000
FXUS61 KPBZ 222147
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
547 PM EDT WED MAY 22 2013

.SYNOPSIS...
SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE UNTIL A COLD FRONT
PASSES THROUGH THURSDAY EVENING. HIGH PRESSURE RETURNS FOR THE
WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
MESO DATA SHOWS ML CAPES 1500 J/KG OVR WV INTO WRN PA. MESO/NR
TERM MDL DATA SHOWS SHEAR SHOULD INCRS VERY SLIGHTLY INTO THE
EVENING...MAINTAINING SOME RISK FOR A FEW SVR TSTMS. ATM SHOULD
BEGIN TO STABILIZE IN THE FCST AREA AFT SUNSET. ANOTHER SURGE OF
MOISTURE SEEN ON STLT IS EXP TO MOVE NWD KEEPING SHWR CHCS INTO
THE OVRNGT PD. STILL A CHC OF A TSTM WITH SOME ELEVATED INSTAB BUT
SVR THREAT SHOULD END. A CDFNT WL APRCH FM THE WEST THU BRINGING
ADDNL SHWRS/TSTMS. MDL PROGS SHOW INSTAB SHOULD BE MINIMAL AND
THIS SEEMS REASONABLE GIVEN EXPD CLD COVER.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A RAPID TRANSITION TO MUCH COLDER CONDITIONS TAKES PLACE DURING
THIS PERIOD AS THE CONSENSUS OF THE MORE RELIABLE GLOBAL MODEL
SYSTEMS SUGGESTING THE MID-LEVEL SYSTEM TRACKING THROUGH THE
REGION SHOULD CLOSE OFF AS IT MOVES OVER PITTSBURGH AND SLOWLY
OOZES SOUTHEASTWARD. THE CLOSED SOLUTIONS FAVORED BY THE MORE
RELIABLE MODELS END UP TRENDING TOWARD THE SLOWER END OF THE
GUIDANCE PACK WITH THIS SYSTEM...WHICH MAKES SENSE GIVEN THE
HIGHER LONG WAVE AMPLITUDE. AS SUCH...THE SYSTEMS DEPARTURE WAS
SLOWED IN THE FORECAST WHICH RESULTED IN INCREASING POPS INTO
FRIDAY.

WHILE ITS DEPARTURE IS SLOWER...MUCH DRIER AIR DOES WORK INTO THE
AREA BY FRIDAY NIGHT WITH THE CONSENSUS OFFERING EXTREMELY LEAN
LAYER RH PROFILES AND WEAKENING NORTHWEST COLD ADVECTION. THIS
SETS THE STAGE FOR STELLAR RADIATIONAL COOLING GOING INTO SATURDAY
MORNING. GRIDDED GUIDANCE SUGGESTS WIDESPREAD 30S ACROSS THE
AREA...WHICH WITH 850 MB TEMPERATURES FALLING TOWARD -2C IS NOT TOO
SHOCKING. FROST WAS ADDED TO THE GRID TO ACCOMMODATE LOWS
GENERALLY IN THE MID 30S ACROSS VAST TRACTS OF THE CWA...AND
FROST/FREEZE HEADLINES SEEM POSSIBLE AT THIS POINT. THESE
TEMPERATURES AT 850 MB FAIL TO MODERATE DURING THE DAY SATURDAY
MUCH...SO TEMPERATURES WILL LIKELY ONLY WANDER FOR HIGHS FROM THE
UPPER 50S FRIDAY TOWARD THE LOWER 60S SATURDAY. FRIES

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SIMILAR CONDITIONS PERSIST THROUGH THE REST OF THE WEEKEND AND
EVEN POSSIBLY INTO MONDAY MORNING WITH VERY DRY CONDITIONS AND
LIGHT WINDS FAVORING SUPERIOR RADIATIONAL COOLING EACH NIGHT. AS
SUCH...LOWS CONTINUE TO LOOK TO HEAD TOWARD THE 30S EACH
NIGHT...WITH A FEW LOCATIONS INEVITABLY DROPPING BELOW FREEZING.
ONCE AGAIN...FROST WAS ADDED TO THE FORECAST INTO THE
OVERNIGHT/EARLY MORNINGS THIS WEEKEND...AND FROST/FREEZE HEADLINES
AGAIN SEEM QUITE POSSIBLE.

OTHERWISE...VERY GRADUAL MODERATION OF LOW LEVEL TEMPERATURES WILL
BE LIKELY AS THE CLOSED SYSTEM DEPARTS EASTWARD BUT DRY CYCLONIC
NORTHWESTERLY FLOW ALOFT REMAINS THE LARGE CONTROLLING FACTOR FOR
OUR WEATHER. THIS IS THANKS IN PART TO THE FACT THAT THE MODEL
CONSENSUS KEEPS THE LARGE SCALE RIDGE AXIS LARGELY TO OUR WEST
THROUGH THE MIDDLE OF NEXT WEEK. AS A RESULT...CONDITIONS SHOULD
REMAIN GENERALLY DRY WITH VERY SLOW MODERATION OF TEMPERATURES
THROUGH THE WEEK. FRIES

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
LOW TO MEDIUM CONFIDENCE FORECAST ON SHOWER AND THUNDERSTORM TIMING.
VFR WEATHER WILL PREVAIL MUCH OF THE FCST PERIOD /AT LEAST INTO
THE OVERNIGHT HOURS/...THE CHALLENGE IS TIMING ON ANY SHRA OR TSRA
IMPACTING THE TERMINALS. MAINTAINED VCTS FOR LATE AFTERNOON AND
EVENING BEFORE TRANSITIONING TO VFR SHRA UNTIL MIDNIGHT. CLOUDS
WILL DEVELOP IN THE PREDAWN HOURS...LATEST GUIDANCE SUGGEST CIGS
IN THE 015-025 WHICH IS HIGHER THAN EARLIER RUNS AND IN LINE WITH
ONGOING FORECAST. STRATOCU WILL LIFT BY MID MRNG INTO A LOW END
VFR DECK. FOR PLACES THAT EXPERIENCE RAINFALL...PATCHY FOG COULD
DEVELOP DURING THE PREDAWN HOURS. 98

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
THE PROBABILITY OF WIDESPREAD IFR WEATHER IS LOW.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

07

000
FXUS61 KPBZ 221812
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
212 PM EDT WED MAY 22 2013

.SYNOPSIS...
UPPER LEVEL IMPULSES BRINGS AN INCREASE IN SHOWERS AND
THUNDERSTORMS THROUGH THURSDAY NIGHT...UNTIL A COLD FRONT CROSSES. MUCH
COOLER WEATHER IS FORECAST THIS HOLIDAY WEEKEND UNDER HIGH
PRESSURE.

&&

.NEAR TERM /THROUGH THURSDAY/...
DAYTIME HEATING CONTINUES TO PUSH OUR TEMPERATURES CLOSE TO THE
CONVECTIVE THRESHOLD. 16Z MESOANALYSIS ILLUSTRATES NO CINH LEFT
AND EQUIV POTENTIAL TEMPS BUILDING. STILL A FAIR AMOUNT OF UNCERTAINTY
WITH THE DEVELOPMENT OF STORMS AND HOW STRONG STORMS WILL BE
LATER TODAY AND TONIGHT. LATEST THINKING IS STORMS WILL DEVELOP
ALONG THE THETA-E RIDGE AXIS WHICH IS BUILDING ACROSS WV AND WRN
PA. TERRAIN INDUCED STORMS ARE ALREADY UNDERWAY OVER THE CENTRAL
MTNS OF WV. FARTHER W ACROSS OHIO...NOT SURE HOW MUCH DEVELOPMENT
WILL OCCUR THIS AFTERNOON UNTIL S/W TROUGH PASSES AROUND 0Z.
LIKELY POPS STILL ARE ON TRACK FOR THIS EVENING FOR THE ENTIRE
AREA. IF THE LATEST HRRR IS CORRECT WE COULD SEE SOME LOCALIZED
HIGH WATER POTENTIAL OVER NRN WV WITH TRAINING OF STORMS.

AFTER MIDNIGHT THINGS SHOULD QUIET DOWN AS LLVLS STABILIZE AND WE
AWAIT MAIN TROF AXIS TO TRAVERSE FROM THE WEST. NAM AND GFS AGREE
ON A PERIOD OF DRY OR ISOLD ACTIVITY TMRW FROM LATE MRNG THROUGH
MID AFTERNOON BEFORE UPPER LEVEL IMPULSES CROSS. DO NOT FORESEE A
SEVERE WEATHER THREAT THURSDAY DUE TO LACK OF HEATING AS AN
ABUNDANCE OF CLOUDS WILL BE PRESENCE KEEPING THERMODYNAMICS LOW.
GREATEST CHALLENGE IS IF NAM SCENARIO OF A BATCH OF TSTMS RIDING
NE FROM WV INTO SWRN PA AROUND DAYBREAK MATERIALIZES. FOR
NOW...HELD OFF IN FAVOR OF CONTINUITY PER LOW CONFIDENCE ON THIS
OUTCOME. 98

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A RAPID TRANSITION TO MUCH COLDER CONDITIONS TAKES PLACE DURING
THIS PERIOD AS THE CONSENSUS OF THE MORE RELIABLE GLOBAL MODEL
SYSTEMS SUGGESTING THE MID-LEVEL SYSTEM TRACKING THROUGH THE
REGION SHOULD CLOSE OFF AS IT MOVES OVER PITTSBURGH AND SLOWLY
OOZES SOUTHEASTWARD. THE CLOSED SOLUTIONS FAVORED BY THE MORE
RELIABLE MODELS END UP TRENDING TOWARD THE SLOWER END OF THE
GUIDANCE PACK WITH THIS SYSTEM...WHICH MAKES SENSE GIVEN THE
HIGHER LONG WAVE AMPLITUDE. AS SUCH...THE SYSTEMS DEPARTURE WAS
SLOWED IN THE FORECAST WHICH RESULTED IN INCREASING POPS INTO
FRIDAY.

WHILE ITS DEPARTURE IS SLOWER...MUCH DRIER AIR DOES WORK INTO THE
AREA BY FRIDAY NIGHT WITH THE CONSENSUS OFFERING EXTREMELY LEAN
LAYER RH PROFILES AND WEAKENING NORTHWEST COLD ADVECTION. THIS
SETS THE STAGE FOR STELLAR RADIATIONAL COOLING GOING INTO SATURDAY
MORNING. GRIDDED GUIDANCE SUGGESTS WIDESPREAD 30S ACROSS THE
AREA...WHICH WITH 850 MB TEMPERATURES FALLING TOWARD -2C IS NOT TOO
SHOCKING. FROST WAS ADDED TO THE GRID TO ACCOMMODATE LOWS
GENERALLY IN THE MID 30S ACROSS VAST TRACTS OF THE CWA...AND
FROST/FREEZE HEADLINES SEEM POSSIBLE AT THIS POINT. THESE
TEMPERATURES AT 850 MB FAIL TO MODERATE DURING THE DAY SATURDAY
MUCH...SO TEMPERATURES WILL LIKELY ONLY WANDER FOR HIGHS FROM THE
UPPER 50S FRIDAY TOWARD THE LOWER 60S SATURDAY. FRIES


&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SIMILAR CONDITIONS PERSIST THROUGH THE REST OF THE WEEKEND AND
EVEN POSSIBLY INTO MONDAY MORNING WITH VERY DRY CONDITIONS AND
LIGHT WINDS FAVORING SUPERIOR RADIATIONAL COOLING EACH NIGHT. AS
SUCH...LOWS CONTINUE TO LOOK TO HEAD TOWARD THE 30S EACH
NIGHT...WITH A FEW LOCATIONS INEVITABLY DROPPING BELOW FREEZING.
ONCE AGAIN...FROST WAS ADDED TO THE FORECAST INTO THE
OVERNIGHT/EARLY MORNINGS THIS WEEKEND...AND FROST/FREEZE HEADLINES
AGAIN SEEM QUITE POSSIBLE.

OTHERWISE...VERY GRADUAL MODERATION OF LOW LEVEL TEMPERATURES WILL
BE LIKELY AS THE CLOSED SYSTEM DEPARTS EASTWARD BUT DRY CYCLONIC
NORTHWESTERLY FLOW ALOFT REMAINS THE LARGE CONTROLLING FACTOR FOR
OUR WEATHER. THIS IS THANKS IN PART TO THE FACT THAT THE MODEL
CONSENSUS KEEPS THE LARGE SCALE RIDGE AXIS LARGELY TO OUR WEST
THROUGH THE MIDDLE OF NEXT WEEK. AS A RESULT...CONDITIONS SHOULD
REMAIN GENERALLY DRY WITH VERY SLOW MODERATION OF TEMPERATURES
THROUGH THE WEEK. FRIES

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
LOW TO MEDIUM CONFIDENCE FORECAST ON SHOWER AND THUNDERSTORM TIMING.
VFR WEATHER WILL PREVAIL MUCH OF THE FCST PERIOD /AT LEAST INTO
THE OVERNIGHT HOURS/...THE CHALLENGE IS TIMING ON ANY SHRA OR TSRA
IMPACTING THE TERMINALS. MAINTAINED VCTS FOR LATE AFTERNOON AND
EVENING BEFORE TRANSITIONING TO VFR SHRA UNTIL MIDNIGHT. CLOUDS
WILL DEVELOP IN THE PREDAWN HOURS...LATEST GUIDANCE SUGGEST CIGS
IN THE 015-025 WHICH IS HIGHER THAN EARLIER RUNS AND IN LINE WITH
ONGOING FORECAST. STRATOCU WILL LIFT BY MID MRNG INTO A LOW END
VFR DECK. FOR PLACES THAT EXPERIENCE RAINFALL...PATCHY FOG COULD
DEVELOP DURING THE PREDAWN HOURS. 98

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
THE PROBABILITY OF WIDESPREAD IFR WEATHER IS LOW.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 221717
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
117 PM EDT WED MAY 22 2013

.SYNOPSIS...
UPPER LEVEL IMPULSES BRINGS AN INCREASE IN SHOWERS AND
THUNDERSTORMS THROUGH THURSDAY NIGHT...UNTIL A COLD FRONT CROSSES. MUCH
COOLER WEATHER IS FORECAST THIS HOLIDAY WEEKEND UNDER HIGH
PRESSURE.

&&

.NEAR TERM /THROUGH THURSDAY/...
DAYTIME HEATING CONTINUES TO PUSH OUR TEMPERATURES CLOSE TO THE
CONVECTIVE THRESHOLD. 16Z MESOANALYSIS ILLUSTRATES NO CINH LEFT
AND EQUIV POTENTIAL TEMPS BUILDING. STILL A FAIR AMOUNT OF UNCERTAINTY
WITH THE DEVELOPMENT OF STORMS AND HOW STRONG STORMS WILL BE
LATER TODAY AND TONIGHT. LATEST THINKING IS STORMS WILL DEVELOP
ALONG THE THETA-E RIDGE AXIS WHICH IS BUILDING ACROSS WV AND WRN
PA. TERRAIN INDUCED STORMS ARE ALREADY UNDERWAY OVER THE CENTRAL
MTNS OF WV. FARTHER W ACROSS OHIO...NOT SURE HOW MUCH DEVELOPMENT
WILL OCCUR THIS AFTERNOON UNTIL S/W TROUGH PASSES AROUND 0Z.
LIKELY POPS STILL ARE ON TRACK FOR THIS EVENING FOR THE ENTIRE
AREA. IF THE LATEST HRRR IS CORRECT WE COULD SEE SOME LOCALIZED
HIGH WATER POTENTIAL OVER NRN WV WITH TRAINING OF STORMS.

AFTER MIDNIGHT THINGS SHOULD QUIET DOWN AS LLVLS STABILIZE AND WE
AWAIT MAIN TROF AXIS TO TRAVERSE FROM THE WEST. NAM AND GFS AGREE
ON A PERIOD OF DRY OR ISOLD ACTIVITY TMRW FROM LATE MRNG THROUGH
MID AFTERNOON BEFORE UPPER LEVEL IMPULSES CROSS. DO NOT FORESEE A
SEVERE WEATHER THREAT THURSDAY DUE TO LACK OF HEATING AS AN
ABUNDANCE OF CLOUDS WILL BE PRESENCE KEEPING THERMODYNAMICS LOW.
GREATEST CHALLENGE IS IF NAM SCENARIO OF A BATCH OF TSTMS RIDING
NE FROM WV INTO SWRN PA AROUND DAYBREAK MATERIALIZES. FOR
NOW...HELD OFF IN FAVOR OF CONTINUITY PER LOW CONFIDENCE ON THIS
OUTCOME.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
A REINFORCING FRONT IS PROGGED FOR FRIDAY WITH RESIDUAL SHWR CHCS
FADING BY AFTN WITH PASSAGE OF THAT FEATURE. AS NW FLOW DVLPS WITH
PASSAGE OF THE AFOREMENTIONED PHASED TROF AXIS...COLD ADVCTN WL
LIMIT TEMP RECOVERY. EXPECT HIGHS ABOUT 10 DEGREES BELOW THE
SEASONAL AVERAGES UNDR THE RESULTING HIGH AMPLITUDE...ERN CONUS
TROF PTN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
LOW TO MEDIUM CONFIDENCE FORECAST ON SHOWER AND THUNDERSTORM TIMING.
VFR WEATHER WILL PREVAIL MUCH OF THE FCST PERIOD /AT LEAST INTO
THE OVERNIGHT HOURS/...THE CHALLENGE IS TIMING ON ANY SHRA OR TSRA
IMPACTING THE TERMINALS. MAINTAINED VCTS FOR LATE AFTERNOON AND
EVENING BEFORE TRANSITIONING TO VFR SHRA UNTIL MIDNIGHT. CLOUDS
WILL DEVELOP IN THE PREDAWN HOURS...LATEST GUIDANCE SUGGEST CIGS
IN THE 015-025 WHICH IS HIGHER THAN EARLIER RUNS AND IN LINE WITH
ONGOING FORECAST. STRATOCU WILL LIFT BY MID MRNG INTO A LOW END
VFR DECK. FOR PLACES THAT EXPERIENCE RAINFALL...PATCHY FOG COULD
DEVELOP DURING THE PREDAWN HOURS.

