960
FXUS61 KCTP 310738
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
338 AM EDT SAT MAY 31 2025
SYNOPSIS
* SHOWERS AND THUNDERSTORMS ON SATURDAY AS A COLD FRONT MOVES
ACROSS THE REGION WITH SEVERE POTENTIAL ACROSS SOUTHEASTERN
PENNSYLVANIA.
* DRY CONDITIONS PREVAIL FOR THE FIRST HALF OF THE WEEK BEFORE
A RETURN TO SHOWERS AND THUNDERSTORMS MID-TO-LATE NEXT WEEK.
* TEMPERATURES WELL-BELOW AVERAGE TODAY TREND WARMER INTO NEXT
WEEK.
NEAR TERM /UNTIL 6 PM THIS EVENING/
CURRENT SURFACE ANALYSIS OUTLINES SURFACE LOW-PRESSURE ACROSS
THE LOWER SUSQUEHANNA VALLEY WITH A PERSISTENT AREA OF SHOWERS
ACROSS EAST-CENTRAL PA THAT HAS BROUGHT AROUND ONE INCH OF
RAINFALL OVER THE PAST 2-3 HOURS. MODEL TRENDS ARE IN FAIR
AGREEMENT THAT HEAVIER SHOWERS WILL GRADUALLY DIMINISH OVER THE
NEXT COUPLE HOUR HOURS WHILE GRADUALLY SHIFTING EASTWARD. AT
THIS TIME, NO LARGE-SCALE HYDROLOGY PROBLEMS ARE EXPECTED ACROSS
THE SOUTHERN TIER OF PENNSYLVANIA SO HAVE CANCELLED THE FLOOD
WATCH THIS FORECAST CYCLE. GIVEN THAT RAINFALL CONTINUES ACROSS
OUR EAST-CENTRAL COUNTIES (NORTH OF THE AFOREMENTIONED FLOOD
WATCH AREA) AND GIVEN CURRENT RADAR TRENDS, HAVE DECIDED TO PULL
THE TRIGGER ON AN AREAL FLOOD WARNING FOR THESE AREAS (SEE
FLWCTP) AS THERE HAVE BEEN NOTABLE STREAM INCREASES OVER THE
PAST COUPLE OF HOURS.
GRADIENT WINDS IN THE WAKE OF THE SURFACE LOW-PRESSURE WILL
ALLOW FOR A PERIOD OF GUSTY WINDS ACROSS THE LOWER SUSQUEHANNA
VALLEY OVERNIGHT. A SPECIAL WEATHER STATEMENT IS IN EFFECT FOR
THESE AREAS FOR SUB-WIND ADVISORY CRITERIA (40-45 MPH) WHICH, ON
TOP OF SATURATED SOILS WILL CONTINUE TO ALLOW FOR DOWNED
TREES/POWER LINES INTO EARLY SATURDAY MORNING. THE BULK OF MODEL
GUIDANCE IS IN DECENT AGREEMENT THAT THE BULK OF GUSTY WINDS
WILL EXIT EAST OF THE AREA AFTER 9Z/5AM EDT, THUS EXPECT A
GRADUALLY DECREASING TREND IN GUSTY WINDS INTO THE MID-MORNING
HOURS. BREEZY WINDS STILL REMAIN A GOOD BET THROUGHOUT THE DAY
ON SATURDAY AS LOW-PRESSURE PULLS NORTHEAST OF THE REGION WITH
WINDS GUSTING BETWEEN 20-30 MPH THROUGHOUT THE DAY.
SURFACE COLD FRONT BEGINS ENTERING W PA DURING THE EARLY MORNING
HOURS, ALLOWING FOR ANOTHER SHOWER-FILLED DAY ACROSS MUCH
CENTRAL PENNSYLVANIA. INSTABILITY EARLY ON IN THE DAY REMAINS
EXTREMELY LIMITED, WITH MINIMAL RECOVERY IN INSTABILITY. SOME
INITIAL CLEARING ACROSS SOUTH-CENTRAL/SOUTHEASTERN PENNSYLVANIA
WILL ALLOW FOR A BRIEF PERIOD OF DESTABILIZATION WITH RECENT
HREF GUIDANCE OUTLINING CAPE VALUES BETWEEN ~500-600 J/KG AND
AMPLE LIFT AND MARGINAL SHEAR. THE COMBINATION OF THESE FACTORS
LEADS TO A MARGINAL RISK FOR SEVERE THUNDERSTORMS MAINLY
SOUTHEAST OF THE I-81 CORRIDOR THIS EVENING.
SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/
DRIER AIR IN THE WAKE OF THE COLD FRONT WITH REINFORCING COLD
AIR UNDER NORTHWESTERLY FLOW WILL LEAD TO COOLER TEMPERATURES
SATURDAY NIGHT INTO SUNDAY MORNING, WITH TEMPERATURES WELL-BELOW
AVERAGE TO START OFF JUNE. COOLER TEMPERATURES ONCE AGAIN
PREVAIL SUNDAY NIGHT INTO MONDAY WITH A GRADUAL WARMING TREND
THROUGH TUESDAY, WITH TEMPERATURES REVERTING CLOSER TO
CLIMATOLOGICAL AVERAGES.
