822
FXUS61 KPHI 161813
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
113 PM EST THU JAN 16 2025
SYNOPSIS
A WEAK AREA OF LOW PRESSURE WILL PASS THROUGH THIS EVENING,
BRINGING A BIT OF LIGHT SNOW. A WARM FRONT WILL LIFT NORTH ON
SATURDAY, BRINGING A SHOT OF WIDESPREAD LIGHT RAINFALL AND
MILDER CONDITIONS. A STRONG ARCTIC COLD FRONT WILL PASS THROUGH
SUNDAY, WITH A WAVE OF LOW PRESSURE RIDING BEHIND IT WHICH MAY
PRODUCE SOME SNOW. A VERY COLD AIR MASS WILL DOMINATE NEXT
WEEK.
NEAR TERM /THROUGH FRIDAY/
WEAK WAVE OF LOW PRESSURE WITH WARM ADVECTION AND DIVERGENCE
ALOFT HAS BEEN JUST ENOUGH FORCING TO GENERATE SOME SNOW
SHOWERS/FLURRIES FROM PHILLY ON NORTH AND WEST AS OF EARLY
AFTERNOON, AND THESE LIKELY TRY TO PROGRESS FURTHER
SOUTHEASTWARD THROUGH THE REST OF THE AFTERNOON INTO TONIGHT AS
THE SYSTEM ULTIMATELY REDEVELOPS OFF THE COAST. THAT
REDEVELOPMENT MAKES A BIT OF A GAP BETWEEN THE MORE SUBSTANTIAL
ACCUMULATING SNOW IN THE POCONOS (JUST AN INCH OR SO) AND SOME
STEADIER PRECIP LIKELY TO FORM OFFSHORE TONIGHT, SO MOST AREAS
GET A COATING AT BEST. TEMPS MOSTLY IN THE 20S TO NEAR 30 THRU
THIS EVENING.
REDEVELOPMENT PROGRESSES OFF THE COAST OVERNIGHT AS THE SYSTEM
PULLS OUT, ALLOWING US TO GRADUALLY CLEAR OUT, BUT A BIT OF
INCREASE IN WINDS MAY KEEP US FROM RADIATING, AND THE AIR MASS
BEHIND THIS SYSTEM ISN'T ARCTIC, ITS ACTUALLY PACIFIC, SO THERE
REALLY ISN'T SIGNIFICANT COLD ADVECTION. LOWS MOSTLY IN THE
VICINITY OF 20.
SUNSHINE WILL COME TO DOMINATE FRIDAY AS THE PACIFIC HIGH BUILDS
TO OUR SOUTHWEST. HIGHS REACH NEAR 40 IN MUCH FO THE AREA.
DEFINITELY THE NICEST DAY FOR OUTDOOR ACTIVITIES IN THE FORECAST
PERIOD, UNLESS YOU PREFER CLOUDS, RAIN, SNOW, OR BRUTAL COLD, AT
LEAST OF BIT OF EACH APPEAR TO BE IN THE OFFING BEYOND FRIDAY.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/
THE STORY OF THIS PERIOD WILL BE THE RELATIVE WARMTH
(ESPECIALLY AS COMPARED TO WHAT WILL BE COMING IN THE LONG
TERM). THANKS TO DEVELOPING LOW LEVEL SOUTHERLY FLOW,
TEMPERATURES BY SATURDAY WILL BE SLIGHTLY ABOVE NORMAL WITH
HIGHS FROM THE MID 30S TO UPPER 40S.
AS THE NEXT COLD FRONT APPROACHES FROM THE WEST, PRECIPITATION
COULD MOVE IN, PRIMARILY IN THE AFTERNOON AND EVENING. THE
PRECIPITATION MAY START AS LIGHT SNOW IN THE POCONOS AND LEHIGH
VALLEY, BUT A QUICK CHANGE TO RAIN IS EXPECTED AND RAIN WILL BE
THE DOMINANT PRECIPITATION TYPE FOR SATURDAY. TOTAL
PRECIPITATION AMOUNTS WILL BE LIGHT, GENERALLY ONE TENTH OF AN
INCH OR LESS, AND AREAS WHERE PRECIPITATION COULD START AS SNOW,
SNOW ACCUMULATION IS EXPECTED TO BE VERY LIGHT - GENERALLY ONLY
A FEW TENTHS OF AN INCH.
LONG TERM /SUNDAY THROUGH THURSDAY/
A STRONG ARCTIC COLD FRONT IS EXPECTED TO ARRIVE SOMETIME
SUNDAY, WITH A MUCH COLDER AIRMASS ADVECTING IN BEHIND IT. STILL
WATCHING THE POTENTIAL FOR A LOW TO DEVELOP ON THE FRONT ONCE
IT IS SOUTH AND EAST OF OUR REGION, WHICH COULD BRING SOME
SNOWFALL TO THE REGION. THE 00Z SUITE OF GUIDANCE BACKED OFF
AGAIN ON THIS POTENTIAL (SIMILAR TO THE TREND FROM 24 HOURS
AGO). GIVEN THAT THERE HAS BEEN POOR RUN TO RUN CONSISTENCY ON
THIS SYSTEM, STAYED CLOSE TO A BLEND OF GUIDANCE AND PREVIOUS
FORECAST. EVEN IF IT DEVELOPS, THE SYSTEM WILL BE RATHER WEAK
AND PROGRESSIVE, SO SNOWFALL TOTALS AND RESULTING IMPACTS APPEAR
MINOR.
