726
FXUS61 KPHI 231127
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
627 AM EST TUE DEC 23 2025
SYNOPSIS
A WARM FRONT ASSOCIATED WITH A CLIPPER SYSTEM WILL LIFT THROUGH
THE REGION BY THIS AFTERNOON, WITH A COLD FRONT FOLLOWING IT
THIS EVENING. WEAK HIGH PRESSURE WILL FOLLOW IN ITS WAKE,
BUILDING IN THROUGH WEDNESDAY NIGHT BEFORE SLIDING OFFSHORE
CHRISTMAS DAY WITH ANOTHER WEAK LOW PRESSURE SYSTEM MOVING
THROUGH. AN ACTIVE PATTERN WILL TAKE SHAPE FOR THE WEEKEND WITH
THE POTENTIAL FOR A SERIES OF STORM SYSTEMS IMPACTING THE AREA
INTO EARLY NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
A PERIOD OF LIGHT SNOW, SOME WINTRY MIX AND RAIN WILL IMPACT
PORTIONS OF THE REGION THROUGH THIS MORNING BEFORE ENDING INTO
THE EARLY AFTERNOON HOURS. THERE HAVE BEEN NO SIGNIFICANT
CHANGES TO THE FORECAST AMOUNTS OR ANTICIPATED IMPACTS FOR THE
SYSTEM THROUGH TODAY. BREEZY CONDITIONS WILL DEVELOP OVERNIGHT
AS A COLD FRONT PUSHES OFFSHORE, INCLUDING POTENTIAL FOR GUSTS
NEAR 40-50 MPH FOR HIGHER ELEVATIONS OF THE POCONOS AND
NORTHWEST NEW JERSEY.
CANADIAN HIGH PRESSURE HAS SHIFTED OFFSHORE. LATEST ANALYSIS AS
OF 6 AM SHOWS TEMPERATURES IN THE LOW TO MID 30S ACROSS MUCH OF
THE AREA WITH DEWPOINTS IN THE MID 20S TO LOW 30S. THUS,
WETBULBS ARE NEAR TO JUST BELOW FREEZING, AND SLOWLY RISING AS
WEAK WARM ADVECTION IS UNDERWAY. RADAR INDICATES STEADIER
PRECIPITATION IS GRADUALLY WORKING ITS WAY TOWARD THE SURFACE,
ERODING AND COOLING THE DRY LOW LEVEL AIR. THIS TREND WILL
CONTINUE THROUGH MID MORNING AS THE DEVELOPING CLIPPER SYSTEM
APPROACHES FROM THE GREAT LAKES REGION, WITH PRECIPITATION
REACHING PEAK INTENSITY AND COVERAGE DURING THE MID MORNING
HOURS BEFORE BEGINNING TO TAPER OFF INTO THE AFTERNOON.
GUIDANCE REMAINS IN DECENT CONSENSUS THAT WE WILL SEE AT LEAST
A FEW HUNDREDTHS OF QPF AS FAR SOUTH AS THE PHILLY THROUGH THIS
MORNING, AND AS MUCH AS 0.1-0.25" NEAR AND NORTH OF I-78. THERE
IS STILL SOME UNCERTAINTY ON HOW FAR SOUTH MEASURABLE SNOWFALL
WILL OCCUR INTO THE PHILLY METRO, SOUTHERN NEW JERSEY, AND
NORTHERN DELAWARE. THE WARM ADVECTION NATURE OF THIS SYSTEM
SHOULD YIELD POOR SNOW RATIOS. WE ARE FORECASTING SNOW RATIOS
NEAR 5:1 TO 10:1 AT BEST.