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
THE PROBABILITY OF WIDESPREAD IFR WEATHER IS LOW.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

SYNOPSIS...98
NEAR TERM...98
SHORT TERM...15
AVIATION...98

000
FXUS61 KPBZ 221413
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1013 AM EDT WED MAY 22 2013

.SYNOPSIS...
UPPER LEVEL IMPULSES BRINGS AN INCREASE IN SHOWERS AND
THUNDERSTORMS THROUGH THURSDAY NIGHT...UNTIL A COLD FRONT CROSSES. MUCH
COOLER WEATHER IS FORECAST THIS HOLIDAY WEEKEND UNDER HIGH
PRESSURE.

&&

.NEAR TERM /THROUGH TONIGHT/...
AREA IS UNDER GOING STRONG HEATING WHICH IS EATING AWAY AT CAP
NEAR THE SURFACE. MODIFIED SOUNDINGS USING PROJECTED MAXT AND TD
SHOW 1.5 KJKG-1 OF SBCAPE AND NO CINH. THIS IS ABOUT HALF OF THE
ENERGY THAT WAS PRESENT YDY...BUT THE DIFFERENCE THIS AFTN IS INC
IN WIND SHEAR AND TRIGGERS. A WEAK IMPULSE WILL CROSS LATER TDY
AND GIVEN NO CAP WILL GENERATE RW/TRW. MAIN THREAT CONTINUES TO BE
DAMAGING WINDS...HOWEVER HAIL CAN NOT BE RULED OUT DESPITE FZL
LVL ARND 12KFT. TWEAKED POP GRIDS TO REFLECT DRY CONDITIONS THIS
MRNG AND FOCUS HIGHER NUMBERS DURING THE LATE AFTERNOON / EVENING
TIME FRAME.

ACTIVITY WILL WANE BY MIDNIGHT...BUT WITH POCKETS OF ENERGY
ASSOCIATED WITH MID LVL HEIGHT FALLS FROM APPROACHING
TROUGH...CONTINUED PCPN MENTION THROUGH THE NIGHT.

DUE TO PROGRESSIVE NATURE OF STORMS...DO NOT FORESEE A FLOOD
THREAT. THE ONLY SCENARIO WHICH MAY LEAD TO FLOODING WOULD BE IF A
LOCATION RECEIVES REPEATED ROUNDS OF RAIN. THE PROBABILITY IN THAT
IS LOW AT THIS TIME.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COLDER AIR IS PROJECTED TO ADVECT OVR THE REGION ON THURSDAY AS
SFC FRONT PROGRESSES EWD. HOWEVER... WITH THE MID-LEVELS COOLING
AS WELL...CONVECTIVE THRESHOLDS WL LOWER CONSIDERABLY WITH SHWRS
AND TSTMS AGAIN BCMG LIKELY AS THE DAY PROGRESSES.

A REINFORCING FRONT IS PROGGED FOR FRIDAY WITH RESIDUAL SHWR CHCS
FADING BY AFTN WITH PASSAGE OF THAT FEATURE. AS NW FLOW DVLPS WITH
PASSAGE OF THE AFOREMENTIONED PHASED TROF AXIS...COLD ADVCTN WL
LIMIT TEMP RECOVERY. EXPECT HIGHS ABOUT 10 DEGREES BELOW THE
SEASONAL AVERAGES UNDR THE RESULTING HIGH AMPLITUDE...ERN CONUS
TROF PTN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
15-20 KT GUSTS CAN BE EXPECTED TO DEVELOP BY NOON AT MOST
TERMINALS ALONG WITH DIURNAL CUMULUS. SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO DEVELOP BY MID AFTERNOON...AND HAVE CONTINUED VCTS
MENTION AT THIS TIME. IF ANYTHING...WIND GUSTS MAY BE
UNDERESTIMATED WITH POSSIBILITY FOR TSRA. THE BEST CHANCE FOR
RESTRICTIONS AND WIND ISSUES WILL COME THIS EVENING AS TSTM
COVERAGE WIDENS IN A STRENGTHENING WIND PROFILE.

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
BRIEF IFR RESTRICTIONS ARE POSSIBLE THUR IN SHOWERS AND
THUNDERSTORMS...MAINLY VIS. OTHERWISE...PROBABILITY OF WIDESPREAD
IFR WEATHER IS LOW.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

SYNOPSIS...98
NEAR TERM...98
SHORT TERM...15
AVIATION...33/98

000
FXUS61 KPBZ 221043
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
643 AM EDT WED MAY 22 2013

.SYNOPSIS...
THUNDERSTORM CHANCES WILL INCREASE TODAY AS A COLD FRONT
APPROACHES THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
LOW PRES WHICH HAS PLAGUED THE PLAINS IS STILL FORECAST TO DVLP
NEWD AND PHASE WITH ERN CANADIAN TROF BY THURSDAY. TAIL OF
COUPLING JET ALOFT IS EXPECTED TO APPRCH THE UPR OHIO THIS EVE AND
CROSS THE REGION TNGT WHILE SFC LOW IS PROJECTED TO MOVE RAPIDLY
NEWD ACRS LAKE ERIE.

WITH RELATIVELY MOIST AIRMASS ALREADY IN PLACE...POST DAYBREAK
DESTABILIZATION AND EWD SLIDING MID/UPR TROF WL LIKELY SPPRT TSTM
DVLPMNT BY AFTN AND INTO THE EVE.

GIVEN THE STRENGTHENING WIND FIELD AS MENTIONED ABOVE...CONCUR
WITH THE STORM PREDICTION CENTER ASSESSMENT OF SEVERE POTENTIAL AS
EVENING APPRCHES. RISK WL RMN IN THE SLIGHT CATEGORY...I.E. APPROX
30 PERCENT CHC OF THE PRIMARY THREAT...WHICH IS OF DAMAGING WIND
VIA SHORT BOWING SEGMENTS.

NR TERM POPS WERE STRUCTURED COLLABORATIVELY FOR THE MOST
PART...WITH CATEGORICAL NMBRS LTD TO OHIO AND PARTS OF NW PA
IMMEDIATELY ALNG THE OH BORDER. CURRENT THINKING IS THAT THESE
AREAS WL HAVE THE BETTER CHC OF WIDESPREAD THUNDERSTORM COVERAGE
AS POTENTIAL MCS PROGRESSES COINCIDENT WITH THE LLVL JET...BEFORE
SFC LOW LIFTS NEWD AND DIURNAL WARMTH/SFC BASED INSTABILITY BGN TO
DIMINISH AFTER NIGHTFALL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COLDER AIR IS PROJECTED TO ADVECT OVR THE REGION ON THURSDAY AS
SFC FRONT PROGRESSES EWD. HOWEVER... WITH THE MID-LEVELS COOLING
AS WELL...CONVECTIVE THRESHOLDS WL LOWER CONSIDERABLY WITH SHWRS
AND TSTMS AGAIN BCMG LIKELY AS THE DAY PROGRESSES.

A REINFORCING FRONT IS PROGGED FOR FRIDAY WITH RESIDUAL SHWR CHCS
FADING BY AFTN WITH PASSAGE OF THAT FEATURE. AS NW FLOW DVLPS WITH
PASSAGE OF THE AFOREMENTIONED PHASED TROF AXIS...COLD ADVCTN WL
LIMIT TEMP RECOVERY. EXPECT HIGHS ABOUT 10 DEGREES BELOW THE
SEASONAL AVERAGES UNDR THE RESULTING HIGH AMPLITUDE...ERN CONUS
TROF PTN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
15-20 KT GUSTS CAN BE EXPECTED TO DEVELOP BY NOON AT MOST
TERMINALS ALONG WITH DIURNAL CUMULUS. SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO DEVELOP BY MID AFTERNOON...AND HAVE CONTINUED VCTS
MENTION AT THIS TIME. IF ANYTHING...WIND GUSTS MAY BE
UNDERESTIMATED WITH POSSIBILITY FOR TSRA. THE BEST CHANCE FOR
RESTRICTIONS AND WIND ISSUES WILL COME THIS EVENING AS TSTM
COVERAGE WIDENS IN A STRENGTHENING WIND PROFILE.

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
OCNL RESTRNS ARE LIKELY INTO THU NGT WITH SHWRS/TSTMS AS A CDFNT
MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL BRING PSBL RESTRNS
IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS RETURN FRI NGT THRU
SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 220720
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
320 AM EDT WED MAY 22 2013

.SYNOPSIS...
THUNDERSTORM CHANCES WILL INCREASE TODAY AS A COLD FRONT
APPROACHES THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
LOW PRES WHICH HAS PLAGUED THE PLAINS IS STILL FORECAST TO DVLP
NEWD AND PHASE WITH ERN CANADIAN TROF BY THURSDAY. TAIL OF
COUPLING JET ALOFT IS EXPECTED TO APPRCH THE UPR OHIO THIS EVE AND CROSS
THE REGION TNGT WHILE SFC LOW IS PROJECTED TO MOVE RAPIDLY NEWD
ACRS LAKE ERIE.

WITH RELATIVELY MOIST AIRMASS ALREADY IN PLACE...POST DAYBREAK
DESTABILIZATION AND EWD SLIDING MID/UPR TROF WL LIKELY SPPRT TSTM
DVLPMNT BY AFTN AND INTO THE EVE...ALTHOUGH DEGREE OF INSTABILITY
IS STILL SOMEWHAT QNABLE GIVEN EXPECTED CLOUD COVER.

NEVERTHELESS...GIVEN THE STRENGTHENING WIND FIELD AS MENTIONED
ABOVE...CONCUR WITH THE STORM PREDICTION CENTER ASSESSMENT OF
SEVERE POTENTIAL AS EVENING APPRCHES. RISK WL RMN IN THE SLIGHT
CATEGORY...I.E. APPROX 30 PERCENT CHC OF THE PRIMARY
THREAT...WHICH IS OF DAMAGING WIND VIA SHORT BOWING SEGMENTS.

NR TERM POPS WERE STRUCTURED WITH CATEGORICAL NMBRS LTD TO OHIO
AND PARTS OF NW PA IMMEDIATELY ALNG THE OH BORDER. CURRENT
THINKING IS THAT THESE AREAS WL HAVE THE BETTER CHC OF WIDESPREAD
THUNDERSTORM COVERAGE AS POTENTIAL MCS PROGRESSES COINCIDENT WITH
THE LLVL JET...BEFORE SFC LOW LIFTS NEWD AND DIURNAL WARMTH/SFC
BASED INSTABILITY BGN TO DIMINISH AFTER NIGHTFALL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
COLDER AIR IS PROJECTED TO ADVECT OVR THE REGION ON THURSDAY AS
SFC FRONT PROGRESSES EWD. HOWEVER... WITH THE MID-LEVELS COOLING
AS WELL...CONVECTIVE THRESHOLDS WL LOWER CONSIDERABLY WITH SHWRS
AND TSTMS AGAIN BCMG LIKELY AS THE DAY PROGRESSES.

A REINFORCING FRONT IS PROGGED FOR FRIDAY WITH RESIDUAL SHWR CHCS
FADING BY AFTN WITH PASSAGE OF THAT FEATURE. AS NW FLOW DVLPS WITH
PASSAGE OF THE AFOREMENTIONED PHASED TROF AXIS...COLD ADVCTN WL
LIMIT TEMP RECOVERY. EXPECT HIGHS ABOUT 10 DEGREES BELOW THE
SEASONAL AVERAGES UNDR THE RESULTING HIGH AMPLITUDE...ERN CONUS
TROF PTN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
GENL VFR EXPD THIS MRNG AS INCRSG PRES GRADIENT IS SPPRTG
SUFFICIENT SFC WIND TO PRECLUDE FOG DVLPMNT...WITH FURTHER
LIMITATION IMPOSED BY SCT TO BKN MID LVL CLDS. HOWEVER...SHWR AND
TSTM COVERAGE IS FORECAST TO INCRS AS THE DAY PROGRESSES. TAFS
THUS INCLUDE VCTS MENTION. THE BEST CHC FOR RESTRICTIONS AND WIND
ISSUES WL COME THIS EVE AS TSTM COVERAGE WIDENS IN A STRENGTHENING
WIND PROFILE.

.OUTLOOK.../TONIGHT THROUGH SUNDAY/...
OCNL RESTRNS LIKELY INTO THU NGT WITH SHWRS/TSTMS AS A CDFNT
MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL BRING PSBL RESTRNS
IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS RETURN FRI NGT THRU
SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

15

000
FXUS61 KPBZ 220425
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1225 AM EDT WED MAY 22 2013

.SYNOPSIS...
THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY AND THURSDAY AS A
COLD FRONT APPROACHES AND MOVES ACROSS THE REGION.

&&

.NEAR TERM /THROUGH WEDNESDAY/...

MIDNGT UPDATE WAS ISSUED TO ADJUST HOURLY TRENDS OF POPS AND TEMPS
WHICH FEATURE A DIMINISHING AREA OF SHWRS AND TSTMS MOVG OUT OF WV
SPPRTD BY SHRTWV IN SW FLOW ALOFT.

EXPECT THIS AREA TO CONT FADING TO SCT/ISOLD SHWRS AS RMNG
INSTABILITY POCKETS FADE.

LOW PRES WHICH HAS PLAGUED THE PLAINS IS STILL FORECAST TO DVLP
NEWD AND PHASE WITH ERN CANADIAN TROF BY THURSDAY. TAIL OF
COUPLING JET ALOFT IS EXPECTED TO APPRCH THE UPR OHIO LATE TODAY
AND CROSS THE REGION TNGT. WITH RELATIVELY MOIST AIRMASS ALREADY
IN PLACE...POST DAYBREAK DESTABILIZATION WL SPPRT NMRS
THUNDERSTORM COVERAGE DURING THE AFTN AND INTO THE EVE...ALTHOUGH
DEGREE OF INSTABILITY IS STILL SOMEWHAT QNABLE GIVEN EXPECTED
CLOUD COVER.

HOWEVER...GIVEN THE STRENGTHENING WIND FIELD AS MENTIONED ABOVE...CONCUR
WITH THE STORM PREDICTION CENTER ASSESSMENT OF SEVERE POTENTIAL AS
EVENING APPRCHES. RISK WL RMN SLIGHT AS MID LVL JET STREAK IS
CURRENTLY TIMED TO CROSS AS DIURNAL HEATING FADES...BUT DAMAGING
WIND GUSTS AND HAIL WL CERTAINLY BE POSSIBLE.

NEAR TERM TEMPS WERE FORECAST USING LAMP GUIDANCE.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...

COLDER AIR IS PROJECTED TO ADVECT OVR THE REGION ON THURSDAY AS
SFC FRONT PROGRESSES EWD. HOWEVER... WITH THE MID-LEVELS COOLING
AS WELL...CONVECTIVE THRESHOLDS WL LOWER CONSIDERABLY WITH SHWRS
AND TSTMS AGAIN BCMG LIKELY AS THE DAY PROGRESSES.

A REINFORCING FRONT IS PROGGED FOR FRIDAY WITH RESIDUAL SHWR CHCS
FADING BY AFTN WITH PASSAGE OF THAT FEATURE. AS NW FLOW DVLPS WITH
PASSAGE OF THE AFOREMENTIONED PHASED TROF AXIS...COLD ADVCTN WL
LIMIT TEMP RECOVERY. EXPECT HIGHS ABOUT 10 DEGREES BELOW THE
SEASONAL AVERAGES UNDR THE RESULTING HIGH AMPLITUDE...ERN CONUS
TROF PTN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
GENL VFR EXPD OVRNGT...ALTHOUGH ISOLD SHWRS CAN BE EXPECTED AS
SHRTWV CROSSES IN SW FLOW ALOFT. A PD OF MVFR VIS IN BR EXPD TWD
SUNRISE THEN VFR RETURNS THRU ERLY AFTN. SCT TSTMS EXP LATER IN
THE AFTN AS A CDFNT BEGINS TO APRCH SO INCLUDED VCTS.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
OCNL RESTRNS LIKELY WED EVE INTO THU NGT WITH SHWRS/TSTMS AS A
CDFNT APRCHS AND MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL
BRING PSBL RESTRNS IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS
RETURN FRI NGT THRU SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

15

000
FXUS61 KPBZ 220151
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
951 PM EDT TUE MAY 21 2013

.SYNOPSIS...
THUNDERSTORM CHANCES WILL INCREASE WEDNESDAY AND THURSDAY AS A
COLD FRONT APPROACHES AND MOVES ACROSS THE REGION. HIGH PRESSURE
WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
ISOLATED THUNDERSTORMS REMAIN FROM NEAR PITTSBURGH SOUTH ALONG
I-79 AND ARE QUICKLY DISSIPATING. OTHER SHOWERS AND STORMS ACROSS
CENTRAL WEST VIRGINIA ARE WEAKENING AS THEY MOVE NORTHEAST WITH
LOSS OF DAYTIME HEATING. WHAT IS LEFT OF THESE SHOWERS MAY BRUSH
MORGANTOWN AREA BEFORE ENDING. LOW CHANCE POPS BETWEEN PITTSBURGH
AND MORGANTOWN UNTIL MIDNIGHT. OTHERWISE PARTLY CLOUDY WITH MID
AND HIGH CLOUDS CROSSING THE REGION. NO CHANGES TO OVERNIGHT
TEMPERATURES.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A VERY PRONOUNCED LOW LEVEL JET IS EVIDENT ON ALL GUIDANCE BY
WEDNESDAY MORNING NOSING INTO SOUTHWESTERN OHIO AHEAD OF AN
INCOMING UPPER LEVEL WAVE. GUIDANCE CONTINUES TO BE A BIT VARIED
ON ITS PLACEMENT AND EVOLUTION GOING INTO THE LATER MORNING
HOURS...HOWEVER ENOUGH GUIDANCE MEMBERS BRING IT INTO CENTRAL OHIO
BY LATE MORNING THAT THUNDERSTORMS MAY WELL DEVELOP ALONG THE NOSE
OF IT. IN CONJUNCTION...SEVERAL CONSECUTIVE NAM RUNS HAVE DEPICTED
A COMPACT SHORTWAVE EMBEDDED INTO THE SOUTHWESTERLY FLOW TO TRACK
OVER WESTERN AND CENTRAL OHIO FROM LATE MORNING THROUGH EARLY
AFTERNOON. AS THIS OCCURS...CONVECTION IS LIKELY TO BREAK OUT. IN
ADDITION...WITH CAPE VALUES AROUND 1500 J/KG AND STRONGER 0-6 KM
SHEAR LIKELY OVER OHIO THAN POINTS FARTHER EAST...BETTER CHANCES
OF THUNDERSTORM DEVELOPMENT EXIST IN OHIO THAN THE REST OF THE
FORECAST AREA THROUGH MOST OF THE DAYTIME ON WEDNESDAY. WITH
DECENT MID-LEVEL SUPPORT AND SHEAR/INSTABILITY...DAMAGING WINDS
WILL BE POSSIBLE WITH ANY MULTI-CELLULAR DEVELOPMENT THAT DOES
OCCUR FROM LATE MORNING ONWARD IN OHIO...WITH A LESSER CHANCE
FARTHER EAST.

