311
FXUS61 KCTP 040725
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
325 AM EDT THU SEP 4 2025
SYNOPSIS
* A SERIES OF COLD FRONTS WILL BRING A RISK FOR STRONG
THUNDERSTORMS THURSDAY AND AGAIN SATURDAY.
* TEMPERATURES TREND BELOW NORMAL AGAIN NEXT WEEK WITH HIGH
PRESSURE AND DRY WEATHER PREVAILING.
NEAR TERM /UNTIL 8 AM THIS MORNING/
LATEST OBSERVATIONS PLAY OUT THE EXPECTED SCENARIO OF WARMER ON
THE RIDGES WHERE THE WIND IS STILL GOING. EARLY MORNING RADAR
RETURNS OVER THE FAR NW ARE PROBABLY REACHING THE GROUND.
EXPECT THE NW TO CONTINUE TO HAVE CHC FOR SHRA/TSRA ALL NIGHT,
BUT IT SHOULD RAMP UP CLOSER TO SUNRISE. THE BETTER FORCING IS
OVER THE NW.
SOUTHERLY WINDS WILL BACK TO SOUTHEASTERLY OR EASTERLY
OVERNIGHT TO THE EAST OF THE SUSQUEHANNA RIVER. THIS FLOW AND
MOISTURE ASCENDING THE RIDGES WILL SUPPORT LOW CLOUDS AND/OR
FOG FORMING EAST OF THE RIVER, ESP IN SCHUYLKILL, LEBANON AND
LANCASTER COS. LOWS ON THURSDAY MORNING WILL BE MILD WITH MAINLY
M-U50S.
SHORT TERM /8 AM THIS MORNING THROUGH 6 PM FRIDAY/
UNDER A PREVAILING UPPER TROUGH, A MID-LEVEL VORTICITY MAXIMUM
WILL ROTATE THROUGH THE MID ATLANTIC ON THURSDAY ACCOMPANIED BY
A SURFACE COLD FRONT. CONVECTION ASSOCIATED WITH THE COLD FRONT
SHOULD BE FAIRLY WEAK BY DAYBREAK THURSDAY AS IT MOVES ACROSS
LAKE ERIE AND INTO NORTHWEST PA. AS THE FRONT MOVES EAST,
THESE SHOWERS AND STORM SHOULD RE-INTENSIFY AS THEY ENCOUNTER
SUFFICIENT MOISTURE WITH DEWPOINTS IN THE UPPER 50S TO LOW 60S,
MARGINAL INSTABILITY (UP TO 750 J/KG), AND AMPLE SHEAR (30 -
40KTS).
CONVECTION ALLOWING MODELS DEPICT POTENTIAL FOR TWO DISTINCT
ROUNDS OF SHOWERS/STORMS. THE FIRST WOULD BE ASSOCIATED WITH THE
AFOREMENTIONED LINE OF STORMS THAT WILL ADVANCE INTO SOUTHEAST
PA BY LATER AFTERNOON AND EVENING. THE SECOND WOULD BE ALONG
THE SURFACE COLD FRONT, WHICH LIKELY STRUGGLES TO GET PAST THE
I-99/I-80 CORRIDOR BY THURSDAY EVENING. THE SPC HAS ISSUED A
MARGINAL RISK FOR NEARLY ALL OF PENNSYLVANIA. THE BEST SHEAR
WILL BE ACROSS NORTHERN PA INTO NEW YORK, WHILE THE BEST
INSTABILITY WILL BE WELL SOUTH OF THE REGION (SOUTHERN
APPALACHIANS). PENNSYLVANIA WILL HAVE SUFFICIENT AMOUNTS OF
INSTABILITY AND SHEAR TO SUPPORT A MARGINAL THREAT OF DAMAGING
WINDS.
HIGHS ON THURSDAY WILL RANGE FROM THE MID 60S IN NORTHWEST PA
WHERE MORE CLOUDS/PRECIPITATION WILL KEEP TEMPERATURES AT BAY,
TO THE MID 80S IN SOUTHEAST PA WHERE MOST OF THE DAY SHOULD
REMAIN SUNNY OR AT LEAST PARTLY CLOUDY BEFORE CONVECTION
ARRIVES. ON THURSDAY NIGHT, LOWER DEWPOINTS WILL FILTER INTO
NORTHWEST PA BEHIND THE COLD FRONT ALLOWING TEMPERATURES TO DROP
INTO THE MID 40S. FARTHER SOUTHEAST, MORE CLOUDS/LINGERING
SHOWERS WILL KEEP TEMPERATURES MUCH MORE MILD IN THE UPPER 50S
TO LOWER 60S.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
FOR THE LONG TERM PERIOD, A PREVAILING UPPER TROUGH ACROSS THE
EASTERN US WILL REMAIN IN PLACE, PERHAPS LIFTING A BIT BY THE
MIDDLE OF NEXT WEEK. ON FRIDAY, HIGH PRESSURE WILL BRIEFLY
REGAIN CONTROL OF THE REGION GIVING WAY TO MOSTLY SUNNY SKIES,
DRY CONDITIONS, AND ANOTHER SEASONABLY MILD DAY. NOTING THAT
THURSDAY'S COLD FRONT WILL GET HUNG UP ACROSS THE CENTRAL
MOUNTAINS, IT WILL STILL BE RATHER HUMID ON FRIDAY AFTERNOON IN
SOUTHEAST PA.
