501
FXUS61 KPHI 081956
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
356 PM EDT SAT AUG 8 2026
WHAT HAS CHANGED
SEVERE THUNDERSTORM WATCHES REMAIN IN EFFECT FOR PORTIONS OF
THE REGION THROUGH THE AFTERNOON AND INTO THE EVENING.
KEY MESSAGES
1. HOT AND HUMID CONDITIONS ARE EXPECTED TO PERSIST THROUGH
TUESDAY OF NEXT WEEK, THOUGH AN IMPROVEMENT IN HUMIDITY IS
EXPECTED SUNDAY INTO MONDAY. A HEAT ADVISORY IS IN EFFECT FOR
PORTIONS OF THE AREA THROUGH TODAY.
2. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO
DEVELOP THIS AFTERNOON AND EVENING. SUNDAY STILL LOOKS TO BE
LARGELY DRY, THEN DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS
WILL RETURN MONDAY AND INTO THE MIDDLE OF NEXT WEEK. THERE IS A
RISK FOR STRONG TO SEVERE THUNDERSTORMS AS WELL AS A MARGINAL
RISK FOR LOCALIZED HEAVY RAINFALL LEADING TO FLASH FLOODING.
DISCUSSION
KEY MESSAGE 1...HOT AND HUMID CONDITIONS ARE EXPECTED TO PERSIST
THROUGH TUESDAY OF NEXT WEEK, THOUGH AN IMPROVEMENT IN HUMIDITY IS
EXPECTED SUNDAY INTO MONDAY. A HEAT ADVISORY IS IN EFFECT FOR
PORTIONS OF THE AREA THROUGH TODAY.
A RELATIVELY STAGNANT SYNOPTIC PATTERN WILL REMAIN IN PLACE ACROSS
OUR REGION. QUASI ZONAL MID AND UPPER LEVEL FLOW WILL BE IN PLACE
THROUGH THE MIDDLE OF NEXT WEEK AS BERMUDA HIGH PRESSURE PERSISTS
OFFSHORE. THIS WILL KEEP A STEADY STREAM OF VERY WARM AND MOIST AIR
IN PLACE ACROSS THE REGION THROUGH THE PERIOD.
A PROLONGED PERIOD OF HOT AND HUMID CONDITIONS WILL CONTINUE FOR THE
NEXT SEVERAL DAYS. WITH DEWPOINTS REMAINING IN THE LOW TO MID 70S
AND HIGHS IN THE UPPER 80S TO LOW 90S TODAY, HEAT INDICES WILL AGAIN
BE NEAR 100 DEGREES THIS AFTERNOON, MAINLY ALONG AND SOUTHEAST OF
THE I-95 CORRIDOR. A WEAK COLD FRONTAL PASSAGE SUNDAY WILL HELP
USHER IN SLIGHTLY DRIER AIR AND ALLOW DEWPOINTS TO MIX OUT DURING
THE AFTERNOON HOURS BOTH SUNDAY AND MONDAY. THIS WILL GIVE SOME
SLIGHT REPRIEVE FROM THE EXCESSIVE HUMIDITY, THOUGH HIGHS WILL STILL
BE IN THE UPPER 80S TO LOW OR EVEN MID 90S. THE LOWER DEWPOINTS
SUNDAY AND MONDAY WILL RESULT IN MAXIMUM HEAT INDICES MAINLY IN THE
MID TO UPPER 90S, THOUGH COULD GET NEAR 100 DEGREES IN DELMARVA.
SINCE THE FORECAST IS DECIDEDLY BELOW HEAT ADVISORY CRITERIA, WE'VE
OPTED NOT TO EXTEND IT TO COVER ADDITIONAL DAYS AT THIS TIME, THOUGH
IT WILL STILL BE HOT AND HUMID.
A HEAT ADVISORY REMAINS IN EFFECT THROUGH 8 PM THIS EVENING FOR
PORTIONS OF SOUTHEASTERN PENNSYLVANIA, PORTIONS OF NEW JERSEY, AND
NORTHERN DELWARE.
FROM THIS FORECAST UPDATE, THERE REMAINS SOME MOISTURE ADVECTION
AHEAD OF THE COLD FRONT. HOWEVER, THE COLD FRONT TIMING LOOKS A BIT
EARLIER TUESDAY WHICH HAS RESULTED IN SOME LOWER TEMPERATURES AND
HEAT INDEX VALUES. TEMPERATURES INTO THE MID 80S TO LOW 90S FOR MANY
AND HEAT INDEX VALUES PEAKING NEAR OR IN THE 90S FOR MANY. ONCE THE
COLD FRONT FULLY COMES THROUGH, WE WILL SEE A CONTINUED SLIGHT
REDUCTION IN TEMPERATURES INTO WEDNESDAY AND THURSDAY. HIGHS BY
WEDNESDAY AND THURSDAY ARE MOSTLY IN THE MID TO UPPER 80S, WHICH
WILL BE CLOSER TO AVERAGE FOR EARLY TO MID AUGUST.
