ADDED A
MENTION OF SCATTERED MVFR LEVEL CLOUDS.
AT KCHS...AFTERNOON THUNDERSTORMS ARE EXPECTED TO REMAIN WEST OF
THE AREA. THE MAIN THING TO KEEP AN EYE ON IS THE OVERNIGHT PERIOD
WHEN MUCH OF THE MODEL GUIDANCE SHOWS ISOLATED/SCATTERED SHOWERS
DEVELOPING ALONG THE SC COASTLINE WITHIN SOME WEAK CONVERGENCE. I
HAVE INTRODUCED VCSH STARTING AT 09Z AND WITH ANY SHOWERS THAT DO
DEVELOP MVFR CEILINGS ARE POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...BSH
MARINE...BSH/SPR
000
FXUS62 KCHS 182000
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
400 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
THIS AFTERNOON...ONGOING SHOWER/THUNDERSTORM DEVELOPMENT WILL
CONTINUE TO BE CONCENTRATED MAINLY ALONG AND WEST OF I-95 THROUGH
THE EARLY EVENING. SO FAR...THESE STORMS HAVE BEEN VERY PULSEY AND
UNABLE TO SUSTAIN GOOD CORES FOR VERY LONG. THE FREEZING LEVEL IS
AROUND 12.5 KFT AND THE -20C LEVEL IS AROUND 23.5 KFT. THE MAIN
THREATS WILL BE SMALL HAIL AND GUSTY WINDS...THOUGH ONE OR TWO
STORMS COULD BECOME STRONG ENOUGH TO WARRANT A SEVERE THUNDERSTORM
WARNING...ESPECIALLY WHERE OUTFLOW AND SEABREEZE BOUNDARY
INTERACTIONS OCCUR.
TONIGHT...WITH THE LOSS OF AFTERNOON HEATING ANY REMAINING
SHOWER/STORM ACTIVITY WILL DECREASE AND BECOME CONTAINED FURTHER TO
THE WEST. THROUGH THE OVERNIGHT...THE BAGGY UPPER TROUGH ALOFT WILL
CONTINUE TO MEANDER AROUND JUST TO THE NORTH AND NORTHWEST OF THE
FORECAST AREA. A PERUSAL OF MODEL SOUNDINGS SHOWS CONTINUED
MOISTENING AND THE PRESENCE OF ELEVATED INSTABILITY THROUGH
DAYBREAK. IN FACT...SHOWALTERS GO TO AROUND -1 OR -2. MANY OF THE
SUITE OF MODELS DEPICTS SHOWER/STORM COVERAGE INCREASING LATE
ACROSS MUCH OF THE AREA AND STREAMING IN FROM OFFSHORE. POPS SHOW A
DECREASING TREND THROUGH THE EVENING AND THEN RAMP BACK UP TO CHANCE
TOWARDS SUNRISE. PLENTIFUL CLOUD COVER AND WARM SOUTHERLY FLOW WILL
KEEP LOWS IN THE MID/UPPER 60S IN MOST AREAS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
AT KSAV...THE MOST IMMEDIATE CONCERN IS THE POTENTIAL FOR
THUNDERSTORM DEVELOPMENT IN THE VICINITY OVER THE NEXT FEW HOURS.
MOST HI-RES MODEL RUNS SHOW STORMS LINING UP ROUGHLY NORTH/SOUTH
WITH THE EASTERN EXTENT BEING RIGHT NEAR THE AIRFIELD. CONFIDENCE
IS LOW IN DIRECT IMPACTS SO I HAVE ADDED A VCTS/CB FOR THE 19-21Z
TIME FRAME. WILL AMEND BASED ON RADAR TRENDS. THEN
OVERNIGHT...MODEL GUIDANCE SHOWS THE POTENTIAL FOR DEVELOPING MVFR
CEILINGS LATE WHICH THEN CONTINUES THROUGH MUCH OF THE MORNING.
STILL NOT CONFIDENT ENOUGH TO ADVERTISE PREVAILING MVFR CONDITIONS
SO I HAVE JUST ADDED A MENTION OF SCATTERED MVFR LEVEL CLOUDS.
AT KCHS...AFTERNOON THUNDERSTORMS ARE EXPECTED TO REMAIN WEST OF
THE AREA. THE MAIN THING TO KEEP AN EYE ON IS THE OVERNIGHT PERIOD
WHEN MUCH OF THE MODEL GUIDANCE SHOWS ISOLATED/SCATTERED SHOWERS
DEVELOPING ALONG THE SC COASTLINE WITHIN SOME WEAK CONVERGENCE. I
HAVE INTRODUCED VCSH STARTING AT 09Z AND WITH ANY SHOWERS THAT DO
DEVELOP MVFR CEILINGS ARE POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...BSH
MARINE...BSH/SPR
000
FXUS62 KCHS 181753
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
153 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH MONDAY.
ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT FEATURE THROUGH MUCH OF
NEXT WEEK BEFORE A COLD FRONT APPROACHES FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS AFTERNOON...NO CHANGE IN THE FORECAST THINKING FROM THE
MORNING. MADE SOME MINOR TWEAKS TO SKY AND HOURLY TEMPS/DEWPOINTS.
PREVIOUS DISCUSSION FOLLOWS BELOW.
LATE THIS MORNING...ONGOING CONVECTION AND SHOWER ACTIVITY HAS
REMAINED JUST TO OUR WEST ACROSS CENTRAL GA. CLOUD TOPS HAVE SHOWN
A WARMING TREND AND IT APPEARS THE BEST FOCUS FOR ADDITIONAL
CONVECTION HAS SHIFTED WESTWARD ACROSS EASTERN AL. THE MAIN IMPACT
FROM THIS COMPLEX WILL LIKELY BE IN THE FORM OF MID/HIGH LEVEL
CLOUDS AND THE PRESENCE OF DIFFERENTIAL HEATING BOUNDARIES ACROSS
SOUTHEAST GA. ALOFT...THE MID LEVEL TROUGH AND ASSOCIATED ENERGY
WILL CONTINUE TO SLOWLY MEANDER EASTWARD...WITH THE BEST SUPPORT
REMAINING JUST TO THE WEST. THIS LINES UP WELL WITH WHERE THE
DIFFERENTIAL HEATING BOUNDARIES WILL BE...ALONG WITH THE BEST
SURFACE BASED INSTABILITY. THE SUITE OF RECENT MODEL GUIDANCE
SEEMS TO AGREE THAT THE BEST CHANCES FOR SCATTERED CONVECTION
CONTINUE TO BE ALONG AND WEST OF I-95 THIS AFTERNOON. LOCATIONS
EAST OF I-95 STILL APPEAR TO HAVE WARMER 850 MB TEMPS AND A MORE
PERSISTENT CAP WHICH WILL LIMIT COVERAGE TO ISOLATED AT BEST. I
HAVE MADE SOME MARGINAL INCREASES TO POPS IN THE SCATTERED
AREA...BUT STILL LIMIT THE MAGNITUDE TO CHANCE. REGARDING THE
POTENTIAL FOR STRONG/SEVERE STORMS...THE OVERALL RISK STILL
APPEARS LOW. MODEL SOUNDINGS SHOW 500 MB FLOW AROUND 25 KTS AND
WET BULB ZERO HEIGHTS ABOUT 1500 FT LESS THAN THE FREEZING LEVEL
FOR A FEW HOURS. SO THERE IS A SMALL CHANCE OF A STORM OR TWO
BECOMING CAPABLE OF PRODUCING STRONG WINDS/HAIL...BUT THE RISK IS
STILL LOW ENOUGH TO PRECLUDE A HWO MENTION AT THIS POINT. WITH
PLENTIFUL SUNSHINE OCCURRING THIS MORNING WE SHOULD HAVE NO
TROUBLE MAXIMIZING OUR POTENTIAL HIGHS BASED ON THICKNESSES.
