562
FXUS61 KPHI 171745
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1245 PM EST MON FEB 17 2025
SYNOPSIS
HIGH PRESSURE GRADUALLY BUILDS IN FROM THE WEST LATER TUESDAY. A
LOW PRESSURE SYSTEM MAY AFFECT THE AREA WEDNESDAY NIGHT THROUGH
THURSDAY. HIGH PRESSURE THEN RETURNS TO CLOSE OUT THE WEEK.
NEAR TERM /THROUGH TUESDAY/
AS OF 1245 PM, STRONG WEST-NORTHWEST WINDS CONTINUE AS INTENSE
SURFACE LOW PRESSURE (CENTRAL PRESSURE NEAR 960 MB) CONTINUES
TO MOVES INTO THE CANADIAN MARITIMES. THIS ALONG WITH STRONG
HIGH PRESSURE ACROSS THE NORTHERN PLAINS TO THE MISSISSIPPI
VALLEY IS MAINTAINING A TIGHT PRESSURE GRADIENT ACROSS OUR AREA.
PLENTY OF COLD AIR ADVECTION CONTINUES AND WITH 925 MB WINDS OF
40 KNOTS AND 850 MB WINDS OF 45-50 KNOTS, EFFICIENT VERTICAL
MIXING WILL KEEP STRONG WINDS AT THE SURFACE GOING THIS
AFTERNOON. AREAS OF STRATOCUMULUS CONTINUE WITHIN THIS COLD
WEST-NORTHWEST FLOW, HOWEVER WITH THE INJECTION OF EVEN DRIER
AIR THESE CLOUDS ARE ERODING FROM THE SOUTH. THE TEMPERATURES
ARE RUNNING A LITTLE HIGHER THAN FORECAST FOR SOME AREAS,
THEREFORE MADE SOME ADJUSTMENTS TO THE HOURLY TEMPERATURE GRIDS.
THIS RESULTED IN A SMALL BOOST IN THE HIGH TEMPERATURES THIS
AFTERNOON FOR SOME LOCALES. THE STRONG WINDS HOWEVER WILL MAKE
IT FEEL MUCH COLDER.
OTHERWISE, WIND GUSTS WILL BE IN THE 40 TO 50 MPH TODAY AND A
WIND ADVISORY CONTINUES FOR THE ENTIRE AREA. THE EXCEPTION IT
THE SOUTHERN POCONOS WHERE A HIGH WIND WARNING REMAINS GIVEN
WIND GUSTS UP TO 60 MPH ESPECIALLY IN THE ELEVATED TERRAIN.
WINDS WILL SLOWLY SUBSIDE THROUGH TONIGHT AS THE LOW AND COLD
FRONT GET FURTHER AWAY FROM OUR REGION. AS STRONG COLD AIR
ADVECTION CONTINUES AND THE TEMPERATURE INVERSION BECOMES
STRONGER, IT WILL BE HARDER TO MIX THE STRONGEST WINDS OF THE
LOW LEVEL JET DOWN TO THE SURFACE TONIGHT. THE SURFACE PRESSURE
GRADIENT SHOULD FURTHER RELAX TONIGHT INTO TUESDAY AS A RIDGE
BEGINS TO BUILD OVER THE REGION.
THE OTHER BIG STORY OF THIS PERIOD IS GOING TO BE TEMPERATURES. AS
MENTIONED ABOVE, STRONG COLD AIR ADVECTION WILL CONTINUE OVER OUR
REGION. AS A RESULT, MANY AREAS WERE PROBABLY AT OR VERY CLOSE TO
THEIR DAILY HIGH TEMPERATURE FOR TODAY JUST AFTER MIDNIGHT. WIND
CHILL VALUES/APPARENT TEMPERATURE WILL LIKELY BE SEVERAL DEGREES
LOWER THAN THE AIR TEMPERATURE DUE TO THE WINDY CONDITIONS.
