587
FXUS61 KPHI 160245
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
945 PM EST SUN DEC 15 2024
SYNOPSIS
STRONG HIGH PRESSURE ACROSS NEW ENGLAND MOVES OFFSHORE BY TONIGHT. A
WEAK UPPER AIR SYSTEM MOVES ACROSS OUR AREA LATER TODAY AND INTO
EARLY MONDAY, FOLLOWED BY ANOTHER SYSTEM LATER MONDAY INTO EARLY
TUESDAY. HIGH PRESSURE LOOKS TO BUILD IN BRIEFLY LATER TUESDAY
BEFORE ANOTHER LOW PRESSURE SYSTEM AFFECTS OUR REGION LATER
WEDNESDAY INTO THURSDAY. HIGH PRESSURE MOVES IN ON THURSDAY, WITH A
CLIPPER SYSTEM POTENTIALLY MOVING INTO THE AREA TO CLOSE OUT THE
WEEK.
NEAR TERM /THROUGH MONDAY/
PRECIP IS EXPANDING OVER THE AREA, WITH A VARIETY OF TYPES. FOR
THE SOUTHERN POCONOS, MOSTLY SNOW, AND FROM PHILADELPHIA SOUTH,
RAIN. IN BETWEEN IS A MIX OF SNOW AND SLEET, AND THIS WINTRY MIX
WILL PERSIST FOR MOST OF THE OVERNIGHT. FOR THE POCONO PLATEAU,
THIS IS LOOKING LIKE IT WILL BE A MAINLY SNOW EVENT WITH A GOOD
2 TO 4 INCHES NOW FORECAST, WITH A FEW SPOTS PICKING UP CLOSE TO
5 INCHES POSSIBLE. FOR LOWER ELEVATIONS IN THE NORTH, THIS WILL
BE MORE LIKE A 1 TO 2 INCH SNOW EVENT FOLLOWED BY A LIGHT GLAZE
OF ICE THAT SHOULD AMOUNT TO LESS THAN A TENTH OF AN INCH.
OVERNIGHT LOWS WILL RANGE FROM THE 20S TO LOW 30S IN OUR AREAS
IN THE NORTH UNDER THE WINTER WEATHER ADVISORY WHILE AREAS
FARTHER SOUTH NEAR AND SOUTH OF THE I-95 CORRIDOR WILL SEE LOWS
RANGING FROM THE MID 30S TO LOW 40S.
WARM ADVECTION SHOULD CHANGE PRECIP TO ALL RAIN BY MIDDAY MONDAY IF
NOT SOONER, JUST AS PRECIP IS WINDING DOWN, WITH JUST LINGERING
PATCHY LIGHT RAIN AND DRIZZLE IN THE WAKE OF THE SYSTEM FOR THE
AFTERNOON HOURS. TOTAL LIQUID PRECIP AMOUNTS (RAIN IN THE SOUTH,
LIQUID EQUIVALENT RAIN/SNOW/ICE IN THE NORTH) LOOK TO GENERALLY
RANGE FROM ONE TO TWO THIRDS OF AN INCH. THE SOUTHEASTERLY FLOW
SHOULD BRING TEMPS INTO THE 50S SOUTHEAST OF I-95 BY MONDAY
AFTERNOON, WITH 40S FURTHER NORTHWEST, THOUGH THE POCONO PLATEAU MAY
REMAIN STUCK IN THE UPPER 30S.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/
ANOTHER SYSTEM ARRIVES FOR MONDAY NIGHT QUICKLY ON THE HEELS OF THE
FIRST ONE AS ANOTHER UPPER LEVEL TROUGH SWINGS BY TO THE NORTH. THIS
WILL PUSH A WARM FRONT THROUGH MONDAY NIGHT FOLLOWED BY A COLD FRONT
EARLY TUESDAY. THE UPSHOT IS THAT FOLLOWING ANY LULL IN PRECIP
MONDAY AFTERNOON, RAIN/SHOWERS WILL PICK UP AGAIN FOR MONDAY NIGHT
AS THIS FRONTAL SYSTEM MOVES THROUGH. IT WILL BE A MILD NIGHT AS WE
GET INTO THE SYSTEM'S WARM SECTOR SO TEMPERATURES WILL PRETTY MUCH
JUST KEEP GRADUALLY RISING THROUGH MONDAY EVENING INTO THE
OVERNIGHT. THUS, MONDAY NIGHT'S LOWS WILL BE PRETTY CLOSE TO
MONDAY'S HIGHS AND SHOULD BE EXPERIENCED IN THE EVENING. WITH THESE
WARMER TEMPERATURES, NO CONCERNS FOR WINTRY PRECIPITATION WITH THIS
SECOND ROUND. THE RAIN ENDS WEST TO EAST TUE MORNING WITH FAIR MILD
CONDITIONS FOLLOWING FOR THE REST OF THE DAY. HIGHS WILL BE MAINLY
IN THE 50S TO LOW 60S EXCEPT UPPER 40S OVER THE POCONO PLATEAU.
