454
FXUS61 KPHI 192125
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
425 PM EST SUN JAN 19 2025
SYNOPSIS
THE LOW RESPONSIBLE FOR THE WINTRY PRECIPITATION ON SUNDAY WILL
PROGRESS NORTHEASTWARD TO THE CANADIAN MARITIMES BY MONDAY MORNING.
ARCTIC HIGH PRESSURE BUILDS INTO THE OHIO VALLEY LATER MONDAY, THEN
INTO OUR AREA TUESDAY INTO WEDNESDAY. A SYSTEM TRACKS TO OUR SOUTH
AND EAST TUESDAY NIGHT AND WEDNESDAY WITH POSSIBLY ANOTHER ONE AT
THE END OF THE WEEK.
NEAR TERM /THROUGH MONDAY/
LATEST REGIONAL SNAPSHOT SHOWS PRECIP SHIELD FILLING IN ACROSS ALL
OF PA AND BEGINNING TO FILL IN ACROSS NORTHWEST NJ. HEAVY SNOW BANDS
ACROSS SOUTHEAST PA (NORTH AND WEST OF THE PHILLY METRO), LEHIGH
VALLEY, POCONOS, AND NORTHWEST NJ ARE RESULTING IN SNOWFALL RATES
AROUND AN INCH PER HOUR OR MORE, REDUCING VISIBILITIES DOWN TO ONE
QUARTER OF A MILE AT TIMES. LOCALLY HEAVIER SNOWFALL AMOUNTS ARE
POSSIBLE AS A RESULT. NO MAJOR CHANGES TO THE SNOWFALL FORECAST IN
THIS AREA WITH A GENERAL 6-8 INCHES BY THE END OF THE EVENT STILL
ANTICIPATED.
FOR THE I-95 CORRIDOR, THE FORECAST DOES REMAIN ON TRACK WITH A
WINTRY MIX COMING DOWN. TEMPERATURES REMAIN JUST A TAD ABOVE
FREEZING AT THE MOMENT, BUT HAVE BEEN STEADILY DECLINING THROUGH THE
AFTERNOON. SOME HEAVIER POCKETS OF PRECIP ARE JUST BEGINNING TO
FILTER INTO THE REGION FROM SOUTHWEST TO NORTHEAST. AS THE SUN SETS
AND OUR COASTAL LOW CONTINUES TO STRENGTHEN, WE ARE FORECASTING
TEMPERATURES TO FALL OVER THE NEXT FEW HOURS TO ALLOW FOR A
CHANGEOVER TO ALL SNOW LATE THIS AFTERNOON AND INTO THE EVENING.
SNOWFALL AMOUNTS IN THIS AREA HAVE DECREASED SLIGHTLY, BUT LARGELY
REMAIN ON TRACK WITH A GENERAL 3-6 INCHES BY THE TIME SNOW ENDS
LATER TONIGHT.
FOR SOUTHERN NJ AND THE SOUTHERN DELMARVA, SURFACE TEMPERATURES HAVE
BEEN SLIGHTLY WARMER THAN INITIALLY FORECASTED. AS A RESULT, IT MAY
TAKE A LITTLE BIT MORE TIME FOR TEMPERATURES TO COOL LATER THIS
AFTERNOON AND EVENING TO SUPPORT SOME LIGHT SNOW ON THE BACK END OF
THIS SYSTEM. STILL EXPECTING PRECIPITATION TO GRADUALLY FILL IN OVER
THE NEXT SEVERAL HOURS STARTING OFF AS MOSTLY RAIN AND SLOWLY
TRANSITIONING TO A WINTRY MIX AND EVENTUALLY LIGHT SNOW. TOTALS IN
THIS REGION HAVE BEEN REDUCED AS A RESULT OF THE LONGER DURATION
EXPECTED FOR PRECIP TO TRANSITION TO SNOW. GENERALLY EXPECTING LESS
THAN 3 INCHES WITH MOST LOCATIONS SEEING LESS THAN 1 INCH OF TOTAL
ACCUMULATION BY THE TIME THE STORM DEPARTS TONIGHT.
