473
FXUS61 KPHI 171900
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
300 PM EDT SAT OCT 17 2026
WHAT HAS CHANGED
A GALE WATCH HAS BEEN ISSUED FOR MONDAY INTO TUESDAY.
UNCERTAINTY CONTINUES FOR WEDNESDAY AND BEYOND WITH THE
POTENTIAL IMPACTS FROM THE NOR'EASTER.
KEY MESSAGES
1. A COLD AIRMASS BUILDS INTO THE REGION THIS WEEKEND. FREEZE
WARNINGS ARE IN EFFECT FOR TONIGHT. ANOTHER ROUND OF FROST IS
POSSIBLE SUNDAY NIGHT INTO MONDAY MORNING.
2. UNCERTAINTY PERSISTS REGARDING A NOR'EASTER DEVELOPING OFF
THE COAST OF THE SOUTHERN MID-ATLANTIC THAT MAY CAUSE UNSETTLED
CONDITIONS AND HAZARDOUS MARINE IMPACTS EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...A COLD AIRMASS BUILDS INTO THE REGION THIS
WEEKEND. FREEZE WARNINGS ARE IN EFFECT FOR TONIGHT. ANOTHER
ROUND OF FROST IS POSSIBLE SUNDAY NIGHT INTO MONDAY MORNING.
A COLD FRONT CONTINUES TO WORK THROUGH SOUTHEAST NEW JERSEY AND
DELMARVA THIS AFTERNOON AS LOW PRESSURE MOVES AWAY. ANY
LINGERING LIGHT RAIN SHOWERS WILL TAPER OFF AS THE AFTERNOON
PROGRESSES. A TIGHT PRESSURE GRADIENT EXISTS BETWEEN THE
DEPARTING LOW AND HIGH PRESSURE BUILDING INTO THE CENTRAL AND
SOUTHERN PLAINS. NORTH WINDS 15 TO 20 MPH WITH 25 TO 35 MPH
GUSTS GOING INTO THIS AFTERNOON SHOULD GRADUALLY DWINDLE TOWARD
SUNSET.
TONIGHT, TEMPERATURES DROP INTO THE 30S NEARLY THROUGHOUT, WITH
LOWS DOWN TO OR BELOW FREEZING FOR THE SOUTHERN POCONOS, LEHIGH
VALLEY, AND NORTHWEST NEW JERSEY. MAINTAINED FREEZE WARNINGS AS
INHERITED, BUT MIXING FROM LINGERING WIND MAY PRECLUDE THE
SOUTHEASTERN EXTENT OF THEM FROM VERIFYING. CONFIDENCE NOT HIGH
ENOUGH TO CANCEL, HOWEVER.
HIGH TEMPERATURES ON SUNDAY WILL THEN ONLY BE IN THE 50S FOR
MOST OF THE REGION DESPITE MOSTLY SUNNY SKIES. WHILE ANOTHER
NIGHT OF TEMPERATURES BELOW FREEZING IS NOT EXPECTED, CONDITIONS
WILL ONCE AGAIN POTENTIALLY FAVOR THE DEVELOPMENT OF SOME
FROST, MAINLY CONFINED TO THE LEHIGH VALLEY, POCONOS AND
NORTHERN NEW JERSEY. LOWS ARE EXPECTED TO BE SEVERAL DEGREES
WARMER THAN SATURDAY NIGHT MAINLY IN THE MID TO UPPER 30S.
ADDITIONAL HEADLINES CAN'T BE RULED OUT FOR SUNDAY NIGHT IF
FROST POTENTIAL IS REALIZED WHERE THE GROWING SEASON REMAINS
ACTIVE, THOUGH THE GROWING SEASON MAY BE ENDED IN THESE AREAS BY
THE FREEZE TONIGHT.
TEMPERATURES WILL THEN BEGIN TO SLOWLY MODERATE SUNDAY NIGHT
INTO EARLY NEXT WEEK.
KEY MESSAGE 2...UNCERTAINTY PERSISTS REGARDING A NOR'EASTER
DEVELOPING OFF THE COAST OF THE SOUTHERN MID-ATLANTIC THAT MAY
CAUSE UNSETTLED CONDITIONS AND HAZARDOUS MARINE IMPACTS EARLY
NEXT WEEK.
THE BASE OF A DEEP TROUGH AXIS WILL PASS THROUGH THE REGION LATE
TONIGHT INTO SUNDAY. AS IT DOES SO, THE TROUGH AXIS WILL THEN
CUTOFF INTO AN UPPER LEVEL LOW WHICH WILL MEANDER OVER THE
SOUTHERN MID- ATLANTIC COAST INTO EARLY NEXT WEEK. AT THE SAME
TIME, STRONG AND EXPANSIVE HIGH PRESSURE WILL BE BUILDING OVER
THE OHIO VALLEY. WHILE CONFIDENCE IS INCREASING REGARDING A
NOR'EASTER DEVELOPING OFF THE NORTH CAROLINA COAST BY SUNDAY
INTO SUNDAY NIGHT, IT MUST BE SAID THERE REMAINS A VAST AMOUNT
OF UNCERTAINTY WITH REGARDS TO POTENTIAL IMPACTS TO OUR REGION
INTO NEXT WEEK.