MID/UPPER 80S ARE STILL ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
ANY EARLY EVENING CONVECTION WITH THE SEA BREEZE MAY TEND TO DRIFT
TOWARD THE COAST BUT ALSO LIKELY DISSIPATE QUICKLY WITH LOSS OF
SURFACE HEATING. OVERNIGHT...MODELS DELIVER A BIT MORE UPPER LEVEL
NW FLOW AND DEEPER LAYERED INSTABILITY WHICH COULD LEAD TO ISOLATED
CONVECTIVE RAINS JUST ABOUT ANYWHERE LATE...SLIGHT CHANCE POPS
AFTER MIDNIGHT WERE MAINTAINED. PARTLY TO MOSTLY CLOUDY SKIES ON
TAP WITH TEMPS IN THE 60S ONCE AGAIN.
A FAIRLY ROBUST SHORTWAVE TROUGH WILL BE NORTH OF THE AREA ON SUNDAY
BUT DROP SOUTHEAST INTO CENTRAL SOUTH CAROLINA ON MONDAY. MEANWHILE
WITH ATLANTIC HIGH PRESSURE JUST OFF THE COAST...A SOUTH-SOUTHEAST
FLOW WILL MAINTAIN A FAIRLY JUICY AIRMASS. PW READINGS POTENTIALLY
EXCEED 1.80 INCHES ON MONDAY. SOME MID AND HIGH CLOUDS WILL SOMEWHAT
LIMIT HEATING SUNDAY AND MONDAY BUT HIGHS WILL LIKELY STILL CLIMB
INTO THE UPPER 80S FAR INLAND WITH MIDDLE 80S ELSEWHERE. THE UPPER
HEIGHT FALLS AND STEEPENING MID-LEVEL LAPSE RATES ASSOCIATED WITH
THE SHORTWAVE ENERGY WILL PROVIDE A FAVORABLE ENVIRONMENT FOR
SCATTERED TO NUMEROUS SHOWERS AND TSTMS BOTH DAYS. INSTABILITY
PARAMETERS INDICATE SOME STRONG STORMS WILL BE POSSIBLE EITHER DAY.
IN ADDITION...WITH PW VALUES NEAR THE 99TH PERCENTILE FOR MAY AND
0-6 KM MEAN WINDS LESS THAN 10 KT...LOCALLY HEAVY RAINFALL WILL
ALSO BE A CONCERN.
THE UPPER VORT ENERGY WILL SHIFT OFFSHORE MONDAY NIGHT WITH
SHORTWAVE RIDGING FOR TUESDAY. ONLY ISOLATED AIRMASS CONVECTION
EXPECTED TUESDAY...PRIMARILY DRIVEN BY THE SEABREEZE SO WE HAVE
SLIGHT CHANCE POPS. TEMPS WILL BE A FEW DEGREES WARMER DUE TO MORE
SUN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KSAV...THE MOST IMMEDIATE CONCERN IS THE POTENTIAL FOR
THUNDERSTORM DEVELOPMENT IN THE VICINITY OVER THE NEXT FEW HOURS.
MOST HI-RES MODEL RUNS SHOW STORMS LINING UP ROUGHLY NORTH/SOUTH
WITH THE EASTERN EXTENT BEING RIGHT NEAR THE AIRFIELD. CONFIDENCE
IS LOW IN DIRECT IMPACTS SO I HAVE ADDED A VCTS/CB FOR THE 19-21Z
TIME FRAME. WILL AMEND BASED ON RADAR TRENDS. THEN
OVERNIGHT...MODEL GUIDANCE SHOWS THE POTENTIAL FOR DEVELOPING MVFR
CEILINGS LATE WHICH THEN CONTINUES THROUGH MUCH OF THE MORNING.
STILL NOT CONFIDENT ENOUGH TO ADVERTISE PREVAILING MVFR CONDITIONS
SO I HAVE JUST ADDED A MENTION OF SCATTERED MVFR LEVEL CLOUDS.
AT KCHS...AFTERNOON THUNDERSTORMS ARE EXPECTED TO REMAIN WEST OF
THE AREA. THE MAIN THING TO KEEP AN EYE ON IS THE OVERNIGHT PERIOD
WHEN MUCH OF THE MODEL GUIDANCE SHOWS ISOLATED/SCATTERED SHOWERS
DEVELOPING ALONG THE SC COASTLINE WITHIN SOME WEAK CONVERGENCE. I
HAVE INTRODUCED VCSH STARTING AT 09Z AND WITH ANY SHOWERS THAT DO
DEVELOP MVFR CEILINGS ARE POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT
IMPACTS FROM ISOLATED TO SCATTERED MAINLY AFTERNOON
SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL PERSIST OFF THE COAST WITH A SOUTH TO
SOUTHEAST FLOW RANGING FROM 10 TO 15 KNOTS PERSISTING. SEAS WILL
AVERAGE 2 TO 4 FEET THROUGH WEDNESDAY WITH SOME BUILDING OF SEAS
LATE WEEK AS THE GRADIENT TIGHTENS A BIT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...BSH
MARINE...JRL
000
FXUS62 KCHS 181439
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1039 AM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH MONDAY.
ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT FEATURE THROUGH MUCH OF
NEXT WEEK BEFORE A COLD FRONT APPROACHES FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...ONGOING CONVECTION AND SHOWER ACTIVITY HAS
REMAINED JUST TO OUR WEST ACROSS CENTRAL GA. CLOUD TOPS HAVE SHOWN
A WARMING TREND AND IT APPEARS THE BEST FOCUS FOR ADDITIONAL
CONVECTION HAS SHIFTED WESTWARD ACROSS EASTERN AL. THE MAIN IMPACT
FROM THIS COMPLEX WILL LIKELY BE IN THE FORM OF MID/HIGH LEVEL
CLOUDS AND THE PRESENCE OF DIFFERENTIAL HEATING BOUNDARIES ACROSS
SOUTHEAST GA. ALOFT...THE MID LEVEL TROUGH AND ASSOCIATED ENERGY
WILL CONTINUE TO SLOWLY MEANDER EASTWARD...WITH THE BEST SUPPORT
REMAINING JUST TO THE WEST. THIS LINES UP WELL WITH WHERE THE
DIFFERENTIAL HEATING BOUNDARIES WILL BE...ALONG WITH THE BEST
SURFACE BASED INSTABILITY. THE SUITE OF RECENT MODEL GUIDANCE
SEEMS TO AGREE THAT THE BEST CHANCES FOR SCATTERED CONVECTION
CONTINUE TO BE ALONG AND WEST OF I-95 THIS AFTERNOON. LOCATIONS
EAST OF I-95 STILL APPEAR TO HAVE WARMER 850 MB TEMPS AND A MORE
PERSISTENT CAP WHICH WILL LIMIT COVERAGE TO ISOLATED AT BEST. I
HAVE MADE SOME MARGINAL INCREASES TO POPS IN THE SCATTERED
AREA...BUT STILL LIMIT THE MAGNITUDE TO CHANCE. REGARDING THE
POTENTIAL FOR STRONG/SEVERE STORMS...THE OVERALL RISK STILL
APPEARS LOW. MODEL SOUNDINGS SHOW 500 MB FLOW AROUND 25 KTS AND
WET BULB ZERO HEIGHTS ABOUT 1500 FT LESS THAN THE FREEZING LEVEL
FOR A FEW HOURS. SO THERE IS A SMALL CHANCE OF A STORM OR TWO
BECOMING CAPABLE OF PRODUCING STRONG WINDS/HAIL...BUT THE RISK IS
STILL LOW ENOUGH TO PRECLUDE A HWO MENTION AT THIS POINT. WITH
PLENTIFUL SUNSHINE OCCURRING THIS MORNING WE SHOULD HAVE NO
TROUBLE MAXIMIZING OUR POTENTIAL HIGHS BASED ON THICKNESSES.
MID/UPPER 80S ARE STILL ON TRACK.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
ANY EARLY EVENING CONVECTION WITH THE SEA BREEZE MAY TEND TO DRIFT
TOWARD THE COAST BUT ALSO LIKELY DISSIPATE QUICKLY WITH LOSS OF
SURFACE HEATING. OVERNIGHT...MODELS DELIVER A BIT MORE UPPER LEVEL
NW FLOW AND DEEPER LAYERED INSTABILITY WHICH COULD LEAD TO ISOLATED
CONVECTIVE RAINS JUST ABOUT ANYWHERE LATE...SLIGHT CHANCE POPS
AFTER MIDNIGHT WERE MAINTAINED. PARTLY TO MOSTLY CLOUDY SKIES ON
TAP WITH TEMPS IN THE 60S ONCE AGAIN.