BY SATURDAY, A STRONGER COLD FRONT (COMPARED TO THURSDAY) WILL
SWEEP THROUGH THE COMMONWEALTH AND BRING A RENEWED CHANCE FOR
SHOWERS AND THUNDERSTORMS. THERE REMAINS SOME UNCERTAINTY
REGARDING HOW MUCH INSTABILITY WILL BE IN PLACE AHEAD OF THE
FRONT, BUT SCATTERED STRONG TO SEVERE THUNDERSTORMS SEEM LIKE A
GOOD BET. AS IS TYPICAL WITH THESE SYSTEMS, THE BEST CHANCE FOR
SEVERE WILL LIKELY BE IN SOUTHEAST PA AND AN SPC MARGINAL RISK
IS PROBABLE FOR SATURDAY.
AFTER THE COLD FRONT SWEEPS THROUGH, ANOTHER FALL-LIKE PATTERN
WILL SETTLE IN FOR THE SECOND HALF OF THE WEEKEND AND INTO NEXT
WEEK. THE AIRMASS MOVING OVERHEAD WILL BE THE COOLEST OF THE
SEASON SO FAR. HIGHS IN THE 60S AND 70S WILL PAIR WITH LOWS IN
THE 30S TO 50S. FROST OR FREEZE CONDITIONS SEEM LIKE A GOOD BET
FOR THE TYPICAL COOL SPOTS IN NORTHWEST PA EARLY NEXT WEEK ALONG
WITH RIVER VALLEY FOG. ABUNDANT SUNSHINE AND DRY CONDITIONS ARE
FAVORED, WITH INCREASING MOISTURE AND CHANCES FOR RAIN TOWARD
THE MIDDLE TO END OF THE WEEK.
AVIATION /08Z THURSDAY THROUGH MONDAY/
HIGH CLOUDS WILL INCREASE THROUGH THE REST OF THE NIGHT AHEAD
OF AN APPROACHING COLD FRONT. FOG FORMATION APPEARS UNLIKELY
TONIGHT, AND ALL TAF SITES ARE EXPECTED TO REMAIN VFR INTO THE
MORNING. THE ONLY EXCEPTION MAY BE NEAR MDT AND LNS WHERE MODEL
SOUNDINGS SUGGEST THE POTENTIAL FOR SOME LOW CLOUDS TO DEVELOP
TOWARDS SUNRISE, BUT VFR CEILINGS STILL APPEAR TO BE THE MOST
LIKELY OUTCOME.
SCATTERED SHOWERS ACROSS NORTHWEST PA MAY IMPACT BFD (~20%
CHANCE) THROUGH THE REST OF THE NIGHT, BUT COVERAGE IS TOO LOW
TO MENTION ANY SHOWERS IN THE TAFS. SOME OF THESE SHOWERS HAVE
BRIEFLY GROWN TALL ENOUGH TO PRODUCE LIGHTNING. THE BETTER
CHANCE FOR RAIN WILL ARRIVE IN THE 13-14Z TIMEFRAME AS THE FIRST
ROUND OF SHOWERS AND STORMS ENTERS THE REGION FROM THE WEST.
THESE STORMS WILL BE ON A WEAKENING TREND AS THEY MOVE IN, BUT
REINTENSIFICATION IS EXPECTED DURING THE AFTERNOON.
PROB30S FOR THUNDER HAVE BEEN INCLUDED WITH THE 06Z TAF CYCLE TO
HIGHLIGHT THE MOST LIKELY PERIODS FOR THUNDERSTORMS. AT THIS
TIME, THE MOST LIKELY TIMING AT UNV REMAINS IN THE 18Z-21Z
TIMEFRAME, IPT IN THE 20-23Z TIMEFRAME, AND MDT/LNS GENERALLY
AFTER 22Z. ANY THUNDERSTORMS WILL BE CAPABLE OF PRODUCING WIND
STRONG WIND GUSTS IN EXCESS OF 25 TO 30 KNOTS AND VERY HEAVY
RAINFALL WHICH MAY BRIEFLY REDUCE VISIBILITY. STORMS WILL EXIT
TO THE EAST AFTER 02Z AND THERE IS A FAIRLY STRONG SIGNAL FOR
MVFR OR IFR CEILINGS ACROSS MUCH OF THE REGION. SOME FOG WILL BE
POSSIBLE AS WELL.
OUTLOOK...
FRI...SHOWERS LINGERING, MAINLY E PA.
SAT...CHANCE OF SHRA W/ TSRA POSSIBLE.
SUN-MON...CLEARING WITH VFR CONDITIONS. BREEZY ON SUNDAY.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BANGHOFF/GARTNER
NEAR TERM...DANGELO/GARTNER
SHORT TERM...BANGHOFF
LONG TERM...BANGHOFF
AVIATION...BAUCO/NPB
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