422
FXUS61 KPHI 070853
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
453 AM EDT FRI AUG 7 2026
WHAT HAS CHANGED
THERE IS AN INCREASING THREAT OF SEVERE THUNDERSTORMS FOR LATE
THIS AFTERNOON AND EVENING ALONG AND NORTHWEST OF I-95.
A PORTION OF THE HEAT ADVISORY FOR NORTHERN NEW JERSEY AND
SOUTHEASTERN PENNSYLVANIA WAS EXTENDED THROUGH SATURDAY.
KEY MESSAGES
1. HOT AND VERY HUMID CONDITIONS ARE EXPECTED TO PERSIST
THROUGH TUESDAY OF NEXT WEEK. A HEAT ADVISORY IS IN EFFECT FOR
PORTIONS OF THE AREA.
2. THERE ARE DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH SATURDAY, AS WELL AS MUCH OF NEXT WEEK. THERE IS AT
LEAST A MARGINAL RISK EACH DAY FOR LOCALIZED HEAVY RAINFALL
LEADING TO FLASH FLOODING AND LOCALLY DAMAGING WIND GUSTS WITH
ANY STRONGER THUNDERSTORMS THAT DEVELOP.
DISCUSSION
KEY MESSAGE 1...HOT AND VERY HUMID CONDITIONS ARE EXPECTED TO
PERSIST THROUGH TUESDAY OF NEXT WEEK. A HEAT ADVISORY IS IN
EFFECT FOR PORTIONS OF THE AREA.
A RELATIVELY STAGNANT SYNOPTIC PATTERN IS DEVELOPING 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, MOST NOTABLY, VERY HUMID
CONDITIONS IS EXPECTED TO REMAIN IN PLACE FOR THE NEXT SEVERAL
DAYS. WE LOOK TO HAVE A WEAK COLD FRONTAL PASSAGE EARLY SUNDAY,
USHERING IN SLIGHTLY DRIER AIR. THIS WILL GIVE SOME SLIGHT
REPRIEVE FROM THE EXCESSIVE HUMIDITY, THOUGH HIGHS WILL STILL BE
IN THE UPPER 80S TO LOW 90S. MOISTURE ADVECTION WILL RETURN
AGAIN BY MONDAY THOUGH, AND HOT AND VERY HUMID CONDITIONS ARE
ANTICIPATED TO RETURN MONDAY THROUGH TUESDAY. A SOMEWHAT
STRONGER COLD FRONT LOOKS TO COME THROUGH LATE TUESDAY OR
WEDNESDAY, WHICH WILL HELP BREAK THE EXCESSIVE HEAT AND HUMIDITY
SOME.
A HEAT ADVISORY REMAINS IN EFFECT FOR PORTIONS OF EASTERN
PENNSYLVANIA, MUCH OF NEW JERSEY EXCEPT THE FAR SOUTHERN
COUNTIES, AS WELL AS NEW CASTLE COUNTY, DELWARE. A PORTION OF
THE HEAT ADVISORY FOR NORTHERN NEW JERSEY AND SOUTHEASTERN
PENNSYLVANIA WAS EXTENDED THROUGH SATURDAY. THIS INCLUDES MORRIS
AND HUNTERDON COUNTIES IN NJ, AND UPPER BUCKS, WESTERN
MONTGOMERY, AND WESTERN CHESTER COUNTIES IN PA.
KEY MESSAGE 2...THERE ARE DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGH SATURDAY, AS WELL AS MUCH OF NEXT WEEK.
THERE IS AT LEAST A MARGINAL RISK EACH DAY FOR LOCALIZED HEAVY
RAINFALL LEADING TO FLASH FLOODING AND LOCALLY DAMAGING WIND
GUSTS WITH ANY STRONGER THUNDERSTORMS THAT DEVELOP.
DIURNALLY DRIVEN INSTABILITY WILL MOSTLY BE IN THE 1000-2000
J/KG EACH AFTERNOON THROUGH THE NEXT SEVERAL DAYS (EXCEPT FOR
SUNDAY) ALONG WITH PWATS IN THE 1.5-2" RANGE. MEAN FLOW WILL BE
PREDOMINANTLY SOUTHWESTERLY AND RELATIVELY WEAK THROUGH
SATURDAY. THIS WILL SUPPORT A CONTINUED LOCALIZED HEAVY RAINFALL
THREAT WITH POTENTIAL FOR FLASH FLOODING, ALTHOUGH WATER LOADED
DOWNDRAFTS COULD CAUSE LOCALIZED WIND DAMAGE. AREAS WITH VERY
SATURATED GROUND FROM RECENT RAINS WILL BE MOST PRONE TO
EXPERIENCING TREES FALLING.
