435
FXUS61 KPHI 292158
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
558 PM EDT SAT MAR 29 2025
SYNOPSIS
A COLD FRONT SLIDES SOUTHWEST INTO THE REGION TONIGHT AND STALL
ACROSS THE AREA ON SUNDAY. THIS FRONT FINALLY LIFTS BACK TO THE
NORTHEAST ONCE AND FOR ALL SUNDAY NIGHT INTO EARLY MONDAY, BEFORE A
MORE POWERFUL FRONT MOVES INTO THE REGION FROM THE NORTHWEST MONDAY
NIGHT. HIGH PRESSURE RETURNS TUESDAY AND WEDNESDAY BEFORE A MORE
ACTIVE WEATHER PATTERN ARRIVES FOR THE END OF THE WEEK.
NEAR TERM /THROUGH SUNDAY/
IT'S THE WARMEST DAY SO FAR THIS YEAR, WITH TEMPERATURES NEAR 80
DEGREES FOR MUCH OF THE REGION THIS AFTERNOON. THE REMAINDER OF THE
AFTERNOON WILL BE BREEZY AND DRY WITH CONTINUING PERIODS OF CLOUDS
AND SUN.
UPPER RIDGING WILL CONTINUE TO BUILD FROM THE WEST THROUGH TONIGHT.
AT THE SURFACE, A FRONTAL BOUNDARY THAT IS STALLED TO THE NORTH OF
OUR AREA WILL BECOME THE MAIN FOCUS OF THE REMAINDER OF THE NEAR
TERM FORECAST AS IT PUSHES SOUTHWEST INTO NEW JERSEY AND SOUTHEAST
PENNSYLVANIA INTO TONIGHT BEFORE STALLING OUT LOCALLY. WITH THE
FRONT PUSHING IN FROM THE NORTHEAST, IT WILL ACT AS A BACKDOOR COLD
FRONT, ALLOWING FOR AT LEAST A SLIGHT CHANCE FOR PRECIPITATION THIS
EVENING ACROSS MUCH OF EASTERN PENNSYLVANIA AND CENTRAL AND NORTHERN
NEW JERSEY. THE MOST LIKELY AREA FOR ANY SHOWERS, OR POTENTIALLY A
THUNDERSTORM, WILL BE NEAR AND NORTH OF THE I-80 CORRIDOR, AS THE
FRONT POTENTIALLY ALLOWS SHOWERS ASSOCIATED WITH A WAVE PASSING TO
OUR NORTH TO SINK FAR ENOUGH SOUTH AND GRAZE THE NORTHERN MOST
PORTIONS OF THE REGION. POPS HERE ARE GENERALLY 25-35 PERCENT. AS
THE FRONT PROGRESSES FURTHER SOUTH, CAM GUIDANCE INDICATES THAT IT
MAY KICK OFF A FEW ISOLATED SHOWERS OF ITS OWN, MOST LIKELY NEAR AND
NORTHWEST OF THE I-95 CORRIDOR. POPS ARE GENERALLY 15-25 PERCENT.
AS THE FRONT CONTINUES SOUTHWARD TONIGHT, WINDS WILL TURN EAST-
NORTHEASTERLY BEHIND IT, RESULTING IN AN ONSHORE FLOW SETUP, AND AS
USUAL, LOW CLOUDS AND SOME AREAS OF FOG AND DRIZZLE ARE LIKELY TO
DEVELOP, PARTICULARLY ACROSS COASTAL NEW JERSEY. LATEST GUIDANCE
INDICATES THAT THE FRONT MAY MAKE IT A BIT FURTHER SOUTH BEFORE
STALLING, PERHAPS AROUND A LINE ORIENTED NORTHWEST TO SOUTHEAST FROM
LANCASTER COUNTY IN PENNSYLVANIA, ACROSS THE SOUTHERN PHILLY METRO
AND INTO FAR SOUTHERN NEW JERSEY. REGARDLESS OF WHERE THE FRONT
STALLS, AREAS NORTH OF THE FRONT ARE FORECAST TO SEE LOWS IN THE 40S
TO NEAR 50 WITH MID 50S TO NEAR 60 FOR ANY AREAS THAT REMAIN SOUTH
OF THE FRONT.