OVERNIGHT, WINDS ARE EXPECTED TO STAY UP, AND MID LEVEL CLOUDS MAY
LINGER FOR MOST, IF NOT ALL OF THE NIGHT. CONSEQUENTLY, NOCTURNAL
RADIATIONAL COOLING WILL BE LIMITED. EVEN SO, LOWS IN THE TEENS FOR
MOST PLACES (SINGLE DIGITS FOR HIGHER TERRAIN AREAS) ARE EXPECTED.
WITH THE WIND, WE WILL BE GETTING CLOSE TO BELOW ZERO WIND CHILL
VALUES, BUT CONFIDENCE ISN'T HIGH THAT A COLD WEATHER ADVISORY WILL
BE NEEDED AS IT IS UNCERTAIN HOW STRONG THE WINDS WILL BE BY TONIGHT.
HIGH PRESSURE WILL BE IN CONTROL ON TUESDAY WITH VERY DRY, COLD, AND
BREEZY CONDITIONS.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
HIGH PRESSURE CONTINUES OVER THE REGION TUESDAY NIGHT WITH WELL
BELOW NORMAL TEMPERATURES EXPECTED. GENERALLY ZONAL FLOW ALOFT
SHOULD LEAD TO QUIET SENSIBLE WEATHER WITH WESTERLY FLOW
EVENTUALLY BECOMING NORTHERLY BY WEDNESDAY EVENING. THE WEST
NORTHWEST FLOW COMBINED WITH THE COLD TEMPERATURES WILL LEAD TO
WIND CHILLS ON TUESDAY EVENING AS LOW AS THE MID TEENS BELOW 0
FOR THE HIGHER ELEVATIONS OF THE POCONOS AND IN THE SINGLE
DIGITS ACROSS THE REST OF SOUTHEASTERN PA, NJ AND THE DELMARVA
PENINSULA.
BY WEDNESDAY AFTERNOON HIGH PRESSURE WILL START TO DEPART AS AN
UPPER LEVEL LOW DEVELOPS SOUTH OF THE GREAT LAKES. THIS WILL RESULT
IN AN INCREASE IN CLOUD COVER OVER THE REGION AHEAD OF A LOW
PRESSURE SYSTEM THAT STARTS TO INITIATE WELL TO OUR SOUTH.
TRENDS IN THE EC ENSEMBLE LOW TRACKS AND GEFS LOW TRACKS CONTINUE TO
SHOW THE MOST LIKELY SCENARIO WITH THE LOW IS THAT IS DEVELOPS WELL
TO THE SOUTH AND DOESN'T STRENGTHEN UNTIL THE LOW IS WELL OFFSHORE.
THE 00Z EC SUBSTANTIALLY JUMPED SOUTH BUT THE EC ENSEMBLE SYSTEM WAS
FAIRLY CONSISTENT WITH A SLIGHT SOUTHERN SHIFT RELATIVE THE TO 18Z
SUITE. GIVEN THAT CONSISTENCY IN A MORE SOUTHERN TRACK, THE FORECAST
HAS BEEN SHIFTED FURTHER SOUTH WITH THE SNOW TOTALS HIGHEST
OVER SOUTHERN DELAWARE. BASED ON THE 17/00Z SUITE OF GUIDANCE,
SNOW IS STILL FORECAST TO MOVE OVER PORTIONS OF CENTRAL AND
SOUTHERN JERSEY HOWEVER IF THE 00Z EC PANS OUT, WE MAY SEE A
MOSTLY DRY EVENT.
LONG TERM /THURSDAY THROUGH SUNDAY/
WHILE THE STRONGEST FORCING FOR SNOW WILL BE DURING THE
OVERNIGHT HOURS WEDNESDAY NIGHT INTO THURSDAY MORNING, GUIDANCE
DOES POINT TO A REINFORCING SHOT OF COLD AIR AS THE UPPER LEVEL
CLOSED LOW DIGS INTO THE MID ATLANTIC. THIS SHOULD LEAD TO SOME
LIGHT SHOW FOR PORTIONS OF THE REGION WITH THE SNOW CLEARING
THROUGH THE DAY. BEHIND THE SYSTEM CONDITIONS ACROSS THE MID
ATLANTIC SHOULD BE FAIRLY BENIGN WITH A GRADUAL WARMING TREND
FROM BELOW NORMAL ON THURSDAY TOWARDS NEAR NORMAL SUNDAY AND
MONDAY.
