938
FXUS61 KPHI 151826
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
126 PM EST WED JAN 15 2025
SYNOPSIS
COLD AND DRY ARCTIC HIGH PRESSURE WILL REMAIN IN PLACE TO OUR
SOUTHWEST THROUGH TONIGHT, KEEPING BELOW NORMAL TEMPERATURES
AND DRY CONDITIONS IN PLACE. A WEAK LOW PRESSURE WILL PASS
THROUGH ON THURSDAY, 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 A LITTLE SNOW. A VERY COLD
AIR MASS WILL DOMINATE NEXT WEEK.
NEAR TERM /THROUGH THURSDAY/
LATEST ANALYSIS PLACES HIGH PRESSURE OVER THE OHIO VALLEY,
EXTENDING THROUGH OUR REGION. A WEAK LOW PRESSURE IS DIVING
SOUTHWARD ACROSS ACROSS NORTHWESTERN ONTARIO, AND THIS SYSTEM IS
THE MAIN FOCUS OF THE NEAR TERM.
FOR TONIGHT, A FEW SNOW SHOWERS MAY BE HAD IN THE POCONOS THIS
EVENING THANKS TO THE CONTINUED NORTHWESTERLY FLOW, BUT THESE
SHOULD END AS THE GRADIENT WILL FINALLY SLACKENS OFF WHILE HIGH
PRESSURE SLOWLY SLIDES SOUTHEASTWARD AND WEAKENS. THIS SHOULD
ALSO RESULT IN LESS WIND TONIGHT, BUT TEMPERATURES WILL STILL BE
QUITE COLD. MOST LOCALES END UP IN THE TEENS, WITH A FEW SPOTS
IN THE SINGLE DIGITS, WHILE THE WARMEST LOCALES NEAR THE COAST
AND IN THE CITIES STAY NEAR 20.
WE'LL HAVE SOME SUN TO START THURSDAY, BUT CLOUDS WILL SPREAD IN
QUICKLY AS WARM ADVECTION GETS UNDERWAY AHEAD OF THE
AFOREMENTIONED LOW PRESSURE DIVING SOUTHEASTWARD TOWARD US.
EXPECT SOME VERY LIGHT SNOW TO START ENCROACHING ON THE AREA
FROM THE NORTHWEST BY MIDDAY, WITH MUCH OF THE AREA SEEING SOME
LIGHT SNOW BY SUNSET. WE'RE NOT TALKING MUCH HERE, THANKS TO THE
WEAK NATURE OF THE SYSTEM AND THE DRY AIR IN PLACE, GENERALLY
LESS THAN AN INCH, BUT SINCE IT WILL LIKELY BE SNOWING LIGHTLY
NEAR OR DURING RUSH HOUR, ITS NOTABLE FOR POTENTIAL MINOR
IMPACTS, ESPECIALLY WITH RELATIVELY COLD GROUND AND ROAD TEMPS.
THAT SAID, HIGHS LIKELY NUDGE INTO THE LOW 30S FOR MANY BEFORE
THE SNOW BEGINS.
THE SYSTEM PULLS OFF THE COAST THURSDAY NIGHT WITH ANY LINGERING
SNOW SHOWERS ENDING AND SKIES CLEARING TOWARD DAWN. HOWEVER,
THIS SYSTEM IS NOT USHERING IN ANY COLD AIR... IF ANYTHING, THE
AIR MASS MODERATES AS A PACIFIC HIGH STARTS BUILDING IN BEHIND
IT, SO TEMPS LIKELY WON'T BE SIGNIFICANTLY COLDER THAN
TONIGHT... IN FACT, THEY MAY END UP A LITTLE MILDER.
SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/
TEMPERATURES WILL FINALLY MODERATE BACK TOWARD NORMAL VALUES ON
FRIDAY FOLLOWING CESSATION OF COLD ADVECTION AND AN UPPER RIDGE
AXIS MOVING IN THROUGHOUT THE DAY. THIS IS DUE TO INCREASING
HEIGHTS ALOFT AND AN UPPER RIDGE AXIS PASSING ACROSS THE REGION
INTO THE NIGHT. HIGHS SHOULD BE MAINLY IN THE UPPER 30S TO LOW
40S UNDER MOSTLY SUNNY SKIES. WHILE NOT THE WARMEST OF WINTER
DAYS, IT WILL DEFINITELY BE THE NICEST DAY FOR ANY OUTDOOR
ACTIVITIES FOR THE FORESEEABLE FUTURE. LOWS IN THE MID TO UPPER
20S FRIDAY NIGHT WITH INCREASING CLOUDS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
FOR THE LONG TERM PERIOD THIS WEEKEND INTO NEXT WEEK, EXPECTING
A REBOUND OF TEMPERATURES TO NEAR OR EVEN SLIGHTLY ABOVE NORMAL
INTO THE WEEKEND THANKS TO INCREASING HEIGHTS ALOFT. A WARM
FRONT SHOULD LIFT NORTH THROUGH THE AREA ON SATURDAY, WITH SOUTH
TO SOUTHWEST FLOW AND WARM ADVECTION PUSHING TEMPERATURES INTO
THE LOW TO MID 40S ACROSS MUCH OF THE AREA. WHILE THE MILD
TEMPERATURES WILL PROVIDE BRIEF REPRIEVE FROM THE PROLONGED
FRIGID TEMPERATURES, THE MILDER WEATHER WILL BE ACCOMPANIED BY
PERIODS OF RAIN SHOWERS, MAINLY BY SATURDAY AFTERNOON. ANY
PRECIPITATION WILL DIMINISH INTO LATE SATURDAY NIGHT.
