477
FXUS61 KPHI 221047
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
547 AM EST THU JAN 22 2026
WHAT HAS CHANGED
CONFIDENCE IS INCREASING IN AN ARCTIC AIRMASS BRINGING
DANGEROUS COLD ON FRIDAY NIGHT WITH WIND CHILLS BELOW ZERO.
CONFIDENCE CONTINUES TO INCREASE IN SIGNIFICANT IMPACTS FROM A
WINTER STORM SATURDAY NIGHT THROUGH EARLY MONDAY ACROSS THE
ENTIRE AREA. AS SUCH, A WINTER STORM WATCH HAS BEEN ISSUED FOR
THE ENTIRE REGION SATURDAY NIGHT THROUGH EARLY MONDAY AFTERNOON.
KEY MESSAGES
1. PRIOR TO THE WEEKEND'S WINTER STORM, AN ARCTIC AIRMASS
POTENTIALLY BRINGS WIND CHILLS BELOW 0 TO NEARLY THE ENTIRE
REGION, POSSIBLY GETTING AS LOW AS -20 IN THE POCONOS ON FRIDAY
NIGHT. COLD WEATHER HEADLINES ARE LIKELY (60-70%).
2. A SIGNIFICANT WINTER STORM APPEARS INCREASINGLY LIKELY
SATURDAY NIGHT THROUGH MONDAY MORNING. SUBSTANTIAL SNOW
ACCUMULATIONS WILL BE POSSIBLE ACROSS MUCH OF THE AREA. SOME
MIXED PRECIPITATION IS EXPECTED AS WELL.
3. BITTER COLD IS EXPECTED TO CONTINUE AFTER THE WINTER STORM
HAS PASSED, WITH TEMPERATURES UNLIKELY TO RISE ABOVE FREEZING
THROUGH WEDNESDAY.
DISCUSSION
KEY MESSAGE 1. PRIOR TO THE WEEKEND'S WINTER STORM, AN ARCTIC
AIRMASS POTENTIALLY BRINGS WIND CHILLS BELOW 0 TO NEARLY THE
ENTIRE REGION, POSSIBLY GETTING AS LOW AS -20 IN THE POCONOS ON
FRIDAY NIGHT. COLD WEATHER HEADLINES ARE LIKELY (60-70%).
FOLLOWING A BRIEF WARMUP BOTH THURSDAY AND FRIDAY, AN ARCTIC
FRONT WILL USHER IN A VERY COLD AIRMASS. THE FRONT COMES THROUGH
DURING THE DAY ON FRIDAY, WITH STRONG COLD-AIR ADVECTION
SETTING UP IN ITS WAKE. 850 MB TEMPERATURES DROP TO -15 TO
-25 C ON FRIDAY NIGHT. THE RESULT WILL BE TEMPERATURES
DROPPING FROM THE MID TO UPPER 30S FRIDAY AFTERNOON DOWN INTO
THE SINGLE DIGITS (OR EVEN BELOW ZERO IN THE POCONOS).
IN ADDITION TO TEMPERATURES TANKING, WINDS WILL PICK UP IN THE
WAKE OF THE FRONT, DRIVEN BY A TIGHT PRESSURE GRADIENT THAT SETS
UP WITH A VERY STRONG INCOMING ARCTIC HIGH DIVING IN FROM
CANADA INTO THE NORTHERN PLAINS AND LOW PRESSURE DEPARTING.
POST- FRONTAL GUSTS WILL BE AROUND 20-25 MPH, GUSTING UP TO
30-35 MPH OR SO. THE COMBINATION OF SINGLE DIGIT TEMPERATURES
AND WIND GUSTS IN THE 20S BRINGS WIND CHILLS BELOW ZERO FOR MOST
OF THE REGION. WITH TEMPERATURES COLDER AND WINDS A BIT
STRONGER IN THE SOUTHERN POCONOS, WIND CHILLS COULD GET AS LOW
AS -20, WHICH IS GUIDANCE FOR AN EXTREME COLD WARNING. STILL TOO
EARLY TO ISSUE ANY HEADLINES, BUT WOULD PUT THE PROBABILITY OF
NEEDING COLD WEATHER HEADLINES AROUND 60-70% OR SO.