AS THE COASTAL LOW DEPARTS TONIGHT, PRECIP WILL END FROM SOUTHWEST
TO NORTHEAST AND OUR FOCUS WILL SHIFT TO THE DOWNRIGHT BLUSTERY AND
COLD CONDITIONS. WINDS WILL BEGIN TO SURGE LATE THIS EVENING AND
INTO THE OVERNIGHT HOURS FROM THE NORTHWEST WITH GUSTS AS HIGH AS 25-
30 MPH (UP TO 35 MPH ACROSS THE POCONOS), USHERING IN OUR FRIGID AIR
FOR THE WEEK. TEMPERATURES WILL CRATER OVERNIGHT WITH LOWS EXPECTED
IN THE TEENS ACROSS THE REGION, EVEN A FEW SINGLE-DIGITS FOR THE
HIGHER ELEVATIONS. COMBINED WITH THE GUSTY WINDS, WIND CHILLS ARE
EXPECTED TO BE AROUND 0 DEGREES FOR AREAS NORTH AND WEST OF THE I-95
CORRIDOR. THE POCONOS WILL CERTAINLY SEE THE WORST, HOWEVER, WITH A
WIND CHILL VALUES AROUND -10 DEGREES (YES, WE DID MEAN TO SAY TEN
DEGREES BELOW ZERO). FOR THESE AREAS WITH THE HAZARDOUS COLD, A COLD
WEATHER ADVISORY HAS BEEN ISSUED. ELSEWHERE, THE WIND CHILLS WILL
STILL BE DANGEROUSLY LOW AND IN THE SINGLE-DIGITS. THIS RAPID ONSET
COLD IN THE WAKE OF OUR WINTER STORM WILL ALSO BRING UP THE CONCERN
OF SLIPPERY AND ICY CONDITIONS POTENTIALLY PERSISTING EVEN AFTER
PRECIPITATION HAS LONG ENDED. ADDITIONALLY, WINDY CONDITIONS ACROSS
OUR HIGHER ELEVATIONS THAT SAW THE BULK OF THE SNOW EARLIER IN THE
DAY COULD CAUSE AREAS OF BLOWING AND DRIFTING SNOW, POTENTIALLY
COVERING STREETS AND SIDEWALKS THAT HAD ALREADY BEEN CLEARED BEFORE.
THE COLD WILL CONTINUE TO SETTLE IN FOR MONDAY TEMPERATURES
REMAINING WELL BELOW FREEZING FOR THE ENTIRE AREA. DESPITE A MIX OF
SUN AND CLOUDS, HIGHS ARE ONLY EXPECTED TO REACH THE LOW TO MID 20S
WITH ONLY TEENS FOR THE POCONO PLATEAU. WINDS WILL ALSO KEEP IT
BLUSTERY THROUGH THE DAY WITH GUSTS OF 20-30 MPH OUT OF THE
NORTHWEST. WIND CHILLS WILL BE IN THE TEENS TO SINGLE DIGITS AS A
RESULT WITH OUR FRIENDS IN THE POCONOS GETTING THE SHORT END OF THE
STICK WITH BELOW ZERO WIND CHILLS ALL DAY.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
DANGEROUS COLD GRIPS THE REGION WITH COLD WEATHER ADVISORIES ISSUED.
THE BIG WEATHER STORY MONDAY NIGHT INTO WEDNESDAY WILL BE THE
DANGEROUSLY COLD CONDITIONS. STARTING WITH MONDAY NIGHT,
TEMPERATURES DROP INTO SINGLE DIGITS ACROSS THE AREA WITH NEGATIVES
FOR THE POCONOS. WINDS DURING MONDAY NIGHT WILL GUST UPWARDS OF 25
MPH WHICH LEADS TO WIND CHILLS RANGING FROM NEAR ZERO IN DELMARVA TO
THE NEGATIVE TEENS IN THE POCONOS. MOST WILL HAVE NEGATIVE WIND
CHILLS MONDAY NIGHT. DUE TO THESE FORECASTED CONDITIONS, A COLD
WEATHER ADVISORY HAS BEEN ISSUED FOR ALL OF THE AREA FOR THIS
TIMEFRAME. TUESDAY IS QUITE THE COLD DAY WITH HIGHS REACHING TEENS
TO LOW 20S FOR MOST. AS FOR THE WINDS, GUSTS REMAIN UPWARDS OF 15
MPH. THE COMBINATION OF THOSE WINDS AND TEMPERATURES WILL RESULT IN
WIND CHILLS IN THE NEGATIVES FOR THE POCONOS, SINGLE DIGITS FOR THE
LEHIGH VALLEY WITH OTHER LOCATIONS BEING SOMEWHERE IN THE TEENS.
ANOTHER DANGEROUSLY COLD NIGHT IS EXPECTED FOR TUESDAY NIGHT. LOWS
TUESDAY NIGHT WILL BE IN THE NEGATIVES FOR THE POCONOS AND SINGLE
DIGITS ELSEWHERE. WINDS REMAIN 5-10 MPH AND LEADS TO WIND CHILLS IN
THE NEGATIVES AREAWIDE FOR TUESDAY NIGHT. WEDNESDAY HIGHS REACH THE
TEENS FOR MOST AND WINDS ARE GENERALLY 5-10 MPH WHICH LEADS TO WIND
CHILLS IN THE TEENS FOR MOST. ADDITIONAL COLD WEATHER HEADLINES WILL
LIKELY BE NEEDED THIS WEEK GIVEN THESE FORECASTED CONDITIONS.
