394
FXUS61 KPHI 091007
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
607 AM EDT THU JUL 9 2026
WHAT HAS CHANGED
A FLOOD WATCH WAS ISSUED FOR SOUTHEAST PENNSYLVANIA, NORTHERN
DELAWARE, AND PORTIONS OF SOUTH JERSEY.
KEY MESSAGES
1) SHOWERS AND THUNDERSTORMS DEVELOP THIS AFTERNOON AND EVENING
WITH HEAVY RAIN AND DAMAGING WIND GUSTS BEING THE PRIMARY
THREAT. A FLOOD WATCH WAS ISSUED FOR SOUTHEAST PA, NORTHERN DE,
AND PORTIONS OF SOUTH JERSEY.
2) ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED
ON FRIDAY WHICH MAY LINGER INTO SATURDAY BEFORE DRIER CONDITIONS
RETURN ON SUNDAY AND INTO EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...SHOWERS AND THUNDERSTORMS DEVELOP THIS AFTERNOON AND EVENING
WITH HEAVY RAIN AND DAMAGING WIND GUSTS BEING THE PRIMARY
THREAT. A FLOOD WATCH WAS ISSUED FOR SOUTHEAST PA, NORTHERN DE,
AND PORTIONS OF SOUTH JERSEY.
HIGH PRESSURE MOVES OFFSHORE THIS MORNING WITH RETURN FLOW
SETTING UP BEHIND THE DEPARTING HIGH, AND SOUTHERLY FLOW
STRENGTHENING THROUGH THE DAY. DEW POINTS WILL CLIMB INTO THE
LOW TO MID 70S. ALTHOUGH TEMPERATURES WILL "ONLY" BE IN THE MID
80S OR SO, WHICH IS RIGHT AROUND NORMAL FOR THIS TIME OF THE
YEAR, THE HEAT INDEX WILL BE IN THE UPPER 80S TO LOW 90S.
THE MAIN CONCERN ON WILL BE THE POTENTIAL FOR SHOWERS AND
THUNDERSTORMS IN THE AFTERNOON AND EVENING. LOW PRESSURE
APPROACHES FROM THE WEST AND TRACKS TOWARDS THE MID- ATLANTIC
BY THIS EVENING A MID-LEVEL TROUGH WILL MOVE INTO THE NORTHEAST
WITH SOME SHORTWAVE ENERGY PASSING THROUGH THE DELAWARE VALLEY,
DELMARVA, AND SOUTHERN NEW JERSEY.
SBCAPE VALUES WILL BE IN EXCESS OF 1500 J/KG WITH PWATS FROM
2-2.5 INCHES, HIGHEST VALUES FROM THE DELAWARE VALLEY, INCLUDING
PHILADELPHIA, SOUTH INTO DELMARVA. 0-6 KM SHEAR WILL BE FROM 25
TO 30 KT. THE TWO MAIN THREATS FROM SEVERE WEATHER WILL BE
DAMAGING WIND GUSTS AND HEAVY RAIN LEADING TO LOCALIZED FLASH
FLOODING. GIVEN THE HIGH PWATS AND POTENTIAL FOR SOME PERIODS OF
TRAINING, HAVE GONE AHEAD AND ISSUED A FLOOD WATCH FOR SOUTHEAST
PA, NORTHERN DELAWARE, AND PORTIONS OF SOUTH JERSEY FROM NOON
UNTIL MIDNIGHT. SOME AREAS WITHIN THE FLOOD WATCH ALSO SAW A
GOOD AMOUNT OF RAIN LATELY AND WHILE WE ARE STILL IN A DROUGHT,
THE SOILS MAY BE OVERWHELMED IF SOME TRAINING WERE TO OCCUR OVER
A CERTAIN AREA. RAINFALL RATES OF 1-2" ARE LIKELY WITIN THE
FLOOD WATCH AREA. THE WEATHER PREDICTION CENTER HAS A SLIGHT RISK
(2 OUT OF 4) FOR EXCESSIVE RAINFALL FOR SOUTHEAST PENNSYLVANIA,
SOUTHERN NEW JERSEY, THE EASTERN SHORES OF MARYLAND, AND
DELAWARE, AND A MARGINAL RISK (1 OUT OF 4) FOR THE SOUTHERN
POCONOS AND NORTHERN NEW JERSEY. ENDED UP LEAVING THE REST OF
DELMARVA OUT OF THE WATCH BECAUSE OF THE MORE RURAL NATURE OF
THE LANDSCAPE AND ABILITY TO TAKE MORE RAINFALL THAN URBAN
AREAS.
THE STORM PREDICTION CENTER HAS A SLIGHT RISK FOR SEVERE
WEATHER (2 OUT OF 5) FOR THE DELAWARE VALLEY SOUTH OF
PHILADELPHIA, DELMARVA, AND SOUTHERN NEW JERSEY, AND A MARGINAL
RISK (1 OUT OF 5) FROM AROUND PHILADELPHIA NORTH TO ALLENTOWN.
