029
FXUS61 KPHI 242345
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
645 PM EST SAT JAN 24 2026
WHAT HAS CHANGED
SNOWFALL TOTALS FOR LATE TONIGHT THROUGH SUNDAY NIGHT LOWERED ABOUT
2-4 INCHES ACROSS THE REGION.
GALE WARNING ISSUED FOR ALL MARINE AREAS FOR SUNDAY INTO SUNDAY
NIGHT.
KEY MESSAGES
1. A MAJOR WINTER STORM WILL IMPACT OUR ENTIRE AREA FROM LATE
TONIGHT/EARLY SUNDAY MORNING THROUGH SUNDAY NIGHT. THIS STORM WILL
BRING SIGNIFICANT SNOW AND ICE ACCUMULATIONS TO THE ENTIRE AREA.
2. ARCTIC AIR REMAINS IN PLACE WITH TEMPERATURES BELOW FREEZING
THROUGH NEXT WEEKEND.
DISCUSSION
KEY MESSAGE 1...A MAJOR WINTER STORM WILL IMPACT OUR ENTIRE AREA
FROM LATE TONIGHT/EARLY SUNDAY MORNING THROUGH SUNDAY NIGHT. THIS
STORM WILL BRING SIGNIFICANT SNOW AND ICE ACCUMULATIONS TO THE
ENTIRE AREA.
ARCTIC AIR IS FIRMLY ENTRENCHED ACROSS THE ENTIRE REGION THIS
AFTERNOON AND THAT WILL CONTINUE RIGHT INTO SUNDAY. THIS WILL SET
THE STAGE FOR A WINTER STORM THAT WILL START TO ARRIVE LATE TONIGHT.
A MASSIVE RIBBON OF LARGE SCALE ASCENT ASSOCIATED WITH JET DYNAMICS
AND LOW PRESSURE WILL OVERSPREAD OUR AREA LATE TONIGHT AND
ESPECIALLY DURING SUNDAY. AS THIS EVENT GETS UNDERWAY LATER TONIGHT,
WARM AIR ADVECTION AROUND THE 700 MB LEVEL WILL DRIVE INCREASING
ASCENT FROM SOUTH TO NORTH. THIS WILL RESULT IN A QUICKLY EXPANDING
SNOW SHIELD FROM SOUTH TO NORTH AND EAST TO WEST OVERNIGHT TONIGHT
INTO THE EARLY MORNING HOURS ON SUNDAY. THE AIR MASS IS VERY COLD
AND ALSO VERY DRY TO START, THEREFORE IT WILL TAKE SOME TIME FOR THE
LOWEST LEVELS TO SATURATE FOR SNOW TO REACH THE SURFACE. ONCE THIS
OCCURS, INCOMING IMPRESSIVE 700-850 MB FRONTOGENESIS WILL RESULT IN
INCREASING SNOWFALL RATES FROM SOUTH TO NORTH SUNDAY MORNING INTO
EARLY SUNDAY AFTERNOON. MODEL CROSS SECTIONS SHOW DEEP LIFT CROSSING
THE PRIME SNOW GROWTH AREA FOR ABOUT A 4-7 HOUR WINDOW FROM SOUTH TO
NORTH. IT IS DURING THIS PERIOD OF TIME WHERE THE SNOW WILL BE
FALLING AT LEAST 1-2 INCHES PER HOUR. THIS WILL RESULT IN QUICK
ACCUMULATIONS DURING THE MORNING HOURS, AND LINGERING INTO THE
AFTERNOON HOURS ESPECIALLY NEAR AND NORTH/WEST OF I-95.