THE FRONTAL BOUNDARY DOES LOOK TO MAKE A SLOW PUSH BACK NORTHWARD
DURING THE DAYTIME ON SUNDAY BEFORE STALLING ACROSS THE AREA ONCE
AGAIN, POTENTIALLY FROM BERKS/LEHIGH SOUTHEASTWARD TO CENTRAL OCEAN
COUNTY IN NEW JERSEY. IF THIS WERE TO PAN OUT, MOST OF PHILLY WOULD
BE SOUTH OF THE FRONT WHILE AREAS NEAR AND NORTH OF TRENTON WOULD
REMAIN ON THE NORTHERN SIDE, THOUGH THIS REMAIN HIGHLY UNCERTAIN.
CONFIDENCE IS HIGHER THAT FOR AREAS SOUTH OF THE FRONT, ANOTHER WARM
DAY IS ON TAP WITH TEMPERATURES IN THE 70S, WHILE NORTH OF FRONT,
TEMPERATURES WILL STRUGGLE TO HIT 60. CONDITIONS WILL BE PARTLY TO
MOSTLY CLOUDY BUT DRY FOR MUCH OF THE DAY. A FEW SHOWERS MAY MOVE
INTO AREAS NORTHWEST OF THE I-95 CORRIDOR LATE IN THE DAY.
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
THE STATIONARY BOUNDARY BISECTING THE REGION WILL BEGIN TO SHIFT
NORTHWARD AGAIN AS A WARM FRONT SUNDAY NIGHT, GRADUALLY BRINGING
WARM AIR ADVECTION BACK INTO THE REGION OVERNIGHT. SOME LEADING
UPPER LEVEL ENERGY MAY TRIGGER A FEW SHOWERS NEAR AND ALONG THIS
FRONT, BUT ANY WIDESPREAD PRECIPITATION WILL HOLD OFF UNTIL MONDAY.
NIGHTTIME LOWS WILL BE EARLY ON IN THE NIGHT WITH LOW-60S AROUND THE
PA TURNPIKE/I-195 SOUTH AND UPPER 40S TO LOW 50S FOR AREAS NORTH AND
DOWN THE SHORE. TEMPERATURES WILL BE NON-DIURNAL, HOWEVER, AND
GRADUALLY WARM OVERNIGHT AND INTO EARLY MONDAY MORNING, WITH MONDAY
MORNING WAKE-UP TEMPERATURES IN THE UPPER 50S TO LOW 60S.
A STRONG COLD FRONT WILL APPROACH THE AREA MONDAY AFTERNOON AND PUSH
THROUGH MONDAY NIGHT. STILL QUITE A BIT OF DIFFERENCE BETWEEN
GUIDANCE REGARDING TIMING, BUT AREAS NORTH AND WEST OF THE I-95
CORRIDOR LOOK TO SEE THE HEAVIEST RAIN AND THUNDERSTORMS NEAR AND
ALONG THE FRONTAL BOUNDARY BEGINNING MID/LATE AFTERNOON INTO THE
EVENING WITH AREAS SOUTH AND EAST EXPECTED TO SEE MOST OF THE
IMPACTS SOMETIME AFTER SUNSET, MORE IN THE NIGHTTIME HOURS. WE COULD
ALSO SEE SOME PRE-FRONTAL SHOWERS AND THUNDERSTORMS AHEAD OF THIS
LINE THROUGHOUT THE AFTERNOON, THOUGH THERE STILL REMAINS SOME
UNCERTAINTY WITH THE COVERAGE. SKIES ARE EXPECTED TO BE MOSTLY
CLOUDY IN THE AFTERNOON, BUT TEMPERATURES ARE STILL FORECASTED TO
WARM INTO THE LOW TO MID 70S. THE CLOUDY SKIES WILL ALSO HELPING
LIMIT DAYTIME HEATING AND OVERALL INSTABILITY WITH MUCAPE VALUES
LARGELY LESS THAN 1000 J/KG. HOWEVER, THERE WILL BE VERY STRONG
DYNAMICS AND SHEAR IN PLACE, SO MUCH OF THE AREA REMAINS IN A SLIGHT
RISK OF SEVERE WEATHER FROM THE STORM PREDICTION CENTER, MAINLY FOR
DAMAGING WIND GUSTS WITHIN SEVERE THUNDERSTORMS. THE BEST CHANCE FOR
SOME SEVERE WEATHER WILL COME DURING THE AFTERNOON AND EARLY EVENING
WHILE THE HEAVY RAIN THREAT WILL INCREASE THROUGH THE EVENING AND
OVERNIGHT HOURS. A STRENGTHENING LOW-LEVEL JET DURING THE EVENING
AND NIGHTTIME HOURS WILL SUPPORT PWAT VALUES SURGING INTO THE 1.5
INCH RANGE, NEAR THE CLIMATOLOGICAL MAXIMUM FOR THIS TIME OF YEAR.