NO CHANGES WERE MADE THIS MORNING TO THE SEVERE WEATHER
OUTLOOK.
ALTHOUGH SOME SHOWERS AND THUNDERSTORMS WILL FIRE UP OVER FAR
WESTERN PORTIONS OF THE FORECAST AREA FROM NOON-2PM, THE MAIN
TIMING WILL BE FROM 3PM TO 9 PM ACROSS THE DELAWARE VALLEY,
INCLUDING PHILADELPHIA, THE EASTERN SHORES OF MARYLAND,
DELAWARE, AND SOUTHERN NEW JERSEY. WHILE SHOWERS AND
THUNDERSTORMS CAPABLE OF DAMAGING WINDS AND LOCALIZED FLASH
FLOODING ARE LIKELY FOR THE NORTHERN ZONES AS WELL, THE HIGHEST
IMPACTS IN TERMS OF POTENTIAL SEVERE WEATHER AND FLASH FLOODING
SHOULD BE FOCUSED GENERALLY SOUTH OF PHILADELPHIA.
A WARM AND MUGGY NIGHT WITH PATCHY FOG DEVELOPING THURSDAY
NIGHT AFTER SHOWERS AND THUNDERSTORMS COME TO AN END BY
MIDNIGHT. LOWS WILL BE IN THE UPPER 60S TO LOW 70S.
KEY MESSAGE 2...ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS
ARE EXPECTED ON FRIDAY WHICH MAY LINGER INTO SATURDAY BEFORE
DRIER CONDITIONS RETURN ON SUNDAY AND INTO EARLY NEXT WEEK.
ON FRIDAY, ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP OUT AHEAD OF A COLD FRONT MOVING SOUTHWARD
INTO THE AREA. SIMILARLY TO THURSDAY, MOISTURE IS ANTICIPATED TO
INCREASE AHEAD OF THE FRONT, WHERE PWAT VALUES ARE PROGGED TO
BE IN EXCESS OF 1.8 INCHES. THIS SUPPORTS THAT ANY GIVEN SHOWER
OR STORM WILL HAVE THE ABILITY TO PRODUCE HEAVY RAINFALL AND
FLASH FLOODING. AS OF NOW, THE MAJORITY OF OUR FORECAST AREA IS
HIGHLIGHTED IN AN MARGINAL RISK (LEVEL 1/4) FOR EXCESSIVE
RAINFALL. HELD OFF ON EXPANDING THE FLOOD WATCH THROUGH FRIDAY
DUE TO UNCERTAINTY IN WHERE THE HEAVIEST RAINFALL WILL SET UP
TODAY.
IN TERMS OF THE SEVERE WEATHER THREAT, ML CAPES ARE
EXPECTED TO REACH AT LEAST 1000 J/KG WITH BULK SHEAR VALUES
AROUND 30 KT. GIVEN BETTER FRONTAL FORCING, THERE LOOKS TO BE AT
LEAST ANOTHER OPPORTUNITY FOR SEVERE WEATHER. AS OF NOW, SPC
HAS OUR ENTIRE AREA HIGHLIGHTED IN JUST A GENERAL THUNDER RISK,
HOWEVER SOME OF THE MLP GUIDANCE INDICATE HIGHER PROBABILITIES
ESPECIALLY IN TERMS OF DAMAGING WINDS. IT IS ALSO WORTH NOTING
THAT FRIDAY WILL BE QUITE STICKY OUTSIDE WITH HIGHS IN THE UPPER
80S TO LOW 90S WITH DEW POINTS IN THE LOW TO MID 70S. THIS WILL
RESULT IN HEAT INDICIES IN THE MID TO UPPER 90S. WE MAY GET
CLOSE TO HEAT ADVISORY CRITERIA IN SOME SPOTS, BUT BASIS THE
CURRENT FORECAST, HEAT INDICIES ARE EXPECTED TO REMAIN JUST
BELOW ADVISORY CRITERIA.
THERE REMAINS A VAST AMOUNT OF UNCERTAINTY WITH HOW SATURDAY
WILL PAN OUT AS GUIDANCE CONTINUES TO STRUGGLE WITH HOW QUICKLY
THE COLD FRONT CLEARS THE AREA. SOME GUIDANCE SLOWS THE
PROGRESSION OF THE FRONT, KEEPING MORE IN THE WAY OF SHOWERS
AROUND ON SATURDAY, WHEREAS OTHERS SHOW A FASTER PROGRESSION,
YIELDING MAINLY DRY WEATHER. AS MENTIONED BY THE PREVIOUS SHIFT,
OPTED TO STAY VERY CLOSE TO NBM POPS FOR THIS PERIOD, WHICH
KEEPS 10-30% POPS NORTH, WITH 30-60% POPS MAINLY ACROSS SOUTH
JERSEY AND THE DELMARVA. TEMPERATURES WILL MAINLY BE IN THE 80S.