FOR LATE THIS AFTERNOON AND EVENING, A MID LEVEL SHORTWAVE
TROUGH WILL APPROACH THE AREA, PROVIDING MORE FORCING (AS
COMPARED TO THURSDAY). AS SUCH, STORM COVERAGE IS EXPECTED TO
BE MORE WIDESPREAD, AND STORMS SHOULD BE MORE ORGANIZED,
ALTHOUGH BULK SHEAR VALUES ARE STILL RELATIVELY MODEST (UP TO 25
KTS). LATEST ENVIRONMENTAL PARAMETERS AND CAMS INDICATE WE
SHOULD SEE SOME SCATTERED THUNDERSTORMS DEVELOPING ACROSS
EASTERN PA BY MID AFTERNOON. GIVEN THE WEAK LOW LEVEL SHEAR,
COLD POOL DEVELOPMENT SHOULD BEGIN TO PROPAGATE EASTWARD FAIRLY
QUICKLY. THIS SHOULD ULTIMATELY SUPPORT AN MCS OR TWO OF SORTS
DEVELOPING AND MOVING TOWARD THE I-95 CORRIDOR AHEAD OF MAXIMUM
BOUNDARY LAYER THERMODYNAMICS. THIS WILL SUPPORT DAMAGING WIND
GUSTS FOR A COUPLE HOURS OR SO AS THIS MCS(S) MOVES EAST.
EXACTLY WHERE THE GREATEST SEVERE THREAT WILL BE WILL DEPEND ON
WHERE THE EARLY ACTIVITY BEGINS DEVELOPING UPSTREAM. AS THE
ACTIVITY MOVES EAST, A LOSS OF DIURNAL HEATING AND ACCELERATING
COLD POOL CUTTING OFF INFLOW SHOULD CAUSE STORMS TO WEAKEN
TOWARD THE COAST. FORWARD MOTION OF THE STORMS SHOULD PRECLUDE A
SIGNIFICANT FLASH FLOOD THREAT, SO WE HAVE NOT ISSUED A FLOOD
WATCH, HOWEVER PWATS OF 2-2.25" WILL SUPPORT VERY HEAVY RAINFALL
RATES OF 2-3" PER HOUR. IF THESE WERE TO IMPACT URBANIZED AREAS
FOR LONG ENOUGH, THERE COULD CERTAINLY BE SOME FLASH FLOODING
CONCERNS.
ALL OF THAT SAID, THE THREAT OF SEVERE THUNDERSTORMS TODAY HAS
INCREASED, AND SPC HAS ADD A SLIGHT RISK FOR DAMAGING WINDS
ALONG AND NORTHWEST OF I-95 (MARGINAL RISK ELSEWHERE IN THE
FORECAST AREA). WE REMAIN IN A MARGINAL RISK FOR EXCESSIVE
RAINFALL FROM WPC.
DETAILS FOR SATURDAY'S CONVECTION REMAIN UNCLEAR, BUT WE COULD
CERTAINLY END UP WITH SOME POTENTIAL FOR FLASH FLOODING AND
SEVERE STORMS AGAIN. CURRENT INDICATIONS IN THE GUIDANCE SUPPORT
A LATER TIMING OF STORMS DURING THE EVENING OR EVEN OVERNIGHT
DEPENDING ON THE TIMING OF A WEAK COLD FRONT AND SHORTWAVE
TROUGH. PWATS LOOK SLIGHTLY LOWER THAN TODAY, AND MEAN FLOW IS A
BIT MORE WESTERLY THAN SOUTHWESTERLY, BUT OVERALL THE
THERMODYNAMICS APPEAR SIMILAR. THERE WILL BE LESS FORCING, SO
CONVECTION PROBABLY WON'T BE AS WIDESPREAD AS TODAY. WE REMAIN
IN A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM WPC AND GENERAL
THUNDER FROM SPC FOR SATURDAY.
WE LOOK TO HAVE A WEAK COLD FRONTAL PASSAGE BY EARLY SUNDAY,
USHERING IN SLIGHTLY DRIER AIR. THIS COMBINED WITH SUBTLE
SUBSIDENCE ALOFT WILL HELP BRIEFLY LIMIT CONVECTION POTENTIAL ON
SUNDAY AND ALSO GIVE SOME SLIGHT REPRIEVE FROM THE EXCESSIVE
HUMIDITY, THOUGH HIGHS WILL STILL BE IN THE UPPER 80S TO LOW
90S. MOISTURE AND FORCING ALOFT WILL RETURN BY MONDAY AS MEAN
FLOW SHIFTS MORE WESTERLY AND MID LEVEL FLOW INCREASES. THIS
SHOULD RESULT IN A GREATER SEVERE THUNDERSTORM THREAT COMPARED
TO THIS WEEK, AND PERHAPS SLIGHTLY LOWER FLASH FLOODING THREAT,
BUT THE DETAILS INTO THE PERIOD EARLY NEXT WEEK REMAIN UNCLEAR.
