377
FXUS61 KPBZ 262319
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
719 PM EDT WED AUG 26 2026
WHAT HAS CHANGED
UPDATE TO THE TIMING OF CONVECTION ON THURSDAY.
KEY MESSAGES
1) DRY TODAY, WITH SHOWER AND THUNDERSTORM CHANCES RETURNING
TONIGHT AND THURSDAY. MARGINAL POTENTIAL FOR SEVERE STORMS
THURSDAY AFTERNOON AND EVENING.
2) DRY WEATHER RETURNS BY THE WEEKEND, BEFORE ADDITIONAL SHOWER
AND THUNDERSTORM CHANCES EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...
THE CENTER OF SURFACE HIGH PRESSURE IS EXPECTED TO SHIFT EAST
TODAY, ALLOWING THE IMPACT OF ANOTHER DISTURBANCE LATE TONIGHT
AND INTO THE DAY ON THURSDAY. A STRONG SHORTWAVE TROUGH WILL
PASS THROUGH THE REGION AS A SURFACE COLD FRONT PUSHES ACROSS
THE AREA ON THURSDAY.
GETTING INTO THE DETAILS AND PARAMETERS, THE TIMING AND HI-RES
CAMS SEEMS TO SUGGEST A BROKEN LINE WEAKENING AND DISSIPATING IN
CENTRAL OH OVERNIGHT. THE FRONT APPROACHES DURING THE DAY ON
THURSDAY AND THE BROKEN LINE OF SHOWERS AND THUNDERSTORMS
DEVELOPS AGAIN AROUND ALLEGHENY COUNTY AND EAST. THIS AREA
DEVELOPS WITH THE FRONTAL FORCING AND HEATING OF THE DAY. THE
AMOUNT OF DRY AIR IN PLACE WILL MAKE THIS AN ENVIRONMENT WHERE
DAMAGING WIND WOULD BE THE MAIN THREAT BUT A FEW INSTANCES OF
HAIL IS POSSIBLE FOR THURSDAY AFTERNOON AND EVENING. THE
ENSEMBLES HAVE BEEN PRETTY CONSISTENT OF 1500 - 2000 J/KG OF SB
CAPE AHEAD OF THE FRONT. THE SUGGESTION OF EVEN THE 75TH
PERCENTILE, ALTHOUGH UNLIKELY, STILL ONLY BUMPS UP THE
INSTABILITY TO AROUND 1750 - 2250 J/KG, SO A REASONABLE THREAT
THAT WILL BE WIDELY SCATTERED. TIMING AND THE LOSS OF HEATING
GIVES THE CONVECTION A PUMPKIN TIME OF AROUND 01Z TO 02Z.
KEY MESSAGE 2...
THE COLD FRONT IS EXPECTED TO EXIT THE REGION THURSDAY
EVENING/NIGHT, WITH SHOWERS AND THUNDERSTORMS ENDING. DRY
WEATHER SHOULD THEN RETURN FRIDAY THROUGH THE WEEKEND AS SURFACE
HIGH PRESSURE BUILDS UNDER BROAD UPPER TROUGHING ALOFT. THE
NEXT UPPER TROUGH IS PROGGED TO APPROACH THE REGION TUESDAY,
THOUGH ENSEMBLES DIFFER ON THE STRENGTH OF THE TROUGH. SHOWER
AND THUNDERSTORM CHANCES SHOULD INCREASE WITH THE APPROACHING
TROUGH.
AVIATION /00Z THURSDAY THROUGH MONDAY/
PREDOMINANTLY VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING.
DIURNAL CUMULUS WILL COLLAPSE WITH LOSS OF DAYTIME HEATING
GIVING WAY TO SCT CIRRUS COVERAGE, AND LIGHT SOUTH WIND 5 KNOTS
OR LESS OVERNIGHT. THE ONE EXCEPTION COULD BE ZZV WITH DECAYING
CONVECTION APPROACHING FROM THE WEST. LATEST RUNS OF HRRR AND
RAP GUIDANCE CONTINUE WEAKENING IT AND BRINGING NO IMPACT TO
EASTERN OH, BUT GIVEN THE MODELED THERMODYNAMIC PROFILES AND
FUMES OF NARROW ELEVATED INSTABILITY, THINK THAT THERE'S ENOUGH
OF A CHANCE TO WARRANT A PROB30 MENTION OF BRIEF MVFR CONDITIONS
AT ZZV AROUND 04Z-05Z.
SPOTTY SHOWERS ARE THEN POSSIBLE IN STRENGTHENING LOW-LEVEL
WARM ADVECTION BEGINNING IN THE PRE-DAWN HOURS THURSDAY MORNING.
HREF AND REFS PROBABILITY FOR MEASURABLE PRECIP CONTINUES
HONING IN ON NORTHWEST PA AT AROUND 30-35%, SO HAVE INCLUDED A
PROB30 MENTION AT FKL AND DUJ FOR HIGH-END MVFR CONDITIONS IN A
PASSING SHOWER AROUND AND A BIT AFTER DAWN.
ANOTHER DECK OF DIURNALLY DRIVEN CU IS LIKELY TOMORROW AS
SOUTHWESTERLY WIND PICKS UP TO 5-10 KNOTS AHEAD OF AN
APPROACHING COLD FRONT. SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP ALONG AND AHEAD OF IT WITH MOST LIKELY
TIMING BETWEEN 18Z-00Z PROGRESSING NORTHWEST TO SOUTHEAST.
NOT CONFIDENCE IN IMPACTS TO ANY TERMINAL, THOUGH THE CHANCE
WILL BE HIGHEST IN WESTERN PA AND NORTHERN WV, SO HAVE INCLUDED
PROB30 -TSRA MENTION FOR ALL BUT ZZV UNTIL CONFIDENCE BECOMES
HIGHER IN IMPACTS TO ANY TERMINAL.
THE COLD FRONT WILL SAG THROUGH IN THE EVENING HOURS RESULTING
IN A WIND SHIFT TO THE NORTHWEST THURSDAY NIGHT.
OUTLOOK...
PREVAILING VFR IS EXPECTED. SOME SCATTERED SHOWERS ARE AGAIN
POSSIBLE ON FRIDAY WITH WEAK SHORTWAVE PASSAGE, LAKE-
ENHANCEMENT, AND STEEPENED LOW-LEVEL LAPSE RATES IN A POST-
FRONTAL REGIME. HIGH PRESSURE SETTLES IN FOR THE WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...SHALLENBERGER
AVIATION...CRAVEN/MLB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page