601
FXUS61 KPHI 180619
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
119 AM EST TUE FEB 18 2025
SYNOPSIS
HIGH PRESSURE BUILDS IN FROM THE WEST BEFORE SLIDING SOUTH AND
EAST OF THE REGION TUESDAY NIGHT. LOW PRESSURE APPROACHES THE
MID-ATLANTIC AND MOVES OFFSHORE WEDNESDAY THROUGH THURSDAY.
HIGH PRESSURE RETURNS FOR THE END OF THE WEEK AND THIS WEEKEND.
NEAR TERM /THROUGH TONIGHT/
NO MAJOR CHANGES WITH THE FORECAST THROUGH THIS PERIOD. THE COLD
WEATHER ADVISORY IS ON TRACK AS WIND CHILL VALUES AT KMPO ARE
RIGHT AROUND -10 F.
THROUGH THE NEAR TERM, THE MAIN STORY IS GOING TO BE CONTINUED
COLD WITH BREEZY (BUT GRADUALLY DIMINISHING) WINDS. A SURFACE
RIDGE WILL BE BUILDING EASTWARD OVER OUR REGION AND SHOULD BE
THE DOMINANT PATTERN FEATURE FOR OUR AREA UNTIL WEDNESDAY
MORNING. THE COMBINATION OF THIS RIDGE BUILDING IN LEADING TO A
DECREASING SURFACE PRESSURE GRADIENT, AND THE LOW AND MID LEVEL
JETS FINALLY PROGRESSING EASTWARD IS WHAT WILL MAKE THE
DIFFERENCE WITH THE WINDS FINALLY DIMINISHING ESPECIALLY INTO
TONIGHT.
WE COULD ONCE AGAIN GET CLOSE TO COLD WEATHER ADVISORY IMPACTS
IN THE SOUTHERN POCONOS TUESDAY NIGHT, BUT IF WE GET CLOUDS TO
MOVE IN EARLY ENOUGH (AHEAD OF THE LOW THAT WILL BE PASSING TO
OUR SOUTH WEDNESDAY INTO THURSDAY), THEN THAT COULD LIMIT HOW
COLD AREAS GET TONIGHT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY/
HIGH PRESSURE REMAINS OVER THE AREA TUESDAY NIGHT WITH
CONTINUED WELL BELOW NORMAL TEMPERATURES. THE PRESSURE GRADIENT
WILL REMAIN TIGHT ENOUGH FOR WINDS TO AVERAGE 10 TO 15 MPH WITH
GUSTS UP TO 20 MPH FOR MOST OF THE NIGHT, AND THIS SHOULD BE
ENOUGH FOR OPTIMAL RADIATIONAL COOLING CONDITIONS TO DEVELOP,
ALLOWING TEMPERATURES TO DROP FURTHER. STILL QUITE COLD WITH
LOWS IN THE SINGLE DIGITS IN THE SOUTHERN POCONOS AND FAR
NORTHWEST NEW JERSEY, AND IN THE TEENS MOST ELSEWHERE. ALONG
WITH THE ELEVATED WINDS, THIS WILL YIELD WIND CHILL VALUES
POSSIBLY AS LOW AS -15 IN THE HIGHER ELEVATIONS OF THE SOUTHERN
POCONOS, BUT OTHERWISE IN THE SINGLE DIGITS.
HIGH PRESSURE WILL BE OFFSHORE BY WEDNESDAY MORNING.
A CLOSED H5 LOW WILL DIVE INTO THE MIDWEST ON WEDNESDAY,
CARVING OUT AN UPPER TROUGH THAT WILL DIG DOWN INTO THE GULF
COAST STATES. SURFACE LOW PRESSURE WILL DEVELOP OUT AHEAD OF THE
BASE OF THE TROUGH, AND THIS LOW WILL LIFT TOWARDS THE MID-
ATLANTIC WEDNESDAY NIGHT.
MODELS TRENDS WITH THE TRACK OF THE LOW CONTINUE TO REMAIN
SOUTH AND EAST OF NEW JERSEY, RESULTING IN THE BULK OF THE SNOW
FALLING OVER SOUTHERN PORTIONS OF DELAWARE AND THE EASTERN
SHORES OF MARYLAND, AND MINIMAL SNOW ACCUMULATIONS FOR THE
MAJORITY OF THE FORECAST AREA. THE LOW LOOKS TO BE OFF THE
VIRGINIA-NORTH CAROLINA COAST LATE WEDNESDAY NIGHT, AND THEN
SOME 350 TO 400 MILES EAST OF ATLANTIC CITY BY THURSDAY
AFTERNOON.
SNOWFALL ACCUMULATIONS EXPECTED, FROM WEDNESDAY AFTERNOON
THROUGH THURSDAY:
LESS THAN AN INCH OVER THE SOUTHERN POCONOS, NORTHERN NEW
JERSEY, AND THE LEHIGH VALLEY DOWN TO THE I-95 CORRIDOR.
1 TO 2 INCHES FOR THE DELAWARE VALLEY, MOST OF SOUTHERN NEW
JERSEY AND COASTAL NEW JERSEY.
2 TO 4 INCHES FOR SOUTHERN PORTIONS OF THE EASTERN SHORES OF
MARYLAND, SOUTHERN DELAWARE, AND EXTREME SOUTHEAST NEW JERSEY
WITH UP TO 5 INCHES POSSIBLE IN PORTIONS OF SOUTHERN DELWARE.
