012
FXUS61 KPBZ 091742
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
142 PM EDT WED SEP 9 2026
WHAT HAS CHANGED
NO MAJOR CHANGES WERE MADE TO THE FORECAST.
KEY MESSAGES
1) STRONG TO SEVERE STORM POTENTIAL LATE THIS EVENING NORTH OF
PITTSBURGH. MARGINAL THREAT FOR LOCALIZED FLASH FLOODING TONIGHT
THROUGH THURSDAY.
2) AN ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO EARLY NEXT
WEEK AND WILL WARRANT MONITORING FOR POTENTIAL LOCAL IMPACTS.
DISCUSSION
KEY MESSAGE 1...
NOT MUCH HAS CHANGED SINCE THE PREVIOUS FORECAST CYCLE. HIGH-
RESOLUTION MODELS CONTINUE TO INDICATE A LINE OF STORMS FORMING
LATE THIS EVENING JUST SOUTH OF LAKE ERIE AS AN APPROACHING
TROUGH AND ASSOCIATED COLD FRONT MOVE INTO THE REGION.
THE MOST LIKELY WINDOW REMAINS BETWEEN 7PM TO 9PM ACROSS
NORTHWEST PA AND NORTHEAST OH. A FEW STORMS COULD BE STRONG TO
SEVERE, PARTICULARLY NORTH AND NORTHWEST OF PITTSBURGH, WHERE A
COMBINATION OF MODEST INSTABILITY (900-1200J/KG OF CAPE) AND
EFFECTIVE SHEAR EXCEEDING 30KTS WILL SUPPORT ORGANIZED STORM
MODES (MOST LIKELY IN THE FORM OF BOWING LINE SEGMENTS).
DAMAGING WIND GUSTS WILL LIKELY BE THE PRIMARY THREAT. HOWEVER,
ANY STORMS OR NOTCHES IN THE LINE THAT ARE ABLE TO ACCELERATE
SOUTHEASTWARD COULD ACQUIRE SOME LOW-LEVEL ROTATION BASED ON
MODEL HODOGRAPHS, POTENTIALLY RESULTING IN TRANSIENT LOW-LEVEL
MESOCYCLONE FEATURES CAPABLE OR PRODUCING A FUNNEL CLOUD OR
BRIEF TORNADO.
INSTABILITY IS EXPECTED TO BEGIN WANING AS STORMS MOVE TOWARD
THE PITTSBURGH AREA BETWEEN 9PM AND 11PM, WHICH COULD LIMIT THE
POTENTIAL FOR ADDITIONAL STRONG TO SEVERE STORMS. LIGHTNING
WOULD BE THE PRIMARY THREAT ALONG WITH A MARGINAL LOCALIZED
FLASH FLOOD THREAT DUE TO HEAVY RAINFALL.
THE PROLONGED PASSAGE OF THE TROUGH AND LINGERING STATIONARY
BOUNDARY MAY SUPPORT PERIODS OF MODERATE TO HEAVY RAINFALL
TOTALS DURING THE DAY THURSDAY, POTENTIALLY RESULTING IN
ISOLATED FLOODING ALONG CREEKS AND STREAMS AS WELL AS URBAN AND
LOW-LYING/POOR-DRAINAGE AREAS. THE GREATEST CHANCE FOR THIS
OCCURRING IS ACROSS NORTHERN WV, WHICH WILL BE IN CLOSER
PROXIMITY TO THE SLOWED/STALLED FRONTAL BOUNDARY AND THEREFORE
HAS THE GREATEST POTENTIAL TO SEE MORE PERSISTENT ROUNDS OF
HEAVIER SHOWERS AND THUNDERSTORMS.
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 ACTIVE PATTERN COULD SUPPORT HEAVY RAIN AND/OR
SEVERE WEATHER THREATS EARLY NEXT WEEK AND WILL NEED TO BE
MONITORED.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR CONDITIONS ARE FORECAST THROUGH THE AFTERNOON AS HIGH
PRESSURE DEPARTS. A TIGHTENING PRESSURE GRADIENT AND STEEP LOW-
LEVEL LAPSE RATES WILL CONTINUE TO FOSTER FREQUENT WIND GUSTS OF
20 TO 25 KNOTS OUT OF THE SOUTHWEST. SCATTERED CUMULUS WILL
PERSIST THROUGH THE AFTERNOON, LATER JOINED BY THICKENING MID
AND UPPER CLOUDS.
A PASSING TROUGH AND ITS ASSOCIATED COLD FRONT WILL BEGIN TO
APPROACH FROM THE NW LATE TODAY, MAINLY AFTER 23Z. SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP SOUTH OF LAKE ERIE BETWEEN
22Z TO 00Z AND ADVANCE SOUTH INTO EARLY THURSDAY MORNING. HAVE
SLIGHTLY REFINED TEMPO TIMING TO 3 HOUR WINDOWS TO SHOW THE
CONSENSUS TIMING ACCORDING TO HI-RES GUIDANCE. HAVE MOST
CONFIDENCE IN POTENTIAL 35-45 KNOT GUSTS NEAR AND NORTH OF PIT
IN THE STRONGER STORMS, AND HAVE INCLUDED THIS IN THE TAFS.
BEHIND THE MAIN LINE, SHOWERS MAY LINGER, AND CEILINGS SHOULD
LOWER INTO THE MVFR/IFR RANGE OVERNIGHT GIVEN THE RAIN AND
ABUNDANT LOW-LEVEL MOISTURE. SLOW RECOVERY BACK TO MVFR IS
POSSIBLE BY LATER IN THE MORNING ON THURSDAY. A FEW SCATTERED
SHOWERS MAY CONTINUE, BUT COVERAGE NEAR/SOUTH OF PITTSBURGH IS
EXPECTED TO PICK UP MAINLY AFTER 18Z THURSDAY.
OUTLOOK...
RESTRICTIONS MAY CONTINUE INTO THURSDAY NIGHT IN SHOWERS/STORMS
UNTIL COLD FRONTAL PASSAGE. 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...CERMAK/HEFFERAN
AVIATION...CL
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