TOTAL RAIN AMOUNTS FOR MONDAY NIGHT / EARLY TUESDAY LOOK TO RANGE
FROM AROUND .50 INCHES NORTH TO JUST SEVERAL HUNDREDTHS OF AN INCH
OVER OUR MOST SOUTHERN AREAS. THE URBAN CORRIDOR SHOULD SEE AROUND
.25 INCHES.
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
HIGH PRESSURE MOVES OFFSHORE ON TUESDAY NIGHT INTO WEDNESDAY WITH A
FRONTAL SYSTEM COMING IN WEDNESDAY NIGHT INTO THURSDAY. TUESDAY
NIGHT AND WEDNESDAY ITSELF LOOKS PRETTY DRY, WITH LOWS ON TUESDAY
NIGHT IN THE 30S. WITH WARM ADVECTION RAMPING UP ON WEDNESDAY AHEAD
OF THE NEXT SYSTEM, HIGHS WILL BE SEVERAL DEGREES ABOVE NORMAL
(UPPER 40S/LOW 50S TO AS HIGH AS 60 OVER SOUTHERN DELAWARE).
A DEEP TROUGH APPROACHES ON WEDNESDAY EVENING WITH A WEAK SURFACE
LOW MOVING NEARLY OVERHEAD. THIS WILL BRING SOME LIGHT TO MODERATE
RAIN TO THE AREA OVERNIGHT INTO THURSDAY MORNING. COLDER AIR WORKING
IN ON THE BACKSIDE OF THE LOW COULD RESULT IN A FEW FLAKES IN THE
POCONOS, BUT THIS IS ANTICIPATED TO BE A RAIN EVENT PRIMARILY
GIVEN THE TRACK OF THE SURFACE LOW. THE SYSTEM DOES NOT LOOK
OVERLY IMPACTFUL AT THIS TIME. JUST A BENEFICIAL RAIN WITH NBM
PROBABILITIES OF RAINFALL OVER AN INCH ONLY AROUND 10-25%
REGION-WIDE.
HIGH PRESSURE MOVES IN FOR THURSDAY WITH TEMPERATURES FALLING BACK
TO NEAR NORMAL. SHOULD BE DRY AND RELATIVELY QUIET OVERALL IN
BETWEEN SYSTEMS.
GUIDANCE HAS STARTED TO KEY IN ON A CLIPPER SYSTEM MOVING THROUGH
FOR THE END OF THE WEEK. STILL FAR OUT BUT CAN'T RULE OUT SOME SNOW
SHOWERS AT POINTS FRIDAY EVENING INTO SATURDAY. THERE IS HIGHER
CONFIDENCE IN A PERIOD OF BELOW NORMAL TEMPERATURES NEXT WEEKEND
HOWEVER IN THE WAKE OF THE CLIPPER.
AVIATION /03Z MONDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS...
