869
FXUS61 KPBZ 090721
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
321 AM EDT WED SEP 9 2026
WHAT HAS CHANGED
UPDATE TO KEY MESSAGES
KEY MESSAGES
1) STRONG TO SEVERE STORM POTENTIAL LATE THIS EVENING NORTH OF
PITTSBURGH
2) AN ACTIVE WEATHER PATTERN COULD OCCUR EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...
HIGH-RESOLUTION MODELS CONTINUE TO INDICATE THAT SHOWER AND
THUNDERSTORM ACTIVITY WILL INCREASE LATE THIS EVENING JUST SOUTH
OF LAKE ERIE AS AN APPROACHING TROUGH AND ITS ASSOCIATED COLD
FRONT MOVE INTO THE REGION.
THE MOST LIKELY WINDOW FOR STORMS TO DEVELOP WOULD BE BETWEEN
7PM TO 9PM NEAR I-80. A FEW STORMS COULD BE STRONG TO SEVERE,
PARTICULARLY NORTH OF PITTSBURGH, WHERE A COMBINATION OF MODEST
INSTABILITY (900-1200J/KG OF CAPE) AND EFFECTIVE SHEAR EXCEEDING
30KTS WILL SUPPORT ORGANIZED CONVECTION. DAMAGING WIND GUST WILL
LIKELY BE THE PRIMARY THREAT. HOWEVER, A STORM THAT ACCELERATES
SOUTHEASTWARD COULD ACQUIRE SOME LOW-LEVEL ROTATION, POTENTIALLY
RESULTING IN A FUNNEL CLOUD OR BRIEF TORNADO.
AS STORMS MOVE TOWARD THE PITTSBURGH AREA BETWEEN 9PM AND 11PM,
INSTABILITY IS EXPECTED TO DECREASE, WHICH COULD LIMIT THE
POTENTIAL FOR ADDITIONAL STRONG TO SEVERE STORMS. LIGHTNING
WOULD BE THE PRIMARY THREAT ALONG WITH LOCALIZED HEAVY RAINFALL.
THE PROLONGED PASSAGE OF THE TROUGH AND LINGERING STATIONARY
BOUNDARY MAY SUPPORT PERIODS OF MODERATE TO HEAVY RAINFALL
TOTALS ON THURSDAY, POTENTIALLY RESULTING IN ISOLATED FLOODING
NEAR CREEKS AND STREAMS.
DRIER CONDITIONS ARE EXPECTED FRIDAY UNDER HIGH PRESSURE.
KEY MESSAGE 2...
MACHINE-LEARNING MODELS SUGGEST THAT AFTER A BRIEF PERIOD OF
RIDGING ON FRIDAY, OUR LARGE-SCALE WEATHER PATTERN WILL
TRANSITION TO A MORE ZONAL FLOW. AS A RESULT, THIS WILL ALLOW
DISTURBANCES FORMING UPSTREAM (TO OUR WEST) TO TRACK INTO OUR
AREA. THIS PATTERN COULD CREATE A HEAVY RAIN THREAT AND/OR A
SEVERE WEATHER THREAT EARLY NEXT WEEK AND WILL NEED TO BE
MONITORED.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
VFR IS EXPECTED THROUGH MUCH OF WEDNESDAY UNDER HIGH PRESSURE.
THE CU RULE AND MODEL SOUNDINGS INDICATE A SCATTERED DIURNAL
CUMULUS LAYER SHOULD DEVELOP ON WEDNESDAY, WITH CONTINUED CIRRUS
ABOVE. A FEW STRAY SHOWERS CAN'T BE RULED IN THE VICINITY OF
TERMINALS BETWEEN 15Z TO 23Z.
A PASSING TROUGH AND ITS ASSOCIATED COLD FRONT WILL BEGIN TO
APPROACH FROM THE NW LATE TODAY, MAINLY AFTER 23Z. AN INCREASING
PRESSURE GRADIENT AND MIXING AHEAD OF THE FRONT SHOULD RESULT
IN GUSTY SW WIND ON WEDNESDAY AS WELL.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP SOUTH OF LAKE
ERIE BETWEEN 22Z TO 00Z AND ADVANCE SOUTH INTO EARLY THURSDAY
MORNING. TEMPOS HAVE BEEN ADDED BASED ON HIGH RESOLUTION MODEL
DATA TIMING.
OUTLOOK...
RESTRICTIONS, MVFR TO IFR CIGS, COULD CONTINUE INTO EARLY
THURSDAY MORNING DUE TO LINGERING LOW-LEVEL MOISTURE.
VFR SHOULD RETURN FRIDAY BEFORE ANOTHER SHORTWAVE TROUGH
RETURNS SHOWER CHANCES SATURDAY AND SUNDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...HEFFERAN
AVIATION...WM/HEFFERAN
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