826
FXUS61 KPBZ 232120
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
520 PM EDT SAT MAY 23 2026
WHAT HAS CHANGED
UPDATES MADE TO TAFS TO REFLECT CURRENT TIMING AND COVERAGE OF
SHOWERS.
KEY MESSAGES
1) FLOOD WATCH CONTINUES INTO TONIGHT
2) SHOWERS/THUNDERSTORMS THIS AFTERNOON INTO TONIGHT, WITH A
MARGINAL RISK FOR A TORNADO THIS AFTERNOON ACROSS SE OH
3) SHOWER/THUNDERSTORM CHANCES CONTINUE AT TIMES INTO THE
MIDDLE OF NEXT WEEK
DISCUSSION
KEY MESSAGE 1...
WET ANTECEDENT CONDITIONS (1-2 INCHES LAST NIGHT) HAVE DROPPED
FLASH FLOOD GUIDANCE VALUES TO LESS THAN 1 IN/HR AND <1.5
IN/3HRS ACROSS MUCH OF EASTERN OHIO. AREA STREAMS AND CREEKS
ALSO REMAIN ELEVATED. THIS SETS UP ENHANCED FLOODING CONCERNS
HEADING INTO THIS AFTERNOON AND EVENING AS ADDITIONAL LINES OF
CONVECTION CROSS THE REGION.
DRY SLOTTING THIS MORNING AND EARLY AFTERNOON HAS HELPED BUILD
A NARROW SWATH OF INSTABILITY, WITH 500-1000 J/KG OF MLCAPE
INTO EASTERN OHIO. MORNING UA AND MODEL SOUNDINGS SHOW
ANOMALOUSLY PWAT VALUES NEAR 1.5 INCHES ACROSS THE REGION. STORM
LEVEL FLOW IS ALSO NEARLY PARALLEL TO THE SLOW-MOVING WARM
FRONT TO OUR WEST. COMBINED, THIS SETUP IS FAVORABLE FOR
TRAINING AND BACKBUILDING THUNDERSTORMS WITH EFFICIENT, WARM-
RAIN PROCESSES. LATEST CAMS SHOW LARGE SWATHS OF 1-3+ INCHES
ACROSS PORTIONS OF EASTERN OH LATER THIS AFTERNOON AND EVENING.
FOR THESE REASONS, THE FLOOD WATCH FOR EASTERN OHIO HAS BEEN
EXTENDED UNTIL 2AM SUNDAY. WPC HAS ALSO INCREASE THE EXCESSIVE
RAINFALL OUTLOOK TO A 2/4 SLIGHT RISK FOR PORTIONS OF EASTERN
OHIO. AREAS FARTHER EAST (I.E. WESTERN PA) HAVE A MUCH LOWER
PROBABILITY FOR FLOODING, OWING TO LESS RAINFALL LAST NIGHT, AND
A LESS FAVORABLE ENVIRONMENT FOR THUNDERSTORMS THIS AFTERNOON
AND EVENING.
KEY MESSAGE 2...
AS MENTIONED ABOVE, DRY SLOTTING THIS MORNING HAS HELPED MUCH OF
THE REGION BREAK OUT OF CLOUD COVER THIS MORNING AND EARLY
AFTERNOON. THIS HAS LEAD TO A SWATH OF 500-1000 J/KG MLCAPE
DEVELOPING INTO EASTERN OHIO, RAPIDLY DECREASING FARTHER EAST.
VEERING PROFILES, LOW LCLS, AND STRONG LOW-LEVEL SRH RESULT IN
AN ENVIRONMENT SUPPORTING OF DEEP, ORGANIZED CONVECTION AND
POTENTIAL FOR BRIEF TORNADOES. THE STORM PREDICTION CENTER HAS
MAINTAINED A 1/5 MARGINAL RISK FOR PORTIONS OF EASTERN OHIO,
PRIMARILY FOR THE BRIEF TORNADO RISK. THE THREAT SHOULD QUICKLY
DIMINISH AFTER SUNSET WITH LOSS OF SURFACE BASED CAPE. FARTHER
EAST, A STRONG SURFACE INVERSION SHOULD PERSIST AHEAD OF THE
SURFACE LOW/BOUNDARY. WHILE A THUNDERSTORM IS STILL POSSIBLE,
ANY INSTABILITY WOULD BE ELEVATED AND LIMITED.
THE SHORTWAVE IS EXPECTED TO CONTINUE EASTWARD ACROSS THE AREA
TONIGHT, WITH ADDITIONAL SHOWERS AND POSSIBLE THUNDERSTORMS.
IN ADDITION, GUSTY SE DOWNSLOPE WIND IS EXPECTED ACROSS THE
WESTERN SLOPE OF THE LAUREL HIGHLANDS THROUGH THE DAY. GUSTS
FROM 30-35 KT ARE LIKELY.