CONSIDERABLE DIFFERENCES AMONGST GLOBAL/ENSEMBLE GUIDANCE EXISTS
WITH REGARDS TO JUST HOW CLOSE/LONG THIS SYSTEM WILL GET/LAST IN OUR
REGION. RELATIVE TO THE PREVIOUS FORECAST DISCUSSION, THERE HAS NOT
BEEN MUCH CHANGE. THE EC ENSEMBLE MEMBER SPREAD IS FAIRLY TIGHTLY
CLUSTERED THROUGH THE EARLY PART OF NEXT WEEK, AND THEN BEGINS TO
DIVERGE, BUT GENERALLY HAS THE LOW TRACKING NORTHWARD AND THEN
MEANDERING OFF THE MID-ATLANTIC COAST INTO MID OR EVEN LATE WEEK.
THE GEFS MEMBERS ARE SIMILAR UNTIL ABOUT MID-WEEK WHEN THEY BEGIN TO
DIVERGE MORE SUBSTANTIALLY. ALL OF THIS BEING SAID, IT DOESN'T
APPEAR LIKELY THAT THERE WILL BE SIGNIFICANT IMPACTS INLAND FROM
THIS SYSTEM, EVEN THOUGH THEY CAN'T BE ENTIRELY RULED OUT AT THIS
TIME. WHAT IS INCREASINGLY LIKELY THOUGH IS AT LEAST SOME IMPACTS TO
COASTAL COMMUNITIES WITH PERIODS OF GUSTY NORTHEAST WINDS, SOME
SHOWERS, AND POTENTIALLY SOME COASTAL FLOODING CONCERNS, POTENTIALLY
FOR MULTIPLE DAYS NEXT WEEK. WE WILL CONTINUE TO MONITOR THE
PROGRESS OF THIS DEVELOPING SYSTEM.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. N WINDS 15 TO 20 KT WITH 25 TO 35 KT
GUSTS, DIMINISHING AFTER 20Z. HIGH CONFIDENCE.
TONIGHT...VFR. N WINDS 10 KT OR LESS. HIGH CONFIDENCE.
SUNDAY...VFR. NE WINDS 10 KT OR LESS. HIGH CONFIDENCE.
OUTLOOK...
SUNDAY NIGHT...VFR. NO SIGNIFICANT WEATHER EXPECTED.
MONDAY AND TUESDAY...VFR. GUSTY NORTHEAST WINDS UP TO 20 KT
POSSIBLE WITH GUSTS UP TO 30 KT ALSO POSSIBLE NEAR KMIV AND
KACY.
WEDNESDAY AND THURSDAY...PRIMARILY VFR, ALTHOUGH SUB-VFR
CONDITIONS POSSIBLE AT TIMES. A CHANCE OF RAIN SHOWERS EACH DAY,
WITH CHANCES HIGHEST FOR KMIV AND KACY. GUSTY NORTHEAST WINDS
UP TO 20 KT POSSIBLE WITH GUSTS UP TO 30 KT ALSO POSSIBLE NEAR
KMIV AND KACY.
MARINE
GALE WARNINGS IN EFFECT FOR ALL WATERS FOR REST OF TODAY FOR
NORTH WINDS 15 TO 25 KT WITH 35 TO 40 KT GUSTS. WINDS DIMINISH A
BIT ON NORTHERN NJ OCEAN WATERS AND DE BAY TONIGHT, AND SMALL
CRAFT ADVISORIES WILL BE NEEDED. FOR ALL OTHER WATERS, GALE
WARNINGS REMAIN IN EFFECT OVERNIGHT, BUT THEN DROPS ON SUNDAY.
SEAS 6-12 FEET.
OUTLOOK...
SUNDAY NIGHT THROUGH THURSDAY...DUE TO DEVELOPING NOR'EASTER
OFF THE SOUTHERN MID-ATLANTIC COAST, A PROLONGED PERIOD OF GALE
FORCE CONDITIONS ARE EXPECTED TO DEVELOP/CONTINUE ACROSS ALL
MARINE WATERS. A GALE WATCH HAS BEEN ISSUED FOR MONDAY THROUGH
TUESDAY. LOWER CONFIDENCE FOR WEDNESDAY AND THURSDAY. NORTHEAST
WINDS OF 25-35 KT WITH GUSTS OF 35-45 KT ARE POSSIBLE. SEAS OF
10-16+ FEET POSSIBLE.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FREEZE WARNING FROM 1 AM TO 9 AM EDT SUNDAY FOR PAZ054-055-
060>062-101-103-105.
NJ...FREEZE WARNING FROM 1 AM TO 9 AM EDT SUNDAY FOR NJZ001-007>009.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 6 PM EDT THIS EVENING FOR ANZ430-431-
450>452.
GALE WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON FOR
ANZ451>455-480>483-485.
GALE WARNING UNTIL 6 AM EDT SUNDAY FOR ANZ453>455.
GALE WARNING UNTIL 7 AM EDT SUNDAY FOR ANZ480>483-485.
DISCUSSION...AKL/COOPER/MPS/RCM
AVIATION...AKL/COOPER/MPS/RCM
MARINE...AKL/COOPER/MPS/RCM
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