NOT MUCH WARMING COMES ON SATURDAY AS THE ARCTIC AIRMASS
SETTLES OVER THE NORTHEASTERN US. HIGHS ONLY GET INTO THE UPPER
TEENS/LOW 20S REGIONWIDE, MAKING IT QUITE UNCOMFORTABLE OUTSIDE
FOR ANY WINTER STORM PREPARATIONS. LAYER UP BOTH FRIDAY NIGHT
AND SATURDAY AHEAD OF THE STORM IF OUT AND ABOUT!
KEY MESSAGE 2...A SIGNIFICANT WINTER STORM APPEARS INCREASINGLY
LIKELY SATURDAY NIGHT THROUGH MONDAY MORNING. SUBSTANTIAL SNOW
ACCUMULATIONS WILL BE POSSIBLE ACROSS MUCH OF THE AREA. SOME
MIXED PRECIPITATION IS EXPECTED AS WELL.
A CLOSED MID-LEVEL LOW OFF THE SOUTHWESTERN COAST OF CA WILL
GRADUALLY OPEN AND PIVOT NORTHEASTWARD, EVENTUALLY PHASING WITH
THE NORTHERN JET AS IT APPROACHES OUR REGION. THIS WILL PLACE
OUR ENTIRE REGION IN THE LEFT EXIT REGION OF A POTENT TROUGH.
SYNOPTIC SCALE ASCENT IS EXPECTED TO BEGIN OVERSPREADING THE
REGION BY SATURDAY EVENING. AS SURFACE LOW PRESSURE BEGINS TO
APPROACH FROM THE SOUTHWEST, PRECIPITATION IS EXPECTED TO BEGIN
OVERSPREADING THE REGION FROM SOUTHWEST TO NORTHEAST SATURDAY
NIGHT. GIVEN THE VERY COLD AIRMASS IN PLACE INITIALLY,
PRECIPITATION IS EXPECTED TO START AS ALL SNOW. AS THE VERTICAL
COLUMN MOISTENS, SNOW RATES MAY QUICKLY BECOME HEAVY, WITH RAPID
ACCUMULATIONS POSSIBLE.
DURING THE DAY ON SUNDAY, ADDITIONAL SURFACE CYCLOGENESIS IS
EXPECTED OFF THE MID-ATLANTIC COAST, WITH THE SURFACE LOW
TRACKING NORTHEASTWARD. THE PRIMARY REMAINING UNCERTAINTY WITH
THIS FORECAST IS THE EXACT LOW TRACK. IN GENERAL, GUIDANCE
CONTINUES TO SUGGEST A LOW TRACK FAIRLY TO THE COAST, WITH THE
GFS AS A RELATIVE OUTLIER A LITTLE BIT FARTHER OUT TO SEA. GIVEN
THIS LOW TRACK, IT IS BECOMING INCREASINGLY LIKELY THAT SLEET,
FREEZING RAIN, AND EVEN PLAIN RAIN WILL ENTER THE PICTURE FOR
PARTS OF THE AREA DURING THE DAY ON SUNDAY. RIGHT NOW, THIS
APPEARS MOST LIKELY FROM ABOUT THE PHILADELPHIA METRO AND SOUTH,
AND PERHAPS FARTHER NORTH FOR THE COASTAL PLAIN. WHILE THIS
COULD DECREASE SNOW TOTALS SOME, EXACTLY WHERE MIXING OCCURS
REMAINS UNCERTAIN, AND CONFIDENCE REMAINS HIGH IN SIGNIFICANT
SNOW ACCUMULATIONS. IN ADDITION, MIXED PRECIPITATION WOULD STILL
CAUSE SIGNIFICANT ISSUES. FOR THIS REGION, DESI PROBABILITIES
OF EXCEEDANCE FOR WARNING CRITERIA SNOW (5 INCHES) ARE OVER 90%.
