678  
FXUS61 KPHI 071459  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
959 AM EST FRI FEB 7 2025  
   
SYNOPSIS  
 
HIGH PRESSURE WILL BRIEFLY RETURN THIS AFTERNOON BEFORE A LOW  
PRESSURE SYSTEM PASSES THROUGH THE REGION LATE SATURDAY INTO  
SATURDAY NIGHT BRINGING ANOTHER ROUND OF MIXED PRECIPITATION TO  
THE AREA. HIGH PRESSURE WILL TEMPORARILY RETURN ON SUNDAY INTO  
MONDAY BEFORE TWO ADDITONAL SYSTEMS APPROACH THE REGION ON  
TUESDAY INTO WEDNESDAY AND THURSDAY INTO FRIDAY.  
 
 
   
NEAR TERM /THROUGH TONIGHT/  
 
10 AM UPDATE...  
TWEAKED SKY COVER, HIGHS AND WINDS UP A BIT FOR TODAY BASED ON  
LATEST OBS. NO MAJOR CHANGES AT THIS TIME.  
 
EARLY MORNING DISCUSSION...  
WARM FRONT OVER THE MID-ATLANTIC HAS MOVED OFFSHORE, AND  
SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHERN DELAWARE HAVE  
MOVED OFFSHORE. COLD FRONT ALSO CONTINUES TO MOVE THROUGH THE  
NORTHEAST. FOG HAS LIFTED AND DISSIPATED, AND LOW CLOUDS HAVE  
LIFTED AS WELL.  
 
BEHIND THE DEPARTING COLD FRONT, HIGH PRESSURE BUILDS IN FROM  
THE WEST. A TIGHT PRESSURE GRADIENT WILL FORM BETWEEN HIGH  
PRESSURE BUILDING IN FROM THE WEST AND LOW PRESSURE NEAR THE  
CANADIAN MARITIMES, AND AS A RESULT, WEST TO NORTHWEST WINDS  
WILL INCREASE TO 15 TO 20 MPH WITH 25 TO 35 MPH GUSTS LATE THIS  
MORNING AND THROUGH THIS AFTERNOON. WINDS DIMINISH FAIRLY  
QUICKLY AFTER SUNSET WITH LOSS OF DIURNAL HEATING. HIGHS TODAY  
WILL RANGE FROM THE UPPER 20S IN THE SOUTHERN POCONOS TO THE MID  
AND UPPER 30S OVER NORTHERN NEW JERSEY AND THE LEHIGH VALLEY TO  
THE LOW 40S IN SOUTHERN NEW JERSEY AND THE DELAWARE VALLEY, AND  
IN THE MID AND UPPER 40S IN DELMARVA. THESE TEMPERATURES ARE A  
COUPLE OF DEGREES SHY OF THE SEASONAL AVERAGE FOR THIS TIME OF  
THE YEAR.  
 
CLEAR AND SEASONABLY CHILLY TONIGHT AS HIGH PRESSURE BUILDS  
EAST AND THE CENTER OF THE HIGH PASSES RIGHT OVER THE AREA. THE  
COMBINATION OF COLD AIR ADVECTION AND RADIATIONAL COOLING WILL  
ALLOW TEMPERATURES TONIGHT TO DROP INTO THE TEENS AND LOW 20S  
FOR MOST OF THE AREA, AND IN THE MID 20S IN DELMARVA.  
 
 
   
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/  
 
ATTENTION DURING THE SHORT TERM PERIOD IS FOCUSED ON THE  
SATURDAY AND SATURDAY NIGHT TIMEFRAME AS THE NEXT LOW PRESSURE  
SYSTEM TAKES AIM AT THE AREA. HIGH PRESSURE WILL SHIFT OFF THE  
MID-ATLANTIC COAST EARLY SATURDAY MORNING AS THE AREA OF LOW  
PRESSURE ACCELERATES OUT OF THE MISSISSIPPI RIVER VALLEY. THIS  
INITIAL SURFACE LOW WILL MOVE EAST INTO THE OHIO VALLEY BY  
SATURDAY NIGHT AS A SECONDARY LOW DEVELOPS OFF THE COAST OF THE  
NC/VA BORDER. THIS SECONDARY LOW WILL THEN DEEPEN WHILE TRACKING  
EAST-NORTHEAST SKIRTING SOUTH OF CAPE COD BY SUNDAY MORNING.  
 
