659
FXUS61 KPHI 121744
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
144 PM EDT TUE MAY 12 2026
WHAT HAS CHANGED
THE AVIATION SECTION IS UPDATED FOR THE 18Z TAFS.
KEY MESSAGES
1. LOW PRESSURE PASSING THROUGH THE REGION WILL BRING SHOWERS
AND ISOLATED THUNDERSTORMS LATE WEDNESDAY THROUGH THURSDAY.
2. BECOMING VERY WARM TO POTENTIALLY HOT THIS WEEKEND THROUGH
EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...LOW PRESSURE PASSING THROUGH THE REGION WILL
BRING SHOWERS AND ISOLATED THUNDERSTORMS LATE WEDNESDAY THROUGH
THURSDAY.
AN UPPER TROUGH EXTENDING FROM A CLOSED H5 LOW OVER CENTRAL
CANADA WILL MOVE THROUGH THE GREAT LAKES AND INTO THE OHIO
VALLEY TONIGHT. SURFACE LOW PRESSURE ASSOCIATED WITH THIS LOW
WILL STAY WELL NORTH OF THE AREA, BUT THE CLOSED LOW WILL SAG
DOWN INTO THE NORTHEAST BY THURSDAY. BEHIND THE DEPARTURE OF THE
SURFACE LOW, A COLD FRONT SLIDES THROUGH THE REGION. UNSETTLED
WEATHER ON TAP DURING THIS PERIOD.
THE TIMING OF PRECIPITATION SEEMS TO HAVE SLOWED DOWN A BIT,
WITH SCATTERED SHOWERS MOVING INTO FAR NORTHERN AND WESTERN
ZONES BY MIDDAY WEDNESDAY, BUT THE BULK OF THE SHOWERS WILL HOLD
OFF UNTIL WEDNESDAY EVENING.
SHOWERS WILL OVERSPREAD THE REGION WEDNESDAY NIGHT THROUGH
THURSDAY MORNING. WHILE LATEST MODELS ARE INDICATING THAT MOST
OF THE SHOWERS WILL BE OUT OF THE AREA ON THURSDAY, WILL NOTE
THAT WITH THE UPPER LOW OVER THE AREA AND SEVERAL SHORTWAVES
PASSING THROUGH THE REGION, UNSETTLED CONDITIONS MAY LINGER
THROUGHOUT THE DAY THURSDAY.
WITH STRONG SHORTWAVES, AT LEAST WEDNESDAY EVENING, INSTABILITY
WILL BE MARGINAL, AND A FEW ISOLATED THUNDERSTORMS ARE POSSIBLE
IN THE FIRST HALF OF THE NIGHT. NOT EXPECTING SEVERE
THUNDERSTORMS.
STORM TOTAL QPF CONTINUES TO BE ON THE LOWER SIDE, GENERALLY
RANGING FROM 1/10 TO 1/4 INCH OVER DELMARVA AND SOUTHEAST NEW
JERSEY, AND FROM 1/4 TO 1/2 INCH MAINLY NORTH AND WEST OF
PHILADELPHIA. LOCALLY HIGHER AMOUNTS COULD FALL IN ANY
THUNDERSTORMS.
MILD AHEAD OF THE SYSTEM ON WEDNESDAY WITH HIGHS IN THE LOW
70S, THEN COOLER ON THURSDAY WITH HIGHS IN THE 60S.
KEY MESSAGE 2...BECOMING VERY WARM TO POTENTIALLY HOT THIS
WEEKEND THROUGH EARLY NEXT WEEK.
AS THE CLOSED LOW CONTINUES TO DEPART ON FRIDAY, A RIDGE STARTS
TO BUILD ACROSS THE EAST THIS WEEKEND AND INTO EARLY NEXT WEEK.
