929
FXUS61 KCTP 310641
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
241 AM EDT MON AUG 31 2026
WHAT HAS CHANGED
* INCREASED RAIN CHANCES ACROSS THE NORTHERN TIER THIS
AFTERNOON.
* LEVEL 2/SLIGHT SEVERE THUNDERSTORM RISK INTRODUCED FOR
TUESDAY (9/1)
KEY MESSAGES
1) LIGHT RAIN NORTH, SCATTERED THUNDERSTORMS SOUTHEAST TODAY
2) LATE SUMMER HEAT+HUMIDITY TO CLOSE AUGUST AND OPEN SEPTEMBER
3) BOUTS OF HEAVY RAIN & SEVERE STORMS POSSIBLE TUESDAY-
THURSDAY
DISCUSSION
KEY MESSAGE 1: LIGHT RAIN NORTH, SCATTERED THUNDERSTORMS
SOUTHEAST TODAY
AN ILL-DEFINED FRONT WILL CONTINUE TO DRIFT INTO CENTRAL PA THIS
AFTERNOON, BRINGING SOME WARM ADVECTION SHOWERS ACROSS THE
NORTHERN TIER. ALTHOUGH SHOWERS ARE EXPECTED TO WEAKEN WITH
EASTWARD EXTENT AS THEY ENCOUNTER SOME DRIER AIR, THE RADAR
PRESENTATION IS SHOWING NO SIGNS OF WEAKENING AND LIGHT RAIN IS
BECOMING INCREASINGLY LIKE ALONG AND NORTH OF I-80 THROUGH THE
AFTERNOON.
MEANWHILE, WE ARE STARTING TO SEE SOME CONVECTION INITIATION IN
THE LOWER SUSQUEHANNA VALLEY. 500 TO 750 J/KG OF MLCAPE WILL
PROVIDE SUFFICIENT FUEL FOR A FEW TALLER SHOWERS TO DEVELOP AND
PERHAPS SOME LIGHTNING. AS WE HEAD INTO THE OVERNIGHT HOURS, A
WAVE OF ENERGY DRIFTING ACROSS THE GREAT LAKES WILL BRING
MORE WIDESPREAD RAIN CHANCES INTO THE OVERNIGHT HOURS. ALL IN
ALL, RAINFALL TOTALS NORTH OF I-80 WILL BE BETWEEN A QUARTER AND
HALF INCH, WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. FARTHER
SOUTH, UP TO A QUARTER INCH IS POSSIBLE BUT LESS THAN A TENTH OF
AN INCH IS MOST LIKELY.
KEY MESSAGE 2: LATE SUMMER HEAT+HUMIDITY TO CLOSE AUGUST AND
OPEN SEPTEMBER
STRONG UPPER RIDGE EXPANDING EAST-NORTHEASTWARD FROM THE
SOUTH CENTRAL PLAINS THROUGH THE TN VALLEY INTO THE SOUTHERN
MID ATLANTIC AND SOUTHEAST STATES WILL DELIVER A STRETCH OF
ABOVE NORMAL LATE SUMMER WARMTH AND VERY HUMID CONDITIONS TO
CLOSE OUT AUGUST AND KICKOFF SEPTEMBER. FORECAST MAX/MIN
TEMPERATURES ARE PROJECTED TO RISE SEVERAL DEGREES ABOVE THE
HISTORICAL AVERAGE SUNDAY-THURSDAY WITH THE LARGEST DEPARTURE
FROM NORMAL (+10-20F) FOUND IN MIDWEEK OVERNIGHT LOWS. THE LATE
SUMMER HEAT IS FORECAST TO PEAK TUESDAY AND WEDNESDAY WITH MAX
HEAT INDICES APPROACHING ADVISORY LEVELS IN THE MID TO UPPER 90S
ACROSS PARTS OF SOUTH CENTRAL PA. THE WELL ABOVE NORMAL
TEMPERATURES COMBINED WITH HIGH HUMIDITY AND VERY WARM OVERNIGHT
LOWS WILL RESULT IN LEVEL 2 (MODERATE) TO LEVEL 3 (MAJOR)
HEATRISK VALUES TUESDAY AND WEDNESDAY. INCREASING TROUGHING
ACROSS THE NORTHEAST U.S. SHOULD DROP TEMPERATURES BACK TOWARD
SEASONAL CLIMO BY FRIDAY/SATURDAY.
KEY MESSAGE 3: BOUTS OF HEAVY RAIN AND SEVERE STORMS POSSIBLE
TUESDAY-THURSDAY
A SERIES OF MID LEVEL IMPULSES TRACKING EASTWARD ALONG THE
NORTHERN PERIPHERY OF THE ELONGATED 500MB RIDGE WILL INTERACT
WITH ANOMALOUS MOISTURE/INSTABILITY AND STRONG FLOW ALOFT TO
PRODUCE A FEW EPISODES OF HEAVY RAINFALL AND POSSIBLE SEVERE
WEATHER THROUGH LATE WEEK. THERE ARE TYPICAL TIMING AND
AMPLITUDE DIFFERENCES OF THE SMALLER SCALE DISTURBANCES THAT
WILL NEED TO BE RESOLVED, BUT THE OVERALL CONVECTIVE SIGNAL FROM
OPERATIONAL/ENSEMBLE/ML/AI GUIDANCE IS SUPPORTIVELY BULLISH.
THERE IS A GROWING SIGNAL FOR SEVERE STORMS AND HEAVY RAIN ON
TUESDAY THROUGH THURSDAY.
SPC INTRODUCED A LEVEL 2 SEVERE T-STORM RISK FOR D3/TUESDAY AND
D5/THURSDAY AND MAINTAINED THE 15% OR LEVEL 2 EQUIVALENT RISK
FOR D4/WEDNESDAY. WPC CONTINUES TO COVER PARTS OF CPA WITH LEVEL
1 EXCESSIVE RAINFALL OUTLOOKS WHICH MAY BE REFINED/UPGRADED AS
THE CONVECTIVE DETAILS BECOME MORE CLEAR AND CONFIDENCE IN
TIMING AND LOCATION INCREASES. THE ENVIRONMENT WILL BE
CHARACTERIZED BY IMPRESSIVE CAPE (ON THE ORDER OF 2-3K J/KG) AND
SUFFICIENT SHEAR. A CORRIDOR OF STRONG STORMS IS LIKELY
SOMEWHERE ACROSS UPSTATE NY INTO PA EACH DAY THROUGH THE WEEK,
WITH THE INITIATING BOUNDARY EACH DAY BEING HIGHLY DEPENDENT ON
THE EXTENT/INTENSITY OF STORMS THE DAY BEFORE. THE BATTLEGROUND BETWEEN
A HOT/HUMID/DRY DAY AND PERHAPS MULTIPLE ROUNDS OF STRONG
THUNDERSTORMS WILL LIKELY BE DRAPED SOMEWHERE ACROSS CENTRAL PA
THIS WEEK, SO THOSE WITH OUTDOOR PLANS SHOULD CONTINUE TO
MONITOR THE FORECAST CLOSELY.
AVIATION /06Z 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/BANGHOFF
KEY MESSAGES...STEINBUGL/BANGHOFF
DISCUSSION...STEINBUGL/BANGHOFF
AVIATION...LAMBERT/BAUCO
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