280
FXUS61 KPHI 180838
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
338 AM EST THU DEC 18 2025
SYNOPSIS
HIGH PRESSURE ACROSS THE AREA THIS MORNING MOVES OFFSHORE BY
AFTERNOON. A WARM FRONT LIFTS NORTH THROUGH THE REGION TONIGHT,
FOLLOWED BY A STRONG COLD FRONT ON FRIDAY. HIGH PRESSURE MOVES
THROUGH THE MID-ATLANTIC ON SATURDAY, FOLLOWED BY A COLD FRONT
SUNDAY. HIGH PRESSURE BRIEFLY RETURNS ON MONDAY, AND THEN ANOTHER
FRONTAL BOUNDARY IMPACTS THE AREA TUESDAY. HIGH PRESSURE RETURNS
ON WEDNESDAY.
NEAR TERM /THROUGH FRIDAY/
HIGH PRESSURE IS CURRENTLY MOVING OFFSHORE AT THIS HOUR, WITH JUST A
FEW HIGH CLOUDS AROUND AS A QUIET MORNING IS ONGOING. THAT WILL
CONTINUE OUTSIDE OF SOME PATCHY FOG OVER THE POCONOS AND NORTHERN
LEHIGH VALLEY, WHICH SHOULD BREAK NOT LONG AFTER DAYBREAK.
FOR TODAY, TEMPERATURES WILL CLIMB INTO THE MID TO UPPER 40S AND LOW
TO MID 50S WITH DEEP SOUTHERLY FLOW SETTING UP AS HIGH PRESSURE MOVE
OFFSHORE AND A DEEPENING AREA OF LOW PRESSURE MOVES THROUGH THE
UPPER MIDWEST AND GREAT LAKES. SKIES START OUT MOSTLY SUNNY BUT
CLOUDS INCREASE AS THE DAY GOES ON AS THE SYSTEM APPROACHES.
OTHERWISE, IT WILL BE RATHER BENIGN TODAY - THE CALM AHEAD OF THE
STORM.
FOR TONIGHT, A WARM FRONT LIFTS THROUGH THE AREA WITH A STRONG COLD
FRONT NOT FAR OFF. THIS WILL RESULT IN RAIN OVERSPREADING THE AREA
OVERNIGHT, WITH POCKETS OF HEAVY RAIN AND PERHAPS A FEW ELEVATED
THUNDERSTORMS MIXED IN. IN TERMS OF TIMING, THE WIDESPREAD RAIN
MOVES INTO THE LEHIGH VALLEY AND POCONOS BY 9-10 PM, GRADUALLY
MOVING EAST. RAIN WILL CONTINUE THROUGH THE MORNING COMMUTE, BUT
SHOULD MOVE OUT QUICKLY AS WE GET INTO THE MIDDAY HOURS ON FRIDAY.
MOST OF THE AREA WILL END UP WITH AROUND A HALF INCH TO AN INCH OF
RAIN, WITH THE HIGHEST AMOUNTS NORTH OF I-78, WHERE UPWARDS OF 1-2"
OF RAINFALL ARE EXPECTED. EVEN WITH A DECENT SNOWPACK IN PLACE,
FLOODING IMPACTS ARE ANTICIPATED TO BE LIMITED AND MAINLY JUST IN
URBAN AND POOR DRAINAGE AREAS. ENSEMBLE RIVER FORECASTS STILL SHOW
LESS THAN A 10% CHANCE OF ANY FORECAST POINT REACHING ACTION STAGE.
WITH SUCH A ROBUST WIND FIELD ALOFT AND 50-70 KT LOW LEVEL JET
MOVING THROUGH, A FEW DAMAGING WIND GUSTS CANNOT BE RULED OUT IN
HEAVIER DOWNPOURS. AS SOME OF THE CAMS GET IN RANGE, THERE IS SOME
SIGNAL OF A LOW-TOPPED CONVECTIVE LINE FORMING AND MOVING THROUGH
ALONG THE FRONT. THIS WOULD BE THE FEATURE TO WATCH FOR ANY DAMAGING
WIND GUSTS, WITH THAT LINE LIKELY MOVING THROUGH BETWEEN 6 AND 9 AM.
HOWEVER, INSTABILITY IS VERY LIMITED, ESPECIALLY SURFACE-BASED
INSTABILITY. AS A RESULT, THINKING THE SEVERE RISK IS LOW ALBEIT NOT
ZERO. SPC HAS A GENERAL THUNDER RISK OVER OUR AREA, WHICH IS ABOUT
RIGHT FOR THIS SETUP. OVERALL, THIS SHOULD BE A BENEFICIAL SOAKING
RAIN, THOUGH THERE LIKELY WILL BE SOME SLOWDOWNS WITH THE MORNING
COMMUTE AS THE HEAVIEST RAIN SHOULD BE MOVING THROUGH THE I-95
CORRIDOR BETWEEN 5 AND 9 AM.