A FAIRLY ROBUST SHORTWAVE TROUGH WILL BE NORTH OF THE AREA ON SUNDAY
BUT DROP SOUTHEAST INTO CENTRAL SOUTH CAROLINA ON MONDAY. MEANWHILE
WITH ATLANTIC HIGH PRESSURE JUST OFF THE COAST...A SOUTH-SOUTHEAST
FLOW WILL MAINTAIN A FAIRLY JUICY AIRMASS. PW READINGS POTENTIALLY
EXCEED 1.80 INCHES ON MONDAY. SOME MID AND HIGH CLOUDS WILL SOMEWHAT
LIMIT HEATING SUNDAY AND MONDAY BUT HIGHS WILL LIKELY STILL CLIMB
INTO THE UPPER 80S FAR INLAND WITH MIDDLE 80S ELSEWHERE. THE UPPER
HEIGHT FALLS AND STEEPENING MID-LEVEL LAPSE RATES ASSOCIATED WITH
THE SHORTWAVE ENERGY WILL PROVIDE A FAVORABLE ENVIRONMENT FOR
SCATTERED TO NUMEROUS SHOWERS AND TSTMS BOTH DAYS. INSTABILITY
PARAMETERS INDICATE SOME STRONG STORMS WILL BE POSSIBLE EITHER DAY.
IN ADDITION...WITH PW VALUES NEAR THE 99TH PERCENTILE FOR MAY AND
0-6 KM MEAN WINDS LESS THAN 10 KT...LOCALLY HEAVY RAINFALL WILL
ALSO BE A CONCERN.
THE UPPER VORT ENERGY WILL SHIFT OFFSHORE MONDAY NIGHT WITH
SHORTWAVE RIDGING FOR TUESDAY. ONLY ISOLATED AIRMASS CONVECTION
EXPECTED TUESDAY...PRIMARILY DRIVEN BY THE SEABREEZE SO WE HAVE
SLIGHT CHANCE POPS. TEMPS WILL BE A FEW DEGREES WARMER DUE TO MORE
SUN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 06Z SUNDAY.
ISOLATED CONVECTION COULD DEVELOP LATER THIS AFTERNOON MAINLY
WEST OF THE I-95 CORRIDOR...PROBABILITIES OF ANY CONVECTION
IMPACTING THE TERMINALS ARE TOO LOW TO INCLUDE IN THE FORECAST AT
THIS TIME. DEEPER MOISTURE MOVES INTO THE TAF CORRIDOR LATER
TONIGHT AND THERE IS A POSSIBILITY FOR MVFR CIGS...ESPECIALLY AT
KSAV. BOTH TERMINALS COULD ALSO SEE AN OVERNIGHT SHOWER BUT FOR
BOTH THESE SCENARIOS...CONFIDENCE IS PRETTY LOW AT THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT
IMPACTS FROM ISOLATED TO SCATTERED MAINLY AFTERNOON
SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL PERSIST OFF THE COAST WITH A SOUTH TO
SOUTHEAST FLOW RANGING FROM 10 TO 15 KNOTS PERSISTING. SEAS WILL
AVERAGE 2 TO 4 FEET THROUGH WEDNESDAY WITH SOME BUILDING OF SEAS
LATE WEEK AS THE GRADIENT TIGHTENS A BIT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 181134
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
734 AM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH MONDAY.
ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT FEATURE THROUGH MUCH OF
NEXT WEEK BEFORE A COLD FRONT APPROACHES FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
QUITE A FEW TRICKY ELEMENTS TO OUR FORECAST TODAY...HOWEVER THE
OVERALL SYNOPTIC PATTERN REMAINS SIMILAR WITH THE OFFSHORE ATLC
RIDGE REFUSING TO BUDGE AND THE SURFACE RIDGE AXIS STILL POKING W
THROUGH NORTHERN FLORIDA.
DEEPER MOISTURE BETWEEN 850MB-500MB AND A POCKET OF UPPER FORCING
WITH THE UPSTREAM SHORT WAVE IS EXPECTED TO REMAIN OVER THE
WESTERN CAROLINAS INTO VIRGINIA TODAY. AS THE 925MB-850MB TROUGH
PULLS MORE N THAN E WITH TIME....THERE WILL LIKELY BE A LOW LEVEL
TROUGH/CONVERGENCE ZONE SETTING UP ALONG AND JUST W OF INTERSTATE
95 THIS AFTERNOON. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT LATER TODAY...ESPECIALLY
ANCHORED IN THIS FAIRLY NARROW CORRIDOR OF LOW LEVEL MOISTURE
CONVERGENCE. MID LEVEL INSTABILITY IS NOT VERY IMPRESSIVE WITH MID
LEVEL LAPSE RATES -5.5C TO -6C IN THE 700MB TO 500MB LAYER AND
SHOWALTER INDICES RUNNING SLIGHTLY POSITIVE. SIMILAR TO PREVIOUS
THINKING WE CHANNELED SLIGHT CHANCE TO CHANCE POPS ALONG THE I-95
CORRIDOR. IT STILL LOOKS UNLIKELY WE WILL SEE MANY INTENSE UPDRAFTS
AND MUCH IN THE WAY OF SEVERE WEATHER.
SKY COVER PROGS ARE TOUCH AND GO AS TIME/HEIGHT CROSS SECTIONS
SHOWING COPIOUS HIGH LEVEL MOISTURE STREAMING THROUGH BUT PRE-DAWN
SATELLITE IMAGERY HINTING THAT WE MAY SEE MORE IN THE WAY OF
SUNSHINE AT LEAST OVER THE SE HALF OF THE FORECAST AREA. OF COURSE
CLOUDS WILL HAVE AN IMPACT ON HIGH TEMPS AND OVERALL PERSISTENCE
WAS MAINTAINED WITH MAX TEMPS IN THE MID TO UPPER 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
ANY EARLY EVENING CONVECTION WITH THE SEA BREEZE MAY TEND TO DRIFT
TOWARD THE COAST BUT ALSO LIKELY DISSIPATE QUICKLY WITH LOSS OF
SURFACE HEATING. OVERNIGHT...MODELS DELIVER A BIT MORE UPPER LEVEL
NW FLOW AND DEEPER LAYERED INSTABILITY WHICH COULD LEAD TO ISOLATED
CONVECTIVE RAINS JUST ABOUT ANYWHERE LATE...SLIGHT CHANCE POPS
AFTER MIDNIGHT WERE MAINTAINED. PARTLY TO MOSTLY CLOUDY SKIES ON
TAP WITH TEMPS IN THE 60S ONCE AGAIN.
A FAIRLY ROBUST SHORTWAVE TROUGH WILL BE NORTH OF THE AREA ON SUNDAY
BUT DROP SOUTHEAST INTO CENTRAL SOUTH CAROLINA ON MONDAY. MEANWHILE
WITH ATLANTIC HIGH PRESSURE JUST OFF THE COAST...A SOUTH-SOUTHEAST
FLOW WILL MAINTAIN A FAIRLY JUICY AIRMASS. PW READINGS POTENTIALLY
EXCEED 1.80 INCHES ON MONDAY. SOME MID AND HIGH CLOUDS WILL SOMEWHAT
LIMIT HEATING SUNDAY AND MONDAY BUT HIGHS WILL LIKELY STILL CLIMB
INTO THE UPPER 80S FAR INLAND WITH MIDDLE 80S ELSEWHERE. THE UPPER
HEIGHT FALLS AND STEEPENING MID-LEVEL LAPSE RATES ASSOCIATED WITH
THE SHORTWAVE ENERGY WILL PROVIDE A FAVORABLE ENVIRONMENT FOR
SCATTERED TO NUMEROUS SHOWERS AND TSTMS BOTH DAYS. INSTABILITY
PARAMETERS INDICATE SOME STRONG STORMS WILL BE POSSIBLE EITHER DAY.
