340
FXUS61 KPHI 092116
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
516 PM EDT THU JUL 9 2026
WHAT HAS CHANGED
A SEVERE THUNDERSTORM WATCH IS NOW IN EFFECT FOR THE EASTERN SHORES
OF MARYLAND, DELAWARE, AND SOUTHERN NEW JERSEY UNTIL 10 PM.
AN INCREASE IN THE POTENTIAL FOR SEVERE THUNDERSTORMS IS POSSIBLE
FRIDAY AFTERNOON INTO FRIDAY EVENING (SEE KEY MESSAGE 2).
KEY MESSAGES
1) SHOWERS AND THUNDERSTORMS PRODUCING HEAVY RAIN AND DAMAGING WIND
GUSTS WILL IMPACT THE REGION THROUGH THIS EVENING. ANOTHER ROUND OF
SHOWERS AND THUNDERSTORMS WILL DEVELOP LATE FRIDAY.
2) ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED ON
FRIDAY NIGHT INTO SATURDAY.
3) DRIER AND WARMER CONDITIONS RETURN BY THE END OF THE WEEKEND INTO
NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...SHOWERS AND THUNDERSTORMS PRODUCING HEAVY RAIN AND
DAMAGING WIND GUSTS WILL IMPACT THE REGION THROUGH THIS EVENING.
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL DEVELOP LATE FRIDAY.
LOW PRESSURE WILL ORGANIZE AND DEVELOP OVER THE SOUTHERN APPALACHIANS
AND MID-ATLANTIC AND WILL LIFT NORTH OVER NEW JERSEY AND INTO THE
NORTHEAST TONIGHT. A COLD FRONT APPROACHES LATE FRIDAY.
ABUNDANT LOW LEVEL MOISTURE IS IN PLACE ACROSS THE REGION WITH
SURFACE DEW POINTS IN THE LOW TO MID 70S, AND DEW POINTS WILL CREEP
UP BY A FEW MORE DEGREES GOING INTO THIS EVENING. PWATS ARE IN
EXCESS OF 2 INCHES ACROSS MOST OF THE REGION. AS THAT LOW LIFTS
NORTH TOWARDS THE NORTHEAST, SOME MID-LEVEL SHORTWAVE ENERGY WILL
PASS THROUGH THE REGION AS A MID-LEVEL TROUGH PASSES THROUGH THE
REGION. THIS WILL BE THE TRIGGER FOR SHOWERS AND THUNDERSTORMS TO
CONTINUE TO DEVELOP ACROSS THE REGION. SHOWERS AND THUNDERSTORMS
PRODUCING HEAVY RAIN HAVE DEVELOPED ALREADY, AND ACTIVITY WILL
INCREASE THROUGH THE EARLY EVENING HOURS. TRAINING OF THUNDERSTORMS
WILL BE LIKELY, AND WITH RAINFALL RATES OF 1-2 INCHES PER HOUR,
POSSIBLY AS HIGH AS 3 INCHES PER HOUR, WILL RESULT IN FLASH
FLOODING. A FLOOD WATCH REMAINS IN EFFECT FOR PORTIONS OF SOUTHEAST
PENNSYLVANIA, INCLUDING PHILADELPHIA, NORTHERN DELAWARE, AND MOST OF
NEW JERSEY UNTIL MIDNIGHT.
DUE TO THE HIGH DEW POINTS, SBCAPE VALUES RANGE FROM 2000-2500 J/KG
WITH DCAPE VALUES UP TO 500 J/KG. THUNDERSTORMS THAT DEVELOP WILL BE
CAPABLE OF DAMAGING WIND GUSTS.
THE WEATHER PREDICTION CENTER HAS A SLIGHT RISK (2 OUT OF 4) FOR
EXCESSIVE RAINFALL FOR MOST OF THE AREA INTO TONIGHT. THE STORM
PREDICTION CENTER HAS A SLIGHT RISK (2 OUT OF 5) FOR THE DELAWARE
VALLEY INCLUDING PHILADELPHIA, THE EASTERN SHORES OF MARYLAND,
DELAWARE, AND SOUTHERN NEW JERSEY AND A MARGINAL RISK FOR (1 OUT OF
5) FROM AROUND I-195 NORTH TO I-78.
A SEVERE THUNDERSTORM WATCH IS NOW IN EFFECT FOR THE EASTERN SHORES
OF MARYLAND, DELAWARE, AND SOUTHERN NEW JERSEY UNTIL 10 PM.
ACTIVITY TAPERS OFF FROM WEST TO EAST, MOSTLY ENDING BY 10 PM FOR
ALL BUT SOUTHEAST NEW JERSEY, AND STORMS WILL END THERE BY MIDNIGHT.
A WARM AND HUMID NIGHT ON TAP FOR THE REGION WITH PATCHY FOG
DEVELOPING. LOWS WILL BE IN THE UPPER 60S TO LOW 70S.
HUMID CONDITIONS CONTINUE ON FRIDAY WITH DEW POINTS GENERALLY IN THE
MID 70S. WITH DAYTIME TEMPERATURES IN THE UPPER 80S TO LOW 90S, THE
MAX HEAT INDEX VALUES WILL BE IN THE UPPER 90S, POSSIBLY TOUCHING
100.
A COLD FRONT APPROACHES FRIDAY AFTERNOON, TOUCHING OFF ANOTHER ROUND
OF LATE DAY SHOWERS AND THUNDERSTORMS, MAINLY OVER FAR WESTERN
PORTIONS OF THE FORECAST AREA (SEE KEY MESSAGE 2 FOR MORE).
KEY MESSAGE 2...ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE
EXPECTED ON FRIDAY NIGHT INTO SATURDAY.