DEPENDING ON HOW SOON, AND TO WHAT EXTENT, MIXING OCCURS,
AMOUNTS COULD EXCEED 10 INCHES FOR THIS AREA. OUTSIDE OF THE
AFOREMENTIONED AREAS, ALL SNOW IS EXPECTED, WITH SIGNIFICANT
ACCUMULATIONS LIKELY. DESI PROBABILITIES OF EXCEEDANCE FOR
WARNING LEVEL SNOW (6 INCHES) ACROSS THE REMAINDER OF OUR
EASTERN PA AND NORTHERN NJ COUNTIES ARE OVER 90%. IN FACT,
PROBABILITIES OF EXCEEDING 10 INCHES ARE 70-90%.
WHILE THIS EVENT REMAINS A FEW DAYS OUT, CONFIDENCE IS HIGHER
THAN USUAL FOR THIS RANGE IN SIGNIFICANT IMPACTS ACROSS THE
REGION. SPECIFICS WILL CONTINUE TO BE REFINED AS THE EVENT
APPROACHES, BUT CONFIDENCE IS HIGH ENOUGH IN WARNING LEVEL SNOW
TO ISSUE A WINTER STORM WATCH FOR THE ENTIRE AREA, STARTING AT 7
PM SATURDAY AND CONTINUING THROUGH EARLY MONDAY AFTERNOON. STAY
TUNED FOR FUTURE UPDATES AS THIS HAS THE POTENTIAL TO BE A VERY
IMPACTFUL STORM FOR MUCH OF THE AREA.
KEY MESSAGE 3...BITTER COLD IS EXPECTED TO CONTINUE AFTER THE
WINTER STORM HAS PASSED, WITH TEMPERATURES UNLIKELY TO RISE
ABOVE FREEZING THROUGH WEDNESDAY.
AFTER THE LOW PRESSURE SYSTEM DEPARTS ON MONDAY, HIGH PRESSURE
WILL BUILD INTO THE REGION. INITIALLY, A FAIRLY TIGHT PRESSURE
GRADIENT IS EXPECTED WITH STRONG COLD AIR ADVECTION AND BREEZY
CONDITIONS MONDAY AFTERNOON INTO TUESDAY. TEMPERATURES ARE
EXPECTED TO REMAIN BELOW FREEZING ACROSS THE ENTIRE AREA THROUGH
WEDNESDAY. IN FACT, MANY LOCATIONS MAY ONLY RISE INTO THE LOW-
MID 20S. MONDAY NIGHT AND TUESDAY NIGHT ARE OF PARTICULAR
CONCERN, WITH LOW TEMPERATURES IN THE SINGLE DIGITS AREAWIDE.
GIVEN THE EXPECTED BREEZY CONDITIONS, WIND CHILLS COULD BE BELOW
ZERO ACROSS THE ENTIRE AREA DURING THE NIGHTTIME HOURS, AND
ONLY RISE INTO THE LOW-MID TEENS DURING THE DAY. THIS TYPE OF
PROLONGED COLD COULD BE QUITE DANGEROUS, PARTICULARLY IF
SPENDING EXTENDED PERIODS OF TIME OUTDOORS WITHOUT PROPER
CLOTHING. ONE FINAL NOTE IS THAT WITH SIGNIFICANT SNOW COVER
POTENTIALLY IN PLACE, WINDS COULD CAUSE SOME BLOWING AND
DRIFTING OF THE SNOW, AND TEMPERATURES COULD POTENTIALLY BE EVEN
COLDER THAN CURRENTLY FORECASTED. TRENDS WILL BE MONITORED IN
THE COMING DAYS.
AVIATION /12Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS...
TODAY...VFR. CLOUD COVER CLEARS OUT IN THE MORNING WITH
SCATTERED AFTERNOON CLOUDS. WINDS GENERALLY OUT OF THE
WEST/SOUTHWEST AROUND 5-10 KT TO START, INCREASING TO AROUND
10-15 KT WITH GUSTS 20-30 KT OR SO OUT OF THE WEST/NORTHWEST.