IN ADDITION...WITH PW VALUES NEAR THE 99TH PERCENTILE FOR MAY AND
0-6 KM MEAN WINDS LESS THAN 10 KT...LOCALLY HEAVY RAINFALL WILL
ALSO BE A CONCERN.
THE UPPER VORT ENERGY WILL SHIFT OFFSHORE MONDAY NIGHT WITH
SHORTWAVE RIDGING FOR TUESDAY. ONLY ISOLATED AIRMASS CONVECTION
EXPECTED TUESDAY...PRIMARILY DRIVEN BY THE SEABREEZE SO WE HAVE
SLIGHT CHANCE POPS. TEMPS WILL BE A FEW DEGREES WARMER DUE TO MORE
SUN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 06Z SUNDAY.
ISOLATED CONVECTION COULD DEVELOP LATER THIS AFTERNOON MAINLY
WEST OF THE I-95 CORRIDOR...PROBABILITIES OF ANY CONVECTION
IMPACTING THE TERMINALS ARE TOO LOW TO INCLUDE IN THE FORECAST AT
THIS TIME. DEEPER MOISTURE MOVES INTO THE TAF CORRIDOR LATER
TONIGHT AND THERE IS A POSSIBILITY FOR MVFR CIGS...ESPECIALLY AT
KSAV. BOTH TERMINALS COULD ALSO SEE AN OVERNIGHT SHOWER BUT FOR
BOTH THESE SCENARIOS...CONFIDENCE IS PRETTY LOW AT THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT
IMPACTS FROM ISOLATED TO SCATTERED MAINLY AFTERNOON
SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL PERSIST OFF THE COAST WITH A SOUTH TO
SOUTHEAST FLOW RANGING FROM 10 TO 15 KNOTS PERSISTING. SEAS WILL
AVERAGE 2 TO 4 FEET THROUGH WEDNESDAY WITH SOME BUILDING OF SEAS
LATE WEEK AS THE GRADIENT TIGHTENS A BIT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 180811
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
411 AM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH MONDAY.
ATLANTIC HIGH PRESSURE WILL BE THE DOMINANT FEATURE THROUGH MUCH OF
NEXT WEEK BEFORE A COLD FRONT APPROACHES FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PRE-DAWN...CONVECTIVE RAINS HAVE CAMPED OUT OVERNIGHT ACROSS NORTH
GEORGIA AS A MID LEVEL SHORT WAVE LIFTS TOWARD THE WESTERN CAROLINAS.
OUR REGION HAS REMAINED DRY WITH CLOUDS SLOW TO WORK INTO INLAND
ZONES. TEMPS WERE IN THE 60S ONCE AGAIN THIS MORNING WITH LIGHT OR
NEAR CALM WINDS MANY AREAS.
QUITE A FEW TRICKY ELEMENTS TO OUR FORECAST TODAY...HOWEVER THE
OVERALL SYNOPTIC PATTERN REMAINS SIMILAR WITH THE OFFSHORE ATLC
RIDGE REFUSING TO BUDGE AND THE SURFACE RIDGE AXIS STILL POKING W
THROUGH NORTHERN FLORIDA.
DEEPER MOISTURE BETWEEN 850MB-500MB AND A POCKET OF UPPER FORCING
WITH THE UPSTREAM SHORT WAVE IS EXPECTED TO REMAIN OVER THE
WESTERN CAROLINAS INTO VIRGINIA TODAY. AS THE 925MB-850MB TROUGH
PULLS MORE N THAN E WITH TIME....THERE WILL LIKELY BE A LOW LEVEL
TROUGH/CONVERGENCE ZONE SETTING UP ALONG AND JUST W OF INTERSTATE
95 THIS AFTERNOON. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT LATER TODAY...ESPECIALLY
ANCHORED IN THIS FAIRLY NARROW CORRIDOR OF LOW LEVEL MOISTURE
CONVERGENCE. MID LEVEL INSTABILITY IS NOT VERY IMPRESSIVE WITH MID
LEVEL LAPSE RATES -5.5C TO -6C IN THE 700MB TO 500MB LAYER AND
SHOWALTER INDICES RUNNING SLIGHTLY POSITIVE. SIMILAR TO PREVIOUS
THINKING WE CHANNELED SLIGHT CHANCE TO CHANCE POPS ALONG THE I-95
CORRIDOR. IT STILL LOOKS UNLIKELY WE WILL SEE MANY INTENSE UPDRAFTS
AND MUCH IN THE WAY OF SEVERE WEATHER.
SKY COVER PROGS ARE TOUCH AND GO AS TIME/HEIGHT CROSS SECTIONS
SHOWING COPIOUS HIGH LEVEL MOISTURE STREAMING THROUGH BUT PRE-DAWN
SATELLITE IMAGERY HINTING THAT WE MAY SEE MORE IN THE WAY OF
SUNSHINE AT LEAST OVER THE SE HALF OF THE FORECAST AREA. OF COURSE
CLOUDS WILL HAVE AN IMPACT ON HIGH TEMPS AND OVERALL PERSISTENCE
WAS MAINTAINED WITH MAX TEMPS IN THE MID TO UPPER 80S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
ANY EARLY EVENING CONVECTION WITH THE SEA BREEZE MAY TEND TO DRIFT
TOWARD THE COAST BUT ALSO LIKELY DISSIPATE QUICKLY WITH LOSS OF
SURFACE HEATING. OVERNIGHT...MODELS DELIVER A BIT MORE UPPER LEVEL
NW FLOW AND DEEPER LAYERED INSTABILITY WHICH COULD LEAD TO ISOLATED
CONVECTIVE RAINS JUST ABOUT ANYWHERE LATE...SLIGHT CHANCE POPS
AFTER MIDNIGHT WERE MAINTAINED. PARTLY TO MOSTLY CLOUDY SKIES ON
TAP WITH TEMPS IN THE 60S ONCE AGAIN.
A FAIRLY ROBUST SHORTWAVE TROUGH WILL BE NORTH OF THE AREA ON SUNDAY
BUT DROP SOUTHEAST INTO CENTRAL SOUTH CAROLINA ON MONDAY. MEANWHILE
WITH ATLANTIC HIGH PRESSURE JUST OFF THE COAST...A SOUTH-SOUTHEAST
FLOW WILL MAINTAIN A FAIRLY JUICY AIRMASS. PW READINGS POTENTIALLY
EXCEED 1.80 INCHES ON MONDAY. SOME MID AND HIGH CLOUDS WILL SOMEWHAT
LIMIT HEATING SUNDAY AND MONDAY BUT HIGHS WILL LIKELY STILL CLIMB
INTO THE UPPER 80S FAR INLAND WITH MIDDLE 80S ELSEWHERE. THE UPPER
HEIGHT FALLS AND STEEPENING MID-LEVEL LAPSE RATES ASSOCIATED WITH
THE SHORTWAVE ENERGY WILL PROVIDE A FAVORABLE ENVIRONMENT FOR
SCATTERED TO NUMEROUS SHOWERS AND TSTMS BOTH DAYS. INSTABILITY
PARAMETERS INDICATE SOME STRONG STORMS WILL BE POSSIBLE EITHER DAY.
IN ADDITION...WITH PW VALUES NEAR THE 99TH PERCENTILE FOR MAY AND
0-6 KM MEAN WINDS LESS THAN 10 KT...LOCALLY HEAVY RAINFALL WILL
ALSO BE A CONCERN.
THE UPPER VORT ENERGY WILL SHIFT OFFSHORE MONDAY NIGHT WITH
SHORTWAVE RIDGING FOR TUESDAY. ONLY ISOLATED AIRMASS CONVECTION
EXPECTED TUESDAY...PRIMARILY DRIVEN BY THE SEABREEZE SO WE HAVE
SLIGHT CHANCE POPS. TEMPS WILL BE A FEW DEGREES WARMER DUE TO MORE
SUN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 06Z SUNDAY.
ISOLATED CONVECTION COULD DEVELOP LATER THIS AFTERNOON MAINLY
WEST OF THE I-95 CORRIDOR...PROBABILITIES OF ANY CONVECTION
IMPACTING THE TERMINALS ARE TOO LOW TO INCLUDE IN THE FORECAST AT
THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT
IMPACTS FROM ISOLATED TO SCATTERED MAINLY AFTERNOON
SHOWERS/THUNDERSTORMS THROUGH EARLY NEXT WEEK.