AS ONE SURFACE LOW TRACKS UP THE OHIO VALLEY DURING SUNDAY WITH
ARCTIC HIGH PRESSURE NEAR NORTHERN NEW ENGLAND, A NEW LOW IS
FORECAST TO DEVELOP OFF THE MID-ATLANTIC COAST. THE MODEL TREND
CONTINUES TO DEVELOP THIS LOW CLOSER TO THE COAST. THIS RESULTS IN A
STRONG EASTERLY JET NEAR 700 MB ADVECTING IN MILDER AIR. THIS MILDER
AIR MASS WILL INITIALLY BE ABOVE THE ARCTIC AIR, HOWEVER CLOSER TO
THE COAST THE MILDER AIR SHOULD WIN OUT AND EDGE SURFACE
TEMPERATURES ABOVE FREEZING FOR A TIME SUNDAY AFTERNOON AND EARLY
EVENING. THIS WILL ALSO TRANSLATE TO SNOW MIXING WITH AND CHANGING
TO SLEET AND THEN FREEZING RAIN, ESPECIALLY FROM I-95 SOUTH AND
EAST. HOWEVER, SOME SLEET LOOKS LIKE IT WILL MAKE IT ALL THE WAY TO
NEAR THE I-80 CORRIDOR DURING THE PEAK OF THE STORM SUNDAY AFTERNOON
OR EVENING. CLOSER TO THE COAST, AS LONG AS SURFACE TEMPERATURES
RISE ABOVE FREEZING THEN JUST PLAIN RAIN OCCURS. THE FORECAST
CHALLENGE CONTINUES TO BE THE EVOLUTION OF THIS WARM LAYER ALOFT AND
THUS THE CHANGING PRECIPITATION TYPES. THIS TIMING WILL
SIGNIFICANTLY DETERMINE HOW MUCH SNOW ACCUMULATES PRIOR TO ANY
MIXING OR CHANGEOVER. THE MODEL SOUNDINGS SHOW THE WARM LAYER ALOFT
INITIALLY BEING NOT ALL THAT DEEP, THEREFORE IF THE PRECIPITATION
INTENSITY IS HEAVY ENOUGH AND LONGER THEN IT WOULD BE ENOUGH TO COOL
THAT LAYER TO KEEP SNOW GOING LONGER. THIS MAY OCCUR ESPECIALLY THE
FARTHER NORTHWEST ONE GOES ACROSS OUR AREA, HOWEVER THIS IS OF LOWER
CONFIDENCE. THERE WILL ALSO BE A ZONE OF FREEZING RAIN WHERE THE
TRANSITION OCCURS, AND THIS LOOKS TO BE CENTERED RIGHT NEAR THE I-95
CORRIDOR.
THE MAIN CHANGE WITH THIS UPDATE IS LOWERING THE SNOW AMOUNTS BY
ABOUT 2-4 INCHES ACROSS THE ENTIRE AREA. THE NBM SNOWFALL TOTALS
HAVE ALSO BEEN TRENDING DOWNWARD GIVEN THE GUIDANCE SHOWING MORE OF
A MIX OR CHANGEOVER FOR MANY AREAS. WE ARE STILL HITTING WARNING
CRITERIA FOR ALL AREAS AT THIS POINT AND THEREFORE WILL MAINTAIN THE
WINTER STORM WARNINGS. THE START TIMES OF THE WARNING HAS BEEN
DELAYED BY SEVERAL HOURS, BUT LEFT THE END TIMES FOR NOW WHICH MAY
BE TO LONG. SNOW RATIOS WILL BE HIGH TO START GIVEN THE ARCTIC AIR
MASS IN PLACE, HOWEVER THESE WILL THEN DECREASE QUITE A BIT FROM
SOUTH TO NORTH AS THE EVENT CONTINUES ON DURING SUNDAY AND SUNDAY
NIGHT. THIS WILL CHANGE THE CONSISTENCY OF THE SNOW FROM A DRY AND
FLUFFY TYPE TO A MORE MOIST/WET TYPE. IN AREAS THAT HAVE A MIX OR
CHANGE TO SLEET AND/OR FREEZING RAIN WILL HAVE AN ICE LAYER ON TOP
OF THE SNOW WHICH WILL MAKE CONDITIONS MORE DIFFICULT. NOT A LOT OF
CHANGE REGARDING ICE AMOUNTS FROM FREEZING RAIN. THE AMOUNT OF
FREEZING RAIN REALIZED WILL DEPEND ON SMALL TEMPERATURE CHANGES
ALOFT WHETHER IT IS SLEET OR FREEZING RAIN. THE COMBINATION OF SNOW,
SLEET AND FREEZING RAIN WILL RESULT IN MAJOR IMPACTS ACROSS THE
REGION. THERE IS AN INCREASING CONCERN THAT SOME AREAS WILL HAVE A
PROLONGED PERIOD OF ACCUMULATING SLEET.
THE PRECIPITATION TAPERS OFF SUNDAY EVENING WITH SOME DRIZZLE OR
EVEN FREEZING DRIZZLE POSSIBLE. SOME GUIDANCE HAS HINTED AT SOME
LIGHT SNOW OCCURRING AGAIN SUNDAY NIGHT INTO EARLY MONDAY MORNING
BEFORE ENDING. THIS IS OF LOWER CONFIDENCE, BUT IF IT WERE TO OCCUR
ANY ADDITIONAL AMOUNTS LOOK TO BE ON THE LIGHT SIDE. NORTHEAST WINDS
WILL BE INCREASING SOME DURING SUNDAY AND WHERE THE SNOW REMAINS
DRIER COULD LEAD TO SOME BLOWING AND DRIFTING SNOW.
