261
FXUS61 KPHI 031139
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
639 AM EST SAT JAN 3 2026
SYNOPSIS
A WEAK AREA OF HIGH PRESSURE WILL EXTEND FROM THE OHIO VALLEY
TO THE NORTHERN MID-ATLANTIC TODAY. AN AREA OF LOW PRESSURE
TRACKS WELL SOUTH OF OUR REGION TONIGHT INTO EARLY SUNDAY, WHILE
ANOTHER ONE TRACKS TO OUR NORTH. HIGH PRESSURE BUILDS IN FOR
MONDAY BEFORE SHIFTING OFFSHORE INTO TUESDAY. A WEAK SYSTEM WITH
A WARM FRONT SLIDES TO OUR NORTH MONDAY NIGHT, THEN A COLD
FRONT CROSSES OUR AREA LATER WEDNESDAY. HIGH PRESSURE BRIEFLY
ARRIVES ON THURSDAY, THEN A WARM FRONT ARRIVES FROM THE
SOUTHWEST ON FRIDAY.
NEAR TERM /THROUGH TONIGHT/
HIGH PRESSURE NOSING EASTWARD FROM THE OHIO VALLEY WILL KEEP THE
WEATHER DRY BUT CHILLY THROUGH TONIGHT. FOR TODAY, WE'LL START
WITH SOME SUN, BUT TWO APPROACHING LOW PRESSURE SYSTEMS, ONE TO
THE SOUTHWEST AND ANOTHER TO THE NORTHWEST, WILL BRING
INCREASING CLOUDS, SUCH THAT OVERALL, THIS WON'T BE A
PARTICULARLY SUNNY DAY. WINDS WILL BE RELATIVELY LIGHT, MAINLY
5-10 MPH WITH A FEW HIGHER GUSTS, AND WITH TEMPS APPROACHING THE
FREEZING POINT IN MUCH OF THE AREA, EVEN EXCEEDING IT FROM
PHILLY SOUTH, IT WON'T FEEL ALL THAT BAD.
LATEST GUIDANCE HAS PUT MUCH OF OUR REGION IN THE SLOT OF
SINKING AIR BETWEEN THE TWO STORMS PASSING US TONIGHT. GUIDANCE
STILL HOLDS SOME SLIGHT CHANCE POPS ACROSS THE SOUTHERN ZONES,
AND WENT WITH CHANCE POPS ACROSS THE NORTHERN TIER WHERE MORE
GUIDANCE PRODUCES SOME LIGHT SNOW WITH THE NORTHERN LOW
PRESSURE. LOWS MOSTLY 20S, TEENS NW NJ AND THE POCONOS, BUT WITH
LIGHT WINDS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
COLD CONDITIONS CONTINUE AS THE AXIS OF AN UPPER-LEVEL TROUGH
SHIFTS TO OUR EAST SUNDAY MORNING. THE CYCLONIC FLOW ASSOCIATED
WITH THIS TROUGH GRADUALLY EASES SUNDAY NIGHT AND ESPECIALLY
MONDAY. SURFACE LOW PRESSURE IS FORECAST TO BE MOVING FARTHER
OUT TO SEA WELL TO OUR SOUTHEAST AND EAST SUNDAY MORNING,
MEANWHILE A WEAK SYSTEM SLIDES BY TO OUR NORTH. ANY LIGHT SNOW
ASSOCIATED WITH THE LATTER WEAK SYSTEM SHOULD BE OVER WITH BY
DAYBREAK SUNDAY. IN THE WAKE OF THESE SYSTEMS, THE PRESSURE
GRADIENT TIGHTENS AND THIS WILL RESULT IN A NORTHWEST BREEZE
INCREASING DURING THE DAY SUNDAY. THE MODEL FORECAST SOUNDINGS
SHOW STEEPENING LOW-LEVEL LAPSE RATES AND THEREFORE AREAS OF
STRATOCUMULUS SHOULD BE AROUND. IT WILL REMAIN ON THE COLD SIDE
WITH HIGHS IN THE 30S (20S IN THE POCONOS), HOWEVER WIND CHILLS
WILL BE A FACTOR GIVEN THE BREEZE DURING THE DAY. THE WINDS EASE
SUNDAY NIGHT AS AN AXIS OF HIGH PRESSURE SLIDES RIGHT ACROSS
OUR AREA, WITH LOW TEMPERATURES DROPPING INTO THE TEENS TO LOW
20S.
HIGH PRESSURE WILL SHIFT OFFSHORE DURING THE DAY MONDAY. A
SHORTWAVE TROUGH SLIDING EASTWARD FROM THE GREAT LAKES WILL
INCREASE THE WARM AIR ADVECTION AND ASSOCIATED ISENTROPIC LIFT.
THIS SHOULD PRODUCE AN AREA OF MAINLY LIGHT SNOW WHICH COULD
CLIP OUR FAR NORTHERN AREAS MAINLY LATE MONDAY AFTERNOON OR
MONDAY NIGHT. THIS FEATURE LOOKS WEAK AND MOISTURE STARVED AND
THEREFORE PRECIPITATION SHOULD BE LIMITED. HIGHS MONDAY ONCE
AGAIN IN THE 30S (20S IN THE POCONOS TO FAR NORTHWESTERN NEW
JERSEY).
