078
FXUS61 KPHI 300941
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
541 AM EDT SUN AUG 30 2026
WHAT HAS CHANGED
THERE IS AN INCREASING THREAT OF SEVERE THUNDERSTORMS DURING THE
MIDDLE OF THE UPCOMING WEEK.
KEY MESSAGES
1. SCATTERED SHOWERS AND THUNDERSTORMS ARE ANTICIPATED TO
DEVELOP ACROSS PORTIONS OF EASTERN PENNSYLVANIA AND NEW JERSEY
LATER TODAY INTO TONIGHT. TEMPERATURES WILL BE WARMER WITH
INCREASING HUMIDITY AS WELL.
2. HEAT AND HUMIDITY WILL BUILD INTO THE MIDDLE OF THE WEEK,
ALONG WITH DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS. THERE IS
AN INCREASING THREAT OF SEVERE THUNDERSTORMS DURING THE MIDDLE
OF THE WEEK, NAMELY TUESDAY THROUGH THURSDAY.
DISCUSSION
KEY MESSAGE 1...SCATTERED SHOWERS AND THUNDERSTORMS ARE
ANTICIPATED TO DEVELOP ACROSS PORTIONS OF EASTERN PENNSYLVANIA
AND NEW JERSEY LATER TODAY INTO TONIGHT. TEMPERATURES WILL BE
WARMER WITH INCREASING HUMIDITY AS WELL.
AS HIGH PRESSURE SHIFTS OFFSHORE THROUGH THE DAY, SOUTHWESTERLY
FLOW WILL RAMP UP INTO THE AFTERNOON. TEMPERATURES WILL WARM
INTO THE MID 80S FOR MOST AREAS (EVEN SOME UPPER 80S IN SPOTS),
ON THE ORDER OF 5 DEGREES WARMER THAN SATURDAY. DEWPOINTS WILL
ALSO SURGE BACK WELL INTO THE 60S TO AROUND 70 DEGREES BY THE
AFTERNOON HOURS, MAKING FOR A NOTICEABLE RETURN IN SUMMER-LIKE
HUMIDITY. SKIES WILL TURN MOSTLY CLOUDY BY THE AFTERNOON,
ESPECIALLY ALONG AND NW OF I-95, WHICH SHOULD HELP NEGATE THE
DEGREE OF UNPLEASANT HUMIDITY.
THE MAIN FORECAST CHALLENGE FOR TODAY WILL BE THE POTENTIAL FOR
SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING LATER THIS
AFTERNOON AND INTO TONIGHT. THE LATEST TREND IN THE CAMS HAS
BEEN FOR AN EVEN LATER CONVECTIVE INITIATION TIME THAN
BEFORE, WHICH WILL SIGNIFICANTLY LIMIT ANY POTENTIAL FOR SEVERE
AND FLASH FLOOD THREATS. THE GREATEST LIMITING FACTOR APPEARS
TO BE A LACK OF SUBSTANTIAL INSTABILITY UNTIL CLOSE TO SUNSET,
WITH EVEN THE HIGHEST MODELED CAPE LARGELY LESS THAN 1,000
J/KG. THIS COMBINED WITH POOR LAPSE RATES AND WEAK FORCING
DURING THE PEAK DIURNAL TIME FRAME SHOULD LIMIT COVERAGE FOR
MUCH OF THE DAYTIME HOURS. HOWEVER, BETTER FORCING DOES LOOK TO
ARRIVE DURING THE EVENING TO EVEN OVERNIGHT HOURS. SO AT LEAST
SOME SCATTERED SHOWERS AND POTENTIAL FOR A FEW THUNDERSTORMS ARE
STILL ANTICIPATED TO DEVELOP AT SOME POINT. WE STILL CANNOT
TOTALLY RULE OUT A COUPLE STRONGER STORMS, WITH GUSTY WINDS,
SMALL HAIL, AND BRIEF HEAVY DOWNPOURS POSSIBLE.
SCATTERED SHOWERS MAY PERSIST WELL INTO THE OVERNIGHT HOURS AS
FORCING REMAINS ALOFT.