AS THE UPPER LEVEL WAVE TRACKS FARTHER EAST WEDNESDAY
EVENING...THE RIGHT ENTRANCE REGION OF THE UPPER JET TRACKS
DIRECTLY OVER THE CWA. WITH IS IN CONCERT WITH THE MAIN SYNOPTIC
WAVE PASSAGE ROUGHLY 06Z/2AM THROUGH PITTSBURGH WEDNESDAY NIGHT.
BOTH NAM AND ECMWF SOLUTIONS ARE SUGGESTIVE OF LINEAR DEVELOPMENT
ALONG THE FRONTAL BOUNDARY AS IT PASSES THROUGH THE AREA LATE
WEDNESDAY EVENING/NIGHT...RESULTING IN THE POSSIBILITY OF A SQUALL
LINE MANAGING TO PERSIST WELL PAST THE NORMAL DIURNALLY FAVORED
HOURS OWING TO LARGE SCALE SUPPORT FOR ASCENT. CHANCES OF SEVERE
THUNDERSTORMS WITH DAMAGING WINDS WERE THUS ALLOWED TO SPREAD
ACROSS THE REST OF THE CWA FROM ROUGHLY 8 PM TO 3 AM AS THIS UPPER
WAVE PASSES THROUGH.

COLDER AIR FLOODS INTO THE AREA ON THURSDAY...HOWEVER WITH THE
MID-LEVELS COOLING MUCH QUICKER THAN THE LOW LEVELS...SHOWERS AND
THUNDERSTORMS WILL AGAIN BY POSSIBLE ACROSS THE AREA WITH SURFACE
TEMPERATURES MODERATING TOWARD 70F.

THE DUMP OF MUCH COLD AIR IS HELD BACK FOR A SECONDARY FRONTAL
PASSAGE ON FRIDAY WITH A WIDE SPREAD IN GUIDANCE FOR AFTERNOON
TEMPERATURES. ECMWF AND GFS 850 MB TEMPERATURES IN THE AFTERNOON
HOURS STRADDLE 0C...WHICH WOULD SUGGEST TEMPERATURES WOULD
STRUGGLE TO REACH 50F IF SUNSHINE FAILED TO MATERIALIZE. AT THE
MOMENT...IT WOULD SEEM MORE REASONABLE TO EXPECT AT LEAST SOME SUN
ON FRIDAY...SO HIGH TEMPERATURES WERE GENERALLY ADJUSTED FOR THE
MID 50S TO MID 60S ACROSS THE AREA. AS CONDITIONS CLEAR BY THE
AFTERNOON AND EVENING FRIDAY...COLD AIR ADVECTING INTO THE AREA
WILL LIKELY ALL FOR A VERY RAPID COOL OFF GOING INTO THE EVENING
AND POSSIBLY FROST BY THE OVERNIGHT. FRIES

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDS EXPD INTO THE NGT. ISOLD TSTMS IN CNTRL OH...BUT UPR AND
MID LVL RIDGE AND CAPPING LIMITING ACTIVITY. WL MONITOR TSTMS BUT
NOT PLANNING ON INCLUDING IN TAFS ATTM. A PD OF MVFR VIS IN BR
EXPD TWD SUNRISE THEN VFR RETURNS THRU ERLY AFTN. SCT TSTMS EXP
LATER IN THE AFTN AS A CDFNT BEGINS TO APRCH SO INCLUDED VCTS.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
OCNL RESTRNS LIKELY WED EVE INTO THU NGT WITH SHWRS/TSTMS AS A
CDFNT APRCHS AND MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL
BRING PSBL RESTRNS IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS
RETURN FRI NGT THRU SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 212325
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
725 PM EDT TUE MAY 21 2013

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MAINLY ACROSS
EASTERN OHIO THIS EVENING. INCREASING THUNDERSTORM CHANCES
WEDNESDAY AND THURSDAY AS A COLD FRONT APPROACHES AND MOVES
ACROSS THE REGION. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
ADJUSTED POPS DOWN A BIT AND REDUCED AREA OF CHANCE POPS THIS
EVENING TO EASTERN OHIO TOWARD I-79. APPEARS HI RES MODELS WERE
OVERDONE IN COMPLETELY BREAKING CAP ACROSS AREA...AND WHILE MUCAPE
IS OVER 2K MID LEVELS APPEAR A BIT WARM FOR DEEP CONVECTION.
STORMS HAVE PULSED ONLY FOR A TIME AND THEN WEAKEN. SCATTERED
STORMS WILL EVENTUALLY APPROACH PITTSBURGH METRO BUT LOOK TO BE
DYING AS THEY DO. ADJUSTED OVERNIGHT LOWS SLIGHTLY BASED ON DEW
POINT TRENDS.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A VERY PRONOUNCED LOW LEVEL JET IS EVIDENT ON ALL GUIDANCE BY
WEDNESDAY MORNING NOSING INTO SOUTHWESTERN OHIO AHEAD OF AN
INCOMING UPPER LEVEL WAVE. GUIDANCE CONTINUES TO BE A BIT VARIED
ON ITS PLACEMENT AND EVOLUTION GOING INTO THE LATER MORNING
HOURS...HOWEVER ENOUGH GUIDANCE MEMBERS BRING IT INTO CENTRAL OHIO
BY LATE MORNING THAT THUNDERSTORMS MAY WELL DEVELOP ALONG THE NOSE
OF IT. IN CONJUNCTION...SEVERAL CONSECUTIVE NAM RUNS HAVE DEPICTED
A COMPACT SHORTWAVE EMBEDDED INTO THE SOUTHWESTERLY FLOW TO TRACK
OVER WESTERN AND CENTRAL OHIO FROM LATE MORNING THROUGH EARLY
AFTERNOON. AS THIS OCCURS...CONVECTION IS LIKELY TO BREAK OUT. IN
ADDITION...WITH CAPE VALUES AROUND 1500 J/KG AND STRONGER 0-6 KM
SHEAR LIKELY OVER OHIO THAN POINTS FARTHER EAST...BETTER CHANCES
OF THUNDERSTORM DEVELOPMENT EXIST IN OHIO THAN THE REST OF THE
FORECAST AREA THROUGH MOST OF THE DAYTIME ON WEDNESDAY. WITH
DECENT MID-LEVEL SUPPORT AND SHEAR/INSTABILITY...DAMAGING WINDS
WILL BE POSSIBLE WITH ANY MULTI-CELLULAR DEVELOPMENT THAT DOES
OCCUR FROM LATE MORNING ONWARD IN OHIO...WITH A LESSER CHANCE
FARTHER EAST.

AS THE UPPER LEVEL WAVE TRACKS FARTHER EAST WEDNESDAY
EVENING...THE RIGHT ENTRANCE REGION OF THE UPPER JET TRACKS
DIRECTLY OVER THE CWA. WITH IS IN CONCERT WITH THE MAIN SYNOPTIC
WAVE PASSAGE ROUGHLY 06Z/2AM THROUGH PITTSBURGH WEDNESDAY NIGHT.
BOTH NAM AND ECMWF SOLUTIONS ARE SUGGESTIVE OF LINEAR DEVELOPMENT
ALONG THE FRONTAL BOUNDARY AS IT PASSES THROUGH THE AREA LATE
WEDNESDAY EVENING/NIGHT...RESULTING IN THE POSSIBILITY OF A SQUALL
LINE MANAGING TO PERSIST WELL PAST THE NORMAL DIURNALLY FAVORED
HOURS OWING TO LARGE SCALE SUPPORT FOR ASCENT. CHANCES OF SEVERE
THUNDERSTORMS WITH DAMAGING WINDS WERE THUS ALLOWED TO SPREAD
ACROSS THE REST OF THE CWA FROM ROUGHLY 8 PM TO 3 AM AS THIS UPPER
WAVE PASSES THROUGH.

COLDER AIR FLOODS INTO THE AREA ON THURSDAY...HOWEVER WITH THE
MID-LEVELS COOLING MUCH QUICKER THAN THE LOW LEVELS...SHOWERS AND
THUNDERSTORMS WILL AGAIN BY POSSIBLE ACROSS THE AREA WITH SURFACE
TEMPERATURES MODERATING TOWARD 70F.

THE DUMP OF MUCH COLD AIR IS HELD BACK FOR A SECONDARY FRONTAL
PASSAGE ON FRIDAY WITH A WIDE SPREAD IN GUIDANCE FOR AFTERNOON
TEMPERATURES. ECMWF AND GFS 850 MB TEMPERATURES IN THE AFTERNOON
HOURS STRADDLE 0C...WHICH WOULD SUGGEST TEMPERATURES WOULD
STRUGGLE TO REACH 50F IF SUNSHINE FAILED TO MATERIALIZE. AT THE
MOMENT...IT WOULD SEEM MORE REASONABLE TO EXPECT AT LEAST SOME SUN
ON FRIDAY...SO HIGH TEMPERATURES WERE GENERALLY ADJUSTED FOR THE
MID 50S TO MID 60S ACROSS THE AREA. AS CONDITIONS CLEAR BY THE
AFTERNOON AND EVENING FRIDAY...COLD AIR ADVECTING INTO THE AREA
WILL LIKELY ALL FOR A VERY RAPID COOL OFF GOING INTO THE EVENING
AND POSSIBLY FROST BY THE OVERNIGHT. FRIES

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
VFR CONDS EXPD INTO THE NGT. ISOLD TSTMS IN CNTRL OH...BUT UPR AND
MID LVL RIDGE AND CAPPING LIMITING ACTIVITY. WL MONITOR TSTMS BUT
NOT PLANNING ON INCLUDING IN TAFS ATTM. A PD OF MVFR VIS IN BR
EXPD TWD SUNRISE THEN VFR RETURNS THRU ERLY AFTN. SCT TSTMS EXP
LATER IN THE AFTN AS A CDFNT BEGINS TO APRCH SO INCLUDED VCTS.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
OCNL RESTRNS LIKELY WED EVE INTO THU NGT WITH SHWRS/TSTMS AS A
CDFNT APRCHS AND MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL
BRING PSBL RESTRNS IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS
RETURN FRI NGT THRU SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 212124
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
524 PM EDT TUE MAY 21 2013

.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE INTO THE EVENING...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AN AREA OF MORE STABLE AIR IS CURRENTLY SHIFTING EASTWARD FROM
EASTERN OHIO INTO WESTERN PENNSYLVANIA...WHICH REPRESENTS THE
REMNANTS OF THE COOL DOME UNDER THIS MORNING`S CONVECTIVE DEBRIS
THAT COVERED EASTERN OHIO. WITH INSOLATION QUICKLY WORKING TO WARM
THIS COOL DOME...IT IS EXPECTED EVEN THIS AREA WILL DEVELOP
CUMULUS WITHIN THE NEXT FEW HOURS. BEHIND THIS AREA...A RATHER
UNDERSTATED LOW LEVEL MOISTURE CONVERGENCE AREA REPRESENTED BY A
DEWPOINT DISCONTINUITY WITH VALUES IN THE MID TO UPPER 50S BEHIND
IT AND MID 60S AHEAD OF THE AREA OF WIND CONVERGENCE. GIVEN CAPE
VALUES FROM LAPS GUIDANCE PUSHING 3000 J/KG ACROSS PORTIONS OF THE
CWA...THIS MAY JUST BE ENOUGH TO SPARK OFF A CLUSTER OF
THUNDERSTORMS ALONG THIS BOUNDARY AS IT EDGES EASTWARD THIS
EVENING. THE FORECAST WAS ADJUSTED FOR THIS IDEA...AND THE HRRR
CONCURS WITH ITS DEVELOPMENT CONSISTENTLY OVER THE PAST SEVERAL
HOURS OF RUNS.

TEMPERATURES OVERNIGHT WERE ALLOWED TO STAY UP IN THE MID TO UPPER
60S ACROSS MUCH OF THE AREA OWING TO STRONG LOW LEVEL MOISTURE AND
CONTINUOUS SOUTHWESTERLY FEED INTO THE AREA. THIS MEANS ANOTHER
WARM AND SOUPY NIGHT ACROSS THE REGION. FRIES

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A VERY PRONOUNCED LOW LEVEL JET IS EVIDENT ON ALL GUIDANCE BY
WEDNESDAY MORNING NOSING INTO SOUTHWESTERN OHIO AHEAD OF AN
INCOMING UPPER LEVEL WAVE. GUIDANCE CONTINUES TO BE A BIT VARIED
ON ITS PLACEMENT AND EVOLUTION GOING INTO THE LATER MORNING
HOURS...HOWEVER ENOUGH GUIDANCE MEMBERS BRING IT INTO CENTRAL OHIO
BY LATE MORNING THAT THUNDERSTORMS MAY WELL DEVELOP ALONG THE NOSE
OF IT. IN CONJUNCTION...SEVERAL CONSECUTIVE NAM RUNS HAVE DEPICTED
A COMPACT SHORTWAVE EMBEDDED INTO THE SOUTHWESTERLY FLOW TO TRACK
OVER WESTERN AND CENTRAL OHIO FROM LATE MORNING THROUGH EARLY
AFTERNOON. AS THIS OCCURS...CONVECTION IS LIKELY TO BREAK OUT. IN
ADDITION...WITH CAPE VALUES AROUND 1500 J/KG AND STRONGER 0-6 KM
SHEAR LIKELY OVER OHIO THAN POINTS FARTHER EAST...BETTER CHANCES
OF THUNDERSTORM DEVELOPMENT EXIST IN OHIO THAN THE REST OF THE
FORECAST AREA THROUGH MOST OF THE DAYTIME ON WEDNESDAY. WITH
DECENT MID-LEVEL SUPPORT AND SHEAR/INSTABILITY...DAMAGING WINDS
WILL BE POSSIBLE WITH ANY MULTI-CELLULAR DEVELOPMENT THAT DOES
OCCUR FROM LATE MORNING ONWARD IN OHIO...WITH A LESSER CHANCE
FARTHER EAST.

AS THE UPPER LEVEL WAVE TRACKS FARTHER EAST WEDNESDAY
EVENING...THE RIGHT ENTRANCE REGION OF THE UPPER JET TRACKS
DIRECTLY OVER THE CWA. WITH IS IN CONCERT WITH THE MAIN SYNOPTIC
WAVE PASSAGE ROUGHLY 06Z/2AM THROUGH PITTSBURGH WEDNESDAY NIGHT.
BOTH NAM AND ECMWF SOLUTIONS ARE SUGGESTIVE OF LINEAR DEVELOPMENT
ALONG THE FRONTAL BOUNDARY AS IT PASSES THROUGH THE AREA LATE
WEDNESDAY EVENING/NIGHT...RESULTING IN THE POSSIBILITY OF A SQUALL
LINE MANAGING TO PERSIST WELL PAST THE NORMAL DIURNALLY FAVORED
HOURS OWING TO LARGE SCALE SUPPORT FOR ASCENT. CHANCES OF SEVERE
THUNDERSTORMS WITH DAMAGING WINDS WERE THUS ALLOWED TO SPREAD
ACROSS THE REST OF THE CWA FROM ROUGHLY 8 PM TO 3 AM AS THIS UPPER
WAVE PASSES THROUGH.

COLDER AIR FLOODS INTO THE AREA ON THURSDAY...HOWEVER WITH THE
MID-LEVELS COOLING MUCH QUICKER THAN THE LOW LEVELS...SHOWERS AND
THUNDERSTORMS WILL AGAIN BY POSSIBLE ACROSS THE AREA WITH SURFACE
TEMPERATURES MODERATING TOWARD 70F.