THE MORE NOTICEABLE IMPACT WITH THIS SYSTEM WILL BE THE WINDS. AT
LEAST FOR TODAY AND THE EARLY EVENING, WINDS SHOULD BE RATHER LIGHT
OUT OF THE SOUTH. THINGS BEGIN TO INCREASE AFTER MIDNIGHT AS A BRISK
LOW-LEVEL JET MOVES OVERHEAD. 00Z NAM HAS 50-70 KT AT 925 MB (2000-
2500 FEET) FROM ABOUT 1 AM UNTIL THE FRONTAL PASSAGE AROUND 10 AM.
NOW, CONSISTENT 50+ KT WINDS WON'T MAKE IT TO THE SURFACE GIVEN A
STRONG LOW-LEVEL INVERSION IN THE WARM-AIR ADVECTION REGIME, BUT
WINDS UPWARD OF 30-40 MPH OUT OF THE SOUTH/SOUTHWEST ARE EXPECTED
AHEAD OF THE FRONT, WITH GUSTS UP TO 45 MPH. THE FRONT COMES THROUGH
IN THE LATE MORNING AND THERE SHOULD BE A LULL IN GUSTY WINDS,
BEFORE POST-FRONTAL WINDS INCREASE. ONCE THE FRONT COMES THROUGH,
DEEP LAYER BOUNDARY MIXING WILL SET UP WITH MODEST COLD-AIR
ADVECTION ALOFT. THIS WILL RESULT IN ANOTHER PERIOD OF GUSTY AND
PERHAPS STRONGER WINDS, WITH GUSTS GENERALLY 35-45 MPH OUT OF THE
WEST/NORTHWEST, BUT UP TO 50 MPH POSSIBLE. OVERALL, THERE WERE NO
CHANGES FOR THE WIND ADVISORY, WHICH IS STILL IN EFFECT FOR ALL OF
NEW JERSEY, ALL OF EASTERN PA, AND NORTHERN DELAWARE BEGINNING AT 1
AM FRIDAY. WINDS SHOULD QUICKLY WIND DOWN LATER FRIDAY AFTER SUNSET.
TEMPERATURES ON THURSDAY NIGHT ACTUALLY SHOULD INCREASE AND GET INTO
THE 50S REGIONWIDE BEFORE THE FRONT COMES THROUGH ON FRIDAY MORNING.
ONCE THE FRONT COMES THROUGH, TEMPERATURES SHOULD DROP PRETTY
QUICKLY THROUGH THE DAYTIME HOURS - DOWN INTO THE UPPER 30S/LOW
40S.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/
HIGH PRESSURE ACROSS THE TENN VALLEY FRI NIGHT QUICKLY PUSHES ACROSS
THE MIDDLE ATLANTIC REGION SAT BEFORE MOVING OFFSHORE SAT NIGHT. THE
PERIOD WILL FEATURE DRY WEATHER WITH COOLER THAN NORMAL TEMPS. HIGHS
SAT WILL BE MOSTLY BE UPPER 30S/LOW 40S ACROSS THE REGION WITH
PERHAPS SOME MID 40S ACROSS SOUTHERN DELAWARE.
THE ONLY OTHER THING OF NOT WILL BE A CONTINUATION OF GUSTY WINDS
FRI EVENING INTO THE OVERNIGHT AS THE PRESSURE GRADIENT AHEAD OF THE
HIGH (AND BEHIND THE DEPARTING LOW) REMAINS STRONG. THE WIND
ADVISORY CONTINUES INTO THE OVERNIGHT PERIOD WITH GUSTS 30 TO 40 MPH
CONTINUING. WINDS WILL DIMINISH BE DAWN SAT.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
A RATHER UNEVENTFUL PERIOD FOR THE LAST PART OF THE WEEKEND AND
INTO NEXT WEEK. A COLD FRONT WILL CROSS THE AREA SUNDAY AS LOW
PRESSURE ADVANCES ACROSS ONTARIO/QUEBEC. RIGHT NOW, THE FRONT
APPEARS TO BE DRY. AFTER THAT. HIGH PRESSURE BUILDS IN FOR MONDAY.
THERE WILL BE A CHANCE FOR SOME SNOWS OR RAINS TUESDAY (30% TO 40%)
AS A WARM FRONT CROSSES WELL NORTH OF THE AREA. MORE DRY WEATHER FOR
WEDNESDAY.
MILD TEMPERATURES SUNDAY WILL RETREAT BACK BELOW NORMAL BY MONDAY
FOLLOWING THE COLD FRONT. READINGS WILL REMAIN A FEW DEGREES BELOW
NORMAL TUESDAY BUT THEN RISE ABOVE NORMAL FOR WEDNESDAY. NORMAL
HIGHS FOR THIS TIME OF YEAR ARE : PHL MID 40S, ABE/RDG LOW 40S, MPO
LOW 30S AND KACY/KGED MID/UPPER 40S. LOWS ARE MOSTLY 20S N/W AND LOW
30S ELSEWHERE.
