093
FXUS61 KPHI 150239
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
939 PM EST SAT DEC 14 2024
SYNOPSIS
STRONG HIGH PRESSURE PROGRESSES EASTWARD ACROSS THE NORTHEASTERN
U.S. BEFORE SHIFTING OFFSHORE SUNDAY NIGHT. A WEAK SYSTEM MOVES
THROUGH SUNDAY NIGHT AND 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.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
NO SIGNIFICANT CHANGES TO THE FORECAST. WILL MAKE SOME MINOR
ADJUSTMENTS TO THE HOURLY GRIDS BASED ON THE LATEST SURFACE OBS.
OTHERWISE, A STRONG AND EXPANSIVE AREA OF HIGH PRESSURE
POSITIONED OVER NEW ENGLAND GRADUALLY MOVES EASTWARD TOWARDS THE
GULF OF MAINE TONIGHT. WITH THE HIGH TO THE NORTH AND INCOMING
LOW PRESSURE TO THE WEST, THERE IS A MODEST GRADIENT RESULTING
IN A LIGHT ONSHORE FLOW THAT WILL CONTINUE THROUGH TONIGHT. WITH
MOSTLY CLEAR SKIES FOR AT LEAST PART OF THE NIGHT THOUGH, THERE
SHOULD BE DECENT RADIATIONAL COOLING CONDITIONS FOR THE FIRST
HALF OF THE OVERNIGHT HOURS, RESULTING IN TEMPERATURES DROPPING
INTO THE MID TO UPPER TEENS NORTH AND WEST OF PHILADELPHIA, WITH
LOW TO MID 20S THROUGH THE PHILLY AREA AND SOUTH JERSEY.
INCREASED CLOUD COVER THIS EVENING WILL RESULT IN WARMER
TEMPERATURES OVER DELMARVA, WHERE UPPER 20S/LOW 30S ARE
EXPECTED. CONTINUED DRY WEATHER EXPECTED.
SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
SUNDAY WILL SEE PLENTY OF CLOUDS THICKENING AND LOWERING ACROSS THE
REGION AS THE DAY WEARS ON WHILE HIGH PRESSURE RETREATS EAST OF NEW
ENGLAND AND A WARM FRONT ACCOMPANIED BY AN UPPER LEVEL LOW
APPROACHES FROM THE WEST-SOUTHWEST. CLOUDS LIKELY KEEP TEMPS FROM
MODERATING MORE THAN THEY MIGHT GIVEN THE FLOW TURNS EASTERLY OFF
THE RELATIVELY MILD OCEAN, SO WHILE HIGHS WILL BE IN THE 40S I-95
SOUTH AND EAST, 30S SHOULD REMAIN NORTHWEST OF I-95.
WARM ADVECTION PRECIP SLOWLY MAKES ITS WAY INTO THE REGION STARTING
SUNDAY EVENING. RIGHT NOW, ODDS APPEAR TO FAVOR MAINLY RAIN FROM I-
95 SOUTH AND EAST, THOUGH WITH A POTENTIALLY DRY AIR MASS STILL IN
PLACE DESPITE THE EASTERLY FLOW, WILL NEED TO WATCH TRENDS CLOSELY
HERE. FARTHER NORTHWEST, A START OF MIXED PRECIP OR SNOW LOOKS MORE
LIKELY WITH THE COLD AIR DAMMING LIKELY TO BE ENHANCED WITH WHATEVER
SLEET AND SNOW FALLS, THOUGH OVERALL AMOUNTS LOOK LIGHT. THIS
BECOMES MORE OF A PROBLEM LATER AT NIGHT INTO MONDAY MORNING AS THE
WARMER AIR TRIES TO INTRUDE BUT MAY BE SHOVED ALOFT, WHICH MAY
RESULT IN A PERIOD OF FREEZING RAIN ACROSS MOST LOCALES NORTHWEST OF
I-95 BEFORE ANY CHANGE TO PLAIN RAIN. CONFIDENCE IN WINTRY
PRECIPITATION IS HIGHEST OVER THE SOUTHERN POCONOS AND NW NJ WHERE
WE'VE ISSUED A WINTER WEATHER ADVISORY WITH THIS UPDATE FOR CARBON
AND MONROE COUNTIES IN PA AND SUSSEX CO IN NJ. GENERALLY EXPECT
UPWARDS OF 1 TO 3 INCHES OF SNOW OVER THE SOUTHERN POCONOS BEFORE
PRECIPITATION STARTS TO TRANSITION...EVENTUALLY TO ALL RAIN MONDAY
MORNING WITH A PERIOD OF SLEET/FREEZING RAIN LIKELY IN THE
TRANSITION PERIOD. NW NJ WILL LIKELY SEE A BIT LESS THAN THIS. FOR
NOW WE CONTINUE TO KEEP ICE AMOUNTS LIGHT, MAINLY LESS THAN A TENTH
OF AN INCH, BUT HIGHER AMOUNTS ARE POSSIBLE DEPENDING ON JUST HOW
THE SITUATION EVOLVES. THIS WILL BE A TROUBLESOME FORECAST RIGHT UP
UNTIL IT IS HAPPENING, ALMOST CERTAINLY, AND CONFIDENCE IS OVERALL
IN ITS TYPICALLY LOW LEVEL WITH THIS SET UP. TEMPS LIKELY DROP AS
PRECIP MOVES IN AND THEN START TO SLOWLY RISE AS THE EASTERLY FLOW
TRIES TO NUDGE THE COLDER AIR BACK OUT OF THE REGION LATE SUNDAY
NIGHT INTO MONDAY MORNING. LOWS IN THE 20S IN THE POCONOS, 30S THE
REST OF THE REGION EXCEPT RIGHT NEAR THE COAST WHERE 40S SHOULD
PREVAIL.
