410
FXUS61 KCTP 310811
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
411 AM EDT MON AUG 31 2026
WHAT HAS CHANGED
* ADJUSTED POP/WX TO BETTER ALIGN WITH DAY 2-4 SPC SLGT RISK
KEY MESSAGES
1) LATE SUMMER SURGE OF HEAT AND HUMIDITY BRINGS MULTIDAY SEVERE
THUNDERSTORM AND EXCESSIVE RAINFALL THREAT TO KICKOFF SEPTEMBER
DISCUSSION
KEY MESSAGE 1:
A SERIES OF MID LEVEL IMPULSES TRACKING EASTWARD ALONG THE
NORTHERN PERIPHERY OF AN EXPANSIVE 500MB RIDGE WILL INTERACT
WITH ANOMALOUS MOISTURE/INSTABILITY AND STRONG WNW FLOW ALOFT
TO PROMOTE A MULTIDAY SEVERE STORM AND EXCESSIVE RAIN RISK
ACROSS PORTIONS OF CPA TUESDAY-THURSDAY. A SURGE OF LATE SUMMER
HEAT (MAX TEMPS 80-90F RANGE) WITH DEWPOINTS IN UPPER 60S TO LOW
70S WILL RESULT IN A VERY MOIST BOUNDARY LAYER WITH IMPRESSIVE
MLCAPE VALUES IN THE NEIGHBORHOOD OF 2-3K J/KG GIVEN MID LEVEL
LAPSE RATES AROUND 7 C/KM. FORECAST SOUNDINGS ALSO SHOW ROBUST
DEEP LAYER/EFFECTIVE SHEAR VALUES AND APPRECIABLY CURVED,
SIZABLE LOW LEVEL HODOGRAPHS. AS SUCH, A COUPLE OF SUPERCELLS
WILL BE POSSIBLE. SEVERE WIND AND HAIL ARE THE MAIN THREATS,
THOUGH A TORNADO OR TWO MAY ALSO OCCUR. ON BALANCE, THE
ENVIRONMENTAL PARAMETERS ARE QUITE BULLISH FOR SEVERE STORM
POTENTIAL. HOWEVER, TIMING (TIME OF DAY), SPEED, AND LOCATION
OF EACH MID LEVEL IMPULSE WILL BE KEY FACTORS THAT COULD
MODULATE THE BULLISH SEVERE SETUP TO SOME EXTENT. INCREASING
MUCAPE VALUES LATE TONIGHT THROUGH TUESDAY MORNING SUGGEST
STORMS/SEVERE RISK LIKELY WON'T BE TIED TO THE TYPICAL DIURNAL
CYCLE. THE SEVERE RISK WILL SHIFT TO THE SOUTH OF CPA BY
FRIDAY, BUT AN UPPER TROUGH PASSAGE SUGGESTS SOME LINGERING
SHOWER ACTIVITY INTO THE WEEKEND.
THE LATE SUMMER HEAT IS FORECAST TO PEAK TUESDAY AND WEDNESDAY
WITH VERY WARM NIGHTS +10-20F ABOVE THE HISTORICAL AVERAGE AND
MAX HEAT INDICES APPROACHING ADVISORY LEVELS/CENTURY MARK
ACROSS PARTS OF SOUTH CENTRAL PA. THE UPPER RIDGE IS FORECAST TO
RETROGRADE BY THE END OF THE WEEK WHICH ALLOWS FOR INCREASED
TROUGHING AND A RETURN TO MORE SEASONAL TEMPERATURES FOR EARLY
SEPTEMBER.
AVIATION /07Z MONDAY THROUGH FRIDAY/
CEILINGS WILL GRADUALLY LOWER ACROSS NORTHERN PENNSYLVANIA
THROUGH THE EARLY MORNING HOURS AS AN AREA OF LIGHT TO MODERATE
RAIN SHOWERS OVER NW PA AT 06Z MOVES SE.
SOME PERIODS OF MVFR WILL OCCUR THROUGH THE MID MORNING HOURS
TODAY AS THIS AREA OF SHOWERS MOVES THROUGH, THEN WE'LL BE LEFT
WITH VARYING AMOUNTS AND BASE HEIGHTS OF MID LEVEL (ALTOCU)
CLOUDS (SOMEWHAT SIMILAR TO SUNDAY).
THE BULK OF THE LATE MORNING THROUGH THIS AFTERNOON AND EVENING
WILL BE DRY AS A RELATIVELY FLAT RIDGE OF HIGH PRESSURE ALOFT
AND THE THERMALLY INDIRECT, DESCENDING BRANCH ASSOCIATED WITH
THE RIGHT EXIT REGION OF A WEAK JETLET MOVES ESE ACROSS THE
REGION.
A FEW STRAY SHOWERS OR EVEN AN ISOLATED LOW-TOPPED TSRA OR TWO
WITH BRIEF MVFR CANT BE RULED OUT THIS AFTERNOON/EVENING AS A
RESULT OF BROAD DIFFLUENT FLOW ALOFT AHEAD OF THE
AFOREMENTIONED RIDGE AND POCKETS OF MU CAPE IN THE 1000-1500
J/KG RANGE.
FOR LATE TONIGHT/EARLY TUESDAY, A SOMEWHAT RARE INCREASE IN
LATE NIGHT CAPE WILL OCCUR ACROSS NW PA THAT COULD SUPPORT TSRA
APPROACHING KBFD AFTER THE END OF THIS 06Z TAF WINDOW. A TREND
TOWARD MVFR WILL LIKELY DEVELOP TONIGHT IN THE INCREASED
WESTERLY 925-850 MB FLOW.
WINDS WILL GENERALLY BE LESS THAN 5 KNOTS THROUGHOUT THIS TAF
CYCLE.
OUTLOOK...
TUE-FRI...SCATTERED SHRA/TSRA WITH BRIEF RESTRICTIONS POSSIBLE;
MORNING FOG POSSIBLE.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...STEINBUGL
KEY MESSAGES...STEINBUGL
DISCUSSION...STEINBUGL
AVIATION...LAMBERT/BAUCO
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