LINGERING SHOWERS AND THUNDERSTORMS IN THE BEGINNING PORTIONS OF
THE SHORT-TERM WILL GRADUALLY EXIT EAST OF THE AREA. DRY
CONDITIONS GRADUALLY PREVAIL BY MONDAY MORNING AND THROUGH THE
END OF THE SHORT-TERM WITH HIGH PRESSURE BUILDING INTO THE
REGION.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
DRY CONDITIONS ARE EXPECTED TO CONTINUE ON WEDNESDAY AS
GUIDANCE AGREES ON A BUBBLE OF HIGH PRESSURE FENDING OFF
MOISTURE. THE MAXES SHOULD GET INTO THE 80S FOR WEDNESDAY AND
THURSDAY. SOME URBAN LOCATIONS COULD TOUCH 90F WED AFTN. THE
NEXT COLD FRONT MAY BRING SOME SHOWERS AND PERHAPS A
THUNDERSTORM OR TWO TO THE AREA NEXT THURSDAY. THE UPPER FLOW
THEN STAYS OUT OF THE SW WITH A RIDGE OFF THE COAST. THAT WILL
ALLOW A MORE OR LESS CONTINUOUS FLOW OF MOISTURE INTO THE AREA
FOR THE WEEKEND. (READ: SHOWERS/TSTORMS)
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
LATE EVENING UPDATE.
SOME ADJUSTMENTS. EXTENDED THUNDER IN THE MDT AREA BY ANOTHER
HOUR. NE TO NW WINDS HAVE KICKED UP AS EXPECTED. MAIN AREA
OF MODERATE TO HEAVY SHOWERS TO OUR EAST. BAND OF DEFORMATION
SHOWERS FROM CLEARFIELD COUNTY, NORTHEAST TO NEAR MANSFIELD.
EARLIER DISCUSSION BELOW.
MAIN CHANGE TO THE 00Z TAF PACKAGE WAS TO BACK OFF ON THE LOWER
CONDITIONS SOME. SHOWERS HAVE BEEN FALLING APART, AS THEY MOVED
TOWARD THE AREA LATE THIS AFTERNOON. OTHER CHANGE WAS TO MAKE
WINDS MORE FROM THE NE EARLY ON, INSTEAD OF NW AND INCREASE THE
SPEED SOME.
CONCERN EARLIER FOR AREAS SOUTH OF JST FOR GUSTY WINDS DUE TO
CONVECTION AND POSSIBLE GRAVITY WAVES, BUT THINGS HAVE BEEN
WEAKENING.
THUS THE MAIN ISSUE OVERNIGHT WILL BE BANDS OF SHOWERS LIFTING
NORTHWARD FROM MD AND VA. I DID PUT THUNDER IN AT LNS AND MDT.
FOR SATURDAY, WINDS WILL SHIFT TO THE NORTHWEST AND INCREASE
IN SPEED. THE SHOWERS SHOULD END BY LATE MORNING OR EARLY
AFTERNOON, AND CONDITIONS TREND VFR BY LATER IN THE AFT.
MORE INFORMATION BELOW.
LIGHT RAIN HAS BEGUN ACROSS SOME OF THE WESTERN AIRFIELDS AS OF
19Z FRI, ALTHOUGH CIGS/VSBY REMAIN LARGELY VFR. JST WILL LIKELY
BE FIRST TO SEE MVFR CONDITIONS, PRIOR TO SUNSET.
DETERIORATING CONDITIONS WILL SPREAD EASTWARD THIS EVENING,
WITH SOME OF THE HEAVIEST RAINFALL AND CHANCE FOR THUNDERSTORMS
IMPACTING MDT AND LNS BETWEEN 23Z AND 05Z. SOME STORMS MAY BE
SEVERE. NW WINDS WILL PICK UP AS A SFC LOW INTENSIFIES, WITH
GUSTS 20-30 KTS, STRONGEST IN THE SOUTHEAST. THE NW UPSLOPE FLOW
WILL PUSH TYPICAL IFR STRATUS INTO BFD/JST AFTER 06Z AND
LASTING INTO AT LEAST LATE SAT MORNING. MOST OF THE HEAVY RAIN
WILL MOVES OUT OF THE AREA BY 06Z, BUT ANOTHER ROUND OF
SCATTERED SHRA/TSRA WILL DEVELOP BENEATH THE COLD UPPER LEVEL
LOW SAT AFTERNOON.
OUTLOOK...
SUNDAY...MAINLY VFR WITH GUSTY NORTHWEST WINDS.
MONDAY-WEDNESDAY...MAINLY VFR.
CLIMATE
MAY 2025 PRECIPITATION RANKINGS
SITE MAY 1-30, 2025 | WETTEST MAY ON RECORD
-----------------------------------------------------------
HARRISBURG 9.72" WETTEST | 9.71" IN 1989 (PREVIOUS)
WILLIAMSPORT 6.99" 5TH WETTEST | 9.91" IN 1919
ALTOONA 7.24" 3RD WETTEST | 7.31" IN 1960
STATE COLLEGE 6.47" 9TH WETTEST | 9.45" IN 1894 (~5/29)
RECORD PRECIPITATION WAS OBSERVED IN HARRISBURG ON MAY 30TH
WHEN 1.75 INCHES OF PRECIPITATION OCCURRED. THIS BROKE THE
PREVIOUS RECORD OF 1.39 INCHES SET BACK IN 1953. FOR REFERENCE,
A CONTINUOUS WEATHER RECORD HAS BEEN KEPT IN HARRISBURG SINCE
1888.
RECORD PRECIPITATION WAS ALSO OBSERVED AT JOHNSTOWN, WHERE 1.05
INCHES OF PRECIPITATION OCCURRED, BREAKING THE OLD RECORD OF
0.89 INCHES SET BACK IN 1975.
A SEASONABLY STRONG/DEEP AREA OF LOW PRESSURE (~990MB) IS
FORECAST TO MOVE ACROSS SOUTHEASTERN PENNSYLVANIA OVERNIGHT. THE
RECORD LOW PRESSURE FOR MAY AT HARRISBURG IS 983.4MB.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...NPB
NEAR TERM...NPB
SHORT TERM...NPB
LONG TERM...DANGELO/MARTIN
AVIATION...MARTIN/COLBERT
CLIMATE...STEINBUGL/NPB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page