KEY MESSAGE 2...ARCTIC AIR REMAINS IN PLACE WITH TEMPERATURES BELOW
FREEZING THROUGH THE START OF NEXT WEEKEND.
A DEEP LONGWAVE TROUGH WILL REMAIN SITUATED OVER THE EASTERN CONUS
THROUGH THE THE START OF NEXT WEEKEND WHERE SEVERAL SHORTWAVES
EMBEDDED WITHIN IT WILL BRING SEVERAL REINFORCING SHOTS OF COLD
ARCTIC AIR TO THE REGION. AT THE SURFACE, STRONG ARCTIC HIGH
PRESSURE SETTLES OVER THE NORTHERN GULF COAST THROUGH WEDNESDAY,
WHEREAS A COUPLE OF COLD FRONTS ARE ALSO PROGGED TO TRACK THROUGH
THE AREA AS WELL.
IN WAKE OF DEPARTING LOW COASTAL STORM AND HIGH PRESSURE BUILDING
OVER THE DEEP SOUTH, THE RETURN OF VERY COLD AIR IS ANTICIPATED TO
BEGIN MONDAY NIGHT INTO TUESDAY MORNING. A COLD FRONT IS THEN
PROJECTED TO CROSS THROUGH THE AREA TUESDAY NIGHT INTO WEDNESDAY
MORNING, FOLLOWED BY ANOTHER COLD FRONT WEDNESDAY NIGHT INTO
THURSDAY MORNING. ALL IN ALL, PERIODS OF WINDY CONDITIONS ARE
EXPECTED THROUGHOUT THE WEEK WITH GUSTS UP TO 30-35 MPH AT TIMES.
HIGH TEMPERATURES WILL LARGELY REMAIN IN THE TEENS AND 20S WITH LOWS
IN THE SINGLE DIGITS TO EVEN SEVERAL DEGREES BELOW ZERO THROUGHOUT
THE COURSE OF THE WEEK.
AS A RESULT, WIND CHILLS WILL MAINLY RANGE IN THE SINGLE DIGITS TO
TEENS DURING THE DAY. MORE IMPORTANTLY AT NIGHT, WIND CHILLS WILL
BECOME DANGEROUSLY COLD GENERALLY RANGING BETWEEN 0 TO -10 DEGREES
IN MOST AREAS. FOR THE AREAS NORTH AND WEST OF I-95 AND ESPECIALLY
IN THE HIGHER TERRAIN WHERE SNOW PACK IS DEEPER, WIND CHILLS MAY
RANGE BETWEEN -10 TO -25 DEGREES AT TIMES. OVERALL, THIS WILL BE A
PROLONGED PERIOD OF COLD WEATHER, WHERE COLD WEATHER HEADLINES WILL
LIKELY BE WARRANTED IN THE COMING DAYS.
WITH SUCH A LONG DURATION OF BELOW FREEZING TEMPS, DO NOT EXPECT THE
NEW SNOW PACK TO MELT MUCH. ASIDE FOR A SLIGHT CHANCE OF SNOW ON
THURSDAY WITH LOW DEVELOPING OFFSHORE, DRY WEATHER IS EXPECTED.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS...
TONIGHT...VFR CEILINGS, WHICH LOWER OVERNIGHT. SUB-VFR
CONDITIONS SHOULD QUICKLY DEVELOP BETWEEN ABOUT 08-10Z AS SNOW
DEVELOPS. LIGHT AND VARIABLE WINDS AT TIMES TURN TO BE OUT OF
THE NORTHEAST 5-10 KNOTS. LOW CONFIDENCE REGARDING THE TIMING
DETAILS.
SUNDAY AND SUNDAY NIGHT...LIFR/IFR CONDITIONS. SNOW, HEAVY AT TIMES
WITH HOURLY SNOWFALL RATES OF 1-2 INCHES, WILL MIX WITH AND CHANGE
TO SLEET AND FREEZING RAIN AT KILG TO KMIV AND KACY FIRST THEN WORK
NORTHWARD DURING THE AFTERNOON. KABE AND KRDG REMAIN ALL SNOW THE
LONGEST. THE PRECIPITATION LOOKS TO CHANGE TO RAIN FOR A TIME AT
KACY AND KMIV BY LATER SUNDAY AFTERNOON AND EVENING.