BY FRIDAY EVENING, CONVECTION IS EXPECTED TO BE ONGOING ACROSS THE
AREA AS SHOWERS AND THUNDERSTORMS 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 INTO FRIDAY NIGHT DUE TO
UNCERTAINTY IN WHERE THE HEAVIEST RAINFALL WILL FALL TODAY.
IN TERMS OF THE SEVERE WEATHER THREAT, ML CAPE IS EXPECTED TO REACH
AT LEAST 1000 J/KG WITH BULK SHEAR VALUES AROUND 30-35 KT. GIVEN
BETTER FRONTAL FORCING, THERE LOOKS TO BE ANOTHER OPPORTUNITY FOR
SEVERE WEATHER. AS OF THE 1730UTC/DAY 2 UPDATE, SPC HAS UPGRADED THE
MAJORITY OF OUR AREA INTO A MARGINAL RISK (LEVEL 1/5) FOR SEVERE
WEATHER WITH THE PRIMARY HAZARD BEING LOCALLY DAMAGING WINDS.
FOR SATURDAY, THERE REMAINS A BIT OF UNCERTAINTY WITH RESPECT TO
FRONTAL PROGRESSION THROUGH THE AREA BUT GUIDANCE HAS TRENDED A BIT
WETTER OVERALL. WE NOW HAVE POPS IN THE 20-50% RANGE FOR AREA NORTH
AND WEST OF THE I-95 CORRIDOR, WITH POPS IN THE 50-80% RANGE FOR
AREAS SOUTHEAST OF I-95. AGAIN, THERE REMAINS A FLASH FLOOD THREAT
ON SATURDAY, PRIMARILY FOR THE SOUTHERN HALF OF THE AREA, WHICH IS
HIGHLIGHTED IN A MARGINAL RISK FOR EXCESSIVE RAINFALL. TEMPERATURES
WILL MAINLY BE IN THE 80S.
KEY MESSAGE 3...DRIER AND WARMER CONDITIONS RETURN BY THE END OF THE
WEEKEND INTO NEXT WEEK.
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 SUNNY/CLEAR SKIES ACROSS THE
MAJORITY OF THE MID-ATLANTIC REGION. TEMPERATURES WILL BE AROUND
NORMAL FOR SUNDAY, MONDAY AND TUESDAY, BUT WILL SWING BACK ABOVE
NORMAL FOR WEDNESDAY AND THURSDAY.
AVIATION /21Z THURSDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...SHRA/TSRA WITH MVFR/IFR CONDS, WITH OCNL VSBYS
AS LOW AS LIFR. SHRA/TSRA WILL TAPER OFF FROM WEST TO EAST BY
00Z. A GENERAL S TO SW FLOW AT 5 TO 10 KT. HIGH CONFIDENCE
OVERALL, LOW CONFIDENCE ON TIMING WHEN ANY GIVEN STORM WILL PASS
OVER ANY GIVEN TERMINAL.
TONIGHT...SHRA/TSRA WILL TAPER OFF AT KMIV/KACY BY 02Z. VFR,
BECOMING MVFR OR LOWER BY OR AFTER 06Z AS BR DEVELOPS. LIGHT S
TO NEARLY CALM WINDS. LOW CONFIDENCE.
FRIDAY...PRIMARILY VFR. ANOTHER ROUND OF SHRA/TSRA WILL IMPACT
THE TERMINALS IN THE LATE AFTERNOON AND AT NIGHT. W WINDS 5 TO
10 KT. MODERATE CONFIDENCE.
OUTLOOK...
FRIDAY NIGHT THROUGH SATURDAY...PREVAILING VFR, HOWEVER PERIODS OF
SUB-VFR CONDITIONS ARE POSSIBLE. A CHANCE FOR SHOWERS AND
THUNDERSTORMS WHICH MAY CAUSE LOCALLY GUSTY WINDS.
SATURDAY NIGHT THROUGH TUESDAY...VFR. NO SIGNIFICANT WEATHER
EXPECTED.
MARINE
SUB-SMALL CRAFT ADVISORY CONDITIONS THROUGH FRIDAY. SOUTHWEST WINDS
AROUND 10 TO 15 KT WILL TURN WEST ON FRIDAY. SEAS 2 TO 3 FEET.
SHOWERS AND THUNDERSTORMS THROUGH THIS EVENING WILL RESULT IN HEAVY
RAIN AND POTENTIALLY DAMAGING WIND GUSTS. VSBY RESTRICTIONS IN FOG
POSSIBLE LATE TONIGHT AND FRIDAY MORNING. ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS IS POSSIBLE LATE FRIDAY AFTERNOON.
OUTLOOK...
FRIDAY NIGHT THROUGH SATURDAY NIGHT...NO MARINE HEADLINES EXPECTED.
WINDS GENERALLY BETWEEN 5-15 KT WITH SEAS AROUND 2-3 FEET.
SUNDAY THROUGH SUNDAY NIGHT...SCA CONDITIONS POSSIBLE. WINDS
GENERALLY BETWEEN 10-20 KT WITH SEAS UP TO 5 FEET.
MONDAY THROUGH TUESDAY...NO MARINE HEADLINES EXPECTED. WINDS
GENERALLY BETWEEN 10-20 KT WITH SEAS AROUND 3-4 FEET.
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 SATURDAY, WINDS TURN NORTHERLY, AND THE SWELL REMAINS WEAK.
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 UNTIL MIDNIGHT EDT TONIGHT FOR PAZ060-070-071-
101>106.
NJ...FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NJZ009-010-012>022-
025>027.
DE...FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...DESILVA/HOEFLICH/MPS
AVIATION...DESILVA/MPS
MARINE...DESILVA/MPS/RCM
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