THIS ALONG WITH HIGH PRESSURE CENTERED OFFSHORE WILL RESULT IN
SOUTHERLY FLOW ADVECTING IN A MUCH WARMER AIR MASS ACROSS OUR
AREA. AS A RESULT, HIGH TEMPERATURES GET INTO THE 70S TO MID 80S
SATURDAY WITH WIDESPREAD 80S ON SUNDAY. GIVEN A SOUTHERLY WIND
COMPONENT THOUGH, IT SHOULD BE COOLER ALONG THE COAST. THE HEAT
LOOKS TO BUILD INTO EARLY NEXT WEEK WITH EVEN HOT CONDITIONS
POSSIBLE. HIGHS MONDAY ARE FORECAST TO BE IN THE 80S WITH EVEN
SOME AREAS REACHING 90 DEGREES (AGAIN COOLER ALONG THE COAST).
GIVEN THE PRESENCE OF THE RIDGE ALOFT, NO PRECIPITATION IS
CURRENTLY ANTICIPATED. HOWEVER NEAR THE EDGE OF THE
RIDGE/SURFACE HIGH, THERE IS A SLIGHT CHANCE (20 PERCENT) FOR
CONVECTION NEAR THE SOUTHERN POCONOS MONDAY AFTERNOON AND
EVENING. ON TUESDAY, THE HEAT BUILDS FURTHER WITH HIGHS FORECAST
TO REACH THE UPPER 80S TO MID 90S (REMAINING COOLER ALONG THE
COAST). BY LATE TUESDAY, THERE ARE SOME SIGNS OF THE RIDGING
STARTING TO LESSEN AND THE SURFACE HIGH MOVING FURTHER OFFSHORE.
THIS WOULD RESULT IN MORE POTENTIAL FOR CONVECTION TO DEVELOP.
HOWEVER, THIS WILL LARGELY DEPEND ON THE TIMING OF THE RIDGING
AND SURFACE HIGH SHIFTING AWAY FROM THE AREA WHICH IS UNCERTAIN
GIVEN THIS BEING AT THE END OF THE EXTENDED FORECAST PERIOD.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
REST OF TODAY...VFR. W-NW WINDS 5 TO 10 KT, BACKING TO THE SW
BY 00Z. HIGH CONFIDENCE.
TONIGHT...VFR. S WINDS 5 KT OR LESS. HIGH CONFIDENCE.
WEDNESDAY...VFR. LIGHT SHRA POSSIBLE LATE IN THE DAY, BUT
RESTRICTIONS ARE NOT EXPECTED. S WINDS INCREASING TO AROUND 15
KT WITH 20 TO 25 KT GUSTS. MODERATE CONFIDENCE.
OUTLOOK...
WEDNESDAY NIGHT THROUGH THURSDAY...SUB-VFR IN SHRA. ISOLATED
TSRA POSSIBLE WEDNESDAY EVENING. CONDITIONS IMPROVE ON THURSDAY.
S WINDS 5 TO 10 KT MOST OF WEDNESDAY NIGHT, TURNING NW 10 TO 15
KT ON THURSDAY.
FRIDAY...MOSTLY VFR. AN ISOLATED SHOWER POSSIBLE.
SATURDAY THROUGH SUNDAY...VFR.
MARINE
SUB-SMALL CRAFT ADVISORY CONDITIONS FOR THE REST OF TODAY AND
TONIGHT. SOUTH WINDS 10 TO 15 KT WITH GUSTS UP TO 20 KT. SOUTH
WINDS INCREASE TO 15 TO 20 KT WITH 25 TO 30 KT GUSTS ON
WEDNESDAY, DIMINISHING WEDNESDAY EVENING. A SMALL CRAFT ADVISORY
WILL BE IN EFFECT FROM 6 AM TO 10 PM WEDNESDAY. WINDS DIMINISH
TO 10 TO 15 KT WEDNESDAY NIGHT, THEN TURN TO THE WEST ON
THURSDAY. SEAS WILL BE 2 TO 4 FT TONIGHT, BUILDING TO 4 TO 6 FT
ON WEDNESDAY, SUBSIDING TO 2 TO 4 FT WEDNESDAY NIGHT AND
THURSDAY.
OUTLOOK...
FRIDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT
ADVISORY CRITERIA.
SATURDAY...SMALL CRAFT ADVISORY CONDITIONS POSSIBLE.
SUNDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT
ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 10 PM EDT WEDNESDAY FOR
ANZ430-431-450>455.
DISCUSSION...GORSE/GUZZO/MPS
AVIATION...GUZZO/MPS
MARINE...GUZZO/MPS
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