&&
.MARINE...
ATLANTIC HIGH PRESSURE WILL PERSIST OFF THE COAST WITH A SOUTH TO
SOUTHEAST FLOW RANGING FROM 10 TO 15 KNOTS PERSISTING. SEAS WILL
AVERAGE 2 TO 4 FEET THROUGH WEDNESDAY WITH SOME BUILDING OF SEAS
LATE WEEK AS THE GRADIENT TIGHTENS A BIT.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
000
FXUS62 KCHS 180510
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
110 AM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ATLANTIC HIGH PRESSURE AT THE SURFACE WILL PREVAIL OVERNIGHT...AS A
SHORT WAVE TROUGH APPROACHES FROM THE WEST. MID AND HIGH LEVEL
CLOUDS WILL INCREASE IN COVERAGE AS THE TROUGH NEARS. THE
INCREASE IN CLOUDS AND A LIGHT SOUTHERLY FLOW WILL KEEP LOW
TEMPERATURES MAINLY IN THE MID 60S TONIGHT...WITH UPPER 60S NEAR
THE IMMEDIATE COAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...A DEEP AND EXPANSIVE LONGWAVE UPPER
RIDGE WILL ENCOMPASS MUCH OF THE EASTERN HALF OF THE COUNTRY WITH AN
EMBEDDED SHORTWAVE TROUGH POSITIONED NEAR THE OHIO VALLEY. THIS
BAGGY TROUGH CAUGHT WITHIN THE LARGER SCALE RIDGE WILL SLOWLY
MEANDER ACROSS THE APPALACHIANS AND TOWARDS THE EAST COAST. PIECES
OF VORT ENERGY ASSOCIATED WITH THIS FEATURE WILL CROSS THE FORECAST
AREA WITH SOME LOWERING OF HEIGHTS. AT THE SURFACE...THE FORECAST
AREA WILL BE IN THE SOUTHERLY FLOW REGIME AROUND HIGH PRESSURE OVER
THE ATLANTIC. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT IN THE AFTERNOON COMPARED TO
PREVIOUS DAYS...ESPECIALLY ALONG AND WEST OF I-95. AREAS EAST OF
I-95 ARE PROGGED TO SEE WARMER 850 MB TEMPS AND A CAP THAT WILL
LIKELY KEEP DEVELOPMENT ISOLATED AT BEST. FURTHER WEST...THE CAP
ERODES AND WITH COOLING/MOISTENING PROFILES...SCATTERED
SHOWERS/THUNDERSTORMS ARE EXPECTED. THE EXPECTATION IS THAT THIS
WILL BE JUST GARDEN VARIETY SHOWERS/STORMS AS NONE OF THE SEVERE
WEATHER PARAMETERS ARE PARTICULARLY IMPRESSIVE. HIGHS WILL CONTINUE
A FEW DEGREES ABOVE NORMAL REACHING THE MID/UPPER 80S.
OVERNIGHT...ONGOING CONVECTION SHOULD BECOME INCREASINGLY CONFINED
FURTHER WEST AND NORTH AS THE SEABREEZE PUSHES INLAND. I HAVE
MAINTAINED A SMALL AREA OF SLIGHT CHANCES THROUGH THE NIGHT CLOSER
TO THE TROUGH AND BETTER MOISTURE. LOWS WILL BE MILD AND IN THE
MID/UPPER 60S.
SUNDAY THROUGH MONDAY...THIS WILL BE THE MOST ACTIVE TIME PERIOD
WITH THE BEST COVERAGE OF SHOWERS/STORMS. THE BAGGY SHORTWAVE TROUGH
AND ASSOCIATED PASSING VORT MAXES WILL LINGER OVERHEAD WHILE A MOIST
S/SE FLOW IN THE LOW LEVELS CONTINUES. THE MODELS CONTINUE TO DEPICT
AN INCREASINGLY MOIST ATMOSPHERE WITH PWATS RISING INTO THE 1.7-1.8
INCH RANGE AT TIMES...WHICH IS NEAR THE 99TH PERCENTILE AND 2
STANDARD DEVIATIONS ABOVE NORMAL FOR MID/LATE MAY. THE RESULT IS A
QUITE MOIST AND UNCAPPED SCENARIO WHERE SHOWERS/STORMS COULD DEVELOP
AT JUST ABOUT ANY TIME. IN FACT IT WOULDN/T BE SURPRISING IF AT TIME
THE COVERAGE OF PRECIP BECOMES NUMEROUS. THIS WILL LIKELY BE MORE
CLOSELY TIMED WITH THE PASSING OF EMBEDDED ENERGY ALOFT WHICH HAS A
LOW CONFIDENCE AT THIS TIME. POPS HAVE BEEN INCREASED MORE INTO THE
MID/HIGH CHANCE RANGE FOR THE DAYTIME HOURS...WITH EVEN LOW CHANCES
GOING OVERNIGHT. WITH CONSIDERABLE CLOUD COVER AROUND INSOLATION
WILL BE A BIT LIMITED KEEPING HIGHS DOWN A FEW DEGREES...BUT STILL
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 06Z SUNDAY.
ISOLATED CONVECTION COULD DEVELOP LATER THIS AFTERNOON MAINLY
WEST OF THE I-95 CORRIDOR...PROBABILITIES OF ANY CONVECTION
IMPACTING THE TERMINALS ARE TOO LOW TO INCLUDE IN THE FORECAST AT
THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT IMPACTS
FROM ISOLATED TO SCATTERED MAINLY AFTERNOON SHOWERS/THUNDERSTORMS
THROUGH EARLY NEXT WEEK.
&&
.MARINE...
OVERNIGHT...QUIET MARINE CONDITIONS WILL PREVAIL AS SURFACE HIGH
PRESSURE EAST OF THE WATERS REMAINS THE DOMINANT WEATHER FEATURE.
GENERALLY EXPECT SOUTH WINDS LESS THAN 15 KT WITH SEAS 2-3
FEET...HIGHEST IN THE OUTER WATERS.
THROUGH EARLY NEXT WEEK...ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY
MARINE INFLUENCE WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL
PERSIST IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...BSH
LONG TERM...JAQ
AVIATION...
MARINE...
000
FXUS62 KCHS 180206
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1006 PM EDT FRI MAY 17 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
ATLANTIC HIGH PRESSURE AT THE SURFACE WILL PREVAIL TONIGHT...AS A
SHORT WAVE TROUGH APPROACHES FROM THE WEST. MID AND HIGH LEVEL
CLOUDS WILL INCREASE IN COVERAGE AND THICKEN SOME OVERNIGHT AS THE
TROUGH NEARS. THE INCREASE IN CLOUDS AND A LIGHT SOUTHERLY FLOW
WILL KEEP LOW TEMPERATURES MAINLY IN THE MID 60S TONIGHT...WITH
UPPER 60S NEAR THE IMMEDIATE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...A DEEP AND EXPANSIVE LONGWAVE UPPER
RIDGE WILL ENCOMPASS MUCH OF THE EASTERN HALF OF THE COUNTRY WITH AN
EMBEDDED SHORTWAVE TROUGH POSITIONED NEAR THE OHIO VALLEY. THIS
BAGGY TROUGH CAUGHT WITHIN THE LARGER SCALE RIDGE WILL SLOWLY
MEANDER ACROSS THE APPALACHIANS AND TOWARDS THE EAST COAST. PIECES
OF VORT ENERGY ASSOCIATED WITH THIS FEATURE WILL CROSS THE FORECAST
AREA WITH SOME LOWERING OF HEIGHTS. AT THE SURFACE...THE FORECAST
AREA WILL BE IN THE SOUTHERLY FLOW REGIME AROUND HIGH PRESSURE OVER
THE ATLANTIC. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT IN THE AFTERNOON COMPARED TO
PREVIOUS DAYS...ESPECIALLY ALONG AND WEST OF I-95. AREAS EAST OF
I-95 ARE PROGGED TO SEE WARMER 850 MB TEMPS AND A CAP THAT WILL
LIKELY KEEP DEVELOPMENT ISOLATED AT BEST. FURTHER WEST...THE CAP
ERODES AND WITH COOLING/MOISTENING PROFILES...SCATTERED
SHOWERS/THUNDERSTORMS ARE EXPECTED. THE EXPECTATION IS THAT THIS
WILL BE JUST GARDEN VARIETY SHOWERS/STORMS AS NONE OF THE SEVERE
WEATHER PARAMETERS ARE PARTICULARLY IMPRESSIVE. HIGHS WILL CONTINUE
A FEW DEGREES ABOVE NORMAL REACHING THE MID/UPPER 80S.