HIGH PRESSURE BUILDS IN FROM THE WEST BEHIND THE DEPARTING
STORM AND WILL EVENTUALLY BUILD OVER THE AREA BY NEXT WEEKEND.
TEMPERATURES WILL SEE A A GRADUAL WARMING TREND FROM AROUND 10
DEGREES BELOW NORMAL ON THURSDAY TOWARDS NEAR NORMAL SUNDAY AND
MONDAY.
AVIATION /18Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THIS AFTERNOON...VFR WITH CLOUD BASES BETWEEN 4000-6000 FEET
AGL. WEST-NORTHWEST WINDS 15-25 KNOTS WITH GUSTS 35-45 KNOTS.
MODERATE CONFIDENCE.
TONIGHT...VFR. WEST-NORTHWEST WINDS DIMINISHING TO 12-15 KNOTS
WITH GUSTS 20-30 KNOTS. SOME TERMINALS HOWEVER MAY LOSE THE
GUSTS FOR A WHILE. MODERATE CONFIDENCE.
TUESDAY...VFR. WEST-NORTHWEST WINDS 15-20 KNOTS WITH GUSTS UP TO
30 KNOTS. MODERATE CONFIDENCE.
OUTLOOK...
TUESDAY NIGHT...VFR. WEST-NORTHWEST WIND DIMINISHING TO NEAR 10
KNOTS.
WEDNESDAY THROUGH THURSDAY...SUB-VFR LIKELY IN SN. IMPROVING
CONDITIONS THURSDAY AFTERNOON.
THURSDAY NIGHT THROUGH FRIDAY...VFR.
MARINE
WINDS HAVE BEGUN TO DIMINISH SLOWLY. GALE WARNING IN EFFECT.
GALES SHOULD CONTINUE AT LEAST THROUGH THE DAY TIME HOURS TODAY.
MAY SEE GALES CONTINUE INTO THE OVERNIGHT, ESPECIALLY FOR THE
COASTAL WATERS ADJACENT TO CENTRAL AND NORTHERN NEW JERSEY, BUT
CONFIDENCE IS LOWER IN HOW LONG THEY WILL LINGER. ONCE WINDS
DROP BELOW GALE FORCE, EXPECT SCA CONDITIONS TO LINGER THROUGH
THE DAY ON TUESDAY.
THE OTHER TWO WEATHER CONCERNS FOR MARINE NAVIGATION ARE FREEZING
SPRAY (PRIMARILY TONIGHT INTO TUESDAY) AND LOW WATER AT THE TIMES OF
LOW TIDE (THROUGH TUESDAY).
OUTLOOK...
TUESDAY AND TUESDAY NIGHT...GENERALLY SCA CONDITIONS WITH A
CHANCE FOR FREEZING SPRAY DUE TO THE STRONG WINDS AND COLD AIR
TEMPERATURES SPREADING OVER THE WATERS.
WEDNESDAY THROUGH WEDNESDAY NIGHT...SUB-SCA CONDITIONS. VSBY
RESTRICTIONS IN SN STARTING WEDENSDAY AFTERNOON.
THURSDAY THROUGH THURSDAY NIGHT...SCA CONDITIONS. VSBY
RESTRICTIONS IN SN THROUGH THURSDAY AFTERNOON.
FRIDAY...LINGERING SCA CONDITIONS POSSIBLE INTO FRIDAY
AFTERNOON.
PHI WATCHES/WARNINGS/ADVISORIES
PA...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR PAZ060>062-070-
071-101>106.
HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR PAZ054-055.
NJ...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NJZ001-007>010-
012>027.
DE...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR DEZ001>004.
MD...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ012-015-019-
020.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ430-431-
453>455.
GALE WARNING UNTIL 6 AM EST TUESDAY FOR ANZ450>452.
SYNOPSIS...MPS
NEAR TERM...GORSE/JOHNSON
SHORT TERM...DEAL
LONG TERM...DEAL
AVIATION...DEAL/GORSE/JOHNSON/MPS
MARINE...DEAL/JOHNSON/MPS
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