MONDAY, THE SYSTEM PULLS TO THE EAST AND PRECIP SHOULD GRADUALLY
TAPER AS WARM ADVECTION WANES AND THE UPPER SUPPORT PASSES TO OUR
EAST. HOWEVER IT MAY NOT COMPLETELY END WITH EVEN SOME LIGHT DRIZZLE
AND SHOWERS POSSIBLY LINGERING THROUGH THE AFTERNOON. MEANWHILE,
TEMPS CONTINUE RISING ON THE NOW INCREASINGLY SOUTHEASTERLY FLOW.
HIGHS SHOULD BE ABOVE FREEZING EVEN IN THE POCONOS, WITH 40S FOR THE
NEXT TIER SOUTHWARD AND 50S FROM AROUND I-95 SOUTH AND EAST.
NEXT UPPER TROUGH BRINGS A COLD FRONT INTO THE REGION LATER MONDAY
NIGHT, WITH RAIN CHANCES INCREASING AGAIN. SOUTHERLY FLOW WILL HOLD
TEMPS UP, WITH TEMPS ONLY FALLING A FEW DEGREES FROM THEIR HIGHS ON
MONDAY AFTERNOON. THE FRONT WILL SWEEP OFF THE COAST EARLY TUESDAY
MORNING BRINGING RAIN/SHOWERS TO AN END WITH SUNSHINE AND MILD
TEMPERATURES TO FOLLOW. EXPECT HIGHS TUESDAY MOSTLY IN THE 50S TO
LOW 60S EXCEPT 40S IN THE SOUTHERN POCONOS.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
HIGH PRESSURE MOVES OFFSHORE ON WEDNESDAY WITH A FRONTAL SYSTEM
COMING IN WEDNESDAY NIGHT INTO THURSDAY. WEDNESDAY ITSELF LOOKS
PRETTY DRY AND MILD, WITH HIGHS LOOKING TO BE SEVERAL DEGREES ABOVE
NORMAL (UPPER 40S TO AS HIGH AS 60 OVER SOUTHERN DELAWARE).
A DEEP TROUGH APPROACHES ON WEDNESDAY EVENING WITH A SURFACE LOW
DEVELOPING SOMEWHERE IN THE VICINITY. THIS WILL BRING SOME LIGHT TO
MODERATE RAIN TO THE AREA OVERNIGHT. 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. THE SYSTEM DOES
NOT LOOK OVERLY IMPACTFUL AT THIS TIME, JUST A BENEFICIAL RAIN.
BEYOND THURSDAY, THE FORECAST BECOMES HIGHLY UNCERTAIN. SOME
GUIDANCE WANTS TO KEEP A TRAIN OF SHORTWAVES ROTATING IN THROUGH THE
END OF THE WEEK, KEEPING SOME RAIN/SNOW SHOWERS AROUND WHILE SOME
HAVE HIGH PRESSURE BUILDING IN RESULTING IN DRY WEATHER TO END THE
WEEK. WHAT SOME OF THE LONGER RANGE GUIDANCE IS ALSO SHOWING IS A
POTENTIAL STORM OFF THE COAST THAT IS WORTH WATCHING BUT NOTHING
EVEN CLOSE TO CONCRETE YET, JUST SOMETHING TO KEEP AN EYE ON IT.
STUCK CLOSE TO THE NBM AS A RESULT. THERE IS A BETTER CONSENSUS FOR
TEMPERATURES RIGHT AROUND NORMAL FOR THE END OF THE WEEK INTO THE
WEEKEND.
AVIATION /03Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR. E-NE WINDS 5 KT OR LESS. MODERATE CONFIDENCE.
SUNDAY...VFR. CIGS LOWERING TO 3500 FT AFTER 18Z. MODERATE
CONFIDENCE.
MARINE
NO MARINE HEADLINES EXPECTED THROUGH SUNDAY. WINDS WILL BE OUT
OF THE EAST/NORTHEAST AROUND 10-15 KT AND SEAS 2 TO 3 FEET
THROUGH TONIGHT INCREASING TO 3 TO 4 FEET BY LATE SUNDAY.
OUTLOOK...
SUNDAY NIGHT THROUGH TUESDAY...A PAIR OF SYSTEM WILL BRING SOME
RAIN OVER THE WATERS AS WELL AS A PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS LIKELY BY LATER MONDAY NIGHT INTO TUESDAY DUE TO
INCREASING SOUTHERLY WINDS.
WEDNESDAY...NO MARINE HEADLINES EXPECTED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER WEATHER ADVISORY FROM 7 PM SUNDAY TO 9 AM EST MONDAY
FOR PAZ054-055.
NJ...WINTER WEATHER ADVISORY FROM 10 PM SUNDAY TO 9 AM EST MONDAY
FOR NJZ001.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...AKL/FITZSIMMONS/JOHNSON/RCM
NEAR TERM...HOEFLICH/MPS
SHORT TERM...FITZSIMMONS/RCM
LONG TERM...HOEFLICH
AVIATION...FITZSIMMONS/HOEFLICH/MPS
MARINE...FITZSIMMONS/HOEFLICH
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