OVERNIGHT...ONGOING CONVECTION SHOULD BECOME INCREASINGLY CONFINED
FURTHER WEST AND NORTH AS THE SEABREEZE PUSHES INLAND. I HAVE
MAINTAINED A SMALL AREA OF SLIGHT CHANCES THROUGH THE NIGHT CLOSER
TO THE TROUGH AND BETTER MOISTURE. LOWS WILL BE MILD AND IN THE
MID/UPPER 60S.
SUNDAY THROUGH MONDAY...THIS WILL BE THE MOST ACTIVE TIME PERIOD
WITH THE BEST COVERAGE OF SHOWERS/STORMS. THE BAGGY SHORTWAVE TROUGH
AND ASSOCIATED PASSING VORT MAXES WILL LINGER OVERHEAD WHILE A MOIST
S/SE FLOW IN THE LOW LEVELS CONTINUES. THE MODELS CONTINUE TO DEPICT
AN INCREASINGLY MOIST ATMOSPHERE WITH PWATS RISING INTO THE 1.7-1.8
INCH RANGE AT TIMES...WHICH IS NEAR THE 99TH PERCENTILE AND 2
STANDARD DEVIATIONS ABOVE NORMAL FOR MID/LATE MAY. THE RESULT IS A
QUITE MOIST AND UNCAPPED SCENARIO WHERE SHOWERS/STORMS COULD DEVELOP
AT JUST ABOUT ANY TIME. IN FACT IT WOULDN/T BE SURPRISING IF AT TIME
THE COVERAGE OF PRECIP BECOMES NUMEROUS. THIS WILL LIKELY BE MORE
CLOSELY TIMED WITH THE PASSING OF EMBEDDED ENERGY ALOFT WHICH HAS A
LOW CONFIDENCE AT THIS TIME. POPS HAVE BEEN INCREASED MORE INTO THE
MID/HIGH CHANCE RANGE FOR THE DAYTIME HOURS...WITH EVEN LOW CHANCES
GOING OVERNIGHT. WITH CONSIDERABLE CLOUD COVER AROUND INSOLATION
WILL BE A BIT LIMITED KEEPING HIGHS DOWN A FEW DEGREES...BUT STILL
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 00Z SUNDAY.
ISOLATED/SCATTERED CONVECTION COULD DEVELOP IN THE AFTERNOON
SATURDAY MAINLY ALONG AND WEST OF THE I-95 CORRIDOR...BUT
PROBABILITIES OF ANY CONVECTION IMPACTING THE TERMINALS ARE TOO LOW
TO INCLUDE IN THE FORECAST AT THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT IMPACTS
FROM ISOLATED TO SCATTERED MAINLY AFTERNOON SHOWERS/THUNDERSTORMS
THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...QUIET MARINE CONDITIONS WILL PREVAIL AS SURFACE HIGH
PRESSURE EAST OF THE WATERS REMAINS THE DOMINANT WEATHER FEATURE.
GENERALLY EXPECT SOUTH WINDS LESS THAN 15 KTS WITH SEAS 2-3
FEET...HIGHEST IN THE OUTER WATERS.
THROUGH EARLY NEXT WEEK...ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY
MARINE INFLUENCE WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL
PERSIST IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...BSH
LONG TERM...JAQ
AVIATION...ECT
MARINE...ECT/BSH
000
FXUS62 KCHS 180020
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
820 PM EDT FRI MAY 17 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
ATLANTIC HIGH PRESSURE AT THE SURFACE WILL PREVAIL TONIGHT...AS A
SHORT WAVE TROUGH APPROACHES FROM THE WEST. MID AND HIGH LEVEL
CLOUDS WILL INCREASE IN COVERAGE AND THICKEN SOME OVERNIGHT AS THE
TROUGH NEARS. THE INCREASE IN CLOUDS AND A LIGHT SOUTHERLY FLOW
WILL KEEP LOW TEMPERATURES MAINLY IN THE MID 60S TONIGHT...WITH
UPPER 60S NEAR THE IMMEDIATE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...A DEEP AND EXPANSIVE LONGWAVE UPPER
RIDGE WILL ENCOMPASS MUCH OF THE EASTERN HALF OF THE COUNTRY WITH AN
EMBEDDED SHORTWAVE TROUGH POSITIONED NEAR THE OHIO VALLEY. THIS
BAGGY TROUGH CAUGHT WITHIN THE LARGER SCALE RIDGE WILL SLOWLY
MEANDER ACROSS THE APPALACHIANS AND TOWARDS THE EAST COAST. PIECES
OF VORT ENERGY ASSOCIATED WITH THIS FEATURE WILL CROSS THE FORECAST
AREA WITH SOME LOWERING OF HEIGHTS. AT THE SURFACE...THE FORECAST
AREA WILL BE IN THE SOUTHERLY FLOW REGIME AROUND HIGH PRESSURE OVER
THE ATLANTIC. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT IN THE AFTERNOON COMPARED TO
PREVIOUS DAYS...ESPECIALLY ALONG AND WEST OF I-95. AREAS EAST OF
I-95 ARE PROGGED TO SEE WARMER 850 MB TEMPS AND A CAP THAT WILL
LIKELY KEEP DEVELOPMENT ISOLATED AT BEST. FURTHER WEST...THE CAP
ERODES AND WITH COOLING/MOISTENING PROFILES...SCATTERED
SHOWERS/THUNDERSTORMS ARE EXPECTED. THE EXPECTATION IS THAT THIS
WILL BE JUST GARDEN VARIETY SHOWERS/STORMS AS NONE OF THE SEVERE
WEATHER PARAMETERS ARE PARTICULARLY IMPRESSIVE. HIGHS WILL CONTINUE
A FEW DEGREES ABOVE NORMAL REACHING THE MID/UPPER 80S.
OVERNIGHT...ONGOING CONVECTION SHOULD BECOME INCREASINGLY CONFINED
FURTHER WEST AND NORTH AS THE SEABREEZE PUSHES INLAND. I HAVE
MAINTAINED A SMALL AREA OF SLIGHT CHANCES THROUGH THE NIGHT CLOSER
TO THE TROUGH AND BETTER MOISTURE. LOWS WILL BE MILD AND IN THE
MID/UPPER 60S.
SUNDAY THROUGH MONDAY...THIS WILL BE THE MOST ACTIVE TIME PERIOD
WITH THE BEST COVERAGE OF SHOWERS/STORMS. THE BAGGY SHORTWAVE TROUGH
AND ASSOCIATED PASSING VORT MAXES WILL LINGER OVERHEAD WHILE A MOIST
S/SE FLOW IN THE LOW LEVELS CONTINUES. THE MODELS CONTINUE TO DEPICT
AN INCREASINGLY MOIST ATMOSPHERE WITH PWATS RISING INTO THE 1.7-1.8
INCH RANGE AT TIMES...WHICH IS NEAR THE 99TH PERCENTILE AND 2
STANDARD DEVIATIONS ABOVE NORMAL FOR MID/LATE MAY. THE RESULT IS A
QUITE MOIST AND UNCAPPED SCENARIO WHERE SHOWERS/STORMS COULD DEVELOP
AT JUST ABOUT ANY TIME. IN FACT IT WOULDN/T BE SURPRISING IF AT TIME
THE COVERAGE OF PRECIP BECOMES NUMEROUS. THIS WILL LIKELY BE MORE
CLOSELY TIMED WITH THE PASSING OF EMBEDDED ENERGY ALOFT WHICH HAS A
LOW CONFIDENCE AT THIS TIME. POPS HAVE BEEN INCREASED MORE INTO THE
MID/HIGH CHANCE RANGE FOR THE DAYTIME HOURS...WITH EVEN LOW CHANCES
GOING OVERNIGHT. WITH CONSIDERABLE CLOUD COVER AROUND INSOLATION
WILL BE A BIT LIMITED KEEPING HIGHS DOWN A FEW DEGREES...BUT STILL
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 00Z SUNDAY.
