957
FXUS61 KPHI 111718
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
118 PM EDT MON MAY 11 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR 18Z TAFS.
FROST ADVISORY NOW IN EFFECT FOR CARBON AND MONROE COUNTIES FOR
LATE TONIGHT THROUGH TUESDAY MORNING.
KEY MESSAGES
1. A DRIER AIRMASS SPREADS INTO THE REGION. A FROST ADVISORY IS NOW
IN EFFECT FOR THE SOUTHERN POCONOS LATE TONIGHT THROUGH TUESDAY
MORNING.
2. MARGINAL FIRE WEATHER CONDITIONS MAY DEVELOP TUESDAY
AFTERNOON.
3. WIDESPREAD RAIN WITH POTENTIALLY A FEW THUNDERSTORMS MOVES
IN FOR THE PM HOURS ON WEDNESDAY, CONTINUING INTO THURSDAY
MORNING.
4. ABOVE NORMAL TEMPERATURES TAKE OVER FOR THE WEEKEND AND
POTENTIALLY CONTINUE INTO NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...A DRIER AIRMASS SPREADS INTO THE REGION. A
FROST ADVISORY IS NOW IN EFFECT FOR THE SOUTHERN POCONOS LATE
TONIGHT THROUGH TUESDAY MORNING.
LOW PRESSURE SOUTH AND EAST OF THE DELMARVA PENINSULA WILL
CONTINUE TO DRIFT OUT TO SEA AS THE AFTERNOON PROGRESSES, AND
ANY LIGHT RAIN OVER DELMARVA AND SOUTHEAST NEW JERSEY WILL TAPER
OFF BY EARLY THIS EVENING. WHILE SKIES WILL BEGIN TO CLEAR OUT,
SOME SHORTWAVE ENERGY PASSING NORTH OF THE AREA MAY KEEP SOME
MID AND HIGH CLOUDS IN NORTHERN PORTIONS OF THE REGION EARLY
TONIGHT.
HIGH PRESSURE OVER THE GREAT LAKES WILL BUILD SOUTH AND WILL BE
CENTERED OVER CENTRAL PENNSYLVANIA BY TUESDAY MORNING, AND
SHIFTS OFF THE MID-ATLANTIC COAST BY EARLY TUESDAY EVENING.
A LIGHT NORTHERLY FLOW DEVELOPS TONIGHT, AND WEAK COLD AIR
ADVECTION WILL BE UNDERWAY. LOWS TONIGHT WILL DROP INTO THE MID
AND UPPER 30S IN THE SOUTHERN POCONOS AND FAR NORTHWEST NEW
JERSEY AND IN THE LOW TO MID 40S ELSEWHERE. WITH FROST
DEVELOPMENT BECOMING LIKELY FOR CARBON AND MONROE COUNTIES, WILL
GO AHEAD AND HOIST A FROST ADVISORY FOR THOSE COUNTIES LATE
TONIGHT THROUGH TUESDAY MORNING. SOME PATCHY FROST MAY DEVELOP
IN PORTIONS OF FAR NORTHWEST NEW JERSEY AS WELL, BUT THE AIRMASS
MAY BE TOO DRY FOR FROST TO BE WIDESPREAD.
KEY MESSAGE 2...MARGINAL FIRE WEATHER CONDITIONS MAY DEVELOP
TUESDAY AFTERNOON.
SUNNY AND MILD CONDITIONS ON TAP FOR TUESDAY. HIGHS WILL MOSTLY
BE IN THE MID AND UPPER 60S TO AROUND 70, THOUGHT COOLER IN THE
SOUTHERN POCONOS AND ALONG THE COASTS. WITH DECENT MIXING UP TO
AROUND 850 MB, DEW POINTS SHOULD MIX DOWN TO THE UPPER 20S AND
LOW 30S IN THE AFTERNOON DURING PEAK HEATING OF THE DAY. MINRH
VALUES WILL GENERALLY BE 25 TO 30 PERCENT, THOUGH AS LOW AS 20
TO 25 PERCENT OVER THE PINE BARRENS OF SOUTHERN NEW JERSEY.
HOWEVER, WITH THE CENTER OF THE HIGH NEARBY, SURFACE WINDS WILL
TURN FROM THE NORTH AT LESS THAN 10 MPH IN THE MORNING TO THE
WEST IN THE AFTERNOON. THOUGH DRY, RECENT RAINFALL AND
RELATIVELY LIGHT WINDS ARE LIMITING FACTORS FOR FIRE WEATHER
CONDITIONS DESPITE THE LOW RH VALUES.