AS FOR FORECAST SNOWFALL ACCUMULATIONS, GENERALLY EXPECTING
LESS THAN 1" FOR AREAS SOUTH OF I-78 DOWN INTO THE PHILLY METRO
AND ADJACENT AREAS OF INTERIOR SOUTHERN NEW JERSEY, FAR NORTHERN
DELAWARE, AND THE NORTHERN JERSEY SHORE (LBI AND NORTH). AREAS
NEAR AND NORTH OF THE I-78 CORRIDOR STILL HAVE THE BEST CHANCES
OF RECEIVING A PLOWABLE 1-3" OF SNOWFALL. THE USUAL HIGHER
ELEVATIONS ABOVE 1,200 FEET OF NORTHERN NEW JERSEY AND EASTERN
PENNSYLVANIA COULD SEE SNOWFALL TOTALS AS MUCH AS 3-4" OF SNOW,
BUT THE PROBABILITY OF THIS IS MODERATE AT BEST (~20-40%), AND
WILL BE CONDITIONAL ON EXACTLY HOW MUCH QPF WE CAN SQUEEZE OUT
OF THIS WEAK SYSTEM. OUR FORECAST IS FOR MOSTLY 1-3" NEAR/NORTH
OF I-78.
THERE ALSO REMAINS POTENTIAL FOR A LIGHT GLAZE OF ICE, MAINLY
FOR ELEVATIONS ABOVE 1,000 FEET NORTH OF I-78, AS PRECIPITATION
COULD CHANGE TO RAIN THERE BEFORE TEMPERATURES WARM ABOVE
FREEZING.
WHILE WE DO HAVE SUFFICIENT FORCING AND MOISTURE FOR SNOW, THE
DYNAMICS AT PLAY ARE VASTLY WEAKER THAN THE SNOW STORM TWO
WEEKENDS AGO. SO THE OVER PERFORMING POTENTIAL WE SAW WITH THAT
SYSTEM IS VERY LOW. WITH THAT SAID, SNOW FALLING THIS MORNING
COULD CERTAINLY CAUSE TRAVEL ISSUES AND SLIPPERY/ICY ROADS FOR
ALL AREAS NORTH AND WEST OF I-95, DESPITE THE LIGHT SNOWFALL
AMOUNTS FOR SOME PLACES.
THE WINTER WEATHER ADVISORY WAS EXPANDED TO INCLUDE MORRIS,
WARREN, NORTHAMPTON, AND LEHIGH COUNTIES BASED ON THE LATEST
GUIDANCE AND TRENDS. THE MORE NOTABLE IMPACTS ARE ANTICIPATED TO
OCCUR WITHIN THE ADVISORY AREA THROUGH EARLY THIS AFTERNOON,
WHERE SNOWFALL TOTALS RANGING MAINLY FROM 1-3" AND A LIGHT GLAZE
OF ICE IS POSSIBLE.
CHANCES FOR PRECIP AND QPF ARE LOWER SOUTH OF THE PHILLY METRO
INTO FAR SOUTHERN NEW JERSEY AND DELMARVA. THIS REGION WILL HAVE
MUCH LESS MOISTURE AND FORCING, AND THUS LOWER MEASURABLE
PRECIP IF ANY. IT WILL ALSO BE WARMER HERE, WITH WETBULB
TEMPERATURES MAINLY ABOVE FREEZING BY THE TIME ANY PRECIP OF THE
MEASURABLE QPF VARIETY ARRIVES AFTER DAWN. SO ANY SNOW THAT
DOES FALL HERE IS MOST LIKELY TO BE "WHITE RAIN" (SNOW MELTING
AS IT FALLS).
ANY LINGERING PRECIPITATION WILL BE ENDING BY EARLY AFTERNOON,
THEN TEMPERATURES SHOULD START WARMING UP BY A FEW DEGREES. HIGH
TEMPERATURES BY LATE AFTERNOON WILL RANGE FROM THE MID 30S
NORTH OF I-78 TO THE MID TO UPPER 40S FOR FAR SOUTHERN NEW
JERSEY AND DELMARVA. SKIES SHOULD REMAIN MOSTLY CLOUDY FOR THE
REMAINDER OF THE DAY, AND WARM ADVECTION GRADIENT WINDS WILL NOT
BE VERY STRONG AT ALL. MOST AREAS SHOULD EVENTUALLY WARM ABOVE
FREEZING INTO THE AFTERNOON, WHICH SHOULD HELP TO START MELTING
AWAY OUR LIGHT SNOWFALL ACCUMULATIONS AND IMPROVE LOUSY ROAD
CONDITIONS FOR THE HOLIDAY TRAVELERS.