ISOLATED/SCATTERED CONVECTION COULD DEVELOP IN THE AFTERNOON
SATURDAY MAINLY ALONG AND WEST OF THE I-95 CORRIDOR...BUT
PROBABILITIES OF ANY CONVECTION IMPACTING THE TERMINALS ARE TOO LOW
TO INCLUDE IN THE FORECAST AT THIS TIME.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT IMPACTS
FROM ISOLATED TO SCATTERED MAINLY AFTERNOON SHOWERS/THUNDERSTORMS
THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...QUIET MARINE CONDITIONS WILL PREVAIL AS SURFACE HIGH
PRESSURE EAST OF THE WATERS REMAINS THE DOMINANT WEATHER FEATURE.
GENERALLY EXPECT SOUTH WINDS LESS THAN 15 KTS WITH SEAS 2-3
FEET...HIGHEST IN THE OUTER WATERS.
THROUGH EARLY NEXT WEEK...ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY
MARINE INFLUENCE WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL
PERSIST IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...BSH
LONG TERM...JAQ
AVIATION...ECT
MARINE...BSH/ECT
000
FXUS62 KCHS 171953
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
353 PM EDT FRI MAY 17 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
QUIET WEATHER EXPECTED THROUGH THE OVERNIGHT PERIOD AS THE FORECAST
AREA REMAINS UNDER THE INFLUENCE OF ATLANTIC HIGH PRESSURE.
VORT ENERGY...ASSOCIATED WITH A SHORTWAVE TROUGH APPROACHING FROM
THE WEST...WILL KEEP SOME MID AND HIGH CLOUDS AROUND THROUGH THE
NIGHT. THIS WILL MODERATE TEMPERATURES AND ALLOW FOR LOWS TO BE A
COUPLE DEGREES ABOVE NORMAL. MIN TEMPERATURES ARE EXPECTED TO BE
MAINLY IN THE MIDDLE 60S...WITH UPPER 60S CLOSER TO THE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY AND SATURDAY NIGHT...A DEEP AND EXPANSIVE LONGWAVE UPPER
RIDGE WILL ENCOMPASS MUCH OF THE EASTERN HALF OF THE COUNTRY WITH AN
EMBEDDED SHORTWAVE TROUGH POSITIONED NEAR THE OHIO VALLEY. THIS
BAGGY TROUGH CAUGHT WITHIN THE LARGER SCALE RIDGE WILL SLOWLY
MEANDER ACROSS THE APPALACHIANS AND TOWARDS THE EAST COAST. PIECES
OF VORT ENERGY ASSOCIATED WITH THIS FEATURE WILL CROSS THE FORECAST
AREA WITH SOME LOWERING OF HEIGHTS. AT THE SURFACE...THE FORECAST
AREA WILL BE IN THE SOUTHERLY FLOW REGIME AROUND HIGH PRESSURE OVER
THE ATLANTIC. MODEL SOUNDINGS SHOW THE ATMOSPHERE BECOME MORE
CONDUCIVE TO CONVECTIVE DEVELOPMENT IN THE AFTERNOON COMPARED TO
PREVIOUS DAYS...ESPECIALLY ALONG AND WEST OF I-95. AREAS EAST OF
I-95 ARE PROGGED TO SEE WARMER 850 MB TEMPS AND A CAP THAT WILL
LIKELY KEEP DEVELOPMENT ISOLATED AT BEST. FURTHER WEST...THE CAP
ERODES AND WITH COOLING/MOISTENING PROFILES...SCATTERED
SHOWERS/THUNDERSTORMS ARE EXPECTED. THE EXPECTATION IS THAT THIS
WILL BE JUST GARDEN VARIETY SHOWERS/STORMS AS NONE OF THE SEVERE
WEATHER PARAMETERS ARE PARTICULARLY IMPRESSIVE. HIGHS WILL CONTINUE
A FEW DEGREES ABOVE NORMAL REACHING THE MID/UPPER 80S.
OVERNIGHT...ONGOING CONVECTION SHOULD BECOME INCREASINGLY CONFINED
FURTHER WEST AND NORTH AS THE SEABREEZE PUSHES INLAND. I HAVE
MAINTAINED A SMALL AREA OF SLIGHT CHANCES THROUGH THE NIGHT CLOSER
TO THE TROUGH AND BETTER MOISTURE. LOWS WILL BE MILD AND IN THE
MID/UPPER 60S.
SUNDAY THROUGH MONDAY...THIS WILL BE THE MOST ACTIVE TIME PERIOD
WITH THE BEST COVERAGE OF SHOWERS/STORMS. THE BAGGY SHORTWAVE TROUGH
AND ASSOCIATED PASSING VORT MAXES WILL LINGER OVERHEAD WHILE A MOIST
S/SE FLOW IN THE LOW LEVELS CONTINUES. THE MODELS CONTINUE TO DEPICT
AN INCREASINGLY MOIST ATMOSPHERE WITH PWATS RISING INTO THE 1.7-1.8
INCH RANGE AT TIMES...WHICH IS NEAR THE 99TH PERCENTILE AND 2
STANDARD DEVIATIONS ABOVE NORMAL FOR MID/LATE MAY. THE RESULT IS A
QUITE MOIST AND UNCAPPED SCENARIO WHERE SHOWERS/STORMS COULD DEVELOP
AT JUST ABOUT ANY TIME. IN FACT IT WOULDN/T BE SURPRISING IF AT TIME
THE COVERAGE OF PRECIP BECOMES NUMEROUS. THIS WILL LIKELY BE MORE
CLOSELY TIMED WITH THE PASSING OF EMBEDDED ENERGY ALOFT WHICH HAS A
LOW CONFIDENCE AT THIS TIME. POPS HAVE BEEN INCREASED MORE INTO THE
MID/HIGH CHANCE RANGE FOR THE DAYTIME HOURS...WITH EVEN LOW CHANCES
GOING OVERNIGHT. WITH CONSIDERABLE CLOUD COVER AROUND INSOLATION
WILL BE A BIT LIMITED KEEPING HIGHS DOWN A FEW DEGREES...BUT STILL
NEAR OR SLIGHTLY ABOVE NORMAL.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
VFR IS EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH 18Z SATURDAY.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. LOW CHANCES OF DIRECT IMPACTS
FROM ISOLATED TO SCATTERED MAINLY AFTERNOON SHOWERS/THUNDERSTORMS
THROUGH EARLY NEXT WEEK.
&&
.MARINE...
OVERNIGHT...QUIET MARINE CONDITIONS WILL PREVAIL AS SURFACE HIGH
PRESSURE EAST OF THE WATERS REMAINS THE DOMINANT WEATHER FEATURE.
GENERALLY EXPECT SOUTH WINDS LESS THAN 15 KTS WITH SEAS 2-3
FEET...HIGHEST IN THE OUTER WATERS.
THROUGH EARLY NEXT WEEK...ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY
MARINE INFLUENCE WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL
PERSIST IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...ECT
SHORT TERM...BSH
LONG TERM...JRL
AVIATION...ECT
MARINE...BSH/ECT
000
FXUS62 KCHS 171717
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
117 PM EDT FRI MAY 17 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ATLANTIC HIGH PRESSURE WILL ONCE AGAIN REMAIN THE DOMINANT WEATHER
FEATURE TODAY. MAIN FORECAST ISSUE WILL REVOLVE AROUND POTENTIAL
PRECIP THIS AFTERNOON. SOME MODELS STILL HINT THAT ACTIVITY COULD
FIRE OFF THE INLAND PENETRATING SEA BREEZE THIS AFTERNOON. HAVE
MAINTAINED LOW END SLIGHT CHANCES WEST OF I-95 AS COVERAGE...IF
ANY...WILL BE VERY ISOLATED. OTHERWISE...EXPECT ANOTHER PLEASANT
DAY WITH HIGHS REACHING THE MID AND UPPER 80S. NO MAJOR CHANGES
WERE NEEDED WITH THIS UPDATE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
DRY WEATHER ANTICIPATED TONIGHT WITH A SHORT WAVE RIDGE BUILDING
ACROSS GEORGIA AND THE CAROLINAS. OCCASIONAL MID/HIGH CLOUDS WILL
PASS THROUGH THE REGION WITH LOWS IN THE 60S...SIMILAR TO READINGS
ON FRI MORNING.