THE DUMP OF MUCH COLD AIR IS HELD BACK FOR A SECONDARY FRONTAL
PASSAGE ON FRIDAY WITH A WIDE SPREAD IN GUIDANCE FOR AFTERNOON
TEMPERATURES. ECMWF AND GFS 850 MB TEMPERATURES IN THE AFTERNOON
HOURS STRADDLE 0C...WHICH WOULD SUGGEST TEMPERATURES WOULD
STRUGGLE TO REACH 50F IF SUNSHINE FAILED TO MATERIALIZE. AT THE
MOMENT...IT WOULD SEEM MORE REASONABLE TO EXPECT AT LEAST SOME SUN
ON FRIDAY...SO HIGH TEMPERATURES WERE GENERALLY ADJUSTED FOR THE
MID 50S TO MID 60S ACROSS THE AREA. AS CONDITIONS CLEAR BY THE
AFTERNOON AND EVENING FRIDAY...COLD AIR ADVECTING INTO THE AREA
WILL LIKELY ALL FOR A VERY RAPID COOL OFF GOING INTO THE EVENING
AND POSSIBLY FROST BY THE OVERNIGHT. FRIES

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
VFR CONDS EXPD THRU THE EVE. ISOLD TSTMS TRYING TO FIRE IN CNTRL
OH...BUT UPR AND MID LVL RIDGE AND CAPPING SHOULD HELP TO LIMIT
ACTIVITY. REMOVED VCTS SINCE TSTM COVG EXPD TO BE LOW...BUT WL AMD
IF TSTMS APRCH A TERMINAL. A PD OF MVFR VIS IN BR EXPD TWD SUNRISE
THEN VFR RETURNS THRU ERLY AFTN.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
RESTRNS EXPD WED EVE INTO THU NGT WITH SHWRS/TSTMS AS A CDFNT
APRCHS AND MOVES ACRS THE RGN. AN UPR LVL DISTURBANCE WL BRING
PSBL RESTRNS IN SHRA FRI BEFORE HIGH PRES AND VFR CONDS RETURN FRI
NGT THRU SUN.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 211938
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
338 PM EDT TUE MAY 21 2013

.SYNOPSIS...
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE INTO THE EVENING...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AN AREA OF MORE STABLE AIR IS CURRENTLY SHIFTING EASTWARD FROM
EASTERN OHIO INTO WESTERN PENNSYLVANIA...WHICH REPRESENTS THE
REMNANTS OF THE COOL DOME UNDER THIS MORNING`S CONVECTIVE DEBRIS
THAT COVERED EASTERN OHIO. WITH INSOLATION QUICKLY WORKING TO WARM
THIS COOL DOME...IT IS EXPECTED EVEN THIS AREA WILL DEVELOP
CUMULUS WITHIN THE NEXT FEW HOURS. BEHIND THIS AREA...A RATHER
UNDERSTATED LOW LEVEL MOISTURE CONVERGENCE AREA REPRESENTED BY A
DEWPOINT DISCONTINUITY WITH VALUES IN THE MID TO UPPER 50S BEHIND
IT AND MID 60S AHEAD OF THE AREA OF WIND CONVERGENCE. GIVEN CAPE
VALUES FROM LAPS GUIDANCE PUSHING 3000 J/KG ACROSS PORTIONS OF THE
CWA...THIS MAY JUST BE ENOUGH TO SPARK OFF A CLUSTER OF
THUNDERSTORMS ALONG THIS BOUNDARY AS IT EDGES EASTWARD THIS
EVENING. THE FORECAST WAS ADJUSTED FOR THIS IDEA...AND THE HRRR
CONCURS WITH ITS DEVELOPMENT CONSISTENTLY OVER THE PAST SEVERAL
HOURS OF RUNS.

TEMPERATURES OVERNIGHT WERE ALLOWED TO STAY UP IN THE MID TO UPPER
60S ACROSS MUCH OF THE AREA OWING TO STRONG LOW LEVEL MOISTURE AND
CONTINUOUS SOUTHWESTERLY FEED INTO THE AREA. THIS MEANS ANOTHER
WARM AND SOUPY NIGHT ACROSS THE REGION. FRIES

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A VERY PRONOUNCED LOW LEVEL JET IS EVIDENT ON ALL GUIDANCE BY
WEDNESDAY MORNING NOSING INTO SOUTHWESTERN OHIO AHEAD OF AN
INCOMING UPPER LEVEL WAVE. GUIDANCE CONTINUES TO BE A BIT VARIED
ON ITS PLACEMENT AND EVOLUTION GOING INTO THE LATER MORNING
HOURS...HOWEVER ENOUGH GUIDANCE MEMBERS BRING IT INTO CENTRAL OHIO
BY LATE MORNING THAT THUNDERSTORMS MAY WELL DEVELOP ALONG THE NOSE
OF IT. IN CONJUNCTION...SEVERAL CONSECUTIVE NAM RUNS HAVE DEPICTED
A COMPACT SHORTWAVE EMBEDDED INTO THE SOUTHWESTERLY FLOW TO TRACK
OVER WESTERN AND CENTRAL OHIO FROM LATE MORNING THROUGH EARLY
AFTERNOON. AS THIS OCCURS...CONVECTION IS LIKELY TO BREAK OUT. IN
ADDITION...WITH CAPE VALUES AROUND 1500 J/KG AND STRONGER 0-6 KM
SHEAR LIKELY OVER OHIO THAN POINTS FARTHER EAST...BETTER CHANCES
OF THUNDERSTORM DEVELOPMENT EXIST IN OHIO THAN THE REST OF THE
FORECAST AREA THROUGH MOST OF THE DAYTIME ON WEDNESDAY. WITH
DECENT MID-LEVEL SUPPORT AND SHEAR/INSTABILITY...DAMAGING WINDS
WILL BE POSSIBLE WITH ANY MULTI-CELLULAR DEVELOPMENT THAT DOES
OCCUR FROM LATE MORNING ONWARD IN OHIO...WITH A LESSER CHANCE
FARTHER EAST.

AS THE UPPER LEVEL WAVE TRACKS FARTHER EAST WEDNESDAY
EVENING...THE RIGHT ENTRANCE REGION OF THE UPPER JET TRACKS
DIRECTLY OVER THE CWA. WITH IS IN CONCERT WITH THE MAIN SYNOPTIC
WAVE PASSAGE ROUGHLY 06Z/2AM THROUGH PITTSBURGH WEDNESDAY NIGHT.
BOTH NAM AND ECMWF SOLUTIONS ARE SUGGESTIVE OF LINEAR DEVELOPMENT
ALONG THE FRONTAL BOUNDARY AS IT PASSES THROUGH THE AREA LATE
WEDNESDAY EVENING/NIGHT...RESULTING IN THE POSSIBILITY OF A SQUALL
LINE MANAGING TO PERSIST WELL PAST THE NORMAL DIURNALLY FAVORED
HOURS OWING TO LARGE SCALE SUPPORT FOR ASCENT. CHANCES OF SEVERE
THUNDERSTORMS WITH DAMAGING WINDS WERE THUS ALLOWED TO SPREAD
ACROSS THE REST OF THE CWA FROM ROUGHLY 8 PM TO 3 AM AS THIS UPPER
WAVE PASSES THROUGH.

COLDER AIR FLOODS INTO THE AREA ON THURSDAY...HOWEVER WITH THE
MID-LEVELS COOLING MUCH QUICKER THAN THE LOW LEVELS...SHOWERS AND
THUNDERSTORMS WILL AGAIN BY POSSIBLE ACROSS THE AREA WITH SURFACE
TEMPERATURES MODERATING TOWARD 70F.

THE DUMP OF MUCH COLD AIR IS HELD BACK FOR A SECONDARY FRONTAL
PASSAGE ON FRIDAY WITH A WIDE SPREAD IN GUIDANCE FOR AFTERNOON
TEMPERATURES. ECMWF AND GFS 850 MB TEMPERATURES IN THE AFTERNOON
HOURS STRADDLE 0C...WHICH WOULD SUGGEST TEMPERATURES WOULD
STRUGGLE TO REACH 50F IF SUNSHINE FAILED TO MATERIALIZE. AT THE
MOMENT...IT WOULD SEEM MORE REASONABLE TO EXPECT AT LEAST SOME SUN
ON FRIDAY...SO HIGH TEMPERATURES WERE GENERALLY ADJUSTED FOR THE
MID 50S TO MID 60S ACROSS THE AREA. AS CONDITIONS CLEAR BY THE
AFTERNOON AND EVENING FRIDAY...COLD AIR ADVECTING INTO THE AREA
WILL LIKELY ALL FOR A VERY RAPID COOL OFF GOING INTO THE EVENING
AND POSSIBLY FROST BY THE OVERNIGHT. FRIES

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOW SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
GENERAL VFR IS EXPECTED THROUGH THE AFTERNOON. HOWEVER...SINCE WE
REMAIN IN THE WARM SECTOR...PLENTY OF INSTABILITY IS PRESENT FOR
THE DEVELOPMENT OF THUNDERSTORMS...WHICH IS PROGGED TO OCCUR
AROUND 21-23Z ACROSS THE REGION BASED ON HI RES MODEL OUTPUT.
CURRENT THINKING IS THAT A WEAK BOUNDARY...INDICATED BY A WIND
SHIFT OVER OH COULD BECOME THE FOCUS FOR DEVELOPMENT AS A WAVE
APPROACHES. SINCE THUNDERSTORMS HAVE YET TO DEVELOP AND CONFIDENCE
THAT ANY ONE SITE WILL BE IMPACTED REMAINING LOW...DECIDED TO
MAINTAIN THE VCTS MENTION FOR APPROX 4-5 HOURS THROUGH THE EARLY
EVENING. THERE COULD BE TEMPORARY RESTRICTIONS TO VISIBILITY IN
ANY SHOWERS THAT DO DEVELOP...BUT ALSO OPTED TO KEEP THIS OUT AT
THIS TIME.

OVERNIGHT FOG COULD ONCE AGAIN DEVELOP AS THE LOW LEVELS REMAIN
MOIST...ESPECIALLY IF ANY AREAS RECEIVE RAINFALL.

S-SW WIND WILL CONTINUE AT 5-10KTS TODAY AND OVERNIGHT.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND CROSSES THE REGION. NORTHWEST FLOW
MAY CONTINUE THE CHANCE FOR SHOWERS AND SOME RESTRICTIONS FRIDAY BEFORE
BUILDING HIGH PRESSURE BRINGS THE RETURN OF VFR FRIDAY NIGHT AND
SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 211854
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
254 PM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE MORNING TRENDS ARE INDICATING DRAMATIC TEMPERATURE RISES
ACROSS WESTERN PENNSYLVANIA IN PARTICULAR. NEW CASTLE WAS ALREADY
83F AT 11 AM...WITH NEAR 80F COMMON ACROSS THE PITTSBURGH AREA.
TEMPERATURES WERE NUDGED UPWARD FOR THIS AFTERNOON IN THE
AFOREMENTIONED AREA...AND MAINTAINED ELSEWHERE.

PREVIOUS DISCUSSION FOLLOWS...CONVECTIVE DEBRIS CLOUDS ARE
CURRENTLY IN TRANSIT ACROSS THE FORECAST AREA AND CONCURRENTLY
DISSIPATING. TEMPERATURE READINGS ARE SEVERAL DEGREES HIGHER THAN
THIS TIME YESTERDAY AS WELL. WITH LITTLE IN THE WAY TO PREVENT
ABUNDANT INSOLATION ACROSS MUCH OF THE AREA...AND THE FACT THAT
THE LOW LEVEL THERMAL TONGUE WILL BE TRAVERSING THE HEART OF THE
CWA AT MAX HEATING...WITH 850 MB TEMPERATURES NEARING +18C AROUND
21Z OVER PITTSBURGH WITH DECENT BOUNDARY LAYER MIXING...IT WOULD
SEEM TEMPERATURES SHOULD SURPASS THOSE REACHED YESTERDAY. AS
SUCH...HIGHS WERE INCREASED INTO THE UPPER 80S FOR THE SOUTHERN
TWO-THIRDS OF THE CWA...AND THE MID 80S UP ALONG I-80.

WITH INCREASED HEATING AND SIMILAR DEWPOINTS AS COMPARED TO
YESTERDAY IN THE UPPER 60S...CAPE VALUES LOOK TO RUN UP TOWARD
3000 J/KG. GIVEN A WEAKLY SHEARED ENVIRONMENT AND NO SIGNIFICANT
SYNOPTIC OR MESOSCALE DISTURBANCE TO HARNESS THE CAPE...WIDESPREAD
THUNDERSTORM DEVELOPMENT IS NOT ANTICIPATED. HOWEVER...WEAK LOCAL
FORCING SEEMS LIKELY TO ALLOW FOR SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP ACROSS MUCH OF THE AREA BY
AFTERNOON...PARTICULARLY IN AREAS WEST OF PITTSBURGH AS WELL AS IN
THE RIDGES. POPS WERE INCREASED IN THESE AREAS. WITH WEAK SHEAR
AND WEAK MOMENTUM IN THE COLUMN...AS WELL AS A RATHER WARM
PROFILE...UPDRAFTS TO SUSTAIN HAIL DEVELOPMENT WILL BE DIFFICULT
TO MAINTAIN...HOWEVER A WIND GUST OR TWO MAY BE POSSIBLE OUT OF A
FEW OF THE CELLS. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVER CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION AND SHEAR VALUES
INCREASE. HAVE DECIDED TO GO WITH LIKELY POPS WED DUE TO THE
AFOREMENTIONED FACTORS. SPC CONTINUES TO KEEP THE AREA IN A SLIGHT
RISK FOR WED...SO WILL INCLUDE WORDING OF POSSIBLE SEVERE AND
MENTION IN HWO.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY...SO WILL
CONTINUE WITH LIKELY POPS. THURSDAYS NOT NEARLY AS UNSTABLE AS
TODAY OR WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL IN
QUESTION.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE MODELS ARE IN GOOD AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN
THROUGH THE EXTENDED WITH AN UPPER LEVEL RIDGING OF THE CENTRAL
CONUS AND TROUGHING IN BOTH THE WEST AND EAST. WHILE THIS WOULD
GENERALLY LEAD TO A MUCH LESS THAN CONFIDENT FORECAST IN THE
SHORTWAVES WITHIN THE FLOW...THIS DOESN`T SEEM TO BE THE CASE AS
BOTH THE GFS AND ECMWF SUGGEST THAT MUCH OF THE PRECIPITATION WILL
BE SUPPRESSED SOUTH OF THE REGION THROUGH MUCH OF THE PERIOD.
THUS...OPTED TO TAKE A BLEND OF THE MODELS AND HPC
GUIDANCE. ALSO...HEDGED A BIT COOLER WITH TEMPERATURES WITH
NORTHWEST FLOW PRESENT ESPECIALLY FOR THE FIRST HALF OF THE
PERIOD. THIS KEPT TEMPERATURES BELOE SEASONAL AVERAGES SAT/SUN
BEFORE MODERATING CLOSER TO NORMAL FOR THE REST OF THE PERIOD.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
GENERAL VFR IS EXPECTED THROUGH THE AFTERNOON. HOWEVER...SINCE WE
REMAIN IN THE WARM SECTOR...PLENTY OF INSTABILITY IS PRESENT FOR
THE DEVELOPMENT OF THUNDERSTORMS...WHICH IS PROGGED TO OCCUR
AROUND 21-23Z ACROSS THE REGION BASED ON HI RES MODEL OUTPUT.
CURRENT THINKING IS THAT A WEAK BOUNDARY...INDICATED BY A WIND
SHIFT OVER OH COULD BECOME THE FOCUS FOR DEVELOPMENT AS A WAVE
APPROACHES. SINCE THUNDERSTORMS HAVE YET TO DEVELOP AND CONFIDENCE
THAT ANY ONE SITE WILL BE IMPACTED REMAINING LOW...DECIDED TO
MAINTAIN THE VCTS MENTION FOR APPROX 4-5 HOURS THROUGH THE EARLY
EVENING. THERE COULD BE TEMPORARY RESTRICTIONS TO VISIBILITY IN
ANY SHOWERS THAT DO DEVELOP...BUT ALSO OPTED TO KEEP THIS OUT AT
THIS TIME.

OVERNIGHT FOG COULD ONCE AGAIN DEVELOP AS THE LOW LEVELS REMAIN
MOIST...ESPECIALLY IF ANY AREAS RECEIVE RAINFALL.

S-SW WIND WILL CONTINUE AT 5-10KTS TODAY AND OVERNIGHT.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND CROSSES THE REGION. NORTHWEST FLOW
MAY CONTINUE THE CHANCE FOR SHOWERS AND SOME RESTRICTIONS FRIDAY BEFORE
BUILDING HIGH PRESSURE BRINGS THE RETURN OF VFR FRIDAY NIGHT AND
SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 211534
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1134 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE MORNING TRENDS ARE INDICATING DRAMATIC TEMPERATURE RISES
ACROSS WESTERN PENNSYLVANIA IN PARTICULAR. NEW CASTLE WAS ALREADY
83F AT 11 AM...WITH NEAR 80F COMMON ACROSS THE PITTSBURGH AREA.
TEMPERATURES WERE NUDGED UPWARD FOR THIS AFTERNOON IN THE
AFOREMENTIONED AREA...AND MAINTAINED ELSEWHERE.

PREVIOUS DISCUSSION FOLLOWS...CONVECTIVE DEBRIS CLOUDS ARE
CURRENTLY IN TRANSIT ACROSS THE FORECAST AREA AND CONCURRENTLY
DISSIPATING. TEMPERATURE READINGS ARE SEVERAL DEGREES HIGHER THAN
THIS TIME YESTERDAY AS WELL. WITH LITTLE IN THE WAY TO PREVENT
ABUNDANT INSOLATION ACROSS MUCH OF THE AREA...AND THE FACT THAT
THE LOW LEVEL THERMAL TONGUE WILL BE TRAVERSING THE HEART OF THE
CWA AT MAX HEATING...WITH 850 MB TEMPERATURES NEARING +18C AROUND
21Z OVER PITTSBURGH WITH DECENT BOUNDARY LAYER MIXING...IT WOULD
SEEM TEMPERATURES SHOULD SURPASS THOSE REACHED YESTERDAY. AS
SUCH...HIGHS WERE INCREASED INTO THE UPPER 80S FOR THE SOUTHERN
TWO-THIRDS OF THE CWA...AND THE MID 80S UP ALONG I-80.

