915
FXUS61 KPBZ 042337
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
737 PM EDT THU SEP 4 2025
SYNOPSIS
SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TODAY WITH A
PASSING COLD FRONT. FOG EXPECTED OVERNIGHT. A SECOND COLD FRONT
MAY RETURN ISOLATED THUNDERSTORM LATE TOMORROW EVENING. COOLER
CONDITIONS ARE EXPECTED OVER THE WEEKEND.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
KEY MESSAGES:
- FOG EXPECTED TONIGHT
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AFTER DARK, PROBABILITY OF THUNDERSTORMS RAPIDLY DECREASES WITH
THE LOSS OF SURFACE HEATING AND THE FRONT STALLING NEAR THE
RIDGES.
AFTER MIDNIGHT, THE POTENTIAL FOR DENSE FOG INCREASES WITH LIGHT
WINDS AT THE SURFACE AND BOUNDARY LAYER SATURATION. THE MOST
LIKELY AREAS THAT WILL BE IMPACTED BY FOG WILL BE NORTH OF
PITTSBURGH AND IN THE VICINITY OF THE STATIONARY FRONT.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/
KEY MESSAGES:
- THE PASSAGE OF A SECONDARY COLD FRONT WILL INCREASE THE
POTENTIAL FOR STRONG TO SEVERE STORMS FRIDAY EVENING INTO
EARLY SATURDAY MORNING
- RAIN CHANCES CONTINUE INTO SATURDAY AFTERNOON; NEAR RECORD
LOW MAXIMUM TEMPERATURE
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THE UPPER LEVEL PATTERN WILL EXPERIENCE A QUICK PIVOT BACK TO
SOUTHWESTERLY FLOW AHEAD OF THE NEXT DEEP SHORTWAVE ROUNDING
THROUGH THE BROADER GREAT LAKES TROUGH. MODEST WARM ADVECTION
AND INITIALLY SUNNIER SKIES ARE LIKELY TO AID TEMPERATURE
RETURNING NEAR THE DAILY AVERAGE HIGH. SUBSIDENCE AHEAD OF THE
APPROACHING MID-LEVEL JET ALSO WILL AID IN FRIDAY INITIALLY
STARTING DRY.
BY LATE FRIDAY EVENING, A NEW COLD FRONT IS EXPECTED TO ADVANCE
INTO THE REGION. JOINT PROBABILITIES OF EFFECTIVE SHEAR
(+30KTS) AND INSTABILITY (500J/KG) IS ELEVATED (ABOVE 70%) AND
COULD PROMPT ORGANIZED STORMS DURING THE TIME PERIOD OF OF 4PM
FRIDAY TO 2AM SATURDAY. SEVERE STORMS COULD PRODUCE DAMAGING
WINDS AND PERHAPS AN ISOLATED TORNADO. STORMS CELLS MOVING DUE
EAST WOULD LIKELY INGEST THE BEST ROTATION UPDRAFTS FOR A
TORNADO THREAT.
THE SEVERE THREAT WILL DECREASE BEFORE DAWN ON SATURDAY.
HOWEVER, REMNANT CONVECTION TOWARDS OUR SOUTHWEST IS EXPECTED TO
TRACK THROUGH THE REGION IN WAVES ON SATURDAY.
THE COMBINATION OF EXCESSIVE CLOUD COVER, RAIN, AND NEAR SURFACE
COLD ADVECTION SATURDAY MEANS AREA HIGH TEMPERATURE MAY BE NEAR
RECORD LOW. SITES THAT WOULD BE WITHIN 3-4 DEGREES FROM TYING OR
BREAKING THE RECORD ARE WHEELING (HLG) AND NEW PHILADELPHIA
(PHD).
LONG TERM /SUNDAY THROUGH THURSDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPERATURES ARE EXPECTED ON SUNDAY
- A LAKE ENHANCED SHOWER NORTH OF I-80 ARE EXPECTED
- WARMING TREND MONDAY INTO WEDNESDAY
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AS THE AFOREMENTIONED UPPER-LEVEL TROUGH SAGS INTO THE OHIO
RIVER VALLEY SUNDAY, EXPECTED BELOW AVERAGE TEMPERATURES TO
CONTINUE. PREVAILING WESTERLY FLOW OVER THE GREAT LAKES WILL
LIKELY KEEP LAKE ENHANCED SHOWERS NORTH OF I-80.
A GRADUAL WARMING PATTERN IS EXPECTED AS THE UPPER-LEVEL TROUGH
EXITS NORTH AND ZONAL FLOW RETURNS MONDAY INTO TUESDAY.
PROBABILITY OF PRECIPITATION IS CONSIDERED LOW MONDAY INTO
WEDNESDAY WITH BUILDING HIGH PRESSURE TO OUR WEST.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
AREAS OF SHOWERS AND SCATTERED THUNDERSTORMS ASSOCIATED WITH THE
COLD FRONT ARE MOVING OUT OF THE REGION. IMPROVEMENT TO MAINLY
VFR IS EXPECTED AFTER FROPA LATE THIS AFTERNOON INTO THIS
EVENING, BEFORE CONDITIONS DETERIORATE TO IFR AGAIN OVERNIGHT AS
STRATUS AND FOG DEVELOPS WITH LOW LEVEL MOISTURE IN PLACE.
STRATUS SHOULD SCATTER OUT FRIDAY MORNING AS MIXING BEGINS.
VFR CONDITIONS WILL PERSIST UNTIL ADDITIONAL SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH A CROSSING REINFORCING COLD FRONT PASS
THROUGH THE REGION LATE FRIDAY INTO SATURDAY. TIMING OF THESE STORMS
IS NOT EXPECTED TO OCCUR UNTIL AROUND 00Z OR LATER. IN THE TAFS, A
TEMPO IS ENTERED AT PIT TO INDICATE THE SECOND FRONTAL PASSAGE.
OUTLOOK.
POST -FRONT, MAINLY VFR IS THEN EXPECTED THROUGH TUESDAY, THOUGH A
CROSSING UPPER-LEVEL TROUGH AND COLD AIR ALOFT COULD LEAD TO CIG
RESTRICTIONS N OF PIT SUNDAY INTO MONDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...HEFFERAN
SHORT TERM...HEFFERAN
LONG TERM...HEFFERAN
AVIATION...WM/LUPO
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