291
FXUS61 KCTP 151900
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
300 PM EDT MON SEP 15 2025
SYNOPSIS
* CLOUD COVERAGE GRADUALLY DECREASES OVERNIGHT WITH VALLEY FOG
POTENTIAL ACROSS THE NORTHERN TIER TONIGHT.
* LIGHT RAIN POSSIBLE ACROSS SOUTHEASTERN PENNSYLVANIA TUESDAY
THROUGH WEDNESDAY.
* DRY CONDITIONS PREVAIL ON THURSDAY AND THROUGH THE FIRST HALF
OF THE WEEKEND.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
CURRENT SATELLITE OUTLINES CUMULUS DEVELOPMENT, WITH THE MOST
EXPANSIVE BATCH ACROSS SOUTH-CENTRAL PENNSYLVANIA AND MORE
EXPANSIVE HIGH CLOUDS ACROSS THE SOUTHERN HALF OF PENNSYLVANIA
AS OF 19Z/3PM EDT. THE CUMULUS FIELD WILL CONTINUE OVER THE NEXT
COUPLE OF HOURS BEFORE DECREASING NEAR/AFTER SUNSET THIS
EVENING, VERY SIMILAR TO THE PREVIOUS EVENINGS. DIFFERING FROM
PREVIOUS EVENINGS, RECENT HREF/RAP MODEL GUIDANCE DOES INDICATE
HIGH-LEVEL CLOUDS HANGING ON OVERNIGHT. VALLEY FOG POTENTIAL
ACROSS THE NORTHERN TIER REMAINS RELATIVELY HIGH DESPITE THE
PRESENCE OF THESE HIGH CLOUDS. LOW TEMPERATURES OVERNIGHT INTO
TUESDAY MORNING ARE EXPECTED TO BE ABOVE CLIMATOLOGICAL
AVERAGES, RANGING FROM THE UPPER 40S ACROSS NW PA TO THE UPPER
50S ACROSS SE PA.
SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/
LOW PRESSURE WILL LIFT SLOWLY NORTHWARD FROM THE OUTER BANKS
AND VA TIDEWATER OFF THE MID-ATLANTIC COAST THROUGH THE MIDDLE
OF THE WEEK. LATEST MODEL GUIDANCE CONTINUES TO INDICATE THE
BEST CHANCE FOR RAIN OVER THE SOUTHEAST ZONES (SOUTHEAST OF
I-81/78) WHERE A MOIST/UPSLOPE EASTERLY LOW-LEVEL FLOW WILL
BRING BETTER MOISTURE RETURNS. FURTHER NORTH/WEST, PRECIPITATION
IS LESS LIKELY; HOWEVER, AFOREMENTIONED EASTERLY FLOW WILL
ALLOW FOR MORE EXPANSIVE CLOUD COVERAGE AND COOLER TEMPERATURES
FOR MUCH OF THE FORECAST AREA. MOST RECENT QPF HAS TAPERED BACK
EVER SO SLIGHTLY, KEEPING THE SOUTHERN REACHES OF ADAMS/YORK AND
MUCH OF LANCASTER COUNTY ABOVE 0.10" RAINFALL OVER A FAIRLY
TIGHT GRADIENT. PRECIPITATION WEDNESDAY NIGHT IS EXPECTED TO
GRADUALLY MOVE EASTWARD OF THE AREA AS THE COASTAL LOW BEGINS TO
PUSH FURTHER OFFSHORE.
LONG TERM /THURSDAY THROUGH MONDAY/
A BRIEF SPELL OF DRY CONDITIONS IS ONCE AGAIN EXPECTED IN THE
WAKE OF THE COASTAL LOW, WITH MODERATE-TO-HIGH CONFIDENCE IN DRY
CONDITIONS BEGINNING ON THURSDAY AND CONTINUING INTO FRIDAY.
RECENT MODEL GUIDANCE HAS SLIGHTLY SLOWED DOWN WITH RESPECT TO
THE LOW PRESSURE SYSTEM IN THE MIDWEST WITH A FAIR AMOUNT OF
UNCERTAINTY BETWEEN DETERMINISTIC MODEL GUIDANCE. GIVEN THESE
CHANGES, HAVE DECIDED TO ROLL WITH NBM THROUGH MONDAY, WITH THE
BEST CHANCES OF PRECIPITATION COMING AFTER SUNRISE ON SUNDAY AND
INTO THE END OF THE LONG-TERM PERIOD.
AVIATION /19Z MONDAY THROUGH SATURDAY/
FOG WILL DISSIPATE BY 14Z, GIVING WAY TO VFR CONDITIONS WITH
VARYING AMOUNTS OF HIGH CLOUDS AS A COASTAL LOW WELL TO OUR
SOUTHEAST SLOWLY MOVES NORTHWARD. THE GREATEST AMOUNT OF CLOUD
COVER WILL BE OVER THE SOUTHEAST, WHILE AREAS NORTH OF I-80 MAY
SEE MAINLY CLEAR SKIES FOR MUCH OF THE DAY.
THE CLOUDS WILL DECREASE IN COVERAGE AFTER 03Z, ALLOWING FOR
VALLEY FOG FORMATION. THE FOG FOOTPRINT WILL LOOK SIMILAR TO
THIS MORNING, WITH THE BEST CHANCE OF IFR CONDITIONS AT BFD AND
IPT, THOUGH LNS LIKELY HAS A LOWER CHANCE OF SEEING FOG AS SOME
HIGH CLOUDS WILL REMAIN OVERHEAD. A FEW SHOWERS MAY TRY TO ENTER
SOUTHEASTERN PA TOWARDS SUNRISE, BUT THE BETTER CHANCE LOOKS TO
BE AFTER 12Z.
OUTLOOK...
TUE...VFR WITH AM VALLEY FOG. ISOLATED SHRA POSSIBLE LATE FOR
SE PA.
WED-THU...GENERALLY VFR, SOME SHRA POSSIBLE (20-40%) SE PA.
FRI...VFR WITH AM VALLEY FOG.
CLIMATE
ASTRONOMICAL FALL OFFICIALLY BEGINS WITH THE AUTUMNAL EQUINOX
ON MONDAY, SEPTEMBER 22, 2025 @ 2:19 P.M. EDT. THE AUTUMN 2025
SEASON WILL LAST 89 DAYS, 20 HOURS, AND 43 MINUTES. DAYLIGHT
SAVING TIME WILL END JUST AFTER HALLOWEEN WITH CLOCKS FALLING
BACK AT 2 A.M. SUNDAY, NOVEMBER 2, 2025.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...NPB
NEAR TERM...NPB
SHORT TERM...NPB
LONG TERM...NPB
AVIATION...BAUCO
CLIMATE...STEINBUGL
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