WITH INCREASED HEATING AND SIMILAR DEWPOINTS AS COMPARED TO
YESTERDAY IN THE UPPER 60S...CAPE VALUES LOOK TO RUN UP TOWARD
3000 J/KG. GIVEN A WEAKLY SHEARED ENVIRONMENT AND NO SIGNIFICANT
SYNOPTIC OR MESOSCALE DISTURBANCE TO HARNESS THE CAPE...WIDESPREAD
THUNDERSTORM DEVELOPMENT IS NOT ANTICIPATED. HOWEVER...WEAK LOCAL
FORCING SEEMS LIKELY TO ALLOW FOR SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP ACROSS MUCH OF THE AREA BY
AFTERNOON...PARTICULARLY IN AREAS WEST OF PITTSBURGH AS WELL AS IN
THE RIDGES. POPS WERE INCREASED IN THESE AREAS. WITH WEAK SHEAR
AND WEAK MOMENTUM IN THE COLUMN...AS WELL AS A RATHER WARM
PROFILE...UPDRAFTS TO SUSTAIN HAIL DEVELOPMENT WILL BE DIFFICULT
TO MAINTAIN...HOWEVER A WIND GUST OR TWO MAY BE POSSIBLE OUT OF A
FEW OF THE CELLS. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVER CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION AND SHEAR VALUES
INCREASE. HAVE DECIDED TO GO WITH LIKELY POPS WED DUE TO THE
AFOREMENTIONED FACTORS. SPC CONTINUES TO KEEP THE AREA IN A SLIGHT
RISK FOR WED...SO WILL INCLUDE WORDING OF POSSIBLE SEVERE AND
MENTION IN HWO.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY...SO WILL
CONTINUE WITH LIKELY POPS. THURSDAYS NOT NEARLY AS UNSTABLE AS
TODAY OR WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL IN
QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS SHOULD PREVAIL FOR MUCH OF THE DAY. HOWEVER SINCE
WE REMAIN IN THE WARM SECTOR...PLENTY OF INSTABILITY WILL BE
PRESENT FOR THE DEVELOPMENT OF SOME THUNDERSTORMS ESPECIALLY IF WE
REACH CONVECTIVE TEMPERATURES TODAY...ALTHOUGH COVERAGE REMAINS IN
QUESTION. FOR NOW...WITH CONFIDENCE THAT ANY ONE THUNDERSTORM WILL
IMPACT A TAF SITE REMAINING LOW...CONTINUED VCTS MENTION. THERE
COULD BE TEMPORARY RESTRICTIONS TO VISIBILITY IN ANY SHOWERS THAT
DO DEVELOP...BUT ALSO OPTED TO KEEP THIS OUT AT THIS TIME.

OVERNIGHT FOG COULD ONCE AGAIN DEVELOP AS THE LOW LEVELS REMAIN
MOIST.

S-SW WIND WILL CONTINUE AT 5-10KTS TODAY AND OVERNIGHT.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND CROSSES THE REGION. BUILDING HIGH
PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 211402
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1002 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CONVECTIVE DEBRIS CLOUDS ARE CURRENTLY IN TRANSIT ACROSS THE
FORECAST AREA AND CONCURRENTLY DISSIPATING. TEMPERATURE READINGS
ARE SEVERAL DEGREES HIGHER THAN THIS TIME YESTERDAY AS WELL. WITH
LITTLE IN THE WAY TO PREVENT ABUNDANT INSOLATION ACROSS MUCH OF
THE AREA...AND THE FACT THAT THE LOW LEVEL THERMAL TONGUE WILL BE
TRAVERSING THE HEART OF THE CWA AT MAX HEATING...WITH 850 MB
TEMPERATURES NEARING +18C AROUND 21Z OVER PITTSBURGH WITH DECENT
BOUNDARY LAYER MIXING...IT WOULD SEEM TEMPERATURES SHOULD SURPASS
THOSE REACHED YESTERDAY. AS SUCH...HIGHS WERE INCREASED INTO THE
UPPER 80S FOR THE SOUTHERN TWO-THIRDS OF THE CWA...AND THE MID 80S
UP ALONG I-80.

WITH INCREASED HEATING AND SIMILAR DEWPOINTS AS COMPARED TO
YESTERDAY IN THE UPPER 60S...CAPE VALUES LOOK TO RUN UP TOWARD
3000 J/KG. GIVEN A WEAKLY SHEARED ENVIRONMENT AND NO SIGNIFICANT
SYNOPTIC OR MESOSCALE DISTURBANCE TO HARNESS THE CAPE...WIDESPREAD
THUNDERSTORM DEVELOPMENT IS NOT ANTICIPATED. HOWEVER...WEAK LOCAL
FORCING SEEMS LIKELY TO ALLOW FOR SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP ACROSS MUCH OF THE AREA BY
AFTERNOON...PARTICULARLY IN AREAS WEST OF PITTSBURGH AS WELL AS IN
THE RIDGES. POPS WERE INCREASED IN THESE AREAS. WITH WEAK SHEAR
AND WEAK MOMENTUM IN THE COLUMN...AS WELL AS A RATHER WARM
PROFILE...UPDRAFTS TO SUSTAIN HAIL DEVELOPMENT WILL BE DIFFICULT
TO MAINTAIN...HOWEVER A WIND GUST OR TWO MAY BE POSSIBLE OUT OF A
FEW OF THE CELLS. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVER CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION AND SHEAR VALUES
INCREASE. HAVE DECIDED TO GO WITH LIKELY POPS WED DUE TO THE
AFOREMENTIONED FACTORS. SPC CONTINUES TO KEEP THE AREA IN A SLIGHT
RISK FOR WED...SO WILL INCLUDE WORDING OF POSSIBLE SEVERE AND
MENTION IN HWO.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY...SO WILL
CONTINUE WITH LIKELY POPS. THURSDAYS NOT NEARLY AS UNSTABLE AS
TODAY OR WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL IN
QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS SHOULD PREVAIL FOR MUCH OF THE DAY. HOWEVER SINCE
WE REMAIN IN THE WARM SECTOR...PLENTY OF INSTABILITY WILL BE
PRESENT FOR THE DEVELOPMENT OF SOME THUNDERSTORMS ESPECIALLY IF WE
REACH CONVECTIVE TEMPERATURES TODAY...ALTHOUGH COVERAGE REMAINS IN
QUESTION. FOR NOW...WITH CONFIDENCE THAT ANY ONE THUNDERSTORM WILL
IMPACT A TAF SITE REMAINING LOW...CONTINUED VCTS MENTION. THERE
COULD BE TEMPORARY RESTRICTIONS TO VISIBILITY IN ANY SHOWERS THAT
DO DEVELOP...BUT ALSO OPTED TO KEEP THIS OUT AT THIS TIME.

OVERNIGHT FOG COULD ONCE AGAIN DEVELOP AS THE LOW LEVELS REMAIN
MOIST.

S-SW WIND WILL CONTINUE AT 5-10KTS TODAY AND OVERNIGHT.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND CROSSES THE REGION. BUILDING HIGH
PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 211345
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
945 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EXPECT MOST OF THE MORNING TO BE QUIET WITH INCREASING HIGH
CLOUDS...THE REMNANTS FROM LAST NIGHTS STORMS OVER THE MIDWEST.
CONVECTION WILL LIKELY HOLD OFF UNTIL THE AFTERNOON...WHEN THE
ATMOSPHERE RAPIDLY DESTABILIZES (CAPES OF 3000-3500 J/KG)...AND A
WEAK FRONTAL BOUNDARY MOVES THROUGH. THIS IS THE FIRST REAL
TRIGGER SINCE LAST WEEK. THE FRONT ITSELF IS WEAK...ONLY
NOTICEABLE BY A SURFACE WIND SHIFT. ADDITIONALLY...THERE IS NOT
MUCH UPPER LEVEL SUPPORT...WITH A SMALL SHORTWAVE SWINGING ACROSS
THE NORTH LATE TODAY. HOWEVER...MODELS ARE SHOWING LOW AND MID
LEVEL FORCING INCREASING WITH THE BOUNDARY AND LOW LEVEL MOISTURE
POOLING. THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN THIS
AFTERNOON...AND IF WE CAN REACH OUR CONVECTIVE TEMP...IN THE MID
80S...NOT MUCH TO STOP THE PARCELS FROM RISING. THAT MAY BE THE
MOST IMPORTANT QUESTION...WHETHER WE CAN REACH THE CONVECTIVE
TEMP. WITH FULL SUN...HAVE NO DOUBT WE WOULD GO ABOVE THE MID
80S...HOWEVER CONCERNED ABOUT THE CIRRUS BLOW-OFF...FROM PREVIOUS
MIDWEST CONVECTION...THAT WILL MOVE OVER THE AREA TODAY. IF THE
HIGH CLOUDS HOLD TOGETHER...COULD NEGATE JUST ENOUGH SUNSHINE TO
KEEP OUR TEMPS DOWN A COUPLE OF DEGREES. WILL CONTINUE WITH HIGH
CHC POPS LATER TODAY...DOING SO WITH UNCERTAINTY ON IF WIDESPREAD
CONVECTION CAN DEVELOP. COULD SEE A SCENARIO WHERE A LINE OF
CONVECTION DEVELOPS OVER EC OHIO AND NW PA EARLY THIS AFTERNOON
AND BARRELS THROUGH...REACHING THE SE MTS BY EVE.

THE WIND FIELD ALOFT IS NOT OVERLY IMPRESSIVE WITH WINDS OF 25 TO
35 KTS...HOWEVER...WITH WBZ LEVELS RANGING FROM 9500-11000 HAIL
WOULD BE A GOOD BET.

SO IF CONVECTION DOES GET GOING THIS AFTERNOON...THERE WILL BE
SOME WIND GUSTS...BUT THINK THE MAIN CONCERN WOULD BE LARGE HAIL.
WILL INCLUDE THE WORDING OF GUSTY WINDS AND HAIL WITH THUNDERSTORMS.

FOR HIGHS TODAY...WILL LEAN CLOSE TO THE LATEST LAMP AS THOSE
NUMBERS HAVE WORKED WELL THAT PAST COUPLE OF DAYS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVER CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION AND SHEAR VALUES
INCREASE. HAVE DECIDED TO GO WITH LIKELY POPS WED DUE TO THE
AFOREMENTIONED FACTORS. SPC CONTINUES TO KEEP THE AREA IN A SLIGHT
RISK FOR WED...SO WILL INCLUDE WORDING OF POSSIBLE SEVERE AND
MENTION IN HWO.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY...SO WILL
CONTINUE WITH LIKELY POPS. THURSDAYS NOT NEARLY AS UNSTABLE AS
TODAY OR WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL IN
QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS SHOULD PREVAIL FOR MUCH OF THE DAY. HOWEVER SINCE
WE REMAIN IN THE WARM SECTOR...PLENTY OF INSTABILITY WILL BE
PRESENT FOR THE DEVELOPMENT OF SOME THUNDERSTORMS ESPECIALLY IF WE
REACH CONVECTIVE TEMPERATURES TODAY...ALTHOUGH COVERAGE REMAINS IN
QUESTION. FOR NOW...WITH CONFIDENCE THAT ANY ONE THUNDERSTORM WILL
IMPACT A TAF SITE REMAINING LOW...CONTINUED VCTS MENTION. THERE
COULD BE TEMPORARY RESTRICTIONS TO VISIBILITY IN ANY SHOWERS THAT
DO DEVELOP...BUT ALSO OPTED TO KEEP THIS OUT AT THIS TIME.

OVERNIGHT FOG COULD ONCE AGAIN DEVELOP AS THE LOW LEVELS REMAIN
MOIST.

S-SW WIND WILL CONTINUE AT 5-10KTS TODAY AND OVERNIGHT.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND CROSSES THE REGION. BUILDING HIGH
PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 210823
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
423 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EXPECT MOST OF THE MORNING TO BE QUIET WITH INCREASING HIGH
CLOUDS...THE REMNANTS FROM LAST NIGHTS STORMS OVER THE MIDWEST.
CONVECTION WILL LIKELY HOLD OFF UNTIL THE AFTERNOON...WHEN THE
ATMOSPHERE RAPIDLY DESTABILIZES (CAPES OF 3000-3500 J/KG)...AND A
WEAK FRONTAL BOUNDARY MOVES THROUGH. THIS IS THE FIRST REAL
TRIGGER SINCE LAST WEEK. THE FRONT ITSELF IS WEAK...ONLY
NOTICEABLE BY A SURFACE WIND SHIFT. ADDITIONALLY...THERE IS NOT
MUCH UPPER LEVEL SUPPORT...WITH A SMALL SHORTWAVE SWINGING ACROSS
THE NORTH LATE TODAY. HOWEVER...MODELS ARE SHOWING LOW AND MID
LEVEL FORCING INCREASING WITH THE BOUNDARY AND LOW LEVEL MOISTURE
POOLING. THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN THIS
AFTERNOON...AND IF WE CAN REACH OUR CONVECTIVE TEMP...IN THE MID
80S...NOT MUCH TO STOP THE PARCELS FROM RISING. THAT MAY BE THE
MOST IMPORTANT QUESTION...WHETHER WE CAN REACH THE CONVECTIVE
TEMP. WITH FULL SUN...HAVE NO DOUBT WE WOULD GO ABOVE THE MID
80S...HOWEVER CONCERNED ABOUT THE CIRRUS BLOW-OFF...FROM PREVIOUS
MIDWEST CONVECTION...THAT WILL MOVE OVER THE AREA TODAY. IF THE
HIGH CLOUDS HOLD TOGETHER...COULD NEGATE JUST ENOUGH SUNSHINE TO
KEEP OUR TEMPS DOWN A COUPLE OF DEGREES. WILL CONTINUE WITH HIGH
CHC POPS LATER TODAY...DOING SO WITH UNCERTAINTY ON IF WIDESPREAD
CONVECTION CAN DEVELOP. COULD SEE A SCENARIO WHERE A LINE OF
CONVECTION DEVELOPS OVER EC OHIO AND NW PA EARLY THIS AFTERNOON
AND BARRELS THROUGH...REACHING THE SE MTS BY EVE.

THE WIND FIELD ALOFT IS NOT OVERLY IMPRESSIVE WITH WINDS OF 25 TO
35 KTS...HOWEVER...WITH WBZ LEVELS RANGING FROM 9500-11000 HAIL
WOULD BE A GOOD BET.

SO IF CONVECTION DOES GET GOING THIS AFTERNOON...THERE WILL BE
SOME WIND GUSTS...BUT THINK THE MAIN CONCERN WOULD BE LARGE HAIL.
WILL INCLUDE THE WORDING OF GUSTY WINDS AND HAIL WITH THUNDERSTORMS.

FOR HIGHS TODAY...WILL LEAN CLOSE TO THE LATEST LAMP AS THOSE
NUMBERS HAVE WORKED WELL THAT PAST COUPLE OF DAYS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVER CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION AND SHEAR VALUES
INCREASE. HAVE DECIDED TO GO WITH LIKELY POPS WED DUE TO THE
AFOREMENTIONED FACTORS. SPC CONTINUES TO KEEP THE AREA IN A SLIGHT
RISK FOR WED...SO WILL INCLUDE WORDING OF POSSIBLE SEVERE AND
MENTION IN HWO.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY...SO WILL
CONTINUE WITH LIKELY POPS. THURSDAYS NOT NEARLY AS UNSTABLE AS
TODAY OR WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL IN
QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
LIGHT SOUTH WINDS WILL REMAIN THROUGH THE OVERNIGHT. ANOTHER
ROUND OF MVFR FOG IS A GOOD POSSIBILITY THROUGH THE MID MORNING.
SCATTERED AFTERNOON THUNDERSTORMS ARE A POSSIBILITY...WITH
SLIGHTLY MORE COVERAGE EXPECTED THAN YESTERDAY. FOR NOW WILL
INCLUDE VCTS FROM KPIT NORTH AND WEST IN TERMINALS. DID NOT HAVE
ENOUGH CONFIDENCE IN YET ANOTHER ROUND OF MVFR FOG TO INCLUDE IN
30 HOUR PIT TAF...WITH THUNDERSTORM COVERAGE AND ASSOCIATED
PRECIPITATION LIKELY PLAYING A ROLE IN THIS FORECAST.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND PASSES ACROSS THE REGION. BUILDING
HIGH PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 210718
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
318 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
QUIET NIGHT ACROSS THE REGION UNDER STRENGTHENING RIDGE. LARGE
AREA OF ACTIVITY WELL TO THE WEST AND ANOTHER AREA SWINGING INTO
SOUTHERN CANADA.

EXPECT MOST OF THE MORNING TO BE QUIET WITH INCREASING HIGH
CLOUDS...THE REMNANTS OF THE LARGE AREA OF STORMS OVER THE
MIDWEST. CONVECTION WILL LIKELY HOLD OFF UNTIL THE AFTERNOON...
WHEN THE ATMOSPHERE RAPIDLY DESTABILIZES (CAPES OF 3000-3500
J/KG)...AND A WEAK FRONTAL BOUNDARY MOVES THROUGH. THIS IS THE
FIRST REAL TRIGGER SINCE LAST WEEK. THE FRONT ITSELF IS WEAK...
ONLY NOTICEABLE BY A SURFACE WIND SHIFT WITH LITTLE TO NO UPPER
LEVEL SUPPORT. HOWEVER...MODELS ARE SHOWING LOW AND MID LEVEL
FORCING INCREASING WITH THE BOUNDARY AND LOW LEVEL MOISTURE
POOLING. THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN THIS
AFTERNOON AND IF WE CAN REACH OUR CONVECTIVE TEMP...IN THE MID
80S...NOT MUCH TO STOP THE PARCELS FROM RISING. THAT MAY BE THE
MOST IMPORTANT QUESTION...WHETHER WE CAN REACH THE CONVECTIVE
TEMP. WITH FULL SUN...HAVE NO DOUBT WE WOULD GO ABOVE THE MID
80S...HOWEVER AM CONCERNED ABOUT THE CIRRUS BLOW-OFF...FROM MIDWEST
CONVECTION...THAT WILL MOVE OVER THE AREA TODAY. IF THE HIGH
CLOUDS HOLD TOGETHER...COULD NEGATE JUST ENOUGH SUNSHINE TO KEEP
OUR TEMPS DOWN A FEW DEGREES. WILL CONTINUE WITH HIGH CHC POPS
LATER TODAY...DOING SO WITH UNCERTAINTY ON IF WE CAN GET MORE
WIDESPREAD CONVECTION TO DEVELOP. COULD SEE A SCENARIO WHERE A
LINE OF CONVECTION DEVELOPS OVER EC OHIO AND NW PA EARLY THIS
AFTERNOON AND BARRELS THROUGH...REACHING THE SE MTS BY EVE.