AS A RESULT, FORECASTED STORM TOTAL RAINFALL WILL BE AROUND 0.75-
1.25 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. DESPITE OUR
ONGOING DROUGHT, THERE ARE LOCALIZED FLOODING CONCERNS, ESPECIALLY
DUE TO POTENTIAL RAINFALL RATES CAUSING SOME LOCALIZED URBAN
FLOODING. ONCE THE COLD FRONT PUSHES THROUGH, OVERNIGHT LOWS WILL
COOL DOWN INTO THE 40S WITH EVEN SOME 30S OVER THE POCONOS AND NW NJ.
THE COLD FRONT WILL PUSH OFFSHORE EARLY TUESDAY MORNING, GIVING WAY
TO BUILDING HIGH PRESSURE FOR TUESDAY. A SURGE OF NW WINDS BEHIND
THE FRONT CAN BE EXPECTED AFTER DAYBREAK TUESDAY WITH GUSTS 20-30
MPH POSSIBLE, BEFORE BEGINNING TO SUBSIDE DURING THE AFTERNOON.
INCREASINGLY SUNNY SKIES TUESDAY WITH SEASONABLE TEMPERATURES IN THE
UPPER 40S TO UPPER 50S.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
COLD CANADIAN AIR MASS BUILDS OVERHEAD FOR TUESDAY NIGHT WITH
REDUCING WINDS, SO MOST AREAS AWAY FROM THE COAST AND MARINE WATERS
MAY BE NEAR OR BELOW FREEZING TUESDAY NIGHT. DEPENDING ON HOW IT
PLAYS OUT, MIGHT NEED FROST ADVISORIES OR FREEZE WARNINGS FOR THE
DELMARVA SOUTH OF WILMINGTON, WHERE THE GROWING SEASON IS DEFINED TO
BEGIN ON APRIL 1, THOUGH AT THIS MOMENT WE ARE NOT FORECASTING TEMPS
TO DROP QUITE THAT MUCH. WEDNESDAY STARTS WITH SOME PARTIAL SUN,
THEN CLOUDS INCREASE AS THE NEXT SYSTEM APPROACHES. HIGHS AGAIN IN
THE 50S FOR MOST.
A MORE ACTIVE WEATHER PATTERN IS EXPECTED FOR THE LATTER HALF OF THE
WEEK. MULTIPLE WAVES OF LOW PRESSURE LOOK TO MOVE THROUGH THE AREA
LATER NEXT WEEK IN THE THURSDAY THROUGH SATURDAY TIMEFRAME. WHILE
THERE IS UNCERTAINTY REGARDING THE DETAILS, THE GENERAL TREND WILL
BE FOR IT TO BECOME MORE UNSETTLED WITH PLENTY OF CHANCES FOR CLOUDS
AND RAIN DURING THIS TIMEFRAME. TEMPERATURES, HOWEVER, WILL BE
WARMING WITH HIGHS IN THE 60S AND 70S THROUGH THIS PERIOD.
AVIATION /22Z SATURDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH 00Z...VFR WITH VARIABLE CLOUDS. WSW WINDS AT 10-15 KTS WITH
GUSTS NEAR 20-25 KTS. HIGH CONFIDENCE.
TONIGHT...INITIALLY VFR. BETWEEN 00Z-06Z, WINDS BECOME MORE EAST TO
SOUTHEAST AT 5-10 KNOTS. MVFR CEILINGS WILL PUSH INLAND, LIKELY
IMPACTING MOST TERMINALS BY 06-09Z. KILG AND KMIV MIGHT BE THE ONLY
TERMINALS TO STAY VFR. KTTN, KPNE, AND KABE MAY FALL TO IFR
DURING THIS PERIOD. MODERATE CONFIDENCE.
SUNDAY...CEILINGS LIFT AFTER 15Z AND SOME BECOME VFR. THERE ARE
SOME EXCEPTIONS. KRDG, KABE, KTTN, AND KPNE MAY STAY MVFR WITH
THEIR CEILINGS STILL AFTER 15Z. WINDS REMAIN OUT OF THE
SOUTHEAST TO SOUTH AT AROUND 5-10 KNOTS. MODERATE CONFIDENCE.
OUTLOOK...