WITH THIS BEING SAID, THE FIRST HALF OF SATURDAY APPEARS TO BE  
DRY AS HIGH PRESSURE STILL REMAINS PARTLY IN CONTROL. THIS WILL  
BE SHORT- LIVED HOWEVER AS PRECIPITATION IS EXPECTED TO MOVE  
INTO AND OVERSPREAD THE AREA FROM SOUTH TO NORTH DURING THE  
AFTERNOON HOURS. WHILE DAYTIME HIGH TEMPERATURES ON SATURDAY ARE  
EXPECTED TO BE IN THE 30S, THERMAL PROFILES SUGGEST THAT ONCE  
PRECIPITATION BEGINS, TEMPERATURES SHOULD DROP TO AROUND/BELOW  
FREEZING. THIS WILL SUPPORT A BRIEF PERIOD OF SNOW ACROSS MUCH  
OF THE REGION LATER SATURDAY AFTERNOON. AS LOW PRESSURE TRACKS  
CLOSER TO THE AREA, WILL SEE A MODEST RAMP-UP IN WARM AIR  
ADVECTION OCCUR AS A WARM NOSE ALOFT AROUND 850-925MB SURGES  
NORTHWARD. SHORT-RANGE GUIDANCE ALSO DEPICTS A CORRIDOR OF  
STRONG FRONTOGENETIC FORCING WILL BE ACCOMPANIED WITH THE  
INCREASE IN WAA. THIS SHOULD ALLOW AN AREA OF HEAVIER  
PRECIPITATION TO DEVELOP BEFORE A CHANGEOVER TO SLEET AND  
FREEZING RAIN OCCURS FROM SOUTH TO NORTH. THIS IS SUPPORTED  
QUITE WELL BY POINT FORECAST SOUNDINGS AS THE DEPTH OF THE WARM  
LAYER INCREASES OVERNIGHT. EVENTUALLY, A CHANGEOVER TO PLAIN  
RAIN IS EXPECTED ACROSS THE DELMARVA AND MUCH OF SOUTHERN NEW  
JERSEY EARLY SUNDAY MORNING. FOR AREAS ACROSS EASTERN  
PENNSYLVANIA (OUTSIDE OF THE PHILADELPHIA METRO) AND NORTHERN  
NEW JERSEY, FROZEN PRECIP WILL LIKELY CONTINUE THROUGH MUCH OF  
THE OVERNIGHT AS COLD AIR AT THE SURFACE HANGS ON A BIT LONGER.  
ONLY THE HIGHEST TERRAIN AREAS OF THE POCONOS AND NORTHERN NEW  
JERSEY MAY REMAIN ALL SNOW.  
 
IN TERMS OF AMOUNTS, THE CURRENT FORECAST CALLS FOR ROUGHLY  
0.50- 0.75" OF LIQUID QPF. BREAKING THIS DOWN INTO SNOW/SLEET  
TOTALS, A COATING TO 1" IS EXPECTED FOR MUCH OF THE DELMARVA, SE  
PA, AND S NJ. FURTHER NORTH, 1-3" OF SNOW IS EXPECTED NORTH OF  
THE PA TURNPIKE UP TOWARD THE I-78 CORRIDOR. ONCE NORTH OF THE  
I-78 CORRIDOR (AND ESPECIALLY NORTH OF I-80), SNOWFALL AMOUNTS  
OF 3-5" ARE EXPECTED. DEPENDING ON HOW MUCH SLEET MIXES IN,  
TOTALS WILL VARY SIGNIFICANTLY. THERE WILL ALSO BE A LARGE SWATH  
OF ICE ACCRETION ACROSS MUCH OF THE AREA. GREATEST POTENTIAL  
FOR ICE ACCUMULATION IN EXCESS OF 0.1" WILL BE ALONG THE I-95  
CORRIDOR UP INTO THE LEHIGH VALLEY. CONSIDERING THIS AND UPON  
COLLABORATION WITH NEIGHBORING FORECAST OFFICES, WINTER WEATHER  
HEADLINES WILL LIKELY BE WARRANTED WITHIN THE NEXT 12 HOURS.  
 
LOW PRESSURE AND PRECIPITATION ARE ANTICIPATED TO EXIT THE  
REGION BY SUNDAY MORNING ALTHOUGH A FEW RESIDUAL RAIN/SNOW  
SHOWERS MAY LINGER THROUGH THE MORNING, ESPECIALLY OVER  
NORTHEAST PA AND NORTHERN NJ. HIGH PRESSURE WILL GRADUALLY BUILD  
IN FROM THE WEST LATE IN THE DAY AND INTO SUNDAY NIGHT, SO  
SUNDAY AFTERNOON AND EVENING ARE ANTICIPATED TO BE DRY.  
TEMPERATURES WILL RETURN TO SEASONABLE LEVELS UNDER A MIX OF SUN  
AND CLOUDS. HOWEVER, SUNDAY WILL BE BLUSTERY AT TIMES WITH WIND  
GUSTS UPWARDS OF 30 MPH AS THE PRESSURE GRADIENT IS MODEST IN  
WAKE OF THE DEPARTING SYSTEM.  
 