THE WIND FIELD ALOFT IS NOT OVERLY IMPRESSIVE WITH WINDS OF 25 TO
35 KTS...HOWEVER...WITH WBZ LEVELS RANGING FROM 9500-11000 HAIL
WOULD BE A GOOD BET.

SO IF CONVECTION DOES GET GOING THIS AFTERNOON...THERE WILL BE
SOME WIND GUSTS...BUT THINK THE MAIN CONCERN WOULD BE LARGE HAIL.

FOR HIGHS TODAY...WILL LEAN CLOSE TO THE LATEST LAMP AS THOSE
NUMBERS HAVE WORKED WELL THAT PAST COUPLE OF DAYS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVERY CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION. HAVE DECIDED TO GO
WITH LIKELY POPS WED DUE TO THE AFOREMENTIONED FACTORS.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY SO WILL
CONTINUE WITH LIKELY POPS. THURSDAY NOT NEARLY AS UNSTABLE AS
TODAY AND WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL
IN QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
LIGHT SOUTH WINDS WILL REMAIN THROUGH THE OVERNIGHT. ANOTHER
ROUND OF MVFR FOG IS A GOOD POSSIBILITY THROUGH THE MID MORNING.
SCATTERED AFTERNOON THUNDERSTORMS ARE A POSSIBILITY...WITH
SLIGHTLY MORE COVERAGE EXPECTED THAN YESTERDAY. FOR NOW WILL
INCLUDE VCTS FROM KPIT NORTH AND WEST IN TERMINALS. DID NOT HAVE
ENOUGH CONFIDENCE IN YET ANOTHER ROUND OF MVFR FOG TO INCLUDE IN
30 HOUR PIT TAF...WITH THUNDERSTORM COVERAGE AND ASSOCIATED
PRECIPITATION LIKELY PLAYING A ROLE IN THIS FORECAST.

.OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND PASSES ACROSS THE REGION. BUILDING
HIGH PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 210515 AAC
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
115 AM EDT TUE MAY 21 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TODAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /THROUGH TODAY/...
QUIET NIGHT ACROSS THE REGION UNDER STRENGTHENING RIDGE. LARGE
AREA OF ACTIVITY WELL TO THE WEST AND ANOTHER AREA SWINGING INTO
SOUTHERN CANADA.

EXPECT MOST OF THE MORNING TO BE QUIET WITH INCREASING HIGH
CLOUDS...THE REMNANTS OF THE LARGE AREA OF STORMS OVER THE
MIDWEST. CONVECTION WILL LIKELY HOLD OFF UNTIL THE AFTERNOON...
WHEN THE ATMOSPHERE RAPIDLY DESTABILIZES (CAPES OF 3000-3500
J/KG)...AND A WEAK FRONTAL BOUNDARY MOVES THROUGH. THIS IS THE
FIRST REAL TRIGGER SINCE LAST WEEK. THE FRONT ITSELF IS WEAK...
ONLY NOTICEABLE BY A SURFACE WIND SHIFT WITH LITTLE TO NO UPPER
LEVEL SUPPORT. HOWEVER...MODELS ARE SHOWING LOW AND MID LEVEL
FORCING INCREASING WITH THE BOUNDARY AND LOW LEVEL MOISTURE
POOLING. THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN THIS
AFTERNOON AND IF WE CAN REACH OUR CONVECTIVE TEMP...IN THE MID
80S...NOT MUCH TO STOP THE PARCELS FROM RISING. THAT MAY BE THE
MOST IMPORTANT QUESTION...WHETHER WE CAN REACH THE CONVECTIVE
TEMP. WITH FULL SUN...HAVE NO DOUBT WE WOULD GO ABOVE THE MID
80S...HOWEVER AM CONCERNED ABOUT THE CIRRUS BLOW-OFF...FROM MIDWEST
CONVECTION...THAT WILL MOVE OVER THE AREA TODAY. IF THE HIGH
CLOUDS HOLD TOGETHER...COULD NEGATE JUST ENOUGH SUNSHINE TO KEEP
OUR TEMPS DOWN A FEW DEGREES. WILL CONTINUE WITH HIGH CHC POPS
LATER TODAY...DOING SO WITH UNCERTAINTY ON IF WE CAN GET MORE
WIDESPREAD CONVECTION TO DEVELOP. COULD SEE A SCENARIO WHERE A
LINE OF CONVECTION DEVELOPS OVER EC OHIO AND NW PA EARLY THIS
AFTERNOON AND BARRELS THROUGH...REACHING THE SE MTS BY EVE.

THE WIND FIELD ALOFT IS NOT OVERLY IMPRESSIVE WITH WINDS OF 25 TO
35 KTS...HOWEVER...WITH WBZ LEVELS RANGING FROM 9500-11000 HAIL
WOULD BE A GOOD BET.

SO IF CONVECTION DOES GET GOING THIS AFTERNOON...THERE WILL BE
SOME WIND GUSTS...BUT THINK THE MAIN CONCERN WOULD BE LARGE HAIL.

FOR HIGHS TODAY...WILL LEAN CLOSE TO THE LATEST LAMP AS THOSE
NUMBERS HAVE WORKED WELL THAT PAST COUPLE OF DAYS.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
BOUNDARY WASHES OUT THIS EVENING...AND WITH THE LOSS OF DAYTIME
HEATING...CONVECTION SHOULD DISSIPATE. AS THE RIDGE CONTINUES TO
WEAKEN...WAVES OF ENERGY...BREAKING AWAY FROM THE MAIN MIDWEST
SYSTEM...WILL RIDE OVER TOP OF WHAT IS LEFT OF THE RIDGE THROUGH
NORTHERN PA. WILL GO WITH LOW CHC POPS ACROSS THE NORTH AND SCHC
IN THE SOUTH. ATMOSPHERE STABILIZES OVERNIGHT AND ANY NOTICEABLE
FORCING IS SPARSE.

EXPECT CONVECTION TO GET GOING AGAIN LATE WEDNESDAY AS THE ENTIRE
SYSTEM CREEPS EVERY CLOSER TO THE UPPER OHIO VALLEY. ATMOSPHERE
WILL AGAIN DESTABILIZE AND THE UPPER LEVEL SUPPORT IMPROVES AS THE
RIDGE CONTINUES TO BREAK DOWN. WIND FIELD ALOFT STRENGTHENS
PULLING MORE DEEP MOISTURE INTO THE REGION. HAVE DECIDED TO GO
WITH LIKELY POPS WED DUE TO THE AFOREMENTIONED FACTORS.

SLOW MOVING FRONT DRIFTS THROUGH THE AREA ON THURSDAY SO WILL
CONTINUE WITH LIKELY POPS. THURSDAY NOT NEARLY AS UNSTABLE AS
TODAY AND WEDNESDAY...SO AMOUNT AND STRENGTH OF CONVECTION STILL
IN QUESTION.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FRONT WILL CLEAR THE AREA THU NIGHT AS A SHORTWAVE TROUGH SWINGS
THROUGH ON ITS HEELS. THIS WILL KEEP IN THE CHANCE FOR SHOWERS
THURSDAY NIGHT INTO EARLY FRIDAY. BEHIND THE COLD FRONT FRIDAY
TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED
FOR THE SECOND HALF OF FRIDAY INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY AND SUNDAY
MORNING.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
DIURNAL CU DISSIPATING AS HEAT OF THE DAY HAS PASSED. LIGHT SOUTH
WINDS WILL REMAIN THROUGH THE OVERNIGHT. ANOTHER ROUND OF MVFR FOG
IS A GOOD POSSIBILITY LATE TONIGHT INTO TUESDAY MORNING. MUCH THE
SAME SCENARIO FOR TUESDAY WITH CHANCE POPS FOR SCATTERED AFTERNOON
THUNDERSTORMS AS MODELS DO SHOW A SHORTWAVE APPROACHING AFTER 21Z.
FOR NOW WILL INCLUDE VCTS FROM KPIT NORTH AND WEST IN TERMINALS.

.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND PASSES ACROSS THE REGION. BUILDING
HIGH PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 210140
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
940 PM EDT MON MAY 20 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TUESDAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
EVE RAOB PLOTS SHOW UPR RIDGING BLDG IN WITH DRY CONDS EXPD
OVRNGT. SKIES HAVE GONE MCLR AND THIS SHOULD CONT TNGT...ALTHOUGH
SHOULD SEE SOME CONVECTIVE DEBRIS CS MOVG IN TWD MRNG. A WARM NGT
IS EXPD WITH LOWS IN THE MID TO UPR 60S.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
ANOTHER DAY MUCH LIKE TODAY LOOKS TO BE IN STORE ON TUESDAY.
ALTHOUGH SOME MODEL SOLUTIONS TRACK A WEAK MID-LEVEL VORT MAXIMUM
THROUGH THE NORTHERN PORTIONS OF THE CWA EARLY IN THE DAY...THE
BEST CHANCES OF SHOWERS SHOULD GENERALLY AGAIN BE RELEGATED TO THE
AFTERNOON. DIURNAL INSTABILITY SHOULD BE A BIT MORE PRONOUNCED ON
TUESDAY AFTERNOON AS THE LOW LEVEL THERMAL RIDGE ARCHES ACROSS THE
AREA DURING THE AFTERNOON HOURS. THIS SHOULD ALLOW FOR CAPE VALUES
TO ECLIPSE 2000 J/KG PER THE NAM. WITH THAT IN MIND...SHEAR IS
ONCE AGAIN RATHER UNIMPRESSIVE...AND GIVEN THE LACK OF LARGE SCALE
FORCING DURING THE MOST UNSTABLE PORTION OF THE DAY...RELATIVELY
DISORGANIZED ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS SEEM
LIKELY DURING THE AFTERNOON.

WITH THE LOW LEVEL THERMAL RIDGE SWINGING THROUGH AND SOUNDINGS
INDICATING BETTER MIXING DURING THE AFTERNOON TUESDAY...THINGS DO
LOOK LIKELY TO HEAT UP NICELY. TEMPERATURES AT 850 MB RUN UP
TOWARD +16 TO +18C OR SO ON THE CONSENSUS...WHICH SUGGESTS HIGHS
IN THE UPPER 80S WOULD BE LIKELY. THIS IS QUITE WARM FOR THIS TIME
OF YEAR AS RECORDS ARE GENERALLY ONLY IN THE LOWER 90S FOR
TUESDAY.

AS THE SYSTEM CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY FINALLY
WANDERS EASTWARD...THE WEATHER GETS MORE INTERESTING HEADING INTO
WEDNESDAY. FIRST OF ALL...A DECENT CONSENSUS ON THE FORMATION OF A
LOW LEVEL JET OVER WESTERN OHIO COULD DRIVE DISSIPATING NOCTURNAL
CONVECTION INTO SOME OF THE AREA WEDNESDAY MORNING. WHILE THIS
WOULD LIKELY INCREASE LOW LEVEL MOISTURE OVER THE
AREA...CONVECTIVE DEBRIS MAY MAKE WARMING LESS EFFICIENT ON
WEDNESDAY AND LIMIT INSTABILITY. THAT SAID...THE UPPER LEVEL
SYSTEM TRUDGING EASTWARD DOESN`T SEEM TO BRING THE BEST SYNOPTIC
FORCING INTO THE AREA UNTIL AFTER 00Z/8 PM...WHICH IS WELL PAST
THE PRIME DAYTIME INSTABILITY HOURS. HOWEVER...35-40 KTS OF 0-6 KM
SHEAR WITH CAPE VALUES IN THE 1500 J/KG RANGE ALONG WITH AN
INCOMING SHORTWAVE TROUGH AND UPPER JET RIGHT ENTRANCE REGION DO
MEAN WIDESPREAD THUNDERSTORM DEVELOPMENT IS LIKELY BY WEDNESDAY
EVENING. POPS WERE TRANSITIONED A FEW HOURS LATER IN THE FORECAST
TO SUGGEST A LATER ARRIVAL OF THE SYSTEM FOR WEDNESDAY EVENING TO
ACCOUNT FOR A BIT LATER ARRIVAL OF THE MAIN SYSTEM ITSELF.

COLDER AIR FLOODS INTO THE FORECAST AREA STARTING THURSDAY WITH
THE UPPER TROUGH AXIS NEARING. AS THIS OCCURS...WE AGAIN
DESTABILIZE DUE TO MORE RAPID MID-LEVEL COOLING RATHER THAN LOW
LEVEL WARMING. SHOWER AND THUNDERSTORM CHANCES WILL THEREFORE
CONTINUE THROUGH THURSDAY. FRIES

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A COLD FRONT MOVING SLOWLY SOUTH FROM THE GREAT LAKES WILL BRING
SHOWERS AND SCATTERED THUNDERSTORMS FOR THURSDAY NIGHT. BEHIND THE
COLD FRONT FRIDAY THE RISK OF SHOWERS WILL DIMINISH AND TEMPERATURES
WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED FOR FRIDAY NIGHT
INTO SUNDAY WITH TEMPERATURES FALLING INTO THE 40S FOR OVERNIGHT
LOWS SATURDAY AND SUNDAY MORNING.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
DIURNAL CU DISSIPATING AS HEAT OF THE DAY HAS PASSED. LIGHT SOUTH
WINDS WILL REMAIN THROUGH THE OVERNIGHT. ANOTHER ROUND OF MVFR FOG
IS A GOOD POSSIBILITY LATE TONIGHT INTO TUESDAY MORNING. MUCH THE
SAME SCENARIO FOR TUESDAY WITH CHANCE POPS FOR SCATTERED AFTERNOON
THUNDERSTORMS AS MODELS DO SHOW A SHORTWAVE APPROACHING AFTER 21Z.
FOR NOW WILL INCLUDE VCTS FROM KPIT NORTH AND WEST IN TERMINALS.

.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND PASSES ACROSS THE REGION. BUILDING
HIGH PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

07

000
FXUS61 KPBZ 202329
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
729 PM EDT MON MAY 20 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TUESDAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
STLT/MESO DATA SHOWS AN UPR WAVE MOVG E INTO CNTRL VA. ISOLD
SHWRS/TSTMS HAVE PUSHED E OF OUR FCST AREA...SO REMOVED POPS TNGT.
SKIES SHOULD CLEAR OUT THIS EVE...BUT SOME ADDNL CONVECTIVE DEBRIS
CLOUD COVER TO THE W MAY WORK IN OVRNGT. WELL ABV AVG LOWS IN THE
60S EXPD TNGT.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
ANOTHER DAY MUCH LIKE TODAY LOOKS TO BE IN STORE ON TUESDAY.
ALTHOUGH SOME MODEL SOLUTIONS TRACK A WEAK MID-LEVEL VORT MAXIMUM
THROUGH THE NORTHERN PORTIONS OF THE CWA EARLY IN THE DAY...THE
BEST CHANCES OF SHOWERS SHOULD GENERALLY AGAIN BE RELEGATED TO THE
AFTERNOON. DIURNAL INSTABILITY SHOULD BE A BIT MORE PRONOUNCED ON
TUESDAY AFTERNOON AS THE LOW LEVEL THERMAL RIDGE ARCHES ACROSS THE
AREA DURING THE AFTERNOON HOURS. THIS SHOULD ALLOW FOR CAPE VALUES
TO ECLIPSE 2000 J/KG PER THE NAM. WITH THAT IN MIND...SHEAR IS
ONCE AGAIN RATHER UNIMPRESSIVE...AND GIVEN THE LACK OF LARGE SCALE
FORCING DURING THE MOST UNSTABLE PORTION OF THE DAY...RELATIVELY
DISORGANIZED ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS SEEM
LIKELY DURING THE AFTERNOON.

WITH THE LOW LEVEL THERMAL RIDGE SWINGING THROUGH AND SOUNDINGS
INDICATING BETTER MIXING DURING THE AFTERNOON TUESDAY...THINGS DO
LOOK LIKELY TO HEAT UP NICELY. TEMPERATURES AT 850 MB RUN UP
TOWARD +16 TO +18C OR SO ON THE CONSENSUS...WHICH SUGGESTS HIGHS
IN THE UPPER 80S WOULD BE LIKELY. THIS IS QUITE WARM FOR THIS TIME
OF YEAR AS RECORDS ARE GENERALLY ONLY IN THE LOWER 90S FOR
TUESDAY.

AS THE SYSTEM CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY FINALLY
WANDERS EASTWARD...THE WEATHER GETS MORE INTERESTING HEADING INTO
WEDNESDAY. FIRST OF ALL...A DECENT CONSENSUS ON THE FORMATION OF A
LOW LEVEL JET OVER WESTERN OHIO COULD DRIVE DISSIPATING NOCTURNAL
CONVECTION INTO SOME OF THE AREA WEDNESDAY MORNING. WHILE THIS
WOULD LIKELY INCREASE LOW LEVEL MOISTURE OVER THE
AREA...CONVECTIVE DEBRIS MAY MAKE WARMING LESS EFFICIENT ON
WEDNESDAY AND LIMIT INSTABILITY. THAT SAID...THE UPPER LEVEL
SYSTEM TRUDGING EASTWARD DOESN`T SEEM TO BRING THE BEST SYNOPTIC
FORCING INTO THE AREA UNTIL AFTER 00Z/8 PM...WHICH IS WELL PAST
THE PRIME DAYTIME INSTABILITY HOURS. HOWEVER...35-40 KTS OF 0-6 KM
SHEAR WITH CAPE VALUES IN THE 1500 J/KG RANGE ALONG WITH AN
INCOMING SHORTWAVE TROUGH AND UPPER JET RIGHT ENTRANCE REGION DO
MEAN WIDESPREAD THUNDERSTORM DEVELOPMENT IS LIKELY BY WEDNESDAY
EVENING. POPS WERE TRANSITIONED A FEW HOURS LATER IN THE FORECAST
TO SUGGEST A LATER ARRIVAL OF THE SYSTEM FOR WEDNESDAY EVENING TO
ACCOUNT FOR A BIT LATER ARRIVAL OF THE MAIN SYSTEM ITSELF.