BY SUNDAY AND INTO EARLY NEXT WEEK, GUIDANCE IS SHOWING AN
EXPANSIVE UPPER LEVEL RIDGE SETTING UP OVER THE NORTHERN HIGH
PLAINS. THIS WILL YIELD DRY WEATHER AND MAINLY CLEAR SKIES
ACROSS THE MID- ATLANTIC. TEMPERATURES WILL BE AROUND NORMAL FOR
SUNDAY AND MONDAY, BUT WILL SWING BACK ABOVE NORMAL BY TUESDAY
AND WEDNESDAY.
AVIATION /10Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...MVFR CONDITIONS EXPECTED AS SOME STRATUS MOVES THROUGH
THE AREA THIS MORNING. EXPECTING STRATUS TO LIFT BY THE
AFTERNOON BEFORE SOME SCATTERED SHOWERS AND THUNDERSTORMS BEGIN
TO DEVELOP IN THE AFTERNOON AND EARLY EVENING. COVERAGE OF
SHOWERS/THUNDERSTORMS WILL BE FOCUSED MAINLY FROM KRDG/KTTN ON
SOUTH. HAVE MAINTAINED TEMPO TSRA GROUPS AT ALL TERMINALS
EXCEPT KABE AS A PERIOD OF THUNDERSTORMS ARE INCREASINGLY LIKELY
(60-70%) SOMETIME BETWEEN 18Z-00Z. WINDS GENERALLY OUT OF THE
SOUTH/SOUTHWEST AROUND 10 KT WITH HIGHER GUSTS ANTICIPATED IN
ANY THUNDERSTORMS. MODERATE CONFIDENCE OVERALL.
TONIGHT...PRIMARILY VFR AS SHOWERS AND THUNDERSTORMS MOVE
OFFSHORE. CANNOT RULE OUT SOME PATCHY FOG, ESPECIALLY OVER AREAS
THAT SEE RAINFALL. WINDS OUT OF THE WEST/SOUTHWEST AROUND 5 KT
OR LESS. LOW CONFIDENCE.
OUTLOOK...
FRIDAY THROUGH FRIDAY NIGHT...PRIMARILY VFR BUT SUB-VFR
CONDITIONS LIKELY (60-70%) IN THE AFTERNOON AND EVENING WITH
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS.
SATURDAY...PRIMARILY VFR THOUGH CANNOT RULE OUT A SHOWER OR
THUNDERSTORM DEVELOPING.
SATURDAY NIGHT THROUGH MONDAY...VFR. NO SIGNIFICANT WEATHER.
MARINE
SUB-SCA CONDITIONS EXPECTED THROUGH FRIDAY. SOUTHWEST WINDS
AROUND 10-15 KT EXPECTED WITH SEAS 2 TO 3 FEET. SHOWERS AND
THUNDERSTORMS POSSIBLE (40-60%) ON THE WATERS BOTH THURSDAY
AFTERNOON AND EVENING AND FRIDAY AFTERNOON AND EVENING.
OUTLOOK...
FRIDAY NIGHT THROUGH SATURDAY NIGHT...NO MARINE HEADLINES
ANTICIPATED.
SUNDAY THROUGH SUNDAY NIGHT...SCA CONDITIONS POSSIBLE (20-30%)
AS SEAS NEAR 5 FEET.
MONDAY...NO MARINE HEADLINES EXPECTED.
RIP CURRENTS...
FOR TODAY, WINDS ARE MORE SOUTHERLY, AND THE MODERATE SWELL
ALSO BECOMES MORE SOUTHEASTERLY. SOUTHERLY FLOW WILL BE A BIT
STRONGER (WINDS 10 TO 20 MPH) AND WAVE HEIGHTS A BIT HIGHER FOR
THE OCEAN AND MONMOUTH COUNTY BEACHES. THIS WILL RESULT IN A
MODERATE RISK FOR RIP CURRENTS AT THESE LOCALES. LOWER WINDS AND
WAVE HEIGHTS FOR THE SOUTHERN JERSEY SHORE AND DELAWARE BEACHES
WILL RESULT IN A LOW RISK FOR RIP CURRENTS.
FOR FRIDAY, WINDS TURN SOUTHWESTERLY, AND THE SWELL WEAKENS.
THUS, THIS SHOULD RESULT IN A LOW RISK OF RIP CURRENTS FOR ALL
BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR
PAZ060-070-071-101>104-106.
NJ...FLOOD WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR
NJZ016>019.
DE...FLOOD WATCH FROM NOON EDT TODAY THROUGH THIS EVENING FOR
DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...DESILVA/HOEFLICH
AVIATION...HOEFLICH
MARINE...HOEFLICH
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