KEY MESSAGE 3...
THE SHORTWAVE CROSSING THE REGION TONIGHT SHOULD EXIT THE
REGION SUNDAY MORNING, AS ANOTHER SHORTWAVE BEGINS TO APPROACH
FROM THE MIDWEST. MUCH SUNDAY IS EXPECTED TO BE DRY, THOUGH A
FEW SHOWERS OR STORMS COULD DEVELOP BY THE AFTERNOON AS
CONVECTIVE TEMPERATURES ARE MET. SHOWERS AND A FEW THUNDERSTORMS
ARE EXPECTED TO INCREASE AGAIN FROM W-E LATE IN THE AFTERNOON
INTO SUNDAY NIGHT AS THE SHORTWAVE CROSSES THE UPPER OHIO VALLEY
REGION. THIS SYSTEM SHOULD BEGIN TO EXIT THE REGION MONDAY
MORNING, WITH DECREASING POPS FROM NW-SE THROUGH THE DAY.
MODEL ENSEMBLES INDICATE THE UPPER OHIO VALLEY REGION WILL BE
BETWEEN A NE CONUS TROUGH, AND A CENTRAL CONUS RIDGE. A STALLED
SURFACE BOUNDARY IN BETWEEN THESE TWO FEATURES IS EXPECTED TO
BE ACROSS THE LOWER OHIO VALLEY TO THE MID ATLANTIC REGION,
RESULTING IN PERIODIC SHOWER AND THUNDERSTORM CHANCES THROUGH
AT LEAST MID WEEK, WITH THE HIGHEST CHANCES SOUTH OF
PITTSBURGH. WARMER TEMPERATURES ARE ALSO EXPECTED, UNTIL LATE
WEEK WHEN HIGH PRESSURE BEGINS TO BUILD IN FROM THE NORTH WITH
COOLER AND DRIER WEATHER.
AVIATION /21Z SATURDAY THROUGH THURSDAY/
A MODEST UPDATE WAS MADE TO TAFS TO REFLECT TIMING OF SHOWERS.
COVERAGE AND INTENSITY OF SHOWERS AS REFLECTED IN PRIOR TAFS HAS
LARGELY VERIFIED FEWER AND WEAKER, AND TIMING/RESTRICTIONS HAVE
BEEN ADJUSTED TO REFLECT THIS EVOLUTION. SHOWERS ARE DEVELOPING,
BUT THOSE WITH GREATEST INTENSITY APPEAR TO BE ON A TRACK THAT
WILL FAVOR A SRN TRACK, WITH THOSE TO THE NORTH LIKELY VICTIM TO
MORE-MODEST BUOYANCY AS A RESULT OF PROLONGED DAYTIME CLOUD
COVER AND LIMITED RECOVERY.
NEVERTHELESS, SCATTERED SHOWERS WILL PROGRESS THRU THE REGION,
LEAVING A MOIST AIRMASS IN THEIR WAKE. AS SUCH, HIGH CONFIDENCE
(GREATER THAN 80%) REMAINS IN WIDESPREAD IFR CIGS TONIGHT
THROUGH THE DAY ON SUN AT ALL AIRPORTS.
SOUTHEAST WIND WILL CONTINUE TO BE AT OR ABOVE THE 12 KNOT
THRESHOLD THROUGH MOST OF THE PERIOD WITH THE HISTORICAL WINDIER
PLACES IN THIS REGIME (LBE, DUJ, AGC, PIT, AND MGW) GUSTING
INTO THE OVERNIGHT HOURS UPWARDS OF 25-30 KNOTS.
WIDESPREAD IFR CIGS ARE LIKELY INTO SUN AFTERNOON AS ADDITIONAL
RAIN SHOWERS DEVELOP SUN WHEN STRONGER FORCING FOR ASCENT
APPEARS PROBABLE. THESE COULD ONCE AGAIN POSE A THREAT OF
MODERATE TO HEAVY RAIN CAPABLE OF FURTHER VSBY RESTRICTIONS.
OUTLOOK...
CIGS COULD REMAIN IFR UNTIL MID-MORNING ON MEMORIAL DAY.
WIDESPREAD RAIN SHOWERS WILL TAPER OFF WEST TO EAST LATE SUN
NIGHT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...FLOOD WATCH UNTIL 2 AM EDT SUNDAY FOR OHZ039-040-048>050-
057>059-068-069.
WV...FLOOD WATCH UNTIL 2 AM EDT SUNDAY FOR WVZ001>004-012.
DISCUSSION...WM/RACKLEY
AVIATION...KRAMAR/MCMULLEN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page