COLDER AIR FLOODS INTO THE FORECAST AREA STARTING THURSDAY WITH
THE UPPER TROUGH AXIS NEARING. AS THIS OCCURS...WE AGAIN
DESTABILIZE DUE TO MORE RAPID MID-LEVEL COOLING RATHER THAN LOW
LEVEL WARMING. SHOWER AND THUNDERSTORM CHANCES WILL THEREFORE
CONTINUE THROUGH THURSDAY. FRIES

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A COLD FRONT MOVING SLOWLY SOUTH FROM THE GREAT LAKES WILL BRING
SHOWERS AND SCATTERED THUNDERSTORMS FOR THURSDAY NIGHT. BEHIND THE
COLD FRONT FRIDAY THE RISK OF SHOWERS WILL DIMINISH AND TEMPERATURES
WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED FOR FRIDAY NIGHT
INTO SUNDAY WITH TEMPERATURES FALLING INTO THE 40S FOR OVERNIGHT
LOWS SATURDAY AND SUNDAY MORNING.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
DIURNAL CU DISSIPATING AS HEAT OF THE DAY HAS PASSED. LIGHT SOUTH
WINDS WILL REMAIN THROUGH THE OVERNIGHT. ANOTHER ROUND OF MVFR FOG
IS A GOOD POSSIBILITY LATE TONIGHT INTO TUESDAY MORNING. MUCH THE
SAME SCENARIO FOR TUESDAY WITH CHANCE POPS FOR SCATTERED AFTERNOON
THUNDERSTORMS AS MODELS DO SHOW A SHORTWAVE APPROACHING AFTER 21Z.
FOR NOW WILL INCLUDE VCTS FROM KPIT NORTH AND WEST IN TERMINALS.

.OUTLOOK.../TUESDAY THROUGH SATURDAY/...
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE WITH POSSIBLE
RESTRICTIONS FROM WEDNESDAY INTO THURSDAY EVENING AS A COLD FRONT
AND UPPER TROUGH APPROACHES AND PASSES ACROSS THE REGION. BUILDING
HIGH PRESSURE WILL BRING VFR FRIDAY AND SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 202201
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
601 PM EDT MON MAY 20 2013

.SYNOPSIS...
PERIODIC SHOWER AND THUNDERSTORM CHANCES WILL RETURN TUESDAY...
WITH INCREASING CHANCES WEDNESDAY AND THURSDAY AS A COLD FRONT
APPROACHES AND MOVES THROUGH. HIGH PRESSURE WILL RETURN FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
STLT/MESO DATA SHOWS AN UPR WAVE MOVG E INTO CNTRL VA. ISOLD
SHWRS/TSTMS HAVE PUSHED E OF OUR FCST AREA...SO REMOVED POPS TNGT.
SKIES SHOULD CLEAR OUT THIS EVE...BUT SOME ADDNL CONVECTIVE DEBRIS
CLOUD COVER TO THE W MAY WORK IN OVRNGT. WELL ABV AVG LOWS IN THE
60S EXPD TNGT.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
ANOTHER DAY MUCH LIKE TODAY LOOKS TO BE IN STORE ON TUESDAY.
ALTHOUGH SOME MODEL SOLUTIONS TRACK A WEAK MID-LEVEL VORT MAXIMUM
THROUGH THE NORTHERN PORTIONS OF THE CWA EARLY IN THE DAY...THE
BEST CHANCES OF SHOWERS SHOULD GENERALLY AGAIN BE RELEGATED TO THE
AFTERNOON. DIURNAL INSTABILITY SHOULD BE A BIT MORE PRONOUNCED ON
TUESDAY AFTERNOON AS THE LOW LEVEL THERMAL RIDGE ARCHES ACROSS THE
AREA DURING THE AFTERNOON HOURS. THIS SHOULD ALLOW FOR CAPE VALUES
TO ECLIPSE 2000 J/KG PER THE NAM. WITH THAT IN MIND...SHEAR IS
ONCE AGAIN RATHER UNIMPRESSIVE...AND GIVEN THE LACK OF LARGE SCALE
FORCING DURING THE MOST UNSTABLE PORTION OF THE DAY...RELATIVELY
DISORGANIZED ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS SEEM
LIKELY DURING THE AFTERNOON.

WITH THE LOW LEVEL THERMAL RIDGE SWINGING THROUGH AND SOUNDINGS
INDICATING BETTER MIXING DURING THE AFTERNOON TUESDAY...THINGS DO
LOOK LIKELY TO HEAT UP NICELY. TEMPERATURES AT 850 MB RUN UP
TOWARD +16 TO +18C OR SO ON THE CONSENSUS...WHICH SUGGESTS HIGHS
IN THE UPPER 80S WOULD BE LIKELY. THIS IS QUITE WARM FOR THIS TIME
OF YEAR AS RECORDS ARE GENERALLY ONLY IN THE LOWER 90S FOR
TUESDAY.

AS THE SYSTEM CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY FINALLY
WANDERS EASTWARD...THE WEATHER GETS MORE INTERESTING HEADING INTO
WEDNESDAY. FIRST OF ALL...A DECENT CONSENSUS ON THE FORMATION OF A
LOW LEVEL JET OVER WESTERN OHIO COULD DRIVE DISSIPATING NOCTURNAL
CONVECTION INTO SOME OF THE AREA WEDNESDAY MORNING. WHILE THIS
WOULD LIKELY INCREASE LOW LEVEL MOISTURE OVER THE
AREA...CONVECTIVE DEBRIS MAY MAKE WARMING LESS EFFICIENT ON
WEDNESDAY AND LIMIT INSTABILITY. THAT SAID...THE UPPER LEVEL
SYSTEM TRUDGING EASTWARD DOESN`T SEEM TO BRING THE BEST SYNOPTIC
FORCING INTO THE AREA UNTIL AFTER 00Z/8 PM...WHICH IS WELL PAST
THE PRIME DAYTIME INSTABILITY HOURS. HOWEVER...35-40 KTS OF 0-6 KM
SHEAR WITH CAPE VALUES IN THE 1500 J/KG RANGE ALONG WITH AN
INCOMING SHORTWAVE TROUGH AND UPPER JET RIGHT ENTRANCE REGION DO
MEAN WIDESPREAD THUNDERSTORM DEVELOPMENT IS LIKELY BY WEDNESDAY
EVENING. POPS WERE TRANSITIONED A FEW HOURS LATER IN THE FORECAST
TO SUGGEST A LATER ARRIVAL OF THE SYSTEM FOR WEDNESDAY EVENING TO
ACCOUNT FOR A BIT LATER ARRIVAL OF THE MAIN SYSTEM ITSELF.

COLDER AIR FLOODS INTO THE FORECAST AREA STARTING THURSDAY WITH
THE UPPER TROUGH AXIS NEARING. AS THIS OCCURS...WE AGAIN
DESTABILIZE DUE TO MORE RAPID MID-LEVEL COOLING RATHER THAN LOW
LEVEL WARMING. SHOWER AND THUNDERSTORM CHANCES WILL THEREFORE
CONTINUE THROUGH THURSDAY. FRIES

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A COLD FRONT MOVING SLOWLY SOUTH FROM THE GREAT LAKES WILL BRING
SHOWERS AND SCATTERED THUNDERSTORMS FOR THURSDAY NIGHT. BEHIND THE
COLD FRONT FRIDAY THE RISK OF SHOWERS WILL DIMINISH AND TEMPERATURES
WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED FOR FRIDAY NIGHT
INTO SUNDAY WITH TEMPERATURES FALLING INTO THE 40S FOR OVERNIGHT
LOWS SATURDAY AND SUNDAY MORNING.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
BROKEN CUMULUS CEILINGS CAN BE EXPECTED THROUGH THE AFTERNOON WITH
THE HEATING OF THE DAY. CEILINGS WILL SLOWLY LIFT FROM MVFR TO VFR
BY LATE AFTERNOON. JUST A SLIGHT RISK OF A SHOWER OR ISOLATED
THUNDERSTORM INTO THIS EVENING...BUT TOO SMALL A RISK TO PUT INTO
THE TAFS. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE TONIGHT INTO
TUESDAY MORNING.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 201928
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
328 PM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY EVENING...AS AN UPPER LEVEL DISTURBANCE
MOVES THROUGH.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
CUMULUS DEVELOPMENT THIS AFTERNOON HAS BEEN WIDESPREAD AND FAIRLY
PROLIFIC WITH EVEN THE LAST VESTIGES OF THIS MORNING`S STRATUS
OVER OHIO BEING DIFFICULT TO GET RID OF. THE COMBINATION OF AMPLE
LOW LEVEL MOISTURE...DECENT INSTABILITY...AND WEAK STEERING FLOW
HAS ALLOWED FOR ALL OF THIS TO OCCUR THROUGH THE DAY. AS THE
EVENING ENSUES...CUMULUS SHOULD GRADUALLY DISSIPATE...HOWEVER
CONVECTIVE DEBRIS CLOUDS AND REFORMATION OF SOME AREAS OF STRATUS
SEEM A DECENT BET OVERNIGHT. THIS WILL RESULT IS LESS THAN CLEAR
SKIES THROUGH THE NIGHT.

LOW LEVEL FLOW...WHILE WEAK...SHOULD CONTINUE TO BE LIGHT OUT OF
THE SOUTH OVERNIGHT. UPSTREAM DEWPOINT READINGS ARE GENERALLY IN
THE MID 60S TO NEAR 70F. WITH THIS IN MIND...AND THE LIKELIHOOD AT
LEAST SCATTERED TO BROKEN CLOUDS OVERNIGHT...LOWS SHOULD BE FAIRLY
RANGE BOUND BY THE HIGH MOISTURE CONTENT OF THE AIR MASS AND POOR
RADIATIONAL COOLING PROSPECTS. AS SUCH...LOWS DROPPING MUCH BELOW
THE MID TO UPPER 60S SEEM LIKE A BIT OF STRETCH. HAVE GENERALLY
KEPT TEMPERATURES ABOVE GUIDANCE THROUGH THE NIGHT AS A RESULT.
FRIES

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
ANOTHER DAY MUCH LIKE TODAY LOOKS TO BE IN STORE ON TUESDAY.
ALTHOUGH SOME MODEL SOLUTIONS TRACK A WEAK MID-LEVEL VORT MAXIMUM
THROUGH THE NORTHERN PORTIONS OF THE CWA EARLY IN THE DAY...THE
BEST CHANCES OF SHOWERS SHOULD GENERALLY AGAIN BE RELEGATED TO THE
AFTERNOON. DIURNAL INSTABILITY SHOULD BE A BIT MORE PRONOUNCED ON
TUESDAY AFTERNOON AS THE LOW LEVEL THERMAL RIDGE ARCHES ACROSS THE
AREA DURING THE AFTERNOON HOURS. THIS SHOULD ALLOW FOR CAPE VALUES
TO ECLIPSE 2000 J/KG PER THE NAM. WITH THAT IN MIND...SHEAR IS
ONCE AGAIN RATHER UNIMPRESSIVE...AND GIVEN THE LACK OF LARGE SCALE
FORCING DURING THE MOST UNSTABLE PORTION OF THE DAY...RELATIVELY
DISORGANIZED ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS SEEM
LIKELY DURING THE AFTERNOON.

WITH THE LOW LEVEL THERMAL RIDGE SWINGING THROUGH AND SOUNDINGS
INDICATING BETTER MIXING DURING THE AFTERNOON TUESDAY...THINGS DO
LOOK LIKELY TO HEAT UP NICELY. TEMPERATURES AT 850 MB RUN UP
TOWARD +16 TO +18C OR SO ON THE CONSENSUS...WHICH SUGGESTS HIGHS
IN THE UPPER 80S WOULD BE LIKELY. THIS IS QUITE WARM FOR THIS TIME
OF YEAR AS RECORDS ARE GENERALLY ONLY IN THE LOWER 90S FOR
TUESDAY.

AS THE SYSTEM CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY FINALLY
WANDERS EASTWARD...THE WEATHER GETS MORE INTERESTING HEADING INTO
WEDNESDAY. FIRST OF ALL...A DECENT CONSENSUS ON THE FORMATION OF A
LOW LEVEL JET OVER WESTERN OHIO COULD DRIVE DISSIPATING NOCTURNAL
CONVECTION INTO SOME OF THE AREA WEDNESDAY MORNING. WHILE THIS
WOULD LIKELY INCREASE LOW LEVEL MOISTURE OVER THE
AREA...CONVECTIVE DEBRIS MAY MAKE WARMING LESS EFFICIENT ON
WEDNESDAY AND LIMIT INSTABILITY. THAT SAID...THE UPPER LEVEL
SYSTEM TRUDGING EASTWARD DOESN`T SEEM TO BRING THE BEST SYNOPTIC
FORCING INTO THE AREA UNTIL AFTER 00Z/8 PM...WHICH IS WELL PAST
THE PRIME DAYTIME INSTABILITY HOURS. HOWEVER...35-40 KTS OF 0-6 KM
SHEAR WITH CAPE VALUES IN THE 1500 J/KG RANGE ALONG WITH AN
INCOMING SHORTWAVE TROUGH AND UPPER JET RIGHT ENTRANCE REGION DO
MEAN WIDESPREAD THUNDERSTORM DEVELOPMENT IS LIKELY BY WEDNESDAY
EVENING. POPS WERE TRANSITIONED A FEW HOURS LATER IN THE FORECAST
TO SUGGEST A LATER ARRIVAL OF THE SYSTEM FOR WEDNESDAY EVENING TO
ACCOUNT FOR A BIT LATER ARRIVAL OF THE MAIN SYSTEM ITSELF.

COLDER AIR FLOODS INTO THE FORECAST AREA STARTING THURSDAY WITH
THE UPPER TROUGH AXIS NEARING. AS THIS OCCURS...WE AGAIN
DESTABILIZE DUE TO MORE RAPID MID-LEVEL COOLING RATHER THAN LOW
LEVEL WARMING. SHOWER AND THUNDERSTORM CHANCES WILL THEREFORE
CONTINUE THROUGH THURSDAY. FRIES

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A COLD FRONT MOVING SLOWLY SOUTH FROM THE GREAT LAKES WILL BRING
SHOWERS AND SCATTERED THUNDERSTORMS FOR THURSDAY NIGHT. BEHIND THE
COLD FRONT FRIDAY THE RISK OF SHOWERS WILL DIMINISH AND TEMPERATURES
WILL DROP BELOW NORMAL. DRY WEATHER CAN BE EXPECTED FOR FRIDAY NIGHT
INTO SUNDAY WITH TEMPERATURES FALLING INTO THE 40S FOR OVERNIGHT
LOWS SATURDAY AND SUNDAY MORNING.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
BROKEN CUMULUS CEILINGS CAN BE EXPECTED THROUGH THE AFTERNOON WITH
THE HEATING OF THE DAY. CEILINGS WILL SLOWLY LIFT FROM MVFR TO VFR
BY LATE AFTERNOON. JUST A SLIGHT RISK OF A SHOWER OR ISOLATED
THUNDERSTORM INTO THIS EVENING...BUT TOO SMALL A RISK TO PUT INTO
THE TAFS. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE TONIGHT INTO
TUESDAY MORNING.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 201628
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1228 PM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES
THROUGH.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A RELATIVELY WEAK FLOW REGIME REMAINS ENTRENCHED OVER THE FORECAST
AREA TODAY...WITH ONE WEAK SYSTEM ATTEMPTING TO MOVE DIRECTLY INTO
THE RIDGE AXIS ALONG THE EAST COAST TO OUR SOUTH AND THE MAIN
LARGE SCALE PLAYER STILL BACK OVER THE DAKOTAS TODAY. WHILE
SOUTHERLY FLOW HAS ALLOWED LOW LEVEL MOISTURE TO CREEP STEADILY
INTO THE AREA...RESULTING IN DEWPOINTS IN THE 60S THIS MORNING AND
POSSIBLY LOCALLY TOUCHING 70F IN OHIO THIS AFTERNOON...THERE IS
SEEMINGLY LITTLE TO HELP INITIATE MUCH IN THE WAY OF CONVECTION.
LARGE SCALE LIFT IS WELL OFF TO THE WEST...HOWEVER CONVECTION IS
MANAGING TO INITIATE THIS MORNING IN A LINE FROM SOUTHEASTERN
LOWER MICHIGAN INTO CENTRAL OHIO. GIVEN THE MOISTURE AND
INSTABILITY PROFILE...IT SEEMS UNLIKELY THAT THESE THUNDERSTORMS
WOULD FAIL TO PROPAGATE DOWNSTREAM A WHILE...SO POPS/THUNDER
CHANCES HAVE BEEN EXPANDED IN OHIO AND ESPECIALLY SOUTHWESTERN
PENNSYLVANIA.