A STRONG ARCTIC FRONT IS EXPECTED TO ARRIVE SOMETIME SUNDAY,
WITH A MUCH COLDER AIRMASS ADVECTING IN BEHIND IT. SOME GUIDANCE
SUGGESTS POTENTIAL FOR A COASTAL SYSTEM LATE SUNDAY INTO EARLY
MONDAY, ALTHOUGH SOME GUIDANCE REMAINS MUCH MORE SUPPRESSED
WITH THIS, KEEPING THE SYSTEM WELL OFFSHORE AT OUR LATITUDE.
HAVE MAINTAINED CHANCE POPS AT THIS TIME, BUT AM SKEPTICAL THIS
POTENTIAL FOR LIGHT ACCUMULATING SNOWFALL WILL PAN OUT AT THIS
POINT. THESE DETAILS SHOULD BECOME A BIT MORE CLEAR WITHIN THE
NEXT DAY OR TWO.
BY MONDAY NIGHT INTO TUESDAY, THE COLDEST AIRMASS SO FAR THIS
SEASON IS EXPECTED TO BE IN PLACE ACROSS A LARGE PORTION OF THE
CONUS FROM THE MIDWEST EASTWARD ACROSS MUCH OF THE NORTHEAST.
850 MB TEMPERATURES IN THE -20C TO -25C RANGE WILL LIKELY SPELL
TEMPERATURES UPWARDS OF 15 TO 20 DEGREES BELOW NORMAL THROUGH HE
MIDDLE OF NEXT WEEK. THIS WOULD MEAN HIGHS NEAR 20 DEGREES AND
LOWS INTO THE SINGLE DIGITS. WIND CHILLS POTENTIALLY BELOW ZERO
AT NIGHT AND IN THE SINGLE DIGITS DURING THE DAYTIME. A PERIOD
OF A FEW DAYS OF WELL BELOW FREEZING TEMPERATURES COULD LEAD TO
SOME COLD WEATHER IMPACTS TO INFRASTRUCTURE, INCLUDING FREEZING
WATER PIPES AND HIGH DEMAND FOR HEATING ENERGY.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR WITH FEW/SCT AFTERNOON CLOUDS AROUND 4000
FT. WEST-NORTHWEST WINDS AROUND 10-20 KT WITH GUSTS 20 TO 25
KT. HIGH CONFIDENCE.
TONIGHT...VFR. WINDS DECREASING AROUND 5-10 KT. HIGH
CONFIDENCE.
THURSDAY...VFR BEFORE 17Z, THEN A PERIOD OF LIGHT SNOW POSSIBLE
AT ALL TERMINALS BETWEEN 17Z TO 03Z WITH POTENTIAL FOR MVFR
CONDITIONS. SOUTHWEST WINDS 5-10 KTS.
OUTLOOK...
FRIDAY...VFR. NO SIGNIFICANT WEATHER EXPECTED. WINDS 10 KTS OR
LESS.
SATURDAY...CEILING AND VISIBILITY RESTRICTIONS LIKELY WITH
PERIODS OF RAIN SHOWERS. LLWS POSSIBLE.
SUNDAY...VFR. NO SIGNIFICANT WEATHER ASIDE FROM BREEZY WINDS.
MARINE
A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL ATLANTIC COASTAL
WATERS AND THE DELAWARE BAY THIS AFTERNOON, LINGERING INTO THIS
EVENING ON THE COASTAL WATERS. NORTHWEST WINDS WILL GENERALLY
BE 15 TO 20 KTS WITH GUSTS UP TO 30 KT AND SEAS OF 4-6 FEET,
SLOWLY DIMINISHING AFTER SUNSET.
DUE TO THE COMBINATION OF COLD AIR/WATER TEMPERATURES, GUSTY
WINDS, AND ENHANCED SEAS, MODERATE FREEZING SPRAY ACCRETION IS
LIKELY BEGINNING AGAIN TONIGHT THROUGH EARLY THURSDAY AS WATER
TEMPS SHOULD BE SUFFICIENTLY COLDER THUS ALLOWING FOR MORE
EFFICIENT ICE ACCRETION. FOR THIS REASON, ANOTHER FREEZING SPRAY
ADVISORY HAS BEEN ISSUED TONIGHT INTO EARLY THURSDAY. NO MARINE
HEADLINES EXPECTED THURSDAY AFTERNOON AND NIGHT, THOUGH SOME
LIGHT SNOW IS POSSIBLE.
OUTLOOK...
FRIDAY THROUGH SATURDAY...NO MARINE HAZARDS EXPECTED. WINDS
10-15 KTS WITH GUSTS UP TO 20 KTS POSSIBLE AT TIMES. SEAS MOSTLY
1-3 FEET. RAIN SHOWERS DEVELOPING LATE SATURDAY, ALONG WITH A
PERIOD OF WIND GUSTS NEAR 25 KTS AND SEAS NEAR 5 FEET POSSIBLE.
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.
FREEZING SPRAY ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
THURSDAY FOR ANZ430-431-450>455.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ANZ450>455.
SYNOPSIS...HOEFLICH/RCM
NEAR TERM...RCM
SHORT TERM...STAARMANN
LONG TERM...STAARMANN
AVIATION...RCM/STAARMANN
MARINE...RCM/STAARMANN
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