SUNDAY NIGHT...SUB-VFR CONDITIONS POSSIBLE EARLY FOR KTTN/KABE/KRDG
BEFORE THE WARM FRONT MOVES NORTH OVERNIGHT WITH MAINLY VFR
CONDITIONS ELSEWHERE. ISOLATED TO SCATTERED SHOWERS POSSIBLE.
MONDAY AND MONDAY NIGHT...SUB-VFR CONDITIONS DEVELOPING IN THE
AFTERNOON THROUGH THE OVERNIGHT WITH A FRONTAL PASSAGE. HEAVY RAIN
AND THUNDERSTORMS LIKELY. GUSTY WINDS 20-25 KTS.
TUESDAY THROUGH WEDNESDAY...VFR. BREEZY EARLY TUESDAY MORNING.
THURSDAY...SUB-VFR CONDITIONS POSSIBLE WITH SHOWERS LATE.
MARINE
THE SMALL CRAFT ADVISORY FROM SANDY HOOK TO THE GREAT EGG INLET
HAS BEEN EXTENDED THROUGH MIDNIGHT. WHILE THERE MIGHT BE A BRIEF
LULL IN WINDS AND SEAS, WINDS SHOULD INCREASE LATER THIS EVENING
BEHIND THE BACKDOOR COLD FRONT. THIS WILL ALSO RESULT IN A WIND
SHIFT FROM SOUTHWEST TO EAST- NORTHEAST. UPSTREAM OBS SHOW A
PERIOD OF GUSTS ABOVE 25 KT IMMEDIATELY BEHIND THE FRONT. THIS
AREA WILL ALSO HAVE POTENTIAL FOR FOG AND DRIZZLE DEVELOPMENT,
WHICH COULD LOWER VISIBILITY TO NEAR 1 NM AT TIMES. THE FRONT IS
NOT EXPECTED TO GET MUCH FURTHER SOUTH THAN THE ATLANTIC CITY
AREA BEFORE STALLING LATE TONIGHT.
WINDS TURN SOUTHERLY, PARTICULARLY SOUTH OF BARNEGAT LIGHT, ON
SUNDAY, AS THE FRONT LIFTS BACK NORTHWARD SLIGHTLY THEN STALLS
AGAIN. SOUTH OF THE FRONT, WIND GUSTS WILL INCREASE ONCE AGAIN TO
AROUND 20 KNOTS, WITH SOME GUSTS UP TO 25 KNOTS POSSIBLE. WATERS
NORTH OF THE FRONT WILL CONTINUE TO SEE EASTERLY WINDS AROUND 10
KNOTS. SEAS OF MAINLY 3-4 FEET EXPECTED.
OUTLOOK...
SCA CONDITIONS POSSIBLE SUNDAY NIGHT THROUGH TUESDAY MORNING.
SOUTHERLY WINDS RAMP UP TO 25-30 KTS AHEAD OF A COLD FRONT SUNDAY
NIGHT INTO MONDAY WITH SEAS BUILDING FROM 3-5 FEET TO 5-7 FEET.
WINDS SHIFT NWRLY BEHIND THE FRONT, WITH GUSTS STILL AROUND 25KTS
AND SEAS 5-7 FEET EARLY TUESDAY. WINDS AND SEAS DIMINISH LATER
TUESDAY, FALLING BELOW SCA CRITERIA TUESDAY NIGHT INTO WEDNESDAY.
SCA CONDITIONS GRADUALLY RETURN WEDNESDAY NIGHT INTO THURSDAY.
FIRE WEATHER
CONDITIONS WILL BE NEAR CRITICAL FIRE WEATHER THRESHOLDS THROUGH
THIS AFTERNOON AND EVENING. WSW WINDS OF 10-20 MPH, WITH GUSTS OF 25-
35 MPH POSSIBLE. THIS WILL BE COMBINED WITH MINIMUM RELATIVE
HUMIDITY VALUES NEAR 30-35% AND TEMPERATURES IN THE UPPER 70S TO LOW
80S IN MOST AREAS. THE SPECIAL WEATHER STATEMENT FOR INCREASED RISK
OF RAPID FIRE SPREAD WILL REMAIN IN EFFECT THROUGH 7 PM.
CONDITIONS SHOULD BE LESS VOLATILE SUNDAY AS A BACKDOOR FRONT BRINGS
SLIGHTLY COOLER AND MORE HUMID AIR TO AT LEAST NORTHEASTERN PORTIONS
OF THE REGION, WHILE THE CHANCE OF SHOWERS WILL BE A BIT HIGHER AND
CLOUD COVER LOOKS MORE WIDESPREAD. MINIMUM RELATIVE HUMIDITY WILL BE
AROUND 50-60%.