LOW TEMPERATURES TONIGHT INTO WEDNESDAY MORNING ARE MOSTLY IN
THE MID TO UPPER 30S (ABOVE FREEZING) SOUTH OF I-78, AND CLOSE
TO 30 DEGREES NORTH OF THERE. SO ANY ICY ROADS FROM REFREEZING
SNOW MELT OR SLUSHY SHOULD BE CONFINED TO UNTREATED ROADS NORTH
OF I-78. WINDS WILL ALSO INCREASE TONIGHT AS A COLD FRONT PUSHES
OFFSHORE, WHICH SHOULD HELP TO DRY THINGS OUT A BIT MORE TOO.
GUIDANCE INDICATES POTENTIAL FOR WIND GUSTS NEAR 40-50 MPH
ACROSS THE POCONO PLATEAU AND HIGHER ELEVATIONS OF NORTHWEST NEW
JERSEY DEVELOPING AFTER MIDNIGHT TONIGHT INTO WEDNESDAY
MORNING. THIS WILL BE DUE TO STRONG LOW LEVEL WINDS DEVELOPING
BENEATH AN INVERSION AND THE BERNOULLI EFFECT ACCELERATING WINDS
ACROSS THE RIDGE LINES AND MOUNTAIN PEAKS, AND SIGNIFICANT WIND
GUSTS ARE NOT EXPECTED OUTSIDE OF THESE AREAS. A WIND ADVISORY
MAY NEED TO BE CONSIDERED. ELSEWHERE, GUSTS AROUND 25-35 MPH ARE
FORECAST.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
NORTHWESTERLY FLOW ALOFT WILL CONTINUE TO OVERSPREAD THE AREA
THROUGH THE PERIOD, WITH ONE EMBEDDED SHORTWAVE DEPARTING TO THE
EAST ON WEDNESDAY AND ANOTHER MOVING THROUGH THE REGION ON
THURSDAY. AT THE SURFACE, HIGH PRESSURE CENTERED OVER THE GREAT
LAKES VICINITY WILL SHIFT EASTWARD INTO THE REGION THROUGH THE
DAY WEDNESDAY. THE HIGH'S INFLUENCE WILL BE SHORT LIVED, WITH A
WEAK AREA OF LOW PRESSURE PASSING THROUGH ON CHRISTMAS DAY.
WEDNESDAY WILL LIKELY START WITH MOSTLY CLEAR SKIES, WITH
INCREASING HIGH CLOUDS DURING THE AFTERNOON AS THE NEXT SYSTEM
BEGINS TO APPROACH. HIGH TEMPERATURES LOOK TO BE IN THE LOW TO
MID 40S FOR MOST. FOR THE POCONOS, TEMPERATURES COULD STRUGGLE
TO GET OUT OF THE 30S, WHILE THEY COULD APPROACH 50 ACROSS THE
DELMARVA AND PERHAPS FAR SOUTHERN NJ. WHILE IT WILL BE DRY, IT
DOES LOOK TO BE BREEZY, WITH NORTHWEST WINDS GUSTING IN THE
25-35 MPH RANGE AREAWIDE. A FEW GUSTS OF 40-45 MPH CAN'T BE
RULED OUT ACROSS THE POCONOS. WEDNESDAY NIGHT APPEARS TO BE
MOSTLY CLOUDY, WITH DIMINISHING WINDS. LOWS LOOK TO BE IN THE
LOW 20S ACROSS THE POCONOS AND INTO FAR NORTHWEST NJ, UPPER 20S
FOR MOST OF EASTERN PA AND NJ, AND LOW 30S FOR THE DELMARVA AND
THE URBAN CORRIDOR.
WITH THE WEAK LOW PRESSURE SYSTEM MOVING THROUGH ON THURSDAY,
THERE WILL BE A CHANCE FOR A LITTLE LIGHT RAIN OR SNOW FOR THE
SOUTHERN HALF OR SO OF THE AREA DURING THE MORNING HOURS.