DUE TO OUR POSITION RELATIVE TO THE LARGE SCALE FEATURES...MIXING
SEEMS LIKE IT SHOULD BE MOST EFFICIENT OVER THE NORTHWESTERN
PORTIONS OF THE FORECAST AREA. THIS IS CO-LOCATED WITH THE AREA OF
BEST WARM ADVECTION AT 850 MB...SO FROM ZANESVILLE TO MERCER
TEMPERATURES WERE INCREASED THIS AFTERNOON. ELSEWHERE...THE STATUS
QUO REMAINS WITH HIGHS IN THE LOWER TO MIDDLE 80S WIDESPREAD THIS
AFTERNOON. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
BROKEN CUMULUS CEILINGS CAN BE EXPECTED THROUGH THE AFTERNOON WITH
THE HEATING OF THE DAY. CEILINGS WILL SLOWLY LIFT FROM MVFR TO VFR
BY LATE AFTERNOON. JUST A SLIGHT RISK OF A SHOWER OR ISOLATED
THUNDERSTORM INTO THIS EVENING...BUT TOO SMALL A RISK TO PUT INTO
THE TAFS. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE TONIGHT INTO
TUESDAY MORNING.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 201427
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1027 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES
THROUGH.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A RELATIVELY WEAK FLOW REGIME REMAINS ENTRENCHED OVER THE FORECAST
AREA TODAY...WITH ONE WEAK SYSTEM ATTEMPTING TO MOVE DIRECTLY INTO
THE RIDGE AXIS ALONG THE EAST COAST TO OUR SOUTH AND THE MAIN
LARGE SCALE PLAYER STILL BACK OVER THE DAKOTAS TODAY. WHILE
SOUTHERLY FLOW HAS ALLOWED LOW LEVEL MOISTURE TO CREEP STEADILY
INTO THE AREA...RESULTING IN DEWPOINTS IN THE 60S THIS MORNING AND
POSSIBLY LOCALLY TOUCHING 70F IN OHIO THIS AFTERNOON...THERE IS
SEEMINGLY LITTLE TO HELP INITIATE MUCH IN THE WAY OF CONVECTION.
LARGE SCALE LIFT IS WELL OFF TO THE WEST...HOWEVER CONVECTION IS
MANAGING TO INITIATE THIS MORNING IN A LINE FROM SOUTHEASTERN
LOWER MICHIGAN INTO CENTRAL OHIO. GIVEN THE MOISTURE AND
INSTABILITY PROFILE...IT SEEMS UNLIKELY THAT THESE THUNDERSTORMS
WOULD FAIL TO PROPAGATE DOWNSTREAM A WHILE...SO POPS/THUNDER
CHANCES HAVE BEEN EXPANDED IN OHIO AND ESPECIALLY SOUTHWESTERN
PENNSYLVANIA.

DUE TO OUR POSITION RELATIVE TO THE LARGE SCALE FEATURES...MIXING
SEEMS LIKE IT SHOULD BE MOST EFFICIENT OVER THE NORTHWESTERN
PORTIONS OF THE FORECAST AREA. THIS IS CO-LOCATED WITH THE AREA OF
BEST WARM ADVECTION AT 850 MB...SO FROM ZANESVILLE TO MERCER
TEMPERATURES WERE INCREASED THIS AFTERNOON. ELSEWHERE...THE STATUS
QUO REMAINS WITH HIGHS IN THE LOWER TO MIDDLE 80S WIDESPREAD THIS
AFTERNOON. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
SPOTTY SHOWERS OVER THE EVENING SEEM TO HAVE DISSIPATED...SO
EXPECT THAT THE REST OF THE NIGHT WILL REMAIN DRY. IFR STRATUS IS
EXPECTED TO CONTINUE OVERNIGHT AT DUJ...ALTHOUGH THERE IS SOME
UNCERTAINTY AS TO WHETHER THE STRATUS WILL MANAGE TO PUSH ANY
FARTHER TO THE WEST. HAVE CONTINUED SCT IFR CIGS NEAR DAWN TO
ACCOUNT FOR THIS UNCERTAINTY. CONDITIONS SHOULD RETURN TO VFR AT
ALL LOCATIONS ACROSS THE REGION BY LATE MORNING. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE
MONDAY NIGHT INTO TUESDAY MORNING...AND HAVE ADDED THIS IN THE 30
HOUR TAF FOR PIT.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 201257
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
857 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES
THROUGH.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A RELATIVELY WEAK FLOW REGIME REMAINS ENTRENCHED OVER THE FORECAST
AREA TODAY...WITH ONE WEAK SYSTEM ATTEMPTING TO MOVE DIRECTLY INTO
THE RIDGE AXIS ALONG THE EAST COAST TO OUR SOUTH AND THE MAIN
LARGE SCALE PLAYER STILL BACK OVER THE DAKOTAS TODAY. WHILE
SOUTHERLY FLOW HAS ALLOWED LOW LEVEL MOISTURE TO CREEP STEADILY
INTO THE AREA...RESULTING IN DEWPOINTS IN THE 60S THIS MORNING AND
POSSIBLY LOCALLY TOUCHING 70F IN OHIO THIS AFTERNOON...THERE IS
SEEMINGLY LITTLE TO HELP INITIATE MUCH IN THE WAY OF CONVECTION.
LARGE SCALE LIFT IS WELL OFF TO THE WEST...WITH THE MODELS REALLY
ONLY HINTING AT MUCH IN THE WAY OF DAYTIME DIURNAL CONVECTION
ALONG THE SOUTHERN AND EASTERN PORTIONS OF THE AREA. GIVEN THE
MOISTURE AND INSTABILITY PROFILE...ISOLATED SHOWERS/THUNDERSTORMS
SEEM POSSIBLE IN THESE LOCATIONS...HOWEVER ANYTHING ORGANIZED
SEEMS HIGHLY UNLIKELY.

DUE TO OUR POSITION RELATIVE TO THE LARGE SCALE FEATURES...MIXING
SEEMS LIKE IT SHOULD BE MOST EFFICIENT OVER THE NORTHWESTERN
PORTIONS OF THE FORECAST AREA. THIS IS CO-LOCATED WITH THE AREA OF
BEST WARM ADVECTION AT 850 MB...SO FROM ZANESVILLE TO MERCER
TEMPERATURES WERE INCREASED THIS AFTERNOON. ELSEWHERE...THE STATUS
QUO REMAINS WITH HIGHS IN THE LOWER TO MIDDLE 80S WIDESPREAD THIS
AFTERNOON. FRIES

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
SPOTTY SHOWERS OVER THE EVENING SEEM TO HAVE DISSIPATED...SO
EXPECT THAT THE REST OF THE NIGHT WILL REMAIN DRY. IFR STRATUS IS
EXPECTED TO CONTINUE OVERNIGHT AT DUJ...ALTHOUGH THERE IS SOME
UNCERTAINTY AS TO WHETHER THE STRATUS WILL MANAGE TO PUSH ANY
FARTHER TO THE WEST. HAVE CONTINUED SCT IFR CIGS NEAR DAWN TO
ACCOUNT FOR THIS UNCERTAINTY. CONDITIONS SHOULD RETURN TO VFR AT
ALL LOCATIONS ACROSS THE REGION BY LATE MORNING. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE
MONDAY NIGHT INTO TUESDAY MORNING...AND HAVE ADDED THIS IN THE 30
HOUR TAF FOR PIT.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 200818
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
418 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES
THROUGH.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
REALLY VERY LITTLE CHANGE IN THE WEATHER TODAY...TO THAT WHICH WE
SAW OVER THE PAST WEEKEND. EASTERN U.S. RIDGE REMAINS IN PLACE
WITH WAVES OF ENERGY MOVING THROUGH THE MID-ATLANTIC REGION.
MODELS ARE HINTING THAT A PIECE OF ENERGY MAY BREAK FROM THE MAIN
WAVE AND MOVE TOWARD MY SOUTHERN ZONES THIS AFTERNOON. THIS COULD
BE ENOUGH TO SPARK A SHOWER OR STORM ACROSS THE SOUTH.

THE ATMOSPHERE WILL BE PLENTY UNSTABLE TODAY...HOWEVER STRONG WAA
ALOFT WILL PROVIDE A CAP...PREVENTING MORE WIDESPREAD CONVECTION
FROM DEVELOPING. ADDITIONALLY...THE 50H RIDGE WILL STRENGTHEN
THIS AFTERNOON INCREASING THE OVERALL SUBSIDENCE.

OVER THE WEEKEND...THE NAM AND GFS HAD BOTH DONE WELL WITH HIGH
TEMPS...SO WILL LEAN CLOSE ON THESE NUMBERS FOR THE FORECAST.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
SPOTTY SHOWERS OVER THE EVENING SEEM TO HAVE DISSIPATED...SO
EXPECT THAT THE REST OF THE NIGHT WILL REMAIN DRY. IFR STRATUS IS
EXPECTED TO CONTINUE OVERNIGHT AT DUJ...ALTHOUGH THERE IS SOME
UNCERTAINTY AS TO WHETHER THE STRATUS WILL MANAGE TO PUSH ANY
FARTHER TO THE WEST. HAVE CONTINUED SCT IFR CIGS NEAR DAWN TO
ACCOUNT FOR THIS UNCERTAINTY. CONDITIONS SHOULD RETURN TO VFR AT
ALL LOCATIONS ACROSS THE REGION BY LATE MORNING. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE
MONDAY NIGHT INTO TUESDAY MORNING...AND HAVE ADDED THIS IN THE 30
HOUR TAF FOR PIT.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 200541
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
141 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR MAINLY AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR ACTIVITY ON
WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH.

&&

.NEAR TERM /THROUGH TODAY/...
LINGERING SPOTTY SHOWERS OVER THE SOUTHEAST CONTINUE TO DISSIPATE
AS THE ATMOSPHERE STABILIZES. FOR THE REMAINDER OF THE
NIGHT...HAVE REMOVED POPS AND LOWERED CLOUD COVER OVER THE WESTERN
HALF.

REALLY VERY LITTLE CHANGE IN THE WEATHER TODAY...TO THAT WHICH WE
EXPERIENCED OVER THE WEEKEND. EASTERN RIDGE REMAINS IN PLACE WITH
WAVES OF ENERGY MOVING THROUGH THE MID-ATLANTIC REGION. MODELS ARE
HINTING THAT A PIECE OF ENERGY MAY BREAK FROM THE MAIN WAVE AND
MOVE TOWARD MY SOUTHERN ZONES THIS AFTERNOON. THIS COULD BE ENOUGH
TO SPARK A SHOWER OR STORM ACROSS THE SOUTH.

THE ATMOSPHERE WILL BE PLENTY UNSTABLE TODAY...HOWEVER STRONG WAA
ALOFT WILL PROVIDE A CAP...PREVENTING MORE WIDESPREAD CONVECTION
FROM DEVELOPING. ADDITIONALLY...THE 50H RIDGE WILL STRENGTHEN
THIS AFTERNOON INCREASING THE OVERALL SUBSIDENCE.

OVER THE WEEKEND...THE NAM AND GFS HAD BOTH DONE WELL WITH HIGH
TEMPS...SO WILL LEAN CLOSE ON THESE NUMBERS FOR THE FORECAST.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
SPOTTY SHOWERS OVER THE EVENING SEEM TO HAVE DISSIPATED...SO
EXPECT THAT THE REST OF THE NIGHT WILL REMAIN DRY. IFR STRATUS IS
EXPECTED TO CONTINUE OVERNIGHT AT DUJ...ALTHOUGH THERE IS SOME
UNCERTAINTY AS TO WHETHER THE STRATUS WILL MANAGE TO PUSH ANY
FARTHER TO THE WEST. HAVE CONTINUED SCT IFR CIGS NEAR DAWN TO
ACCOUNT FOR THIS UNCERTAINTY. CONDITIONS SHOULD RETURN TO VFR AT
ALL LOCATIONS ACROSS THE REGION BY LATE MORNING. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE
MONDAY NIGHT INTO TUESDAY MORNING...AND HAVE ADDED THIS IN THE 30
HOUR TAF FOR PIT.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 200510
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
110 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR MAINLY AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR ACTIVITY ON
WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH.

&&

.NEAR TERM /THROUGH TODAY/...
LINGERING SPOTTY SHOWERS OVER THE SOUTHEAST CONTINUE TO DISSIPATE
AS THE ATMOSPHERE STABILIZES. FOR THE REMAINDER OF THE
NIGHT...HAVE REMOVED POPS AND LOWERED CLOUD COVER OVER THE WESTERN
HALF.

REALLY VERY LITTLE CHANGE IN THE WEATHER TODAY...TO THAT WHICH WE
EXPERIENCED OVER THE WEEKEND. EASTERN RIDGE REMAINS IN PLACE WITH
WAVES OF ENERGY MOVING THROUGH THE MID-ATLANTIC REGION. MODELS ARE
HINTING THAT A PIECE OF ENERGY MAY BREAK FROM THE MAIN WAVE AND
MOVE TOWARD MY SOUTHERN ZONES THIS AFTERNOON. THIS COULD BE ENOUGH
TO SPARK A SHOWER OR STORM ACROSS THE SOUTH.

THE ATMOSPHERE WILL BE PLENTY UNSTABLE TODAY...HOWEVER STRONG WAA
ALOFT WILL PROVIDE A CAP...PREVENTING MORE WIDESPREAD CONVECTION
FROM DEVELOPING. ADDITIONALLY...THE 50H RIDGE WILL STRENGTHEN
THIS AFTERNOON INCREASING THE OVERALL SUBSIDENCE.

OVER THE WEEKEND...THE NAM AND GFS HAD BOTH DONE WELL WITH HIGH
TEMPS...SO WILL LEAN CLOSE ON THESE NUMBERS FOR THE FORECAST.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /05Z MONDAY THROUGH FRIDAY/...
VFR CONDS EXPD INTO THE EVE...EXCPT FOR DUJ WHERE IFR CIGS ARE
EXPD TO CONT OVRNGT. ELSW...COULD SEE SOME PTCHY STRATUS/MVFR BR
DVLPG OVRNGT. EXTENT OF THE STRATUS IS UNCERTAIN...WITH THE MOST
LIKELY PLACES TO SEE CIGS S-E OF PIT...AS WELL AS FKL/DUJ. CONDS
SHOULD RETURN TO VFR ACRS THE RGN MON MRNG. AN EXITING UPR LVL
WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM.

.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

000
FXUS61 KPBZ 200134
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
934 PM EDT SUN MAY 19 2013

.SYNOPSIS...
A SERIES OF WEATHER DISTURBANCES WILL BRING PERIODIC SHOWER AND
THUNDERSTORM CHANCES THROUGH THURSDAY. HIGH PRESSURE WILL BUILD IN
FRIDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
EVE RAOB PLOTS/STLT DATA SHOW AN UPR LVL WAVE OVR WV. THIS WL
CONT TO DRIFT SLOWLY EWD THRU MON. ISOLD SHWRS S OF PIT SHOULD
CONT TO DMNSH AND GRDLY END OVRNGT. REMOVED TSTMS FM THE FCST AS
INSTAB DROPS OFF. NR TERM MDL DATA SHOWS POTENTIAL FOR STRATUS
DVLPG AREAS N-E OF PIT TNGT AS WELL. WL KEEP CHC POPS FOR
SHWRS/TSTMS MAINLY E-SE OF PIT MON AS THE UPR WV BEGINS TO EXIT TO
THE E. MDL PROGS SHOW INSTAB SHOULD BE MINIMAL MON.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
ANY CONVECTION SHOULD BE DSPTG MON EVE AS THE UPR WAVE CONTS TO
MOVE OUT. LOW CHC FOR SHWRS/TSTMS RETURNS TUE AFTN...ALTHOUGH
SOME UPR AND MID LVL RIDGING AND LACK OF A GOOD TRIGGER SHOULD
HELP LMT ACTIVITY. TEMPS WL CONT MUCH ABV AVG.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR CONDS EXPD INTO THE EVE...EXCPT FOR DUJ WHERE IFR CIGS ARE
EXPD TO CONT OVRNGT. ELSW...COULD SEE SOME PTCHY STRATUS/MVFR BR
DVLPG OVRNGT. EXTENT OF THE STRATUS IS UNCERTAIN...WITH THE MOST
LIKELY PLACES TO SEE CIGS S-E OF PIT...AS WELL AS FKL/DUJ. CONDS
SHOULD RETURN TO VFR ACRS THE RGN MON MRNG. AN EXITING UPR LVL
WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM.

.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

07

000
FXUS61 KPBZ 192327
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
727 PM EDT SUN MAY 19 2013

.SYNOPSIS...
A SERIES OF WEATHER DISTURBANCES WILL BRING PERIODIC SHOWER AND
THUNDERSTORM CHANCES THROUGH THURSDAY. HIGH PRESSURE WILL BUILD IN
FRIDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
STLT/MESO DATA SHOWS AN UPR LVL WAVE OVR CNTRL WV. THIS WL CONT TO
DRIFT SLOWLY EWD THRU MON. ISOLD SHWRS/TSTMS S OF PIT SHOULD
QUICKLY DSPT AFT SUNSET. NEAR TERM MDL DATA SHOWS POTENTIAL FOR
STRATUS DVLPG AREAS N-E OF PIT TWD MRNG AS WELL. WL KEEP CHC POPS
FOR SHWRS/TSTMS MAINLY E-SE OF PIT MON AS THE UPR WV BEGINS TO
EXIT TO THE E. MDL PROGS SHOW INSTAB SHOULD BE MINIMAL MON. WELL
ABV AVG TEMPS FCST FOR MON.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
ANY CONVECTION SHOULD BE DSPTG MON EVE AS THE UPR WAVE CONTS TO
MOVE OUT. CHC FOR SHWRS/TSTMS RETURNS TUE AFTN...ALTHOUGH SOME UPR
AND MID LVL RIDGING AND LACK OF A GOOD TRIGGER SHOULD HELP LMT
ACTIVITY. TEMPS WL CONT MUCH ABV AVG.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
VFR CONDS EXPD INTO THE EVE...EXCPT FOR DUJ WHERE MVFR CIGS ARE
EXPD TO CONT. AS LLVL MOISTURE INCRS EXP DUJ CIGS WL DROP TO IFR
LTR THIS EVE AND CONT OVRNGT. ELSW...COULD SEE SOME PTCHY STRATUS/MVFR
BR DVLPG OVRNGT. EXTENT OF THE STRATUS IS UNCERTAIN...WITH THE
MOST LIKELY PLACES TO SEE CIGS S-E OF PIT...AS WELL AS FKL/DUJ.
CONDS SHOULD RETURN TO VFR ACRS THE RGN MON MRNG. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM.

.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL CONT TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

07