 
   
LONG TERM /MONDAY THROUGH THURSDAY/  
 
MINOR ADJUSTMENTS WERE MADE TO THE LONG TERM FORECAST AS THE  
MONDAY THROUGH THURSDAY PERIOD WAS STRICTLY BASIS LATEST NBM  
GUIDANCE. BOTH DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO  
DEPICT A VERY ACTIVE WEATHER PATTERN SHAPING UP NEXT WEEK, WITH  
SEVERAL WEATHER SYSTEMS IMPACTING THE AREA. THE FIRST SYSTEM  
LOOKS TO ARRIVE ON TUESDAY WHERE 01Z/NBM PROBABILITIES CONTINUE  
TO SHOW A 40-60% CHANCE OF OBSERVING SNOWFALL 4 INCHES OR  
GREATER ACROSS MUCH OF THE AREA. THE SECOND SYSTEM WILL BE RIGHT  
ON ITS HEELS ARRIVING ON THURSDAY. IT IS STILL QUITE TOO EARLY  
TO BE CERTAIN ON PRECIPITATION TYPE FOR THIS SYSTEM, BUT  
GUIDANCE DOES SUGGEST THAT THIS MAY FAVOR LIQUID OVER FROZEN.  
REGARDLESS, THERE IS AT LEAST SOME CONFIDENCE IN ENCOUNTERING  
SOME ACCUMULATING SNOWFALL NEXT WEEK ACROSS MUCH OF THE REGION.  
 
 
   
AVIATION /15Z FRIDAY THROUGH TUESDAY/  
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS...  
 
REST OF TODAY...VFR CONDITIONS ON TAP FOR THE REST OF THE DAY.  
W-NW WINDS 15 TO 20 KT WITH 25 TO 30 KT GUSTS. WINDS DIMINISH  
TO AROUND 10 KT PRIOR TO 00Z. MODERATE CONFIDENCE.  
 
TONIGHT...VFR. NW WINDS 5 KT OR LESS. HIGH CONFIDENCE.  
 
OUTLOOK...  
 
SATURDAY THROUGH SATURDAY NIGHT...SUB-VFR CONDITIONS LIKELY.  
PERIODS OF SNOW TRANSITIONING TO SLEET, FREEZING RAIN, AND RAIN  
BY SATURDAY NIGHT.  
 
SUNDAY THROUGH MONDAY NIGHT...MAINLY VFR. NO SIGNIFICANT  
WEATHER EXPECTED.  
 
TUESDAY...SUB-VFR CONDITIONS PROBABLE. PERIODS OF SNOW AND/OR  
RAIN LIKELY.  
 
 
   
MARINE  
 
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR THE OCEAN WATERS  
AND FOR DELAWARE BAY FOR TODAY WITH W-NW WINDS 15 TO 20 KT WITH  
25 TO 30 KT GUSTS. SEAS WILL AVERAGE 5 TO 7 FT. WINDS DIMINISH  
FAIRLY QUICKLY THIS EVENING AFTER SUNSET, AND THEN NW WINDS WILL  
RANGE FROM 10 TO 15 KT TONIGHT ALONG WITH 2 TO 4 FT SEAS. SUB-  
SCA CONDITIONS TONIGHT.  
 
OUTLOOK...  
 
SATURDAY THROUGH SATURDAY NIGHT...NO MARINE HEADLINES EXPECTED.  
PERIODS OF RAIN AND SNOW LIKELY.  
 
SUNDAY...A BRIEF PERIOD OF SCA CONDITIONS ARE POSSIBLE WITH  
WIND GUSTS UP TO 30 KT.  
 
SUNDAY NIGHT THROUGH TUESDAY...NO MARINE HEADLINES EXPECTED.  
 
 
   
PHI WATCHES/WARNINGS/ADVISORIES  
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ430-  
431-450>455.  
 
 
 
 
 
SYNOPSIS...DESILVA/KRUZDLO  
NEAR TERM...MPS/RCM  
SHORT TERM...DESILVA  
LONG TERM...DESILVA  
AVIATION...DESILVA/MPS/RCM  
MARINE...DESILVA/MPS/RCM  
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