KEY MESSAGE 3...WIDESPREAD RAIN WITH POTENTIALLY A FEW
THUNDERSTORMS MOVES IN FOR THE AFTERNOON HOURS ON WEDNESDAY,
CONTINUING INTO THURSDAY MORNING.
THE UPPER-LEVEL PATTERN IS FORECAST TO BECOME RATHER AMPLIFIED
THROUGH THIS WEEK. A STRONG UPPER-LEVEL TROUGH AXIS SHIFTS TO
OUR EAST TUESDAY AS HIGH PRESSURE WILL ALSO BE SHIFTING
OFFSHORE. ANOTHER UPPER-LEVEL TROUGH THEN MOVES OVER THE EASTERN
US WEDNESDAY INTO THURSDAY BEFORE LIFTING OUT FRIDAY INTO
SATURDAY. GUIDANCE SEEMS TO BE TRENDING TOWARD THE EARLIER
ECMWF'S IDEA THAT THE INCOMING TROUGH WILL CLOSE OFF EITHER OVER
OUR AREA OR JUST OFF TO THE EAST. THE TIMING AND LOCATION OF
WHERE THE CUTOFF OCCURS WILL DETERMINE WHEN THINGS DRY OUT. IF
THE TROUGH CUTS OFF OVER OUR AREA, SHOWERS COULD LINGER INTO
THURSDAY. IF IT CUTS OFF JUST TO THE EAST, SHOWERS SHOULD MOVE
OUT BY THURSDAY, GIVING WAY TO A NICE WEEKEND (MORE ON THAT IN
KEY MESSAGE 3). REGARDLESS OF HOW THIS TRANSPIRES, A ROUND OF
WIDESPREAD RAIN IS EXPECTED WITH AS THE INCOMING TROUGH AND COLD
FRONT ARRIVE.
AS THE AFOREMENTIONED UPPER-LEVEL TROUGH MOVES INTO THE REGION
WEDNESDAY, LOW-LEVEL WARM AIR ADVECTION WILL INCREASE AHEAD OF
IT AS THE LOW TO MID LEVEL FLOW ALSO INCREASES. THIS WILL RESULT
IN AN INCREASE IN FORCING FOR ASCENT, AND SOME INSTABILITY
SHOULD DEVELOP AHEAD OF THE MAIN FORCING. A WARM FRONT SHOULD
ALSO LIFT ACROSS OUR AREA WEDNESDAY WITH SOME ASCENT ASSOCIATED
WITH IT. AS A RESULT, SHOWERS SHOULD INCREASE WEDNESDAY FROM
WEST TO EAST, ESPECIALLY IN THE AFTERNOON WITH FORCING PEAKING
WEDNESDAY NIGHT AS THE COLD FRONT ARRIVES. THE AMOUNT OF
DESTABILIZATION IS MORE UNCERTAIN, HOWEVER GUIDANCE DOES SHOW
SOME INSTABILITY WHICH SHOULD BE ENOUGH TO SUPPORT AT LEAST A
FEW THUNDERSTORMS. THE INTENSITY OF ANY THUNDERSTORMS HOWEVER
WILL DEPEND ON THE MAGNITUDE OF THE INSTABILITY AND SHEAR.
HOWEVER, GUIDANCE THIS MORNING DOES NOT SHOW MUCH IN TERMS OF
INSTABILITY, WITH SHEAR LOOKING RATHER MEAGER AS WELL. THIS
WOULD RESULT IN A LOW TO ZERO SEVERE THREAT, WITH BETTER
KINEMATICS WELL OFF TO OUR WEST.
THE MAIN FORCING SHOULD SHIFT TO OUR EAST AND NORTHEAST
THURSDAY WITH THE BULK OF THE SHOWERS ENDING. HOWEVER, IF THE
CLOSED LOW SCENARIO ENDS UP HAPPENING, THEN THE CORE OF THE COLD
AIR ALOFT WITH THIS SLIDES OVERHEAD AND THIS COULD RESULT IN
ADDITIONAL SHOWER DEVELOPMENT ON THURSDAY BEFORE THE SYSTEM
DEPARTS OUR REGION. RAINFALL AMOUNTS ARE TRENDING TO BE RIGHT
AROUND A HALF INCH OR SO.
