330
FXUS61 KCTP 040235
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1035 PM EDT SAT MAY 3 2025
SYNOPSIS
* RAIN CONTINUES TONIGHT WITH PATCHY FOG POSSIBLE ON THE
RIDGETOPS.
* LARGELY BENEFICIAL MULTI-DAY RAINFALL EVENT SHAPING UP FOR
SUNDAY THROUGH TUESDAY AS AN UPPER LOW SWIRLS NEARBY; SOME
MINOR FLOODING WILL BE POSSIBLE WITH ANY REPEATED ROUNDS OF
HEAVY RAIN.
* TRENDING DRIER LATE WEEK WITH A TREND TOWARD BELOW NORMAL
TEMPERATURES.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
THE QUASI-STATIONARY OR PERHAPS VERY SLOW MOVING COLD FRONT IS
DRAPED ACROSS CENTRAL PA THIS EVENING WITH AN APPROACHING UPPER
TROUGH/CLOSED LOW. STORMS NEVER QUITE GOT GOING TONIGHT IN SOUTH
CENTRAL PA WITH MEAGER INSTABILITY IN PLACE, THOUGH A COUPLE
DISCRETE SUPERCELLS DROPPED A SWATH OF WIND DAMAGE AND LARGE
HAIL ACROSS NORTHERN VA AND MD THIS EVENING. THE THREAT FOR
SEVERE WEATHER IS NOW OVER, THOUGH A FEW THUNDERSTORMS REMAIN
POSSIBLE (IF NOT LIKELY) OVERNIGHT ACROSS SOUTHEAST PA AS
CONVECTION CONTINUES TO DRIFT NORTH AHEAD OF AN APPROACHING
WRAPPED UP SURFACE LOW.
OVERNIGHT, MULTIPLE ROUNDS OF SHOWERS AND A FEW STORMS WILL
CONTINUE ACROSS THE REGION, WITH ANOTHER QUARTER TO THREE
QUARTERS OF AN INCH OF RAIN EXPECTED BY MORNING. ANTECEDENT
PRECIPITATION DEFICITS PRECLUDE ANY MAJOR FLOODING CONCERNS, BUT
LOCATIONS THAT RECEIVE SIGNIFICANT RAINFALL TONIGHT COULD BE
PRIMED FOR AN ELEVATED FLOOD RISK OVER THE NEXT FEW DAYS AS RAIN
CONTINUES.
AMPLE CLOUD COVER AND RAINFALL WILL KEEP TEMPERATURES QUITE MILD
TONIGHT. LOWS BY DAYBREAK SUNDAY WILL RANGE FROM THE UPPER 40S NORTH
OF US-6 TO THE LOWER 60S IN SOUTHEAST PA. LOW CLOUDS WILL SHROUD
RIDGES ACROSS WESTERN AND NORTHERN PA AND PATCHY FOG IS POSSIBLE
THROUGHOUT THE COMMONWEALTH.
SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
A BLOCKING PATTERN WILL REMAIN OVER THE FCST AREA SUNDAY INTO
NEXT WEEK WITH A DEEP/VERTICALLY STACKED LOW IN THE OH VALLEY.
SOUTHERLY FLOW ON THE EAST SIDE OF THE LOW WILL CHANNEL MOISTURE
INTO THE AREA WITH PERIODS OF RAIN AND AFTERNOON STORMS EXPECTED
SUNDAY THROUGH TUESDAY. A FEW STRONGER STORMS ARE POSSIBLE IN
SOUTHWEST PA SUNDAY AFTERNOON THANKS TO THE COMBINATION OF
MARGINAL INSTABILITY, SUFFICIENT SHEAR, AND STEEP MID-LEVEL
LAPSE RATES. THE THREAT FOR SEVERE WEATHER APPEARS TO DECREASE
INTO NEXT WEEK.
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-TUESDAY WITH A GRADUAL
EASTWARD SHIFT OF THOSE AREAS COINCIDENT WITH A SLOWLY ADVANCING
UPPER LOW. SHOWER ACTIVITY SHOULD TREND MORE STRATIFORM IN
NATURE (AS OPPOSED TO CONVECTIVE) AS WE GET INTO NEXT WEEK,
WHICH WILL LIMIT THE RISK OF HEAVY RAINFALL SOMEWHAT, BUT A
SLIGHT RISK UPGRADE AT SOME POINT WOULD NOT BE TOO SURPRISING.
ENSEMBLE MEANS PAINT A WIDESPREAD 2-3" ACROSS THE REGION THROUGH
TUESDAY, WITH LOCALLY HIGHER AMOUNTS IN THUNDERSTORMS.
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. NOT MUCH
IN THE WAY OF SUNSHINE.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
THE UNSETTLED PATTERN CONTINUES INTO THE LONG-TERM THROUGHOUT
THE MIDDLE OF WEEK AS A CLOSED LOW MOVES NORTHEAST OF THE AREA.
THE BULK OF HEAVIEST RAINFALL WILL GRADUALLY BEGIN LIFTING
NORTHEAST OF THE AREA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT;
HOWEVER, LOCALIZED MAXIMA ACROSS PORTIONS OF THE ENDLESS
MOUNTAINS WILL RETAIN SOME THREAT FOR URBAN AND POOR DRAINAGE
FLOODING ACROSS THE NORTHEASTERN SECTOR OF THE CWA. HIGHER
CONFIDENCE REMAINS IN THIS SOLUTION WITH MODEL DETERMINISTIC
GUIDANCE OUTLINING FAVORABLE AGREEMENT.
