868
FXUS61 KPHI 180523
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1223 AM EST THU DEC 18 2025
SYNOPSIS
A WEAK FRONT MOVES THROUGH THE REGION THIS EVENING, THEN HIGH
PRESSURE BUILDS OVER THE AREA TONIGHT BEFORE MOVING OFFSHORE ON
THURSDAY. A WARM FRONT LIFTS NORTH THROUGH THE REGION THURSDAY
NIGHT, 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 TODAY/
RADIATIONAL COOLING CONDITIONS WILL BE GOOD WITH THIS SET UP
AND SO TEMPERATURES HAVE THE POTENTIAL TO FALL CLOSE TO DEW
POINTS RESULTING IN SOME FOG OR LOW STRATUS POTENTIALLY
DEVELOPING. THERE WILL ALSO BE ADDED LOW LEVEL MOISTURE FROM THE
SNOW PACK. MITIGATING FACTORS THOUGH ARE THAT SLIGHTLY DRIER
AIR WILL BE TRYING TO WORK IN FOR A TIME THIS EVENING BEHIND THE
COLD FRONT AND ALSO THAT THE WINDS NOT TOO FAR OFF THE GROUND
SHOULD REMAIN ELEVATED OVERNIGHT WHICH COULD CAUSE ENOUGH MIXING
TO KEEP WIDESPREAD FOG AT BAY. FOR THE TIME BEING, ADDED IN
PATCHY FREEZING FOG FOR MOST OF THE AREA. EXPECT LOWS TONIGHT
GENERALLY IN THE 20S EXCEPT LOW 30S NEAR THE COAST.
FOR THURSDAY, HIGH PRESSURE MOVES EASTWARD OFF THE COAST AS A
LARGE AREA OF LOW PRESSURE ADVANCES EASTWARD INTO THE WESTERN
GREAT LAKES REGION. THIS WILL RESULT IN THE FLOW TURNING MORE
S/SE. IT WILL ONCE AGAIN BE A TRICKY FORECAST AS THERE'S THE
POTENTIAL FOR INCREASING LOW LEVEL MOISTURE TO REMAIN TRAPPED
BELOW AN INVERSION WHICH COULD KEEP THE AREA UNDER A DECK OF LOW
STRATUS. BEST CHANCE OF SEEING ANY SUN WILL BE IN THE MORNING
TO EARLY AFTERNOON BEFORE CLOUDS ASSOCIATED WITH THE SYSTEM TO
OUR WEST MOVE IN BY LATER IN THE DAY.
IN TERMS OF TEMPERATURES, THERE WILL BE A WARM FRONT BEGINNING
TO MOVE BACK INTO THE AREA FROM THE SOUTH SO THE WARMEST
TEMPERATURES AND AREAS MOST FAVORED TO SEE ANY SUN WILL BE OUR
SOUTHERN MOST ZONES OVER DELMARVA INTO ADJACENT FAR SOUTHERN NJ.
THESE AREAS LOOK TO GET INTO THE 50S. FARTHER NORTH, GENERALLY
EXPECT DAYTIME HIGHS IN THE 40S EXCEPT UPPER 30S OVER THE
SOUTHERN POCONOS. ONE THING TO NOTE THOUGH IS THAT THESE
TEMPERATURES WILL CONTINUE TO WARM AT NIGHT DUE TO STRENGTHENING
WARM AIR ADVECTION. THE DAYTIME SHOULD BE MAINLY FREE OF ANY
PRECIPITATION EXCEPT BY LATE DAY THERE COULD BE SOME SHOWERS
DEVELOPING OVER PORTIONS OF NORTHERN DELMARVA INTO EASTERN PA
AND NEARBY LOCATIONS IN NJ NEAR THE PA BORDER. POPS THOUGH ARE
ONLY AROUND 20-30 PERCENT. SOME ADVECTION FOG IS POSSIBLE DURING
THE DAYTIME AS WELL, DUE TO THE HIGHER DEWPOINTS MOVING OVER
ANY REMAINING AREAS OF SNOW PACK. THE HIGHER DEWPOINTS AND WINDS
SHOULD WORK TO QUICKLY ERODE ANY REMAINING SNOW, BUT SOMETHING
WORTH MENTIONING.
