257
FXUS61 KPBZ 270304
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1104 PM EDT TUE MAY 26 2026
WHAT HAS CHANGED
TIMING OF THE HEAVIER SHOWERS AND THUNDERSTORMS APPEAR TO BEGIN
JUST AFTER 06Z AND CONTINUE THROUGH THE MORNING AND INTO THE
COMING DAY.
KEY MESSAGES
1) FLOOD WATCH IN EFFECT FROM MIDNIGHT TONIGHT TO 10PM WEDNESDAY
AS SHOWERS/THUNDERSTORMS PRODUCING HEAVY RAIN MAY RESULT IN
FLASH FLOODING.
2) DRY AND SEASONABLE WEATHER CONDITIONS FAVORED THURSDAY
THROUGH THE WEEKEND.
DISCUSSION
KEY MESSAGE 1...
A WEAK TROUGH TRAVELING THE PERIPHERY ON THE RIDGE OVERNIGHT AND
WILL PROVIDE THE NEEDED LIFT FOR SHOWERS AND THUNDERSTORMS. IN
ADDITION, ENOUGH NW FLOW WITH TROUGHING NORTH OF THE AREA LENDS
TO THE DEVELOPMENT OF STRONG FRONTOGENESIS NEAR TO SOUTH OF THE
I-70 CORRIDOR THAT RESULTS IN A PROLONGED PERIOD OF LIFT/FORCING
THAT WILL CREATE ROUNDS OF SHOWERS AND THUNDERSTORMS STARTING
TONIGHT AND CONTINUING INTO WEDNESDAY EVENING. THIS CONVECTION
WILL PRODUCE HEAVY RAINFALL AT TIMES THAT MAY LEAD TO FLOODING.
THE RISK FOR FLASH FLOODING, WHICH RESULTED IN THE ISSUANCE OF A
FLASH FLOODING, IS FUELED BY THE COMBINATION OF FAIRLY
SATURATED GROUNDS FROM RECENT RAINS (THOUGH NOT ANOMALOUSLY SO)
AND A STORM ENVIRONMENT THAT IS CONDUCIVE TO HEAVY RAIN PLUS
TRAINING STORMS. FOR THE ENVIRONMENT, PWATS REACH THE 95TH
PERCENTILE VALUES FOR LATE MAY WHILE CAPE 500-1000 J/KG OFFER
ENOUGH UP-SCALE GROWTH TO BETTER MAXIMIZE MOISTURE CONTENT. THEN
MID-LEVEL FLOW WILL BE SLOW (AROUND 15 KTS), WESTERLY AND
FAIRLY PARALLEL TO THE SURFACE STALLED BOUNDARY, INCREASING THE
ODDS OF TRAINING. THE COMBINATION OF PEAK FRONTOGENESIS AND
INSTABILITY FAVOR RISKS MAXIMIZING BETWEEN 9AM TO 5PM WEDNESDAY,
BUT STORMS PRIOR TO AND AFTER THESE HOURS COULD STILL LEAD TO
FLASH FLOODING. THE CONCERNING FACTOR HERE IS THAT MOST
LOCATIONS IN THE WATCH AREA HAVE 1 HOUR FFG GUIDANCE AROUND 1.10
TO 1.25. THE ENSEMBLES SUGGEST A ROUGHLY 60% TO 70% PROB OF
EXCEEDING 1 INCH AND WITH THE FFG SOMEWHAT LOW, THERE IS
DEFINITELY A CHANCE FOR IMPACTFUL FLOODING.
TRENDS CONTINUE TO SUPPORT THE IMPACT OF FLOODING RAINFALL
REMAINING SOUTH OF PITTSBURGH. THE MAIN IMPACTS CONTINUE TO SHOW
THE AREA ALONG I-70 AND SOUTH.
KEY MESSAGE 2...
THOUGH ENSEMBLE MODELS EXHIBIT SOME VARIANCE IN THE BATTLE
BETWEEN THE DRIER AND MORE SEASONABLE AIRMASS UNDERNEATH A
SOUTHEASTERN CANADIAN TROUGH VERSUS THE WARMER AND WETTER
AIRMASS SITTING IN THE SE CONUS, PROBABILITIES FAVOR THE REGION
REMAINING MORE ON THE DRY AND SEASONABLE SIDE OF THE SPECTRUM
THURSDAY THROUGH THE WEEKEND. NO IMPACTS ARE EXPECTED AT THIS
TIME.
AVIATION /02Z WEDNESDAY THROUGH SUNDAY/
RAIN WILL CONTINUE TO SPREAD NORTH OVERNIGHT AS THE FRONT SLOWLY
LIFTS NORTH. INITIALLY, VFR CEILINGS AND VISIBILITIES ARE
EXPECTED WITH SCATTERED SHOWERS. COVERED THIS WITH PROB30S FOR
BVI SOUTHWARDS. A QUICK DROP TO MVFR/IFR CEILINGS IS THEN
EXPECTED FOR PIT SOUTH WITH BVI ON THE GRADIENT. CEILINGS SHOULD
LIFT ONCE AGAIN FROM NORTH TO SOUTH BY MID-MORNING AS THE FRONT
DRIFT SOUTH, WITH VFR RETURN AT ALL TERMINAL BY 21Z.VFR IS THEN
EXPECTED OVERNIGHT INTO THURSDAY, THOUGH FOG MAY BE POSSIBLE AT
MGW.
OUTLOOK...
AREAWIDE VFR IS ANTICIPATED THURSDAY AND FRIDAY UNDER HIGH
PRESSURE, WITH DRY WEATHER EXPECTED INTO NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR PAZ029-031-075-076.
OH...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR OHZ057>059-068-069.
WV...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR WVZ003-004-012-021-
509>514.
DISCUSSION...FRAZIER/SHALLENBERGER
AVIATION...RACKLEY/AK
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