NORTHEASTERLY WINDS INCREASE DURING THE MORNING TO 15-20 KNOTS
WITH GUSTS TO 20-25 KNOTS DURING THE AFTERNOON. LOW CONFIDENCE
REGARDING THE TIMING DETAILS FOR THE CHANGING PRECIPITATION
TYPES.
OUTLOOK...
MONDAY...LINGERING SUB-VFR CONDITIONS LIKELY IN THE MORNING WITH
LIGHT SNOW POSSIBLE, IMPROVING TO VFR BY THE AFTERNOON. GUSTY WINDS
UP TO 25-30 KT IN THE AFTERNOON.
MONDAY NIGHT THROUGH THURSDAY...VFR. ASIDE FOR A SLIGHT CHANCE OF
SNOW ON THURSDAY, NO SIGNIFICANT WEATHER EXPECTED.
MARINE
THE CONDITIONS CONTINUE TO DIMINISH THIS AFTERNOON AS ARCTIC HIGH
PRESSURE BUILDS NEARBY. AS LOW PRESSURE DEVELOPS NEAR OUR MARINE
AREA DURING SUNDAY, NORTHEASTERLY WINDS WILL INCREASE. A PERIOD OF
GALE FORCE WIND GUSTS LOOK PROBABLE ESPECIALLY FOR THE NEW JERSEY
ATLANTIC COASTAL WATERS. IT MAY BE MORE MARGINAL SOUTH OF THERE
INCLUDING DELAWARE BAY. GIVEN THAT IT IS CLOSE, WENT AHEAD AND
UPGRADED THE GALE WATCH TO A WARNING FOR SUNDAY INTO SUNDAY EVENING.
OUTLOOK...
MONDAY THROUGH MONDAY NIGHT...SCA CONDITIONS CONTINUING WITH GALES
POSSIBLE ON MONDAY NIGHT. SUSTAINED WINDS OF 20-30 KT WITH GUSTS UP
TO 35 KT. SEAS OF 6-9 FEET. FREEZING SPRAY POSSIBLE.
TUESDAY THROUGH TUESDAY NIGHT...LINGERING SCA CONDITIONS PROBABLE ON
TUESDAY BEFORE DIMINISHING TUESDAY NIGHT. WIND GUSTS UP TO 20-25 KT
AND SEAS OF 3-6 FEET. FREEZING SPRAY POSSIBLE.
WEDNESDAY THROUGH WEDNESDAY NIGHT...NO MARINE HEADLINES EXPECTED.
WINDS UP TO 20 KT AND SEAS OF 2-4 FEET.
THURSDAY...SCA CONDITIONS PROBABLE. WIND GUSTS UP TO 25-30 KT WITH
SEAS OF 2-4 FEET.
CLIMATE
AN IMPACTFUL WINTER STORM BRINGING SIGNIFICANT SNOW
ACCUMULATIONS TO THE AREA IS EXPECTED ON SUNDAY. HERE ARE THE
1-DAY DAILY RECORD TOTALS FOR JANUARY 25TH FROM OUR SNOW
OBSERVING SITES. SOME OF THESE COULD BE CHALLENGED.
JANUARY 25TH DAILY SNOWFALL RECORDS
ALLENTOWN (ABE) 10.4" (1988)
AC AIRPORT (ACY) 8.3" (2000)
PHILADELPHIA (PHL) 8.5" (2000)
READING (RDG) 9.0" (1905)
TRENTON (TTN) 14.0" (1905)
WILMINGTON (ILG) 10.0" (2000)
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER STORM WARNING FROM 2 AM SUNDAY TO 1 PM EST MONDAY FOR
PAZ054-055-060>062-070-071-101>106.
NJ...WINTER STORM WARNING FROM 2 AM SUNDAY TO 1 PM EST MONDAY FOR
NJZ001-007>010-012-015>019-021.
WINTER STORM WARNING FROM 2 AM SUNDAY TO 7 AM EST MONDAY FOR
NJZ013-014-020-022>027.
DE...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST MONDAY
FOR DEZ001>004.
MD...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 1 PM EST MONDAY
FOR MDZ012-015-019-020.
MARINE...GALE WARNING FROM 6 AM TO 6 PM EST SUNDAY FOR ANZ430-431-
452>455.
GALE WARNING FROM NOON SUNDAY TO MIDNIGHT EST SUNDAY NIGHT FOR
ANZ450-451.
DISCUSSION...DESILVA/GORSE
AVIATION...DESILVA/GORSE/GUZZO
MARINE...DESILVA/GORSE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page