AN UPPER SHORTWAVE WILL DRIFT SOUTHEAST FROM THE OHIO VALLEY INTO
NORTH CAROLINA SATURDAY THROUGH MONDAY. ALTHOUGH THE BRUNT OF THE
VORTICITY WILL STAY NORTH OF THE FORECAST AREA...THE UPPER HEIGHT
FALLS WILL PRODUCE A MORE FAVORABLE ENVIRONMENT FOR SHOWERS AND
THUNDERSTORMS. LOW-LEVEL MOISTURE WILL INCREASE SUBSTANTIALLY SUNDAY
INTO MONDAY WHEN THE UPPER VORT MAKES ITS CLOSEST APPROACH. ON
SATURDAY THE SEABREEZE SHOULD BE THE PRIMARY DRIVER FOR CONVECTION.
SUNDAY INTO MONDAY THE COVERAGE SHOULD BE A BIT GREATER AS
MID-LEVELS COOL SLIGHTLY IN CONCERT WITH INCREASING LOW-LEVEL
MOISTURE. WE HAVE 30-40 POPS BOTH DAYS...WITH SLIGHT CHANCES DURING
THE OVERNIGHT HOURS. HIGH TEMPS WILL BE SOLIDLY IN THE 80S WITH LOWS
IN THE 60S.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR IS EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH 18Z SATURDAY.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. ISOLATED TO SCATTERED
AFTERNOON SHOWERS/THUNDERSTORMS EXPECTED EACH AFTERNOON THROUGH
EARLY NEXT WEEK.
&&
.MARINE...
THROUGH TONIGHT...THE LOW LEVEL RIDGE AXIS REMAINS CONSTANT AND
SO DOES OUR FORECAST WITH A SOUTHERLY COMPONENT LESS THAN 15 KT
AND SEAS 3 FT OR LESS. DIRECTIONS SHOULD BACK A BIT MORE SE ALONG
THE GEORGIA COAST THIS AFTERNOON AS THE LAND WARMS AND THE SEA
BREEZE PUSHES INLAND.
ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY MARINE INFLUENCE THROUGH
THE PERIOD WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL PERSIST
IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...ECT
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...ECT
MARINE...ECT/JRL
000
FXUS62 KCHS 171417
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1017 AM EDT FRI MAY 17 2013
.SYNOPSIS...
AN UPPER DISTURBANCE WILL MOVE NORTH OF THE AREA THROUGH THE WEEKEND
AS ATLANTIC HIGH PRESSURE BUILDS ACROSS THE REGION. HIGH PRESSURE
WILL BE THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK BEFORE A COLD
FRONT POSSIBLY APPROACHES ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ATLANTIC HIGH PRESSURE WILL ONCE AGAIN REMAIN THE DOMINANT WEATHER
FEATURE TODAY. MAIN FORECAST ISSUE WILL REVOLVE AROUND POTENTIAL
PRECIP THIS AFTERNOON. MODELS ARE A BIT SCATTERED ON SHOWING
DEVELOPMENT...WITH MOST NOT SHOWING MUCH OVER OUR FORECAST AREA. HAVE
MAINTAINED LOW END SLIGHT CHANCES WEST OF I-95 AS COVERAGE...IF
ANY...WILL BE VERY ISOLATED. OVERALL...PARAMETERS ARE NOT THAT
FAVORABLE FOR DEEP MOIST CONVECTION...AS SHEAR IS WEAK AND
FORECAST SOUNDINGS ARE PRETTY DRY.
OTHERWISE...EXPECT ANOTHER PLEASANT DAY. SHOULD SEE MORE SUNSHINE
AND WARMER TEMPERATURES THAN THURSDAY...WITH HIGHS IN THE MID AND
UPPER 80S. NO MAJOR CHANGES WERE NEEDED WITH THIS UPDATE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
DRY WEATHER ANTICIPATED TONIGHT WITH A SHORT WAVE RIDGE BUILDING
ACROSS GEORGIA AND THE CAROLINAS. OCCASIONAL MID/HIGH CLOUDS WILL
PASS THROUGH THE REGION WITH LOWS IN THE 60S...SIMILAR TO READINGS
ON FRI MORNING.
AN UPPER SHORTWAVE WILL DRIFT SOUTHEAST FROM THE OHIO VALLEY INTO
NORTH CAROLINA SATURDAY THROUGH MONDAY. ALTHOUGH THE BRUNT OF THE
VORTICITY WILL STAY NORTH OF THE FORECAST AREA...THE UPPER HEIGHT
FALLS WILL PRODUCE A MORE FAVORABLE ENVIRONMENT FOR SHOWERS AND
THUNDERSTORMS. LOW-LEVEL MOISTURE WILL INCREASE SUBSTANTIALLY SUNDAY
INTO MONDAY WHEN THE UPPER VORT MAKES ITS CLOSEST APPROACH. ON
SATURDAY THE SEABREEZE SHOULD BE THE PRIMARY DRIVER FOR CONVECTION.
SUNDAY INTO MONDAY THE COVERAGE SHOULD BE A BIT GREATER AS
MID-LEVELS COOL SLIGHTLY IN CONCERT WITH INCREASING LOW-LEVEL
MOISTURE. WE HAVE 30-40 POPS BOTH DAYS...WITH SLIGHT CHANCES DURING
THE OVERNIGHT HOURS. HIGH TEMPS WILL BE SOLIDLY IN THE 80S WITH LOWS
IN THE 60S.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE UPPER SHORTWAVE NORTH OF THE AREA ON MONDAY WILL ESSENTIALLY
DISSOLVE ACROSS THE EASTERN CAROLINAS ON TUESDAY LEAVING A VERY WEAK
RIDGE PATTERN IN PLACE. ATLANTIC HIGH PRESSURE WILL PRODUCE AN
ONSHORE FLOW WITH SEA BREEZES DEVELOPING EACH AFTERNOON. SURFACE
DEWPOINTS WILL PERSIST IN THE MIDDLE 60S WITH HIGHS CLIMBING WELL
INTO THE 80S EACH DAY. ALTHOUGH THERE ARE NO STRONG FORCING
MECHANISMS...WE KEPT ISOLATED SHOWERS AND THUNDERSTORMS IN THE
FORECAST EACH AFTERNOON/EVENING. A COLD FRONT COULD MOVE INTO THE
AREA ON FRIDAY.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 12Z SATURDAY.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. ISOLATED TO SCATTERED
AFTERNOON SHOWERS/THUNDERSTORMS EXPECTED EACH AFTERNOON THROUGH
EARLY NEXT WEEK.
&&
.MARINE...
THROUGH TONIGHT...THE LOW LEVEL RIDGE AXIS REMAINS CONSTANT AND
SO DOES OUR FORECAST WITH A SOUTHERLY COMPONENT LESS THAN 15 KT
AND SEAS 3 FT OR LESS. DIRECTIONS SHOULD BACK A BIT MORE SE ALONG
THE GEORGIA COAST THIS AFTERNOON AS THE LAND WARMS AND THE SEA
BREEZE PUSHES INLAND.
ATLANTIC HIGH PRESSURE WILL BE THE PRIMARY MARINE INFLUENCE THROUGH
THE PERIOD WITH SOUTHERLY FLOW PREVAILING. WIND SPEEDS WILL PERSIST
IN THE 10-15 KT RANGE WITH SEAS 4 FT OR LESS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...ECT
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...ECT
MARINE...ECT/JRL
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