TONIGHT...DETERIORATING TO MVFR AND THEN IFR CIGS AND VSBY AS
RAIN OVERSPREADS THE REGION. CONDITIONS LOOK TO DROP TO MVFR
BETWEEN 00Z AND 03Z FOR MOST SITES (CLOSER TO 03Z-05Z FOR SOUTH
JERSEY TERMINALS). FREEZING RAIN AND SNOW POSSIBLE AT THE ONSET
FOR KRDG AND ESPECIALLY KABE, CHANGING TO ALL RAIN BY AROUND
03-05Z AND IFR CONDITIONS BEGIN DEVELOPING AROUND THIS TIME. IFR
CONDITIONS PROGRESS EASTWARD REACHING I-95 TERMINALS AROUND
07-09Z AND SOUTH JERSEY TERMINALS CLOSER TO DAWN. E-NE WINDS 5
KTS OR SO. LLWS POSSIBLE AS SOUTHEASTERLY WINDS AROUND 30-35 KTS
DEVELOP AROUND 2000 FT, MOST LIKELY AFTER 05Z. LOW CONFIDENCE,
PARTICULARLY ON TIMING OF CATEGORY CHANGES.
MONDAY...IFR/LIFR CIGS MOST OF THE DAY WITH SOME CHANCE OF IFR
VSBY TOO DUE TO LINGERING MIST/DRIZZLE. WINDS BECOMING E-SE
AROUND 5-10 KTS. LOW CONFIDENCE.
OUTLOOK...
MONDAY NIGHT AND TUESDAY...MAINLY IFR WITH WIDESPREAD RAIN MONDAY
NIGHT THEN GRADUALLY IMPROVING BACK TO VFR DURING THE DAY ON TUESDAY
AS RAIN ENDS WITH THE PASSAGE OF A COLD FRONT. WIND GUSTS UP AROUND
20 KNOTS POSSIBLE AT TIMES.
TUESDAY NIGHT...VFR. NO SIGNIFICANT WEATHER.
WEDNESDAY...PRIMARILY VFR, THOUGH SOME SHOWERS WORK IN LATE IN THE
DAY, POTENTIALLY RESULTING IN LOWER CEILINGS.
WEDNESDAY NIGHT...SUB-VFR CONDITIONS LIKELY (80-100% CHANCE) WITH
PERIODS OF RAIN AND LOW CLOUDS/VISIBILITIES EXPECTED.
THURSDAY...SUB-VFR CONDITIONS POSSIBLE (40-50%) TO START THE DAY,
BUT IMPROVEMENT TO VFR PROBABLE LATER IN THE DAY.
THURSDAY NIGHT...VFR. NO SIGNIFICANT WEATHER.
FRIDAY...SUB-VFR CONDITIONS POSSIBLE (20-40%) WITH SCATTERED
RAIN/SNOW SHOWERS IN THE FORECAST.
MARINE
SEAS START TO RAMP UP TONIGHT WITH A SMALL CRAFT ADVISORY
BEGINNING IN OUR SOUTHERN OCEAN ZONES THIS EVENING AND EXPANDING
INTO OUR NORTHERN ZONES MONDAY. A PERIOD OF STRONGER SOUTHERLY
WINDS GUSTING UPWARDS OF 25 TO 30 KNOTS WILL FOLLOW FOR MONDAY
NIGHT FOLLOWED BY LINGERING HIGH SEAS INTO TUESDAY. THEREFOR, WE
CONTINUE THE SMALL CRAFT ADVISORY RIGHT THROUGH MUCH OF
TUESDAY.
OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY...NO MARINE HEADLINES EXPECTED.
WEDNESDAY NIGHT THROUGH THURSDAY...SCA CONDITIONS POSSIBLE (40-50%)
WITH WIND GUSTS OUT OF THE WEST/NORTHWEST APPROACHING 25 KT
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR PAZ054-055.
WINTER WEATHER ADVISORY UNTIL 3 AM EST MONDAY FOR PAZ060>062.
NJ...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR NJZ001-008.
WINTER WEATHER ADVISORY UNTIL 6 AM EST MONDAY FOR NJZ007.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON MONDAY TO 6 PM EST TUESDAY FOR
ANZ450.
SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 6 PM EST TUESDAY FOR
ANZ451.
SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR ANZ452>455.
SYNOPSIS...HOEFLICH/OHARA
NEAR TERM...FITZSIMMONS/MPS
SHORT TERM...FITZSIMMONS
LONG TERM...HOEFLICH
AVIATION...AKL/HOEFLICH/MPS
MARINE...FITZSIMMONS/HOEFLICH
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