GUSTS DIMINISHING QUICKLY BETWEEN 21Z-23Z. HIGH CONFIDENCE IN
PREVAILING VFR, MODERATE CONFIDENCE IN TIMING AND MAGNITUDE OF
WIND SHIFTS AND INCREASES.
TONIGHT...VFR. WESTERLY WINDS 5 TO 10 KT. HIGH CONFIDENCE.
OUTLOOK...
FRIDAY THROUGH FRIDAY NIGHT...VFR. WIND GUSTS 20-30 KT OUT OF
THE NORTHWEST EXPECTED.
SATURDAY...VFR. NO SIGNIFICANT WEATHER.
SATURDAY NIGHT...VFR EARLY, WITH SUB-VFR CONDITIONS BECOMING
INCREASINGLY LIKELY WITH TIME AS SNOW MOVES INTO THE AREA FROM
SOUTHWEST TO NORTHEAST.
SUNDAY THROUGH SUNDAY NIGHT...SUB-VFR CONDITIONS EXPECTED IN
PERIODS OF SNOW. SOME MIXED PRECIPITATION WILL ALSO BE POSSIBLE
AT KMIV AND KACY.
MONDAY...SUB-VFR CONDITIONS EXPECTED IN PERIODS OF SNOW EARLY,
WITH CONDITIONS IMPROVING LATE.
MARINE
A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 18Z FOR COASTAL
ZONES NORTH OF CAPE MAY AS WIND GUSTS OUT OF THE SOUTHWEST WILL
BE AROUND 25 KT AND SEAS 4 TO 6 FEET. LESSER SEAS AND WINDS
EXPECTED ON THE DELAWARE BAY AND COASTAL ZONES SOUTH OF CAPE
MAY.
SUB-SCA CONDITIONS EXPECTED FROM THIS AFTERNOON THROUGH FRIDAY
MORNING. WINDS OUT OF THE WEST AROUND 10-20 KT AND SEAS 2 TO 4
FEET.
OUTLOOK...
FRIDAY AFTERNOON THROUGH SATURDAY...SCA CONDITIONS EXPECTED
(90-100%) AS WIND GUSTS OUT OF THE NORTHWEST GET TO 25 TO 30 KT.
SEAS 3 TO 5 FEET. WILL WAIT FOR CURRENT SCA TO EXPIRE BEFORE
ISSUING A NEW ONE.
SATURDAY NIGHT...SCA CONDITIONS LIKELY TO DEVELOP LATE WITH
NORTHEAST WIND 20-25 KT AND GUSTS TO NEAR 30 KT. SEAS 3-6 FEET.
SUNDAY THROUGH MONDAY...SCA CONDITIONS LIKELY, WITH PERIODS OF
GALES POSSIBLE. SUNDAY INTO SUNDAY NIGHT, NORTHEAST WIND 20-30
KT WITH GUSTS AS HIGH AS 35 KT AND SEAS INCREASING TO 5-9 FEET.
MONDAY, WIND SHIFTS TO NORTHWESTERLY, REMAINING 20-30 KT WITH
GUSTS AS HIGH AS 35 KT AND SEAS 5-9 FEET. VISIBILITY
RESTRICTIONS ARE LIKELY IN HEAVY PRECIPITATION SUNDAY, WITH
GRADUAL IMPROVEMENT ON MONDAY.
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
AFTERNOON FOR PAZ070-071-101-102-104.
WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY
AFTERNOON FOR PAZ054-055-060>062-103-105-106.
NJ...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
AFTERNOON FOR NJZ016>019-021>025-027.
WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY
AFTERNOON FOR NJZ001-007>010-012>015-020-026.
DE...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
AFTERNOON FOR DEZ001>004.
MD...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH MONDAY
AFTERNOON FOR MDZ012-015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
ANZ450>453.
DISCUSSION...COOPER/HOEFLICH
AVIATION...COOPER/HOEFLICH
MARINE...COOPER/HOEFLICH
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