326
FXUS61 KPBZ 191749
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
149 PM EDT WED AUG 19 2026
WHAT HAS CHANGED
SATURATED GROUNDS AND HIGHER PROBABILITIES FOR HEAVY RAIN HAVE
RAISED THE RISK FOR LOCALIZED FLASH FLOODING TONIGHT INTO
THURSDAY. A FLOOD WATCH IS NOW IN EFFECT.
KEY MESSAGES
1) SLIGHTLY HIGHER RISK FOR FLASH FLOODING OVERNIGHT TONIGHT
INTO THURSDAY MORNING WITH POTENTIAL TRAINING OF HEAVIER RAIN
STORMS. A FLOOD WATCH HAS BEEN ISSUED.
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. A FLOOD WATCH HAS BEEN ISSUED
FOR PORTIONS OF EASTERN OH, NORTHERN WV, AND EXTREME SOUTHWEST
PA WHERE RECENT HEAVY RAIN EVENTS HAVE LOCALLY INCREASED
VULNERABILITY TO FLASH FLOODING.
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 /18Z WEDNESDAY THROUGH MONDAY/
A SCT/BKN CU FIELD AND DENSE MID/UPPER CLOUD DECK HAS OVERSPREAD
THE AREA THIS AFTERNOON AND WILL CONTINUE THROUGH THE REST OF
THE DAY. A COLD FRONT IS CURRENTLY SUPPORTING SCATTERED SHOWER
ACTIVITY ACROSS NORTHWEST PA AS IT SAGS SOUTHWARD. THIS FEATURE
WILL INTRODUCE SOME POTENTIAL FOR RAIN AND BRIEF VISIBILITY
RESTRICTIONS AT FKL/DUJ THROUGH THE AFTERNOON, BUT IS UNLIKELY
TO INITIATE CONVECTION FARTHER SOUTH AS IT LOSES STEAM WITH THE
LOSS OF PEAK HEATING THIS EVENING.
A PASSING UPPER SHORTWAVE, IN COMBINATION WITH THE SAGGING (AND
EVENTUALLY STALLING) COLD FRONT DRAPED ACROSS THE LOCAL AREA,
WILL PROMOTE A MORE WIDESPREAD COVERAGE IN SHOWERS AND
ASSOCIATED RESTRICTIONS OVERNIGHT INTO THURSDAY MORNING. WHILE
INSTABILITY IS FORECAST TO BE LIMITED AT BEST, CAN'T ENTIRELY
RULE OUT A FEW RUMBLES OF THUNDER.
OUTLOOK...
DRIER CONDITIONS AND PREVAILING VFR RETURN THURSDAY AFTERNOON
AND CONTINUE 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...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR PAZ029-031.
OH...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR OHZ039-040-048>050-
057>059-068-069.
WV...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR WVZ001>004-012-021-
509.
DISCUSSION...FRAZIER/CERMAK
AVIATION...CERMAK
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