SHORT TERM /TONIGHT THROUGH SATURDAY/
LOW PRESSURE MOVING THROUGH THE GREAT LAKES THURSDAY NIGHT WILL
LIFT INTO EASTERN CANADA ON FRIDAY. A DEEP H5 TROUGH WILL DIG
DOWN INTO THE TENNESSEE VALLEY AND THE MID-ATLANTIC, AND A
STRONG COLD FRONT WILL CROSS THE AREA ON FRIDAY. STRONG WARM AIR
ADVECTION DEVELOPS AHEAD OF THE COLD FRONT THURSDAY NIGHT
THROUGH FRIDAY MORNING, THEN STRONG COLD AIR ADVECTION DEVELOPS
BEHIND THE DEPARTING COLD FRONT. THIS RESULTS IN A NON-DIURNAL
TEMPERATURE CURVE IN WHICH TEMPERATURES WILL RISE THURSDAY
NIGHT, AND THEN TEMPERATURES FALL DURING THE DAY FRIDAY AS THE
COLD FRONT WORKS ITS WAY THROUGH THE REGION.
IN TERMS OF SENSIBLE WEATHER, THE TWO MAIN IMPACTS FROM THIS
SYSTEM ARE MODERATE TO HEAVY RAIN AND GUSTY TO POTENTIALLY
DAMAGING WINDS. THE SOUTHERLY PRESSURE GRADIENT TIGHTENS OVER
THE AREA BETWEEN HIGH PRESSURE OFFSHORE, LOW PRESSURE PASSING
NORTH OF THE AREA, AND HIGH PRESSURE BUILDING INTO THE CENTRAL
UNITED STATES. IN ADDITION, A 60 TO 70 KT LOW LEVEL JET WILL
MOVE ACROSS THE REGION LATE THURSDAY NIGHT THROUGH FRIDAY
MORNING. FOR THE MOST PART, CAN EXPECT SOUTH WINDS 15 TO 25 MPH
WITH 30 TO 40 MPH GUSTS LATE THURSDAY NIGHT THROUGH FRIDAY
MORNING, THOUGH GUSTS UP TO 50 MPH ARE LIKELY FOR THE SOUTHERN
POCONOS, THE LEHIGH VALLEY, THE DELAWARE VALLEY, MOST OF NEW
JERSEY AND COASTAL DELAWARE. THERE SHOULD BE A LULL IN THE WINDS
LATE FRIDAY MORNING, THEN WEST TO NORTHWEST WINDS RAMP UP
FRIDAY AFTERNOON AND EVENING ONCE AGAIN WITH 30 TO 40 MPH GUSTS
FOR MOST OF THE AREA, AND GUSTS UP TO 50 MPH FOR THOSE SAME
AREAS. WINDS THEN DIMINISH LATE FRIDAY NIGHT. A WIND ADVISORY IS
NOW IN EFFECT FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT FOR MOST
OF THE AREA, THOUGH WILL NOTE A LULL IN THE STRONGEST WINDS. THE
OVERALL TREND IS SHOWING STRONGER WIND GUSTS, SO WILL FOLLOW
SUIT ACCORDINGLY.
RAIN DEVELOPS THURSDAY EVENING, AND THEN THE HEAVIEST RAIN
DEVELOPS LATE THURSDAY NIGHT THROUGH FRIDAY MORNING IN
ASSOCIATION WITH THE AFOREMENTIONED LOW LEVEL JET. THERE SHOULD
BE A LULL IN THE RAIN FRIDAY MORNING, BUT THEN THE COLD FRONT
PASSES THROUGH THE REGION LATE FRIDAY MORNING THROUGH FRIDAY
AFTERNOON. WHILE SURFACE BASED INSTABILITY WILL BE MINIMAL,
THERE WILL BE SOME 200 TO 300 J/KG OF ML MUCAPE AHEAD OF THE
FRONT AND 65 TO 75 KT 0-6 KM BULK SHEAR WITH THE PASSAGE OF THE
FRONT. THIS SHOULD BE ENOUGH TO PRODUCE A FEW ELEVATED
THUNDERSTORMS ACROSS THE REGION. WILL GO AHEAD AND ADD SLIGHT
CHANCE FOR THUNDERSTORMS TO THE FORECAST FRIDAY MORNING. A FEW
STRONGER STORMS COULD PRODUCE LOCALLY DAMAGING WIND GUSTS, BUT
CHANCES IN THIS HAPPENING ARE QUITE LOW, BUT NOT ZERO. A LINE OF
HEAVY RAIN SHOWERS WILL DEVELOP WITH THE PASSAGE OF THE COLD
FRONT. TEMPERATURES THEN CRASH AS STRONG COLD AIR ADVECTION
DEVELOPS.
LOW TEMPERATURES THURSDAY NIGHT WILL OCCUR THURSDAY EVENING,
AND WILL RANGE FROM THE LOW TO MID 40S, THOUGH PERHAPS A FEW
DEGREES COOLER IN THE SOUTHERN POCONOS AND A FEW DEGREES WARMER
IN SOUTHERN DELMARVA. HIGHS ON FRIDAY WILL OCCUR IN THE MORNING,
AND WILL GENERALLY BE IN THE LOW TO MID 50S NORTH AND WEST OF
THE FALL LINE AND IN THE UPPER 50S ACROSS SOUTHERN NEW JERSEY,
THE DELAWARE VALLEY, AND DELMARVA. TEMPERATURES WILL FALL INTO
THE UPPER 30S AND LOW 40S BY FRIDAY AFTERNOON. LOWS FRIDAY NIGHT
WILL BE IN THE 20S.