AS FOR THE WEATHER FEATURES DURING THIS TIME PERIOD, WE HAVE AN
ARCTIC HIGH PRESSURE SYSTEM BUILDING IN THROUGH TUESDAY. MEANWHILE,
AT THE UPPER-LEVELS, A TROUGH MOVES INTO THE REGION FROM TUESDAY
INTO WEDNESDAY MORNING. NOW THIS TROUGH WILL MAKE THINGS A LITTLE
INTERESTING BECAUSE THERE IS A PIECE OF ENERGY ROTATING THROUGH
TUESDAY NIGHT INTO WEDNESDAY MORNING. AT THE SURFACE, THIS IS A LOW
PRESSURE SYSTEM WHICH MOST MODELS KEEP OFFSHORE WITH NO
PRECIPITATION REACHING OUR AREA. RIGHT NOW, ONLY PART OF THE AREA
HAS BEEN SHADED FOR SLIGHT CHANCE TO CHANCE FOR SNOW. THE MODELS
THAT KEEP THE PRECIPITATION OFFSHORE HAVE A STRONGER HIGH IN PLACE
WHILE THE ONES THAT SHOW SOME PRECIPITATION REACHING THE AREA SHOW
WEAKNESS IN THE HIGH ALLOWING THE LOW TO GET CLOSER TO THE COAST.
HIGH PRESSURE IS THE MAIN WEATHER FEATURE FOR WEDNESDAY AND KEEPS
THINGS QUIET WITH WEAK UPPER-LEVEL RIDGING IN THE UPPER-LEVELS.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
TEMPERATURES START TO IMPROVE THURSDAY AND IT CONTINUES INTO THE
WEEKEND.
AFTER A VERY COLD FIRST HALF OF THE WEEK, TEMPERATURES START TO
IMPROVE IN THE LONG TERM. HIGHS ON THURSDAY ARE IN THE UPPER
TEENS TO UPPER 20S ACROSS THE AREA. FOLLOWING THURSDAY, EACH DAY
BUILDS UPON THE PREVIOUS DAY IN TERMS OF HIGH TEMPERATURES.
FOR WEATHER FEATURES, THERE IS STILL THAT HIGH PRESSURE SYSTEM
HAVING ITS INFLUENCE ON OUR REGION. UPPER-LEVEL TROUGHING IS MOVING
INTO THE REGION THURSDAY THROUGH FRIDAY NIGHT AND ANOTHER PIECE OF
ENERGY IS HINTED TO ROTATE THROUGH. ONCE AGAIN, THIS WOULD BE IN THE
FORM OF A LOW PRESSURE SYSTEM. THERE IS STILL A LARGE AMOUNT OF
UNCERTAINTY GIVEN THIS BEING IN THE LONG TERM. MODEL GUIDANCE
SHOWS THE POTENTIAL FOR SOME SNOW TO BRUSH PARTS OF OUR AREA
THURSDAY INTO FRIDAY MORNING. GIVEN THE UNCERTAINTY, SLIGHT
CHANCE TO CHANCE WERE THE EXTENT FOR ANY PRECIPITATION DURING
THAT TIME PERIOD. FOR THE WEEKEND, SATURDAY LOOKS MAINLY DRY
WITH A FEW SHOWERS POSSIBLE BY SUNDAY.
AVIATION /22Z SUNDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS...
REMAINDER OF TODAY...MAINLY IFR. PRECIPITATION CONTINUES TO
OVERSPREAD THE REGION THIS AFTERNOON. ALL SNOW IS EXPECTED AT KRDG
AND KABE. FOR KILG, KPHL, KPNE AND KTTN, MAINLY ALL SNOW IS EXPECTED
BUT ANOTHER BRIEF PERIOD OF MIXED PRECIP (RAIN/SNOW/SLEET) CAN'T BE
COMPLETELY RULED OUT. FOR KMIV AND KACY, SOME LIGHT RAIN TO START
THEN THIS SHOULD MIX WITH SNOW BEFORE CHANGING TO SNOW PRIOR TO
ENDING. A PERIOD OF MODERATE (1/2SM) TO HEAVY SNOW (1/4SM) SNOW IS
PROBABLE AT NEARLY ALL TERMINALS BEFORE IT ENDS. NORTH TO NORTHEAST
WINDS 5-10 KNOTS, THEN BACK TO NORTH/NORTHWEST LATE THIS AFTERNOON
INTO THE EVENING AND INCREASE TO 10- 15 KNOTS. LOW CONFIDENCE WITH
THE TIMING OF PRECIPITATION CHANGES AND LOWER CONDITIONS.