PROGRESSING INTO THE END OF THE WEEK, MODEL GUIDANCE HAS
STARTED TO HONE IN ON DRIER CONDITIONS PREVAILING BY LATE
THURSDAY AND INTO FRIDAY; HOWEVER, WOULD REALISTICALLY LIKE TO
SEE ANOTHER CYCLE OF DRY CONDITIONS PREVAILING ACROSS THE CWA
BEFORE NIXING MENTIONS AT THIS TIME. GIVEN THERE IS SOME (ALBEIT
SHRINKING) UNCERTAINTY, HAVE DECIDED TO ROLL WITH NBM
THROUGHOUT MUCH OF THE LATE WEEK PERIOD. LONG RANGE ENSEMBLES
PROG HIGH PRESSURE BUILDING IN BY EARLY FRIDAY MORNING, LEADING
THE SIGNAL FOR DRYER CONDITIONS LEADING INTO NEXT WEEKEND.
AVIATION /03Z SUNDAY THROUGH THURSDAY/
SCATTERED SHRA ACROSS WESTERN PENNSYLVANIA WILL GRADUALLY
OVERSPREAD THE AREA; HOWEVER, GENERALLY VFR CONDITIONS ARE
EXPECTED TO PREVAIL. TEMPORARY MVFR CEILINGS WILL REMAIN
POSSIBLE (< 30%) AT BFD/JST IN HEAVIER SHOWERS IN THE NEAR-TERM
BEFORE MORE WIDESPREAD SUB-VFR CONDITIONS OCCUR AFTER 00Z. THE
BIGGEST CHANGE IN THE 18Z TAF PACKAGE COMES WITH THUNDERSTORMS
BETWEEN 20Z SAT THROUGH 03Z SUN ACROSS THE EASTERN AIRSPACE
(MDT/LNS/IPT). HIGHEST CONFIDENCE IN THUNDERSTORMS AT MDT/LNS IN
THE 22Z SAT TO 02Z SUN TIMEFRAME, WITH HREF PROBS LIGHTING UP
BETWEEN 30-40%; HOWEVER, THE SCATTERED NATURE OF CONVECTION IS
GOING TO BE THE TRICKIEST PART OF THE FORECAST. RECENT
OBSERVATIONS OUTLINE LNS APPROACHING 60F DEW POINTS RELATIVELY
HIGHER CONFIDENCE IN THUNDERSTORM POTENTIAL COMPARED TO MDT AND
HAVE OUTLINED THIS IN THE NEWEST FORECAST PACKAGE. FURTHER
NORTH, TABLE AIR AND CLOUD COVER IS EXPECTED TO LIMIT POTENTIAL
AT IPT; HOWEVER, CANNOT RULE OUT A ROUGE THUNDERSTORM BETWEEN
00-03Z SUN WITH LIMITED CHANCES FURTHER WEST. THUNDERSTORMS
IMPACTING THE EASTERN AIRFIELDS HAVE THE POTENTIAL TO CAUSE
GUSTY-TO-DAMAGING WINDS, SO MESOSCALE TRENDS WILL NEED TO BE
OBSERVED CLOSELY BETWEEN 18Z SAT THROUGH 03Z SUN FOR
THUNDERSTORM DEVELOPMENT AT THE AIRFIELDS.
AFTER 03Z SUN, THUNDERSTORM CHANCES DECREASE DRAMATICALLY WITH
LESS INSTABILITY PRESENT ACROSS THE AREA. INCREASED LOW-LEVEL
MOISTURE IN THE LOWER LEVELS DO WARRANT WIDESPREAD MVFR-TO-IFR
CONDITIONS AS MOISTURE INCREASES ACROSS EASTERN PENNSYLVANIA
UNDER SOUTHEASTERLY FLOW. HREF MODEL GUIDANCE IS HESITANT TO
INTRODUCE IFR CONDITIONS AT MDT/LNS UNTIL AFTER 06Z; HOWEVER,
GIVEN THE AFOREMENTIONED SE'LY FLOW HAVE BROUGHT CEILINGS DOWN
OVERNIGHT WITH MODERATE (~50%) CONFIDENCE. LINGERING SHOWERS MAY
DO WELL TO QUELL THE LOWER CEILINGS; HOWEVER, AND CANNOT RULE
OUT LOW-END MVFR AT MDT/LNS/IPT OVERNIGHT BEFORE FLOW TURNS MORE
SOUTHERLY. FURTHER WEST, HIGH CONFIDENCE IN BFD/JST PREVAILING
IFR AFTER 02Z SUN WITH MODEL GUIDANCE ALL POINTING TOWARDS AN
EXTENDED PERIOD OF LIFR OVERNIGHT INTO EARLY SUNDAY MORNING. AT
AOO/UNV/IPT, MODEL GUIDANCE FAIRLY WELL-RESOLVED WITH IFR
CEILINGS AND THESE SEEM PLAUSIBLE BASED ON RECENT RAP MODEL
SOUNDINGS, THUS HAVE TRENDED CLOSE TO A COMBINATION OF
HREF/GLAMP GUIDANCE.
OUTLOOK...
MON-TUE...FREQUENT RAIN SHOWERS; SOME LOCALLY HEAVY WITH
PROLONGED SUB-VFR CONDITIONS.
WED-THU...SHOWERS BECOME MORE SCATTERED WITH HIGHER CHANCES IN
THE AFTERNOON/EVENING HOURS. RESTRICTIONS POSSIBLE.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BANGHOFF
NEAR TERM...BANGHOFF
SHORT TERM...LAMBERT/BANGHOFF
LONG TERM...NPB/BOWEN
AVIATION...NPB
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