STORM TOTAL RAINFALL IS TRENDING UP FOR THE NORTHERN HALF OF
THE FORECAST AREA AND TRENDING DOWN FOR THE SOUTHERN HALF, AND
GENERALLY 1 TO AS MUCH AS 2 INCHES ACROSS THE SOUTHERN POCONOS,
NORTHERN NEW JERSEY, AND THE LEHIGH VALLEY AND 1/2 INCH TO 1
INCH ACROSS SOUTHERN NEW JERSEY, THE DELAWARE VALLEY, AND
DELMARVA. WIDESPREAD MAINSTEM FLOODING IS NOT A CONCERN, BUT
MINOR FLOODING AND URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE
DUE TO THE HEAVY RAINFALL AND MELTING SNOW.
DRY AND COLDER ON SATURDAY WITH HIGHS IN THE UPPER 30S TO LOW
40S.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
ALTHOUGH SEVERAL FRONTAL BOUNDARIES WILL IMPACT THE AREA DURING
THE LONG TERM PERIOD, MOST OF THESE FRONTS WILL BE FAIRLY
BENIGN. HIGH PRESSURE MOVES OFFSHORE SATURDAY NIGHT AND THEN A
COLD FRONT PASSES THROUGH ON SUNDAY. NO SIGNIFICANT WEATHER WITH
ITS PASSAGE. WARMER AHEAD OF THE FRONT WITH HIGHS IN THE 40S,
THEN COLDER ON MONDAY WITH HIGHS IN THE 30S.
ANOTHER COLD FRONT PASSES THROUGH ON TUESDAY WITH A MIX OF RAIN
AND SNOW, WITH RAIN TO THE SOUTH AND SNOW TO THE NORTH AND A
MIX IN BETWEEN.
CONDITIONS DRY OUT ON WEDNESDAY. NEAR NORMAL TEMPERATURES
TUESDAY AND WEDNESDAY.
AVIATION /06Z 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.
FRIDAY NIGHT...VFR. W-NW WINDS 15 TO 20 KT WITH GUSTS UP TO 30
KT, DIMINISHING TO 5 TO 10 KT LATE.
SATURDAY THROUGH MONDAY...VFR. NO SIGNIFICANT WEATHER.
MARINE
WINDS AND SEAS LOOK TO REMAIN AT BELOW ADVISORY LEVELS THROUGH
THURSDAY. VARIABLE WINDS 5-10 KTS OVERNIGHT, SETTLING OUT OF THE
SOUTHEAST TO SOUTH AND INCREASING TO 10-20 KTS BY THURSDAY
AFTERNOON. SEAS 2-4 FEET.
OUTLOOK...
THURSDAY NIGHT...GALE WARNING NOW IN EFFECT. S-SW WINDS 20 TO
33 KT WITH 35 TO 45 KT GUSTS. SEAS BUILDING TO 6 TO 9 FEET.
VISIBILITY RESTRICTIONS IN RAIN AND FOG.
FRIDAY...GALE WARNING NOW IN EFFECT. S-SW WINDS 20 TO 35 KT
WITH 35 TO 45 KT GUSTS IN THE MORNING, THEN WINDS DIMINISH A BIT
AROUND MIDDAY, THEN TURN W-NW AND INCREASE TO 20 TO 30 KT WITH
35 TO 40 KT GUSTS IN THE AFTERNOON BEHIND A DEPARTING COLD
FRONT. VISIBILITY RESTRICTIONS IN RAIN AND FOG IN THE MORNING.
A ISOLATED THUNDERSTORM IS POSSIBLE IN THE LATE MORNING/EARLY
AFTERNOON WITH THE PASSAGE OF THE COLD FRONT.
FRIDAY NIGHT...GALE FORCE WINDS IN THE EVENING, DIMINISHING
AFTER MIDNIGHT. SCA CONDITIONS FOR THE REST OF THE NIGHT.
SATURDAY...SUB-SCA CONDITIONS.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...SCA CONDITIONS EXPECTED
WITH WIND GUSTS TO 30 KT AND SEAS 4 TO 7 FEET.
MONDAY...LINGERING SCA CONDITIONS POSSIBLE.
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
NEAR TERM...FITZSIMMONS/STAARMANN
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...FITZSIMMONS/HOEFLICH/MPS/STAARMANN
MARINE...FITZSIMMONS/MPS/STAARMANN
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