TIDES/COASTAL FLOODING
WIDESPREAD MINOR TIDAL FLOODING IS POSSIBLE ESPECIALLY WITH THE
SUNDAY NIGHT HIGH TIDE FOR PORTIONS OF THE NJ ATLANTIC COAST AND
SOUTHERN SHORES OF THE RARITAN BAY.
ASTRONOMICAL HIGH TIDES ARE VERY CLOSE TO MINOR FLOOD THRESHOLDS FOR
THE NEXT SEVERAL HIGH TIDE CYCLES WITH THE NEW MOON ON SATURDAY.
WITH THE EXCEPTION OF THE CHESAPEAKE BAY, ASTRONOMICAL TIDE LEVELS
FOR ALL OTHER TIDAL SITES IN OUR REGION ARE WITHIN ONE FOOT OF MINOR
FLOOD THRESHOLDS, AND IN MANY CASES WITHIN ONE HALF FOOT OF MINOR
FLOODING.
FOR THE MOST PART, WINDS WON'T HAVE A STRONG ONSHORE FLOW COMPONENT,
WHICH WILL LIMIT THE AMOUNT OF FLOODING FOR MOST AREAS. HOWEVER, FOR
AREAS THAT END UP NORTH OF THE BACKDOOR COLD FRONT, LIGHT, BUT
PERSISTENT EASTERLY FLOW WILL OCCUR STARTING TONIGHT CONTINUING
THROUGH SUNDAY. AT THIS POINT, WE ARE EXPECTING THE FRONT TO STALL
IN THE AREA OF BARNEGAT BAY.
THE BIGGEST CONCERN AT THIS POINT IS FOR TIDAL LOCATIONS IN
MIDDLESEX AND MONMOUTH COUNTIES WITH THE HIGH TIDE SUNDAY NIGHT.
HOWEVER, HAVE HELD OFF ON A TIDAL FLOOD ADVISORY DUE TO UNCERTAINTY
IN EXACTLY WHERE THE FRONT WILL STALL. ELSEWHERE ON THE ATLANTIC
COAST, DELAWARE BAY, AND TIDAL DELAWARE RIVER, TIDE LEVELS ARE
FORECAST TO BE NEAR BUT JUST BELOW ADVISORY THRESHOLDS.
ON THE NORTHEASTERN CHESAPEAKE BAY, TIDAL FLOODING ISN'T EXPECTED
DUE TO LOWER ASTRONOMICAL TIDES.
CLIMATE
AS OF 4 PM, A NUMBER OF LOCATIONS IN OUR REGION HAVE HAD THE
FIRST 80 DEGREE DAY OF THE YEAR, BUT THUS FAR HAVE FALLEN SHORT
OF RECORD HIGHS. HOWEVER, WITH MOST SITES STILL WITH IN A DEGREE
OR TWO OF THE HIGH FOR TODAY, WILL CONTINUE TO MONITOR FOR THE
NEXT FEW HOURS. RECORDS FOR OUR CLIMATE SITES ARE LISTED BELOW:
RECORD HIGH TEMPERATURES
MARCH 29
SITE RECORD/YEAR
ALLENTOWN (ABE) 86/1945
AC AIRPORT (ACY) 87/1945
AC MARINA (55N) 82/1998
GEORGETOWN (GED) 87/1945
MOUNT POCONO (MPO) 79/1945
PHILADELPHIA (PHL) 87/1945
READING (RDG) 87/1907
TRENTON (TTN) 86/1945
WILMINGTON (ILG) 85/1945
RECORD WARMEST LOW TEMPERATURES
MARCH 29
SITE RECORD/YEAR
ALLENTOWN (ABE) 57/1985
AC AIRPORT (ACY) 56/1985
AC MARINA (55N) 58/1985
GEORGETOWN (GED) 61/1989 & 1998
MOUNT POCONO (MPO) 60/1998
PHILADELPHIA (PHL) 63/1907
READING (RDG) 62/1989
TRENTON (TTN) 56/1902 & 1907
WILMINGTON (ILG) 61/1989
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ450>452.
SYNOPSIS...FITZSIMMONS/MJL
NEAR TERM...AKL
SHORT TERM...FITZSIMMONS/MJL
LONG TERM...FITZSIMMONS/MJL
AVIATION...GUZZO/MJL
MARINE...AKL/JOHNSON/MJL
FIRE WEATHER...
TIDES/COASTAL FLOODING...
CLIMATE...
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