KEY MESSAGE 2...HEAT AND HUMIDITY WILL BUILD INTO THE MIDDLE OF
THE WEEK, ALONG WITH DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS. THERE IS AN INCREASING THREAT OF SEVERE
THUNDERSTORMS DURING THE MIDDLE OF THE WEEK, NAMELY TUESDAY
THROUGH THURSDAY.
BROAD UPPER LEVEL RIDGING RETURNS TO THE EASTERN US EARLY NEXT
WEEK, BRINGING IN SURFACE HIGH PRESSURE ACROSS THE EASTERN US.
AFTERNOON HIGHS WILL CREEP BACK INTO THE MID 80S TO LOW 90S FOR
MOST AREAS, ABOUT 5 DEGREES ABOVE AVERAGE FOR EARLY SEPTEMBER.
DEWPOINTS WILL ALSO REMAIN IN THE UPPER 60S TO LOW 70S. THE
HOTTEST DAY LOOKS TO BE TUESDAY, WHEN HIGH TEMPERATURES COULD
GET INTO THE MID 90S ACROSS DELMARVA AND INTO THE PHILLY METRO.
RESULTING HEAT INDICES WILL BE WELL INTO THE 90S TO LOW 100S. WE
WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR HEAT ADVISORIES.
ONE OTHER ASPECT TO WATCH WITH THIS RIDGING PATTERN IS THE
POTENTIAL FOR THUNDERSTORMS TO ROTATE AROUND THE PERIPHERY OF
THE RIDGE AND THE POSITION OF A FRONTAL BOUNDARY DURING THE
MIDDLE OF THE WEEK. GUIDANCE IS COMING INTO A CONSENSUS THAT THE
PATTERN WILL BE SUPPORTIVE OF MULTIPLE ROUNDS OF THUNDERSTORMS,
ESPECIALLY DURING THE TUESDAY THROUGH THURSDAY TIME FRAME. WE
COULD SEE SOME SCATTERED SHOWERS AND STORMS ON MONDAY, THOUGH
THE SEVERE AND FLASH FLOOD RISKS APPEAR TO BE LOW FOR MONDAY.
SPC MAINTAINS 15% PROBABILITIES FOR SEVERE THUNDERSTORMS FOR
OUR REGION ON WEDNESDAY (DAY 4). AS OF THIS MORNING, SPC HAS
INTRODUCED A DAY 3 SLIGHT RISK (LEVEL 2 OUT OF 5) FOR TUESDAY
(DAY 3), AND INTRODUCED 15% PROBABILITIES FOR THURSDAY (DAY 5)
AS WELL. THE NORTHWEST FLOW PATTERN THAT WILL BE IN PLACE WILL
BE SUPPORTIVE OF ALL SEVERE THREATS, INCLUDING DAMAGING WINDS,
LARGE HAIL, AND TORNADOES, THOUGH THE THREAT OF FLASH FLOODING
IS TYPICALLY LOWER IN THESE PATTERNS. LONG STORY SHORT, THE
TUESDAY THROUGH THURSDAY PERIOD LOOKS VERY ACTIVE WITH MULTIPLE
ROUNDS OF THUNDERSTORMS ACROSS THE REGION, BUT DETAILS REMAIN
UNCLEAR. STAY TUNED FOR UPDATES ON THE THREAT FOR SEVERE
THUNDERSTORMS IN THE COMING DAYS.
BY FRIDAY, CURRENT MODEL CONSENSUS INDICATES THE FRONTAL
BOUNDARY WILL BE PUSHING SOUTH OF OUR REGION WITH CANADIAN HIGH
PRESSURE BUILDING ACROSS THE NORTHEAST, WHICH WOULD BRING AN
END TO THE RISK OF THUNDERSTORMS AND SEVERE WEATHER. SOME STORMS
COULD LINGER TOWARD OUR SOUTH, ESPECIALLY NEAR DELMARVA ON
FRIDAY THOUGH. THIS EXTENDED RANGE PATTERN ALSO SUPPORTS DRY
AND PLEASANT WEATHER FOR LABOR DAY WEEKEND.
