324
FXUS61 KPBZ 151640
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1240 PM EDT TUE SEP 15 2026
WHAT HAS CHANGED
SHOWER AND THUNDERSTORM CHANCES HAVE INCREASED FOR WEDNESDAY,
WITH LOCALLY HEAVY RAIN AND GUSTY WIND POSSIBLE.
KEY MESSAGES
1) SHOWER AND THUNDERSTORM CHANCES RETURN WEDNESDAY AND
THURSDAY, WITH LOCALLY HEAVY RAINFALL AND GUSTY WIND POSSIBLE
2) UNSETTLED PATTERN RETURNS THIS WEEKEND INTO EARLY NEXT WEEK
DISCUSSION
KEY MESSAGE 1...
A SURFACE COLD FRONT IS EXPECTED TO DRIFT SEWD TONIGHT, REACHING
LAKE ERIE/NORTHERN OHIO WEDNESDAY MORNING. A FEW SHOWERS ARE
POSSIBLE, MAINLY ACROSS NW PA LATE TONIGHT INTO WEDNESDAY
MORNING WITH CONVERGENCE AHEAD OF THE FRONT.
RECENT MODEL DATA HAS TRENDED TOWARD A MORE RAPID
WEAKENING/SOUTHWARD SHIFT OF A RIDGE ACROSS THE UPPER OHIO
VALLEY REGION, WHICH RESULTS IN A FASTER ARRIVAL OF A COLD FRONT
ON WEDNESDAY. THIS FRONT SHOULD DRIFT SOUTHWARD TO CENTRAL
OHIO/WEST CENTRAL PA BY LATE WEDNESDAY AFTERNOON. INCREASING
MOISTURE AND A WEAK MID LEVEL SHORTWAVE TROUGH IS ALSO EXPECTED
TO APPROACH THE REGION AT THE SAME TIME, SPARKING SCATTERED
SHOWERS AND THUNDERSTORMS. 0-6KM SHEAR IS PROGGED TO REMAIN AT
OR BELOW 20KT, THOUGH ML CAPE OF 1000-1500 J/KG AND SOME DCAPE
(500-700 J/KG) COULD RESULT IN A GUSTY WIND POTENTIAL IN SOME OF
THE STORMS. IN ADDITION, PWATS INCREASE 1.8 TO NEAR 2.0 MAINLY
NORTH OF I-70 BY LATE IN THE DAY, RESULTING IN A LOCALLY HEAVY
RAIN/FLASH FLOOD POTENTIAL. THE EXTENT OF THE STORM COVERAGE IS
STILL UNCERTAIN, THOUGH RECENT TRENDS DO SHOW SOME INCREASED
POTENTIAL FOR THE HEAVY RAIN/STRONG STORM THREAT LATE WEDNESDAY.
THE INTENSITY OF ANY SHOWERS/STORMS SHOULD DECREASE WEDNESDAY
NIGHT WITH WANING INSTABILITY, THOUGH WITH THE FRONT IN THE AREA
AND ANOTHER APPROACHING SHORTWAVE SCATTERED SHOWERS/ISOLATED
STORMS ARE STILL EXPECTED.
THE FLOW SHOULD BACK ALOFT WEDNESDAY NIGHT/THURSDAY MORNING,
RESULTING IN THE FRONT STALLING ACROSS THE REGION. THIS WAVE
SHOULD TRACK ACROSS THE UPPER OHIO VALLEY REGION THURSDAY, WITH
ADDITIONAL SHOWERS AND THUNDERSTORMS EXPECTED. WNW FLOW ALOFT
BEHIND THE WAVE SHOULD PUSH THE FRONT THROUGH THE AREA THURSDAY
AFTERNOON AND EVENING. DIURNAL INSTABILITY AND CONTINUED HIGH
PWATS WILL RESULT IN MAINLY A LOCALLY HEAVY RAINFALL POTENTIAL
THROUGH THE DAY. THE SHOWERS AND STORMS SHOULD GRADUALLY END BY
THURSDAY NIGHT AS THE FRONT EXITS, WITH DRY WEATHER RETURNING
FOR FRIDAY.
KEY MESSAGE 2...
MODEL ENSEMBLES INDICATE A WNW FLOW ALOFT ACROSS THE REGION THIS
WEEKEND INTO EARLY NEXT WEEK, AS A SURFACE FRONT APPROACHES AND
STALLS ACROSS THE UPPER OHIO VALLEY REGION. MULTIPLE WAVES
EMBEDDED IN THE FLOW WILL RESULT IN PERIODIC SHOWERS AND
THUNDERSTORMS ACROSS THE REGION, ESPECIALLY LATE SATURDAY INTO
MONDAY. UNCERTAINTY REMAINS IN HOW LONG THIS PATTERN WILL
PERSIST, WITH SOME GUIDANCE INDICATING SOME IMPROVEMENT TOWARD
MID WEEK.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
VFR WITH LIGHTER SOUTHEASTERLY TO SOUTHERLY WIND UNDER THE
INFLUENCE OF HIGH PRESSURE IS FAVORED THROUGH THE TAF PERIOD.
AREAS OF MID-TO-UPPER LEVEL CLOUDS WILL OCCASIONALLY CROSS,
MOST NOTABLY OVER NORTHWEST PA.
LOW PROBABILITY SHOWER CHANCES (THAT COULD RESULT IN A PERIOD OF
RESTRICTIONS) EXIST NEAR/NORTH OF FKL/DUJ AFTER 06Z TONIGHT BUT
ARE TOO LOW FOR MENTION AT THIS TIME.
OUTLOOK...
GRADUAL SHORTWAVE PROGRESSION OVER THE TOP OF THE CURRENT UPPER
LEVEL RIDGE WILL INCREASE SHOWER AND THUNDERSTORM CHANCES ALONG
WITH RESULTANT RESTRICTIONS WEDNESDAY EVENING INTO THURSDAY.
BRIEF PASSING HIGH PRESSURE FRIDAY OFFERS QUIETER WEATHER BEFORE
A POTENTIALLY ACTIVE PATTERN DEVELOPS SATURDAY INTO NEXT EARLY
NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM
AVIATION...FRAZIER
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