MONDAY THROUGH WEDNESDAY WILL FEATURE THE COLDEST AIRMASS SO
FAR THIS SEASON AS ARCTIC AIR IS EXPECTED TO BE IN PLACE ACROSS
A LARGE PORTION OF THE CONUS FROM THE MIDWEST EASTWARD ACROSS
MUCH OF THE NORTHEAST. THE COLDEST DAY APPEARS TO BE TUESDAY,
BEFORE THE AIR MASS MODERATES SOME. HIGHS ON TUESDAY ARE
CURRENTLY FORECAST TO RANGE FROM THE MID SINGLE DIGITS ABOVE
ZERO IN THE SOUTHERN POCONOS TO NEAR 20 AT COASTAL AREAS. ON
BOTH MONDAY NIGHT AND TUESDAY NIGHT, LOWS ARE EXPECTED TO BE IN
THE SINGLE DIGITS (SINGLE DIGITS BELOW ZERO FOR THE HIGHER
TERRAIN, AND SINGLE DIGITS ABOVE ZERO FOR AREAS NEAR AND
SOUTHEAST OF THE FALL LINE.
IT IS INCREASINGLY LIKELY THAT THIS RELATIVELY PROLONGED PERIOD
OF DANGEROUSLY COLD TEMPERATURES WILL HAPPEN, RESULTING IN
IMPACTS TO PEOPLE, ANIMALS, AND INFRASTRUCTURE. DANGEROUSLY COLD
CONDITIONS FOR PEOPLE AND ANIMALS ARE POSSIBLE RESULTING IN AN
INCREASED RISK OF HYPOTHERMIA AND FROST BITE. FOR
INFRASTRUCTURE, IMPACTS COULD INCLUDE FREEZING WATER PIPES AND
HIGH DEMAND FOR HEATING ENERGY. STAY TUNED TO THE LATEST
FORECAST FOR ADDITIONAL INFORMATION AS WE GET CLOSER.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THRU THIS EVENING...AREAS OF LIGHT SNOW WILL BRING INTERVALS OF
MVFR CONDITIONS (CIG/VSBY) WITH A FEW INSTANCES OF IFR, MOST
LIKELY AT KRDG/KABE, BUT ALSO PERHAPS SNEAKING DOWN TO KTTN.
KPHL PROBABLY GOES NO LOWER THAN LOW-END MVFR, BUT THE ODDS OF A
LITTLE IFR BRIEFLY THERE ARE NOT ZERO, JUST VERY LOW. WINDS
MAINLY SOUTHWEST 5-10 KTS. LOW-MODERATE CONFIDENCE.
OVERNIGHT THRU FRIDAY...VFR. WINDS BECOMING WEST-NORTHWEST 5-10
KTS. HIGH CONFIDENCE.
OUTLOOK...
FRIDAY NIGHT...VFR.
SATURDAY AND SUNDAY...PERIODS OF MVFR CONDITIONS POSSIBLE WITH
RAIN (SAT) AND SNOW (SUN).
MONDAY...VFR. GUSTY NW WINDS UP TO 25 KT.
MARINE
SOUTHWEST WINDS TODAY INTO THIS EVENING WITH SOME LIGHT SNOW
POSSIBLE AT TIMES. WINDS BECOME NORTHWESTERLY AS LOW PRESSURE
REDEVELOPS OFF THE COAST AND MOVES OUT TO SEA OVERNIGHT. THUS,
HAVE AN SCA FOR THE LOWER AND MIDDLE OCEAN ZONES FOR LATE
TONIGHT INTO EARLY FRIDAY MORNING. FREEZING SPRAY MAY BE AN
ISSUE DURING THIS PERIOD AS WELL. THEREAFTER, WINDS SHOULD
DECLINE BELOW ADVISORY LEVELS. SEAS THRU THE PERIOD 2-4 FT.
OUTLOOK...
FRIDAY NIGHT AND SATURDAY...WINDS AND SEAS SHOULD STAY BELOW
SCA CRITERIA. HOWEVER, THERE IS A SMALL CHANCE (20 - 30%) FOR A
PERIOD OF SCA CONDITIONS ON THE NORTHERN NJ COASTAL WATERS ON
SATURDAY.
SUNDAY...SEAS ON THE COASTAL WATERS ARE LIKELY TO BUILD NEAR OR
ABOVE 5 FEET DURING THE DAY ON SUNDAY.
SUNDAY NIGHT THROUGH MONDAY (AND BEYOND)...INCREASING CONCERN
FOR A PROLONGED PERIOD OF FREEZING SPRAY STARTING SUNDAY NIGHT
AND CONTINUING INTO MID WEEK. SCA CONDITIONS LIKELY (60-70%) ON
THE COASTAL WATERS, PRIMARILY DUE TO ELEVATED SEAS, THOUGH A
PERIOD OF WIND GUSTS OF 25 TO 30 KT IS POSSIBLE ESPECIALLY
MONDAY, WHICH COULD ALSO RESULT IN SCA CONDITIONS ON THE
DELAWARE BAY.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 9 AM EST
FRIDAY FOR ANZ451>455.
SYNOPSIS...DESILVA/RCM
NEAR TERM...RCM
SHORT TERM...HOEFLICH/JOHNSON
LONG TERM...HOEFLICH/JOHNSON
AVIATION...JOHNSON/RCM
MARINE...JOHNSON/RCM
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