KEY MESSAGE 2...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
CONTINUE TO DEVELOP THIS AFTERNOON AND EVENING. SUNDAY STILL
LOOKS TO BE LARGELY DRY, THEN DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL RETURN MONDAY AND INTO THE MIDDLE OF NEXT
WEEK. THERE IS A RISK FOR STRONG TO SEVERE THUNDERSTORMS AS WELL
AS A MARGINAL RISK FOR LOCALIZED HEAVY RAINFALL LEADING TO
FLASH FLOODING.
ISOLATED TO SCATTERED THUNDERSTORMS ARE DEVELOPING ACROSS THE
AREA THIS AFTERNOON AND ARE EXPECTED TO CONTINUE INTO THIS
EVENING. WITH THESE, THERE IS A THREAT FOR SEVERE THUNDERSTORMS,
AND A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR TWO PORTIONS
OF THE AREA. THE INITIAL AREA OF FOCUS IS NEAR AND SOUTH OF
I-195 AND THE PA TURNPIKE. THE SECOND AREA IS ACROSS
NORTHWESTERN NEW JERSEY. SYNOPTIC FORCING ISN'T AS STRONG AS
WHAT WE HAD FRIDAY, THOUGH THE REMNANT DYNAMICS FROM THE
CONVECTION UPSTREAM ARE GIVING US BETTER FORCING AT THE
MESOSCALE LEVEL. PWATS LOOK SLIGHTLY LOWER THAN TODAY, BUT
OVERALL THE THERMODYNAMICS APPEAR SIMILAR TO FRIDAY (2000-3000
J/KG CAPE). NOTABLY, MEAN FLOW IS MORE WESTERLY AND A BIT
STRONGER THAN FRIDAY, SO DEEP LAYER WIND SHEAR IS A LITTLE
STRONGER IN THE 25-30 KT RANGE. THIS WILL POSE MORE OF A LARGE
HAIL RISK COMPARED TO FRIDAY AS WELL, BUT DAMAGING WINDS WILL BE
THE MAIN THREAT WITH ANY STRONGER STORMS. LOCALLY HEAVY
RAINFALL LEADING TO FLASH FLOODING IS ALSO POSSIBLE, BUT
THINKING THE STRONGER FLOW ALOFT SHOULD KEEP STORMS MOVING
FASTER AND POSE SLIGHTLY LESS OF A FLASH FLOOD RISK.
SPC MAINTAINS A SLIGHT (LEVEL 2 OUT OF 5) RISK FOR SEVERE
THUNDERSTORMS FOR MOST OF OUR AREA. WE REMAIN IN A MARGINAL
(LEVEL 1 OUT OF 4) RISK FOR EXCESSIVE RAINFALL FROM WPC.
WE LOOK TO HAVE A WEAK COLD FRONTAL PASSAGE BY SUNDAY, USHERING IN
SLIGHTLY DRIER AIR. THIS COMBINED WITH SUBTLE SUBSIDENCE ALOFT WILL
HELP BRIEFLY LIMIT CONVECTION POTENTIAL ON SUNDAY, THOUGH CANNOT
COMPLETELY RULE OUT SOME ISOLATED SEA BREEZE CONVECTION IN THE
AFTERNOON.
BETTER SUPPORT FOR FORCING ALOFT WILL RETURN BY LATE MONDAY AS MEAN
FLOW SHIFTS MORE WESTERLY AND MID LEVEL FLOW INCREASES.
AT THIS POINT THOUGH, IT APPEARS THE GREATER THREAT OF STORMS WILL
BE TO OUR WEST ON MONDAY WHERE SPC HAS A MARGINAL RISK HIGHLIGHTED.
STILL COULD GET SOME ISOLATED STORMS, BUT MONDAY IS TRENDING DRIER
LOCALLY AS THE LINGERING LOWER DEWPOINTS SHOULD LIMIT OUR
INSTABILITY A BIT.
RECENT FORECAST TRENDS HAVE RESULTED IN LOWER INSTABILITY COMPARED
TO PREVIOUS MODEL RUNS ON TUESDAY GIVEN THE TIMING OF THE COLD FRONT
TO BE EARLIER. THERE DOES REMAIN UNCERTAINTY AROUND THE SPECIFIC
TIMING DETAILS OF THE FRONT AT THIS TIME. HOWEVER, WITH THAT SAID,
THERE IS STILL BETTER STORM CHANCES ON TUESDAY COMPARED TO MONDAY.
WITH THE STRONGER MID LEVEL FLOW ALOFT, SEVERE THUNDERSTORMS STILL
LOOK TO BE A GREATER THREAT COMPARED TO FLASH FLOODING, BUT THESE
DETAILS CONTINUE TO REMAIN UNCLEAR.