AMOUNTS APPEAR NEGLIGIBLE AT THIS TIME, AND ANY LIGHT
PRECIPITATION THAT DOES OCCUR SHOULD DEPART BY AFTERNOON. SKIES
WILL REMAIN MOSTLY CLOUDY, HOWEVER. HIGH TEMPERATURES LOOK TO BE
IN THE LOW-MID 40S FOR MOST, SLIGHTLY COOLER IN THE POCONOS AND
SLIGHTLY WARMER IN THE DELMARVA. SKIES LOOK TO REMAIN MOSTLY
CLOUDY THURSDAY NIGHT, WITH LOWS IN THE UPPER TEENS TO LOWER 20S
ACROSS MUCH OF EASTERN PA AND NORTHERN NJ, AND MID TO UPPER 20S
FOR SOUTHEASTERN PA, SOUTHERN NJ, AND THE DELMARVA.
LONG TERM /FRIDAY THROUGH MONDAY/
SIGNIFICANT UNCERTAINTY REMAINS REGARDING THE EXTENDED
FORECAST, BUT THERE IS HIGH CONFIDENCE THAT MULTIPLE STORM
SYSTEMS WILL IMPACT THE AREA AS A VERY PROGRESSIVE PATTERN TAKES
SHAPE.
IT APPEARS THAT A SHORTWAVE EMBEDDED WITHIN NORTHWESTERLY FLOW
ALOFT WILL PASS THROUGH THE AREA FRIDAY AFTERNOON INTO SATURDAY
MORNING. AT THE SURFACE, LOW PRESSURE LOOKS TO TRACK OUT OF THE
OHIO VALLEY AND TOWARDS OUR REGION, WITH ADDITIONAL SURFACE
CYCLOGENESIS POSSIBLE SOMEWHERE OFF THE EASTERN SEABOARD FRIDAY
NIGHT. THERE REMAINS SIGNIFICANT SPREAD AMONGST GEFS AND EPS
MEMBERS IN WHERE THIS WILL OCCUR, RANGING FROM JUST EAST OF
NORTH CAROLINA TO EAST OF THE NEW JERSEY COASTLINE. WHERE THIS
OCCURS WILL DEPEND IN LARGE PART ON A STRONG AREA OF HIGH
PRESSURE CENTERED OVER QUEBEC, AND HOW QUICKLY IT RETREATS
NORTHEASTWARD. LATEST TRENDS HAVE BEEN FAVORING A STRONGER HIGH,
AND THEREFORE LOW PLACEMENT FARTHER SOUTH. WIDESPREAD
PRECIPITATION IS EXPECTED ACROSS OUR AREA WITH THIS SYSTEM, AND
WITH THE TRENDS TOWARDS A STRONGER AND SLOWER RETREATING HIGH,
THE FORECAST HAS ALSO CONTINUED TO TREND COLDER. IT IS TOO SOON
AND MODEL SPREAD REMAINS TOO HIGH TO SPECULATE ON SPECIFICS, BUT
THE ODDS OF IMPACTFUL WINTRY PRECIPITATION ARE INCREASING.
THE PATTERN LOOKS TO REMAIN VERY UNSETTLED INTO EARLY NEXT
WEEK, WITH MODEL GUIDANCE INDICATING ANOTHER STORM SYSTEM
IMPACTING THE AREA SUNDAY INTO MONDAY. THIS COULD ONCE AGAIN
BRING A VARIETY OF WEATHER IMPACTS AND PRECIPITATION TYPES TO
THE REGION. HOWEVER, AS PREVIOUSLY STATED, CONFIDENCE IS
CURRENTLY QUITE LOW AT THIS RANGE.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...MVFR CEILINGS DEVELOPING THROUGH 15Z AS LIGHT SNOW AND
LIGHT RAIN SPREAD INTO THE REGION. MVFR VISIBILITY LIKELY, WITH
IFR MOST LIKELY FOR RDG/ABE. CEILINGS LOWERING TO IFR FOR I-95
TERMINALS AND NORTH FOR AT LEAST A BRIEF PERIOD BY 18Z OR SO.