LONG STORY SHORT, MONDAY AND TUESDAY LOOK TO CONTINUE THE HOT
AND HUMID CONDITIONS AND DAILY THUNDERSTORM CHANCES.
A SOMEWHAT STRONGER COLD FRONT LOOKS TO COME THROUGH LATE
TUESDAY OR WEDNESDAY, WHICH WILL HELP BREAK THE EXCESSIVE HEAT
AND HUMIDITY SOME, BUT THE PATTERN ALOFT MAY STILL SUPPORT
DIURNALLY DRIVEN CONVECTION.
AVIATION /07Z FRIDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH 12Z...PREVAILING VFR EXPECTED. SOME FOG DEVELOPMENT IS
POSSIBLE, ESPECIALLY AT KRDG, KABE, AND KTTN, BUT CANNOT RULE
OUT SOME PATCHY FOG AT SOME OTHER TERMINALS. WINDS WILL
GENERALLY SETTLE OUT OF THE SOUTHWEST AROUND 5 KTS OR LESS, BUT
MAY BECOME LIGHT AND VARIABLE AT TIMES. MODERATE CONFIDENCE AS
A WHOLE, LOW CONFIDENCE ON ANY FOG DEVELOPMENT.
TODAY...VFR EXPECTED FOR MOST OF THE DAY. SCATTERED SHOWERS AND
THUNDERSTORMS WILL DEVELOP LATE IN THE DAY AND ORGANIZE INTO A
LINE OF SORTS, PRIMARILY AFTER 20-23Z FROM WEST TO EAST.
HIGHLIGHTED THIS WITH VCTS AT ALL TAF SITES, AND INCLUDED TEMPO
GROUPS FOR IFR VISIBILITY WHERE THUNDERSTORMS ARE MOST LIKELY.
SOUTHWEST WINDS GENERALLY BETWEEN 5-10 KTS, LOCALLY UP TO 15
KTS. MODERATE TO HIGH CONFIDENCE.
TONIGHT...PRIMARILY VFR EXPECTED, HOWEVER RESTRICTIONS ARE
POSSIBLE AT TIMES PRIOR TO 04Z WITH ANY SHOWERS OR
THUNDERSTORMS. PATCHY FOG POSSIBLE LATE. MODERATE CONFIDENCE
OVERALL.
OUTLOOK...
SATURDAY-SATURDAY NIGHT...MOSTLY VFR EXCEPT LOWER CONDITIONS
POSSIBLE WITH AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS.
SUNDAY-SUNDAY NIGHT...VFR CONDITIONS EXPECTED.
MONDAY-TUESDAY...MOSTLY VFR EXCEPT LOWER CONDITIONS POSSIBLE
WITH AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS.
MARINE
NO PREVAILING MARINE HAZARDS ARE EXPECTED THROUGH TONIGHT.
SOUTHERLY WINDS INCREASING TO 15-20 KTS. SEAS 2-4 FEET. A LINE
OF SHOWERS AND THUNDERSTORMS MAY MOVE OFFSHORE LATE IN THE
EVENING, WITH GUSTS OF 30-40 KTS AND LOCALLY HIGHER SEAS
POSSIBLE.
OUTLOOK...
SATURDAY-TUESDAY...NO PREVAILING MARINE HAZARDS EXPECTED.
THUNDERSTORMS POSSIBLE SATURDAY NIGHT AND TUESDAY NIGHT.
RIP CURRENTS...
FOR TODAY...SOUTHWEST TO SOUTH WINDS AROUND 10-15 MPH WITH
BREAKING WAVES IN THE SURF ZONE OF 1 TO 3 FEET. A MEDIUM PERIOD
EAST TO SOUTHEAST SWELL CONTINUES (DOMINANT WAVE PERIOD OF 5-7
SECONDS). OPTED TO GO WITH A LOW RISK FOR THE DEVELOPMENT OF
DANGEROUS RIP CURRENTS AT ALL BEACHES.
FOR SATURDAY...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 4 FEET. GIVEN THE INCREASING SURF AND SOUTHERLY WINDS, WENT
WITH A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS RIP
CURRENTS FOR THE JERSEY SHORE. BREAKING WAVES SHOULD BE A LITTLE
LOWER STILL FOR THE DELAWARE BEACHES AND COASTAL MONMOUTH
COUNTY, THEREFORE WENT WITH A LOW RISK FOR THE DEVELOPMENT OF
DANGEROUS RIP CURRENTS.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR PAZ070-071-102-104-
106.
HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ060>062.
HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR PAZ101-103-105.
NJ...HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR NJZ010-012>015-
017>020-027.
HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NJZ001-007.
HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR NJZ008-009.
DE...HEAT ADVISORY UNTIL 8 PM EDT SATURDAY FOR DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...JOHNSON/ROBERTSON/STAARMANN
AVIATION...JOHNSON/STAARMANN
MARINE...GORSE/STAARMANN
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