THE 13Z/17 NBM SHOWS A 0 TO 5 PERCENT PROBABILITY OF GREATER
THAN 4 INCHES OF SNOW FOR THE SOUTHERN POCONOS, LEHIGH VALLEY,
AND NORTHERN NEW JERSEY AND DOWN TO THE I-95 CORRIDOR FROM
PHILADELPHIA TO WILMINGTON, A 15 TO 20 PERCENT PROBABILITY FOR
GREATER THAN 4 INCHES OF SNOW FOR MOST OF SOUTHERN NEW JERSEY
AND THE DELAWARE VALLEY, AND A 20 TO 40 PERCENT PROBABILITY FOR
GREATER THAN 4 INCHES OF SNOW FOR SOUTHERN DELMARVA AND EXTREME
SOUTHEAST NEW JERSEY IN THE 48 HOUR PERIOD FROM 7 PM TUESDAY
THROUGH 7 PM THURSDAY.
WILL GO AHEAD AND ISSUE A WINTER STORM WATCH FOR SUSSEX COUNTY
(DE) FOR WEDNESDAY AFTERNOON THROUGH THURSDAY. WINTER WEATHER
ADVISORIES MAY BE NEEDED FOR PORTIONS OF MARYLAND, DELAWARE, AND
EXTREME SOUTHERN NEW JERSEY. IT IS ALSO POSSIBLE FOR THIS WATCH
TO BE CONVERTED TO AN ADVISORY IF LOWER TOTALS ARE EXPECTED IN
SUSSEX COUNTY (DE).
TRENDS CONTINUE TO KEEP TAKING THE LOW SOUTH AND EAST FROM THE
LOCAL AREA, SO THESE TOTALS MAY GO DOWN FURTHER.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
LOW PRESSURE CONTINUES TO DEPART THURSDAY EVENING, AND
LINGERING SNOW WILL ROTATE BACK TOWARDS THE JERSEY SHORE,
RESULTING IN MINIMAL, AT BEST, ADDITIONAL SNOW ACCUMULATIONS.
FROM THERE, HIGH PRESSURE WILL DOMINATE INTO THE START OF THE
NEW WEEK. SURFACE HIGH PRESSURE OF 1040 MB WILL BE CENTERED OVER
THE CENTRAL PLAINS THURSDAY NIGHT BEFORE PROPAGATING OVER THE
OHIO AND TENNESSEE VALLEYS BY FRIDAY, THEN SLIDING OFF THE MID-
ATLANTIC COAST OVER THE WEEKEND.
TEMPERATURES WILL REMAIN BELOW SEASONAL AVERAGES FRIDAY AND
SATURDAY BEFORE MODERATING BACK TO THE SEASONAL AVERAGES BY
SUNDAY AND MONDAY.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH TODAY...VFR. WEST-NORTHWEST WINDS 15-20 KNOTS WITH
GUSTS UP TO 30 KNOTS.
TONIGHT...VFR, THOUGH HIGH CLOUDS WILL BE ON THE INCREASE LATE
TONIGHT. WEST-NORTHWEST WINDS WILL DIMINISH TO NEAR 10 KT BY
VERY LATE TONIGHT.
OUTLOOK...
WEDNESDAY THROUGH THURSDAY...SUB-VFR CONDITIONS LIKELY IN SN
FOR KMIV/KACY, AND A SUB-VFR CONDITIONS POSSIBLE IN SN FOR THE
REST OF THE TERMINALS.
THURSDAY NIGHT THROUGH SATURDAY...VFR.
MARINE
THE STRONG WINDS CONTINUE TO DIMINISH SOME FROM SOUTH TO NORTH,
AND THEREFORE THE GALE WARNING HAS BEEN REPLACED WITH A SMALL
CRAFT ADVISORY FOR ALL AREAS EXCEPT THE NORTHERN NEW JERSEY
ATLANTIC COASTAL WATERS. THE ADVISORY GOES THROUGH THE DAY
TUESDAY. THE GALE WARNING FOR THE TWO NORTHERN NEW JERSEY ZONES
GOES THROUGH TONIGHT, HOWEVER THIS MAY COME DOWN SOONER. SEAS
5-7 FEET WILL GRADUALLY SUBSIDE THROUGH TUESDAY GIVEN THE STRONG
OFFSHORE WIND.
AS THE COLD AIR CONTINUES TO POUR IN ACROSS OUR AREA THROUGH
TUESDAY, GUSTY WINDS COMBINED WITH WAVE ACTION WILL RESULT IN
AREAS OF LIGHT FREEZING SPRAY DEVELOPING TONIGHT INTO TUESDAY.
AS OF NOW, LIGHT ICE ACCRETION RATES ARE ANTICIPATED AND
THEREFORE NO ADVISORY HAS BEEN ISSUED.
OUTLOOK...
TUESDAY NIGHT...SCA CONDITIONS. THERE IS A CHANCE FOR FREEZING
SPRAY.
WEDNESDAY THROUGH WEDNESDAY NIGHT...SUB-SCA CONDITIONS. VSBY
RESTRICTIONS IN SN POSSIBLE STARTING LATE WEDNESDAY AFTERNOON.
THURSDAY THROUGH THURSDAY NIGHT...SCA CONDITIONS. VSBY
RESTRICTIONS IN SN THURSDAY.
FRIDAY THROUGH FRIDAY NIGHT...SCA CONDITIONS FRIDAY, SUBSIDING
FRIDAY NIGHT.
SATURDAY...SUB-SCA CONDITIONS.
PHI WATCHES/WARNINGS/ADVISORIES
PA...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ054-
055.
NJ...NONE.
DE...WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
AFTERNOON FOR DEZ003-004.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ430-
431-452>455.
GALE WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ450-451.
SYNOPSIS...MPS
NEAR TERM...JOHNSON
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...COOPER/JOHNSON/MPS
MARINE...GORSE/MPS
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