TONIGHT...MAINLY IFR CONDITIONS WITH SNOW TO START THE EVENING THEN
CONDITIONS GRADUALLY IMPROVE TO MVFR THEN VFR AS THE SNOW ENDS.
WIDESPREAD MVFR CONDITIONS LOOK TO RESUME AROUND 01-03Z, WITH
WIDESPREAD VFR BY AROUND 05-07Z. NORTHWEST WINDS NEAR 15 KNOTS WITH
GUSTS 20-25 KNOTS. LOW CONFIDENCE ON THE TIMING DETAILS.
MONDAY...VFR CONDITIONS. WEST-NORTHWEST WINDS 10-15 KNOTS WITH GUSTS
UP TO 20-25 KNOTS. HIGH CONFIDENCE.
OUTLOOK...
MONDAY NIGHT AND TUESDAY...VFR. WEST-NORTHWEST WIND GUSTS
DIMINISHING SOME MONDAY NIGHT AND THEN ESPECIALLY TUESDAY.
TUESDAY NIGHT THROUGH FRIDAY...PREVAILING VFR. SMALL CHANCE (20 -
30%) OF MVFR OR IFR CONDITIONS IN SNOW TUESDAY NIGHT AND AGAIN
THURSDAY NIGHT.
MARINE
GALE WARNING IN EFFECT. WINDS AND SEAS WILL RAMP UP THROUGH TONIGHT
AS A LOW PRESSURE SYSTEM MOVES UP THE COAST AND OUT TO SEA. EXPECT
SMALL CRAFT ADVISORY CONDITIONS THIS AFTERNOON WILL GIVE WAY TO A
PERIOD OF GALE FORCE WIND GUSTS TONIGHT. RAIN WILL CHANGE TO SNOW
OVER THE WATERS TONIGHT BEFORE ENDING. THEN FREEZING SPRAY BECOMES A
CONCERN OVERNIGHT AS TEMPERATURES DROP WITH GUSTY WINDS.
FOR MONDAY, WINDS AT SMALL CRAFT ADVISORY LEVELS CONTINUE ALONG WITH
FREEZING SPRAY.
A FREEZING SPRAY ADVISORY WAS ISSUED FOR ALL MARINE ZONES BEGINNING
LATE TONIGHT THROUGH MONDAY.
OUTLOOK...
MONDAY NIGHT...SCA CONDITIONS. FREEZING SPRAY EXPECTED.
TUESDAY AND WEDNESDAY...A PERIOD OF SCA CONDITIONS ARE POSSIBLE
LATER TUESDAY NIGHT AND WEDNESDAY MORNING. FREEZING SPRAY AT TIMES.
THURSDAY AND FRIDAY...WINDS AND SEAS SHOULD STAY BELOW SCA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY FROM 6 PM MONDAY TO 6 AM EST TUESDAY FOR
PAZ070-071-102-104-106.
WINTER STORM WARNING UNTIL 1 AM EST MONDAY FOR PAZ054-055-
060>062-070-071-101>106.
COLD WEATHER ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
TUESDAY FOR PAZ054-055-060>062-101-103-105.
NJ...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR NJZ012>014-
016>020-027.
COLD WEATHER ADVISORY FROM 6 PM MONDAY TO 6 AM EST TUESDAY FOR
NJZ010-012>027.
WINTER STORM WARNING UNTIL 1 AM EST MONDAY FOR NJZ001-007>010-
015.
COLD WEATHER ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST
TUESDAY FOR NJZ001-007>009.
DE...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR DEZ001.
COLD WEATHER ADVISORY FROM 6 PM MONDAY TO 6 AM EST TUESDAY FOR
DEZ001>004.
MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR MDZ012-015.
COLD WEATHER ADVISORY FROM 6 PM MONDAY TO 6 AM EST TUESDAY FOR
MDZ012-015-019-020.
MARINE...GALE WARNING UNTIL 6 AM EST MONDAY FOR ANZ430-431-450>455.
FREEZING SPRAY ADVISORY FROM 1 AM TO 7 PM EST MONDAY FOR
ANZ430-431-450>455.
SYNOPSIS...JOHNSON
NEAR TERM...MJL
SHORT TERM...GUZZO
LONG TERM...GUZZO
AVIATION...AKL/JOHNSON
MARINE...JOHNSON/MJL
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