339
FXUS61 KPBZ 191145
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
745 AM EDT WED AUG 19 2026
WHAT HAS CHANGED
THE COMBINATION OF STILL SATURATED GROUNDS AND HIGHER
PROBABILITIES FOR HEAVY RAIN HAS RAISED THE RISK FOR LOCALIZED
FLASH FLOODING OVERNIGHT TONIGHT INTO THURSDAY.
KEY MESSAGES
1) SLIGHTLY HIGHER RISK FOR FLASH FLOODING OVERNIGHT TONIGHT
INTO THURSDAY MORNING WITH POTENTIAL TRAINING OF HEAVIER RAIN
STORMS.
2) ADDITIONAL ROUNDS OF RAIN FAVORED OVER THE WEEKEND WITH
LIMITED HAZARDOUS WEATHER RISKS.
DISCUSSION
KEY MESSAGE 1...
A WEAK FRONTAL BOUNDARY DROPPING OUT OF SOUTHERN MI WILL COMBINE
WITH LIMITED MID-LEVEL SHORTWAVE MOVEMENT TO CREATE LOW
PROBABILITY SHOWER AND THUNDERSTORM CHANCES MAINLY NEAR THE I-80
CORRIDOR THIS AFTERNOON TO EARLY EVENING. EVEN AS THE FRONT
STALLS SOMEWHERE NEAR THE I-70 CORRIDOR THIS EVENING, AREA
CLOUD COVER AND MINIMAL BUOYANCY (LESS THAN 700 J/KG SBCAPE)
SHOULD KEEP ANY ACTIVITY FAIRLY ISOLATED.
GREATER ORGANIZATION OF UPPER TROUGHING OVER THE SOUTHERN OH
RIVER VALLEY LATE TONIGHT INTO THURSDAY MORNING RESULTS IN MORE
WIDESPREAD SHOWER (AND LOW PROBABILITY THUNDERSTORM) ACTIVITY.
THE COMBINATION OF THE STALLED SFC BOUNDARY SITTING PARALLEL TO
UPPER FLOW PLUS PWATS QUICKLY RISING TOWARDS THE 90TH PERCENTILE
AND JET DYNAMICS AIDING STRONGER MID-LEVEL FRONTOGENESIS CREATES
THE POTENTIAL FOR A NARROW CORRIDOR OF ENHANCED RAINFALL
RATES/ACCUMULATIONS AS STORMS SIT AND TRAIN OVER SIMILAR
LOCATIONS. 00Z HREF PROBABILITIES OF 6-HR ACCUMULATIONS
EXCEEDING 2" WITHIN A 40KM RADIUS HAS RISEN TOWARDS 40-60% IN A
RELATIVE AXIS FROM MUSKINGUM COUNTY (OH) THROUGH BUTLER COUNTY
(PA), MEANING THIS SECTOR IS MORE LIKELY TO SEE RAIN TOTALS THAT
COULD RAISE FLASH FLOOD RISKS. HOWEVER, VARIANCE IN SOME OF THE
AXIS POSITIONING PLUS FORECASTER DOUBT IN MAXIMIZING THE
HEIGHTENED PWATS DUE TO A DEARTH OF BUOYANCY (SURFACE OR
ELEVATED) PRECLUDES ANY FLOOD WATCH ISSUANCE AT THIS TIME.
CONVECTIVE ACTIVITY SHIFTS EAST OF THE REGION WITH THE EMBEDDED
SHORTWAVE THROUGH THE DAY THURSDAY AND GENERALLY SUPPORTS THE
END OF PRECIPITATION CHANCES. KEEP AN EYE FOR A RE-INTRODUCTION
OF POPS THURSDAY NIGHT AS RESIDUAL SAGGING TROUGHING TO THE WEST
PLUS RESIDUAL MOISTURE COULD BE ENOUGH FOR ISOLATED SHOWERS.
KEY MESSAGE 2...
SURFACE HIGH PRESSURE CROSSING THE GREAT LAKES PORTENDS TO DRY
WEATHER FRIDAY BEFORE THE NEXT LOW PRESSURE SYSTEM WITH A
DEEPENING UPPER TROUGH INTRODUCTION THE NEXT RAIN CHANCES
SATURDAY AFTERNOON INTO SUNDAY. SOME VARIANCE REMAINS IN THE
WAVE TIMING WHICH COULD ALTER THE PEAK PRECIPITATION PERIOD, BUT
THIS FLOW WILL RESULT IN FAIRLY WIDESPREAD SHOWERS WITH LOWER
PROBABILITY THUNDERSTORMS ALONG WITH SLIGHT AREA TEMPERATURE
FALLS.
THE MAIN HAZARD RISK, IF ONE WERE TO DEVELOP, OCCURS WITH
AFTERNOON FRONTAL PASSAGE SATURDAY WHILE ENOUGH HEATING/MOISTURE
RETURNS PUSHES BUOYANCY VALUES HIGH ENOUGH TO OFFER A LOWER
PROBABILITY WIND RISK. OTHERWISE, ENSEMBLE GUIDANCE IS TRENDING
TOWARD A DRIER START TO THE FOLLOWING WEEK.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
INCREASING MID AND HIGH CLOUDS EXPECTED TODAY AS WELL AS SOME
MIDDAY CUMULUS AT ABOUT 6-8 KFT. A COLD FRONT DROPS SOUTH AND
BRINGS SOME ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON
MOSTLY NORTH OF PIT, WITH LOW CONFIDENCE IN IMPACTS AT ANY
SPECIFIC TERMINALS. A SHORTWAVE TROUGH, IN COMBINATION WITH A
SLOWING/STALLING FRONT DRAPED SOMEWHERE ACROSS THE CENTRAL OUR
SOUTHERN PORTION OF OUR AREA, WILL SUPPORT A MORE WIDESPREAD
COVERAGE IN SHOWERS AND THUNDERSTORMS (AND ASSOCIATED
RESTRICTIONS) OVERNIGHT INTO THURSDAY MORNING.
OUTLOOK...
DRIER CONDITIONS AND PREVAILING VFR RETURN THURSDAY AFTERNOON
AND PREVAIL THROUGH EARLY SATURDAY, WITH THE EXCEPTION OF
PATCHY FOG/STRATUS POSSIBLE DURING OVERNIGHT AND EARLY MORNING
HOURS. RESTRICTIONS AND RAIN CHANCES ARE FAVORED TO RETURN LATE
SATURDAY INTO SUNDAY AS ANOTHER DISTURBANCE CROSSES THE REGION.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER
AVIATION...CERMAK
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