554
FXUS61 KCTP 031022
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
622 AM EDT SAT MAY 3 2025
SYNOPSIS
* SEVERAL ROUNDS OF SHOWERS AND SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS FOR TODAY WITH THE STRONGEST STORMS AND LIKELY
HEAVIEST RAINFALL OF LOCALLY OVER ONE INCH OCCURRING NEAR AND
TO THE SOUTH OF INTERSTATE 81.
* A FEW STORMS THIS AFTERNOON AND EVENING MAY PRODUCE DAMAGING
WIND GUSTS AND LARGE HAIL OVER THE LOWER SUSQUEHANNA VALLEY.
* LARGELY BENEFICIAL MULTI-DAY RAINFALL EVENT SHAPING UP FOR SUNDAY
THROUGH TUESDAY; SOME MINOR FLOODING WILL BE POSSIBLE WITH
ANY REPEATED ROUNDS OF HEAVY RAIN
NEAR TERM /UNTIL 6 PM THIS EVENING/
THE MOST CONTOURS ON THE LATEST SFC MAP INTERSECT OVER CENTRAL
PA AND THE SUSQUEHANNA VALLEY, AND THAT'S NOT A GOOD THING IF
YOU'RE NOT A FAN OF ACTIVE CONVECTIVE WEATHER AND/OR LOCALLY
HEAVY RAINFALL.
A QUASI-STNRY FRONTAL BOUNDARY EXTENDS FROM A WEAK SFC LOW
(1010 MB) NEAR KCAK EARLY THIS MONRING ESE ALONG THE I-80, AND
THEN ALONG THE LENGTH OF THE RT 322 CORRIDOR FROM KFIG TO KUNV
AND KMDT. A LEE TROUGH EXTENDS SOUTH FROM THIS BOUNDARY TO KMRB
AND NEAR THE I-81 CORRIDOR THROUGH VA.
SEVERAL KFT AGL (IN THE 925-850 MB LAYER), WE SEE TWO DISTINCT
FRONTAL BOUNDARIES - ONE CENTERED JUST NW OF THE I-81 CORRIDOR
AND THE SECOND FROM NW OHIO TO KIAG AND KBUF.
THE PRIMARY UPPER LEVEL JET AXIS EXTENDED FROM THE LOWER GLAKES
TO THE LOWER ST LAWRENCE VALLEY. COMBINING THE AFOREMENTIONED
FEATURES WE ARRIVE AT A BROAD AREA OF LIGHT TO MODERATE RAIN
OVER THE LAUREL HIGHLANDS AND NW MTNS, WHILE A FEW ADDITIONAL
SHOWERS WERE FORMING ALONG AND JUST NORTH OF THE SFC STATIONARY
FRONT ACROSS THE LOWER AND MID SUSQ VALLEY.
PLENTY OF CLOUD COVER IN MULTIPLE LAYERS WILL BE FOUND ACROSS
THE ENTIRE REGION TODAY, WHICH WILL PUT IN QUESTION THE
INSTABILITY INGREDIENT OF A GOOD CONVECTIVE RECIPE FOR TODAY.
LATEST HREF DOES CREATE POCKETS OF MU CAPE EXCEEDING 1000 J/KG
IN A MODERATELY SHEARED LOW-MID LEVEL ENVIRONMENT OVER THE LOWER
AND SUSQ VALLEY LATER THIS AFTERNOON INTO THIS EVENING, WITH
NUMEROUS CELLS DEVELOPING MAX 1 HOUR 2-5 KM HELICITY VALUES OVER
75 M2/S2 NEAR AND TO THE SE OF THE I-81 CORRIDOR. SPC HAS
ADDRESSED THESE ASPECTS OF TODAY'S CONVECTIVE EVENT WITH THE
SLGT FOR SVR TSRA ACROSS ROUGHLY THE SE THIRD OF THE CWA.
24 HOUR MAX 2-5 KM UPDRAFT HELICITY IS FORECAST TO BE CENTERED
OVER THE KMDT/KMUI AND KLNS AREA.
LCL HEIGHTS PER NBM GUIDANCE WILL RISE TO 3500-4000 FT AT THE
TIME OF PEAK HEATING TODAY, BUT WILL GRADUALLY LOWER TO
1500-2000 FT AFTER 22Z, WHICH WILL POSE THE BEST CHANCE FOR
SEEING AN ISOLATED WEAK TORNADO FROM ANY OF THE STRONGER TSRAS
, ESPECIALLY THOSE THAT DRIFT OVER THE QUASI-STNRY BOUNDARY
FORECAST TO LINGER NEAR THE I-81 CORRIDOR FROM THE GREATER
HARRISBURG AREA, NORTHEAST.
FOR THE REST OF THE FORECAST AREA, LOOK FOR SEVERAL ROUNDS OF
LIGHT TO MODERATE, BENEFICIAL RAIN SHOWERS TODAY, AND A FEW
BRIEF PERIODS OF HEAVY RAIN FROM EMBEDDED, FAIRLY LOW TOPPED
TSRA.
BASIN AVERAGE MEAN QPF TODAY WILL BE ON THE ORDER OF 0.5 TO 1.0
INCH, THOUGH ANY LOCATION RECEIVING 2-3 TSRA COULD EASILY SEE
UPWARDS OF AROUND 2 INCHES. WPC HAS ALL BUT THE NORTHERN TIER
COUNTIES IN THEIR MRGL RISK FOR EXCESSIVE RAIN TODAY AND
TONIGHT.