AVIATION /08Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
REST OF TONIGHT (THROUGH 12Z)...PRIMARILY VFR. SOME PATCHY FOG
POSSIBLE AROUND KRDG, BUT ENDED UP TAKING FOG OUT AT KABE/KTTN AS
PROBABILITY IS ONLY AROUND 10-15% FOR FOG DEVELOPMENT. WINDS LIGHT
(UNDER 5 KNOTS) AND VARIABLE, THOUGH FAVORING A NORTH/NORTHEAST
DIRECTION AS THE NIGHT GOES ON. MODERATE CONFIDENCE OVERALL.
TODAY...PRIMARILY VFR. THINKING RESTRICTIONS HOLD OFF AT ALL
TERMINALS UNTIL AFTER 00Z. WINDS PICK UP OUT OF THE SOUTHEAST AROUND
5-10 KT OR SO BETWEEN 13Z-15Z. CLOUD BASES GRADUALLY LOWERING AS THE
DAY GOES ON WITH CLOUD COVER INCREASING.
MODERATE CONFIDENCE OVERALL.
THURSDAY NIGHT...CONDITIONS DROPPING TO MVFR AND THEN IFR AS THE
NIGHT GOES ON AS RAIN, SOME OF WHICH COULD BE HEAVY AT TIMES,
OVERSPREADS THE AREA. SOUTHERLY WINDS INCREASING TO AROUND 10-20 KT
WITH GUSTS GETTING NEAR 30 KT BY DAYBREAK. HAVE ADDED PERIODS OF LOW-
LEVEL WIND SHEAR AS A BRISK LOW-LEVEL JET MOVES OVERHEAD,
POTENTIALLY UPWARDS OF 50-60 KT AT FL020. LOW CONFIDENCE IN TIMING
OF RESTRICTIONS, MODERATE CONFIDENCE IN EXTENT RESTRICTIONS, AND
HIGH CONFIDENCE IN A PERIOD OF LLWS OVERNIGHT.
OUTLOOK...
FRIDAY... MVFR TO IFR IN THE MORNING IN RA. AN ISOLATED TSRA
POSSIBLE AROUND MIDDAY. VFR IN THE AFTERNOON. S-SW WINDS 15 TO
25 KT WITH 35 TO 45 KT GUSTS, TURNING W-NW IN THE AFTERNOON.
FRI NIGHT... VFR. GUSTY WEST WINDS WITH GUSTS 25-30 KTS EARLY.
SAT THRU MONDAY... VFR EXPECTED.
MARINE
NO MARINE HEADLINES IN PLACE FOR TODAY. WINDS OUT OF THE SOUTHEAST
AROUND 10-15 KT AND SEAS 2 TO 4 FEET.
FOR TONIGHT, A GALE WARNING IS IN PLACE FOR ALL MARINE ZONES. WINDS
OVERNIGHT WILL BE OUT OF THE SOUTH/SOUTHWEST WITH GUSTS 30-40 KT AND
SEAS 6 TO 10 FEET.
FOR FRIDAY, THE GALE WARNING REMAINS IN PLACE FOR ALL MARINE ZONES.
A COLD FRONT WILL COME THROUGH, RESULTING IN A PERIOD OF SUB-GALE
WINDS, BUT WINDS WILL PICK OUT OF THE WEST/NORTHWEST IN THE WAKE OF
THE COLD FRONT, WITH ANOTHER PERIOD OF 30-40 KT GUSTS EXPECTED. SEAS
8 TO 13 FEET.
OUTLOOK...
FRIDAY NIGHT... GALES DIMINISH AND BECOME LESS THAN SCA BY DAWN.
FAIR.
SATURDAY... SUB-SCA CONDITIONS. FAIR.
SATURDAY NIGHT THROUGH SUNDAY NIGHT... SCA CONDITIONS EXPECTED
WITH WIND GUSTS TO 30 KT AND SEAS 4 TO 7 FEET. FAIR.
MONDAY...LINGERING SCA CONDITIONS POSSIBLE. FAIR.
PHI WATCHES/WARNINGS/ADVISORIES
PA...WIND ADVISORY FROM 1 AM FRIDAY TO 1 AM EST SATURDAY FOR PAZ054-
055-060>062-070-071-101>106.
NJ...WIND ADVISORY FROM 1 AM FRIDAY TO 1 AM EST SATURDAY FOR NJZ001-
007>010-012>027.
DE...WIND ADVISORY FROM 1 AM FRIDAY TO 1 AM EST SATURDAY FOR DEZ001-
004.
MD...NONE.
MARINE...GALE WARNING FROM 6 PM THIS EVENING TO 1 AM EST SATURDAY FOR
ANZ430-431-450>455.
SYNOPSIS...MPS/OHARA
NEAR TERM...HOEFLICH
SHORT TERM...OHARA
LONG TERM...OHARA
AVIATION...HOEFLICH/OHARA
MARINE...HOEFLICH/OHARA
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