AVIATION /09Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH 12Z...PREVAILING VFR, THOUGH THERE IS A LOW CHANCE
(LESS THAN 20%) OF SOME PATCHY FOG, PARTICULARLY FOR MIV AND
ACY. WINDS FAVORING A SOUTH-SOUTHWESTERLY DIRECTION AT LESS THAN
5 KTS, WITH CALM PERIODS LIKELY. MODERATE CONFIDENCE OVERALL.
TODAY...MAINLY VFR EXCEPT SOME LOW STRATUS IS LIKELY IN THE
MORNING FOR RDG AND ABE WHERE WE'VE INTRODUCED A TEMPO GROUP FOR
MVFR CIGS. ISOLATED TO SCATTERED SHOWERS AND STORMS WILL BE
AROUND IN THE AFTERNOON AND EVENING, WHICH COULD LEAD TO
RESTRICTIONS AFTER 20Z. RDG AND ABE HAVE THE HIGHEST CHANCE FOR
RESTRICTIONS, BUT THEY CANNOT BE RULED OUT AS FAR SOUTHEAST AS
THE I-95 TERMINALS. HAVE MAINTAINED VCTS AND VCSH FOR MOST
AREAS, THOUGH TEMPO GROUPS MAY BE NEEDED EVENTUALLY. SOUTH TO
SOUTHWEST WINDS 5-10 KTS. MODERATE CONFIDENCE.
TONIGHT...MVFR CEILINGS ANTICIPATED AFTER 06Z OR SO IN THE WAKE
OF THE AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. SOUTH
TO SOUTHWEST WINDS AROUND 5 KTS OR LESS, SHIFTING NORTHEAST
AFTER 06Z. LOW CONFIDENCE.
OUTLOOK...
MONDAY THROUGH THURSDAY...RESTRICTIONS POSSIBLE IN SHOWERS AND
THUNDERSTORMS EACH DAY, MAINLY DURING THE AFTERNOON TO EVENING
HOURS.
MARINE
NO PREVAILING MARINE HAZARDS EXPECTED. WINDS WILL SHIFT SOUTH-
SOUTHWESTERLY AT 10-15 KTS. SEAS 2-3 FEET. SHOWERS AND STORMS
ARE POSSIBLE BEGINNING THIS EVENING, PARTICULARLY FOR THE
NORTHERN NJ COASTAL WATERS.
OUTLOOK...
MONDAY THROUGH THURSDAY...NO PREVAILING MARINE HAZARDS
EXPECTED. CHANCES FOR THUNDERSTORMS EACH DAY, MAINLY IN THE
AFTERNOON AND EVENING HOURS.
RIP CURRENTS...
FOR TODAY, SOUTH TO SOUTH-SOUTHWEST WINDS OF 5-10 MPH INCREASE
TO 10-15 MPH IN THE AFTERNOON. BREAKING WAVES OF 1 TO 3 FEET. A
LIGHT SOUTHEASTERLY SWELL WITH A PERIOD AROUND 8 SECONDS WILL
REMAIN. AS A RESULT, THERE IS A LOW RISK FOR THE DEVELOPMENT OF
DANGEROUS AND LIFE THREATENING RIP CURRENTS AT THE JERSEY SHORE
AND DELAWARE BEACHES.
FOR MONDAY, NORTH TO NORTHWEST WINDS IN THE MORNING WILL SHIFT
TO EAST IN THE AFTERNOON AROUND 5 MPH. BREAKING WAVE HEIGHTS
AROUND 1 FOOT. A LIGHT SOUTHEASTERLY SWELL WITH A PERIOD AROUND
8 SECONDS WILL REMAIN. THIS WILL CONTINUE TO LEAD TO A LOW RISK
FOR THE DEVELOPMENT OF DANGEROUS AND LIFE THREATENING RIP
CURRENTS AT THE JERSEY SHORE AND DELAWARE BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...AS
AVIATION...AS/WFO PHI
MARINE...AS/WFO PHI
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