BEHIND THE SOMEWHAT STRONGER COLD FRONT THAT LOOKS TO COME THROUGH
TUESDAY INTO WEDNESDAY, WHICH WILL HELP BREAK THE EXCESSIVE HEAT AND
HUMIDITY SOME, THE PATTERN ALOFT MAY STILL SUPPORT DIURNALLY DRIVEN
CONVECTION.
AVIATION /19Z SATURDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...ISOLATED TO SCATTERED THUNDERSTORMS IN THE AFTERNOON
MAY CAUSE LOCALIZED RESTRICTIONS, HOWEVER CONFIDENCE ON WHERE
ANY OF THIS MAY DEVELOP IS LOW. CONTINUING TO INCLUDE PROB30
GROUPS FOR TSRA AT ALL TERMINALS AND UPDATING AS CONFIDENCE
INCREASES WITH APPROACHING CONVECTION. SOUTHWEST WINDS NEAR 10
KTS, WITH GUSTS UP TO 18 KTS. STRONG GUSTS UP TO 40-50 KTS
POSSIBLE WITH ANY THUNDERSTORMS. HIGH CONFIDENCE IN PREVAILING
VFR, LOW CONFIDENCE ON SHOWER AND STORM DETAILS.
TONIGHT...PREVAILING VFR, THOUGH SOME PATCHY FOG MAY DEVELOP.
SOME ISOLATED SHOWERS AND THUNDERSTORMS COULD LINGER THROUGH
06Z, BUT CONFIDENCE ON THIS IS TOO LOW TO INCLUDE A TAF MENTION
AT THIS TIME. SOUTHWEST WINDS NEAR 5 KTS OR LESS. MODERATE
CONFIDENCE.
SUNDAY...PREVAILING VFR. CAN'T RULE OUT AN AFTERNOON
THUNDERSTORM BRINGING RESTRICTIONS TO KACY OR KMIV BUT
CONFIDENCE IS TOO LOW TO INCLUDE AT THIS TIME. WESTERLY WINDS
AROUND 5-10 KTS. MODERATE CONFIDENCE.
OUTLOOK...
SUNDAY NIGHT...VFR CONDITIONS EXPECTED.
MONDAY-THURSDAY...MOSTLY VFR EXCEPT RESTRICTIONS POSSIBLE WITH
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS.
MARINE
A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR ALL COASTAL WATERS
OUT TO 20 NM AS WELL AS THE DELAWARE BAY (EXCEPT FOR COASTAL
WATERS NORTH OF MANASQUAN INLET) THROUGH 6 PM. WIND GUSTS
POTENTIALLY UP TO 40-50 KTS ARE POSSIBLE WITH ANY STRONG TO
SEVERE THUNDERSTORMS AS WELL AS LIGHTNING AND BRIEFLY HIGHER
SEAS. OUTSIDE OF ANY STORMS, SOUTHWEST TO SOUTH WINDS AROUND
10-20 KT WITH SEAS OF 2-4 FEET ARE EXPECTED THROUGH SUNDAY.
OUTLOOK...
MONDAY THROUGH THURSDAY...NO PREVAILING MARINE HAZARDS EXPECTED.
THUNDERSTORMS POSSIBLE TUESDAY AFTERNOON INTO TUESDAY NIGHT AND
AGAIN WEDNESDAY NIGHT.
RIP CURRENTS...
FOR TODAY...SOUTHWESTERLY WINDS CONTINUE AND SHOULD INCREASE
SOME TO 10-20 MPH. BREAKING WAVES IN THE SURF ZONE ARE FORECAST
TO INCREASE SOME, ESPECIALLY FOR MUCH OF THE JERSEY SHORE, AT 2
TO 3 FEET. GIVEN THE INCREASING SURF AND SOUTHERLY WINDS, WENT
WITH A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS RIP
CURRENTS FOR MOST OF THE JERSEY SHORE. BREAKING WAVES SHOULD BE
A LITTLE LOWER AND WINDS WILL HAVE MORE OF AN OFFSHORE OR SHORE
PARALLEL COMPONENT FOR THE DELAWARE BEACHES AND COASTAL
MONMOUTH COUNTY, THEREFORE WENT WITH A LOW RISK FOR THE
DEVELOPMENT OF DANGEROUS RIP CURRENTS.
FOR SUNDAY...SIMILAR CONDITIONS SUNDAY AS TODAY. SOUTHWESTERLY
WINDS CONTINUE AROUND 10-15 MPH. BREAKING WAVES IN THE SURF
ZONE ARE FORECAST TO REMAIN 1 TO 3 FEET. MAINTAINED THE SAME
RISK OF RIP CURRENTS FOR ALL COASTAL AREAS.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ070-071-
101>106.
NJ...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NJZ008>010-
012>015-017>020-027.
DE...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...AKL/GUZZO/STAARMANN
AVIATION...AKL/GUZZO
MARINE...AKL/GUZZO
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