ACY/MIV LIKELY STAY MVFR. PRECIPITATION ENDING BETWEEN 18-21Z
AT THE LATEST, THOUGH SOME LIGHT DRIZZLE OR FOG/MIST MAY LINGER
FOLLOWING PRECIP CESSATION. SOUTH TO SOUTHWEST WINDS NEAR 5-10
KTS. LOW CONFIDENCE ON THE EXACT TIMING OF RESTRICTIONS
DEVELOPING AND IMPROVING AS THE DAY PROGRESSES, BUT HIGH
CONFIDENCE IN AT LEAST MVFR CONDITIONS OCCURRING EVERYWHERE.
TONIGHT...ANY LINGERING MVFR CEILINGS LIFTING AND SCATTERING
OUT TO VFR BY 03Z. WESTERLY WINDS INCREASING TO 10-15 KTS AND
SHIFTING NORTHWEST BY 06Z WITH GUSTS 20-25 KTS. HIGH CONFIDENCE.
OUTLOOK...
WEDNESDAY THROUGH WEDNESDAY NIGHT...VFR. BREEZY NORTHWEST WINDS
DURING THE DAY ON WEDNESDAY, WITH GUSTS 25-30 KT POSSIBLE.
THURSDAY...PRIMARILY VFR. SLIGHT CHANCE (AROUND 20%) OF BRIEF
RESTRICTIONS IN LIGHT RAIN OR SNOW.
THURSDAY NIGHT...VFR. NO SIGNIFICANT WEATHER.
FRIDAY THROUGH SATURDAY...RESTRICTIONS LIKELY WITH WIDESPREAD
PRECIPITATION.
MARINE
MARGINAL ADVISORY CONDITIONS ANTICIPATED TO DEVELOP TODAY
ACROSS THE ATLANTIC COASTAL WATERS AS SOUTHERLY WIND GUSTS
INCREASE TO AROUND 20-25 KTS AND SEAS BUILD TO 3-5 FEET.
CONDITIONS WILL IMPROVE FOR A FEW HOURS THIS EVENING, THEN WINDS
AND SEAS WILL BUILD AGAIN AFTER MIDNIGHT AS A COLD FRONT MOVES
OFFSHORE. NORTHWEST WINDS GUSTING 25- 30 KTS FORECAST BY DAWN
WEDNESDAY WITH SEAS 3-5 FEET.
THE SMALL CRAFT ADVISORY WAS EXTENDED THROUGH TONIGHT INTO
WEDNESDAY FOR THE ATLANTIC WATERS, AND EXPANDED TO INCLUDE
DELAWARE BAY FOR EARLY WEDNESDAY MORNING.
RAIN LIKELY THIS MORNING, THEN FAIR WEATHER WITH NO VISIBILITY
RESTRICTIONS THROUGH TONIGHT.
OUTLOOK...
WEDNESDAY...SCA CONDITIONS EXPECTED WITH NORTHWEST WINDS 20-25
KT AND GUSTS AROUND 30 KT. THERE IS A LOW CHANCE (AROUND 20%) OF
GALES. SEAS 3-5 FEET.
WEDNESDAY NIGHT...NO MARINE HEADLINES ARE CURRENTLY ANTICIPATED
WITH WINDS REMAINING BELOW 25 KT AND SEAS BELOW 5 FEET.
THURSDAY THROUGH THURSDAY NIGHT...SCA CONDITIONS POSSIBLE WITH
SOUTHWEST WINDS INCREASING TO 15-25 KT ON THURSDAY AND SHIFTING
TO NORTHWESTERLY THURSDAY NIGHT. SEAS 3-5 FEET.
FRIDAY THROUGH SATURDAY...SCA CONDITIONS LIKELY WITH NORTHERLY
WINDS 15-25 KT SHIFTING TO EAST-NORTHEASTERLY ON SATURDAY. SEAS
3-5 FEET ON FRIDAY INCREASING TO 4-6 FEET SATURDAY.
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
PAZ054-055.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
PAZ061-062.
NJ...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
NJZ001-007-008.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 AM TO 4 PM EST WEDNESDAY FOR
ANZ430-431.
SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ450>455.
SYNOPSIS...COOPER
NEAR TERM...STAARMANN
SHORT TERM...COOPER
LONG TERM...COOPER
AVIATION...COOPER/STAARMANN
MARINE...COOPER/STAARMANN
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