LONG TERM /TUESDAY THROUGH FRIDAY/
SUMMARY...A PATTERN CHANGE USHERS IN MILDER AIR.
SYNOPTIC OVERVIEW...A SHORTWAVE TROUGH WITHIN THE WESTERLY FLOW
ALOFT SLIDES ACROSS THE NORTHEAST AND NORTHERN MID-ATLANTIC
REGIONS WEDNESDAY, POTENTIALLY IMMEDIATELY FOLLOWED BY ANOTHER
ONE. SOME UPPER-LEVEL RIDGING THEN DEVELOPS ACROSS THE EAST
THURSDAY INTO FRIDAY AS A STRONG UPPER-LEVEL TROUGH GRADUALLY
SHIFTS INTO THE PLAINS. AT THE SURFACE, A WARM FRONT IS NEARBY
TUESDAY FOLLOWED BY A COLD FRONT LATER WEDNESDAY. A WARM FRONT
THEN ARRIVES FRIDAY.
FOR TUESDAY AND WEDNESDAY...A WEAK SHORTWAVE SLIDING BY SHOULD
HAVE A WARM FRONT NEAR OUR NORTHERN AREAS TUESDAY. THIS WILL
BOOST AFTERNOON TEMPERATURES TUESDAY INTO THE 40S FOR MUCH OF
THE AREA. AS A SHORTWAVE TROUGH SLIDES ACROSS THE NORTHEAST
WEDNESDAY, A WEAK SURFACE LOW SHOULD BE TIED TO IT. THIS FEATURE
IS ALSO FORECAST TO TRACK TO OUR NORTH, HOWEVER ITS COLD FRONT
MOVES ACROSS OUR AREA LATER WEDNESDAY. THE AMOUNT OF MOISTURE
WITH THIS FRONT IS UNCERTAIN, ESPECIALLY GIVEN THAT THE MAIN
ENERGY MAY END UP LIFTING TO OUR NORTH, THUS LEAVING OUR REGION
WITHIN AN AREA OF MUCH WEAKER FORCING. IF SOME LIGHT
PRECIPITATION OCCURS ESPECIALLY ACROSS OUR NORTHERN AREAS, THEN
SOME FREEZING RAIN CANNOT BE RULED OUT TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING. DAYTIME TEMPERATURES ON WEDNESDAY ARE
FORECAST TO TOP OUT SEVERAL DEGREES ABOVE AVERAGE, WITH HIGHS IN
THE 40S TO EVEN LOW TO MID 50S.
FOR THURSDAY AND FRIDAY...SOME UPPER-LEVEL RIDGING OVERSPREADS
THE EAST WELL AHEAD OF A STRONG UPPER-LEVEL TROUGH OUT IN THE
WEST. AS THAT TROUGH GRADUALLY SHIFTS INTO THE PLAINS, HIGH
PRESSURE INITIALLY OVER OUR AREA THURSDAY QUICKLY SHIFTS
OFFSHORE. SOME SLIGHTLY COOLER AIR SHOULD BE WITH THIS AND ALSO
IN THE WAKE OF A WEAK COLD FRONT. HIGH TEMPERATURES ARE STILL
FORECAST TO BE ABOVE AVERAGE THURSDAY HOWEVER. AS THE WARM AIR
ADVECTION INCREASES THURSDAY NIGHT AND FRIDAY, A WARM FRONT WILL
ARRIVE FROM THE SOUTHWEST. THIS WILL RESULT IN SOME INCREASED
CLOUDINESS ALONG WITH SOME CHANCES FOR RAIN. THE MAIN SYSTEM MAY
BE SLOW TO ARRIVE, AND DEPENDING ON HOW FAR NORTH THE WARM
FRONT GETS, FRIDAY MAY END UP BEING RATHER MILD ACROSS AT LEAST
PARTS OF THE REGION WITH HIGHS NEARING 60 DEGREES IN THE COASTAL
PLAIN.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR. A WEST/NORTHWEST AROUND 5 TO 10 KT WITH INCREASING
CLOUDS. HIGH CONFIDENCE.
TONIGHT...MOSTLY VFR. CHANCE OF SUB-VFR WITH A PERIOD OF LIGHT
SNOW, MOST LIKELY AT KABE. FOR NOW WILL KEEP VCSH IN KABE AND
KRDG TAFS AND KEEP OUT OF REMAINDER. WINDS LIGHT/VARIABLE.
MODERATE CONFIDENCE.
OUTLOOK...
SUNDAY AND MONDAY...VFR. NORTHWEST WIND GUSTS TO AROUND 20
KNOTS DURING THE DAY SUNDAY.
TUESDAY AND WEDNESDAY...A PERIOD OF SUB-VFR CONDITIONS
POSSIBLE.
MARINE
WINDS AND SEAS SHOULD STAY BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH TONIGHT. WINDS OUT OF THE NW AT 5-10 KNOTS WITH SEAS OF
2 FEET TODAY, BOTH DIMINISHING A BIT TONIGHT.
OUTLOOK...
SUNDAY...WIND GUSTS UP TO 25 KNOTS POSSIBLE FOR A TIME.
MONDAY THROUGH WEDNESDAY...THE CONDITIONS ARE ANTICIPATED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...GORSE
NEAR TERM...RCM
SHORT TERM...GORSE
LONG TERM...GORSE
AVIATION...GORSE/RCM
MARINE...GORSE/RCM
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