KEY MESSAGE 4...ABOVE NORMAL TEMPERATURES TAKE OVER FOR THE
WEEKEND AND POTENTIALLY CONTINUE INTO NEXT WEEK.
MEDIUM TO LONG RANGE GUIDANCE CONTINUES TO HINT AT A RIDGE
SETTING UP OVER THE EASTERN US WITH AN ASSOCIATED AREA OF HIGH
PRESSURE OVER THE SOUTHEAST US AND SLOWLY PUSHING OFFSHORE. THIS
WOULD RESULT IN A WARM SOUTHERLY RETURN FLOW SETTING UP AND
TEMPERATURES LIKELY GETTING INTO THE 80S. STILL SEVERAL DAYS OUT
THOUGH AND THINGS COULD CHANGE, BUT CONSENSUS AMONG THE
DETERMINISTIC AND ENSEMBLE GUIDANCE HAS A STRETCH OF ABOVE
NORMAL TEMPERATURES BEGINNING THIS WEEKEND. THE CURRENT FORECAST
DOES NOT HAVE MUCH IN TERMS OF PRECIPITATION CHANCES FOR THIS
STRETCH EITHER.
AVIATION /18Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
REST OF TODAY...VFR. LINGERING SHRA AT KMIV/KACY WITHOUT
RESTRICTIONS. NW WINDS 5 TO 10 KT, THOUGH THE DIRECTION MAY BE
MORE VARIABLE AT KMIV/KACY. MODERATE CONFIDENCE.
TONIGHT...VFR. N WINDS 5 KT OR LESS. HIGH CONFIDENCE.
TUESDAY...VFR. N WINDS AROUND 5 KT IN THE MORNING, THEN WINDS
BECOME W TO SW 5 TO 10 KT IN THE AFTERNOON WITH SEA BREEZES
LIKELY AT KACY WITH S TO SE WINDS AROUND 10 KT.
OUTLOOK...
TUESDAY NIGHT THROUGH WEDNESDAY MORNING...VFR. NO SIGNIFICANT
WEATHER.
WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING...IFR CONDITIONS
EXPECTED AT TIMES WITH PERIODS OF RAIN AND A SLIGHT CHANCE (15%)
OF THUNDERSTORMS. SOUTHERLY WIND GUSTS AROUND 20-25 KT EXPECTED
ON WEDNESDAY AFTERNOON.
THURSDAY AFTERNOON THROUGH FRIDAY...PRIMARILY VFR. CANNOT RULE
OUT SOME LINGERING SHOWERS WHICH COULD RESULT IN SOME MVFR
CONDITIONS.
MARINE
SUB-SMALL CRAFT ADVISORY CONDITIONS FOR THE REST OF TODAY,
TONIGHT, AND TUESDAY. NORTHEAST WINDS AROUND 10 KT WILL BECOME
VARIABLE THIS EVENING AS LOW PRESSURE PASSES OVER THE OCEAN
WATERS. WINDS THEN SHIFT TO THE WEST, THEN NORTHWEST AT 10 TO 15
KT WITH GUSTS UP TO 20 KT BY MIDNIGHT OR SO TONIGHT. WINDS
DIMINISH TUESDAY MORNING TO AROUND 10 KT, THEN WINDS TAKE ON AN
EAST TO SOUTHEAST FLOW AT 10 TO 15 KT WITH GUSTS UP TO 20 KT IN
THE AFTERNOON. SEAS WILL GENERALLY AVERAGE 2 TO 4 FT.
OUTLOOK...
TUESDAY NIGHT...NO MARINE HEADLINES EXPECTED.
WEDNESDAY THROUGH WEDNESDAY NIGHT...SCA CONDITIONS LIKELY (70-80%)
WITH SOUTHERLY WINDS AROUND 20-30 KT AND SEAS 4 TO 7 FEET.
THURSDAY...CANNOT RULE OUT SOME LINGERING 5 FOOT SEAS, BUT PRIMARILY
SUB-SCA CONDITIONS EXPECTED.
THURSDAY NIGHT THROUGH FRIDAY...NO MARINE HEADLINES EXPECTED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FROST ADVISORY FROM 3 AM TO 8 AM EDT TUESDAY FOR PAZ054-055.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...HOEFLICH/MPS
AVIATION...HOEFLICH/MPS
MARINE...HOEFLICH/MPS
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