HIGHS TODAY WILL HIGHLIGHT THE QUASI STNRY BOUNDARY WITH
LOCATIONS ACROSS THE LOWER SUSQ VALLEY TOPPING OUT IN THE 80-83F
RANGE, WHILE THE NORTHERN TIER COUNTIES WILL STRUGGLE TO MAKE IT
ABOVE 60F.
SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/
BLOCKING PATTERN SETS UP OVER THE FCST AREA THROUGH THIS WEEKEND
WITH A DEEP/VERTICALLY STACKED LOW IN THE OH VALLEY.
THE UPPER LEVEL CLOSED LOW MEANDERS IN THE OHIO VALLEY INTO
EARLY NEXT WEEK. SOUTHERLY FLOW ON THE EAST SIDE OF THE LOW WILL
CHANNEL MOISTURE INTO THE AREA WITH PERIODS OF RAIN EXPECTED
SUNDAY AND MONDAY. WHILE RAINFALL WILL BE CERTAINLY BENEFICIAL
AND BRING SOME RELIEF TO DROUGHT CONDITIONS PARTICULARLY IN THE
SOUTHEAST PART OF THE FORECAST AREA, WE WILL NEED TO MONITOR
CONDITIONS FOR REPEATED ROUNDS OF HEAVY RAINFALL WHICH COULD
PRODUCE LOCALLY HEAVY TOTALS AND MAY RESULT IN LOCALIZED
FLOODING IN URBAN AND POOR DRAINAGE AREAS. WPC HAS MAINTAINED
MARGINAL EXCESSIVE RAIN RISKS FOR SATURDAY-MONDAY.
THIS PERIOD WILL REMAIN MILD RELATIVE VS. CLIMO WITH THE
LARGEST DEPARTURES FROM NORMAL IN THE OVERNIGHT MIN TEMPS
ON THE ORDER OF +10-20F ABOVE THE HISTORICAL AVERAGE.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
BLOCKY PATTERN WITH CLOSED LOW LIFTING VERY SLOWLY TO THE
NORTHEAST FROM THE OHIO VALLEY WILL MAINTAIN A STRONG WET
PATTERN SIGNAL OVER THE AREA THROUGH MIDWEEK. INITIALLY,
RAINFALL SHOULD BE BENEFICIAL PARTICULARLY OVER THE SOUTHEAST
ZONES/LOWER SUSQ WHERE D1/D2 DROUGHT CONDITIONS HAVE PERSISTED
FOR SOME TIME. WPC HAS INDICATED A MARGINAL RISK OF EXCESSIVE
RAIN WITH SOME POTENTIAL FOR REPEATED ROUNDS OF RAIN CAPABLE OF
PRODUCING LOCALIZED FLOODING RISK IN URBAN AND POOR DRAINAGE
AREAS. THE MAIN UNCERTAINTY IN THE FORECAST PERIOD IS IN REGARD
TO HOW QUICKLY THE UPPER LOW BEGINS TO MOVE OFF TO THE EAST.
SOME GUIDANCE SUGGESTS A MAINLY DRY SECOND HALF OF THE WEEK AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING UPPER LOW, WHILE
SOME MODELS KEEP THE LOW AROUND A LITTLE LONGER. BECAUSE OF
THIS UNCERTAINTY, WE HAVE NOT DEVIATED FROM THE NBM THROUGH THE
END OF THE EXTENDED PERIOD.
AVIATION /10Z SATURDAY THROUGH WEDNESDAY/
AS OF 615 AM SKIES MAINLY CLEAR TO THE SOUTHEAST OF THE OFFICE
HERE, WITH SOME SHOWERS TO THE WEST. ADJUSTED TAFS FOR THIS
TREND, TAFS WILL BE SENT BY 730 AM.
PATCHY FOG DID FORM EARLIER, BUT IS MAINLY GONE AS OF SUNRISE.
OTHERWISE NOT A LOT DHANGE FOR THE 12Z TAFS.
EARLIER DISCUSSION BELOW.
LOOKING AT CLEAR SKIES WITH SOME FOG ACROSS THE REGION EARLY
ON, THEN THE REMAINS OF SHOWERS AND STORMS TO THE WEST WILL
TAPER THE FOG AT SITES LIKE UNV AND AOO, AS THERE WILL BE MORE
CLOUDS IN A FEW HOURS.
FOR MOST OF THE DAY, EXPECT SOME SHOWERS AND STORMS TO FORM
AGAIN, WITH A WIDE RANGE OF CONDITIONS.
NO REAL CHANGE TO THE PATTERN BEFORE THE MIDDLE OF NEXT WEEK.
THERE WILL BE A DAILY CHANCE OF SHOWERS AND STORMS OVER THE
NEXT FEW DAYS.
OUTLOOK...
SUN-TUE...FREQUENT RAIN SHOWERS; SOME LOCALLY HEAVY WITH
PROLONGED SUB-VFR CONDITIONS.
WED...SOME IMPROVEMENT EXPECTED WITH A DECREASING CHANCE OF
SHOWERS.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...LAMBERT/STEINBUGL/BAUCO
NEAR TERM...LAMBERT/BAUCO
SHORT TERM...LAMBERT/STEINBUGL/BAUCO
LONG TERM...STEINBUGL/BAUCO
AVIATION...MARTIN
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