944
FXUS61 KPHI 032118
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
518 PM EDT MON AUG 3 2026
WHAT HAS CHANGED
THE FLOOD WATCH HAS BEEN CANCELED FOR THE REMAINDER OF THE AREA,
HOWEVER THERE IS STILL A RISK OF SOME FLOODING IN SOUTHERN
COASTAL NEW JERSEY AND SOUTHERN DELAWARE THROUGH 8 PM THIS
EVENING.
THERE IS INCREASING CONCERN FOR HEAT IMPACTS DURING THE LATER
HALF OF THE WEEK.
KEY MESSAGES
1. A COLD FRONT PASSING THROUGH THE REGION WILL TRIGGER
ADDITIONAL SHOWERS AND THUNDERSTORMS CAPABLE OF HEAVY RAIN
LEADING TO FLASH FLOODING. THERE IS ALSO A RISK FOR STRONG TO
SEVERE THUNDERSTORMS.
2. LOW PRESSURE SOUTH OF THE AREA WILL PUSH A WARM FRONT NORTH
THROUGH THE REGION TUESDAY NIGHT THROUGH WEDNESDAY.
3. FOR THE LATER HALF OF THE WEEK, WE WILL HAVE A HOT, HUMID,
AND AT TIMES STORMY PATTERN IN PLACE.
DISCUSSION
KEY MESSAGE 1...A COLD FRONT PASSING THROUGH THE REGION WILL
TRIGGER ADDITIONAL SHOWERS AND THUNDERSTORMS CAPABLE OF HEAVY
RAIN LEADING TO FLASH FLOODING. THERE IS ALSO A RISK FOR STRONG
TO SEVERE THUNDERSTORMS.
THE COLD FRONT CONTINUES TO WORK ITS WAY THROUGH EASTERN
PENNSYLVANIA, AND LATEST SURFACE OBS SHOW A NOTED DROP IN DEW
POINTS. AHEAD OF THE COLD FRONT, DEW POINTS ARE WELL IN THE 70S,
BUT BEHIND THE FRONT, DEW POINTS ARE GENERALLY IN THE LOW TO
MID 60S.
SHOWERS AND THUNDERSTORMS CONTINUE TO FIRE UP AHEAD OF THE
FRONT, AND DUE TO THOSE HIGH DEW POINTS AND PWATS IN EXCESS OF 2
INCHES, HEAVY RAIN CONTINUE TO DEVELOP. THIS HAS RESULTED IN
FLASH FLOODING EARLIER TODAY. THE FLOOD WATCH HAS BEEN CANCELED
AS OF 5 PM, AS THE THREAT FOR FLASH FLOODING WITHIN THE WATCH
AREA HAS ENDED. HOWEVER, THERE IS STILL A RISK OF SOME FLOODING
IN SOUTHERN COASTAL NEW JERSEY AND SOUTHERN DELAWARE THROUGH 8
PM THIS EVENING. THE WEATHER PREDICTION CENTER HAS NEW JERSEY
AND PORTIONS OF SOUTHEAST PENNSYLVANIA IN A SLIGHT RISK FOR
EXCESSIVE RAINFALL (2 OUT OF 4) FOR THE REST OF TODAY.
THE SEVERE RISK REMAINS UNCERTAIN, THOUGH BREAKS IN THE CLOUDS
WILL ALLOW TEMPERATURES TO WARM INTO THE LOWER 80S OR SO. SBCAPE
VALUES ARE UPWARDS OF 1500 TO 2000 J/KG. THERE IS ALSO 40 KT OF
SHEAR THAT WILL PASS THROUGH THE REGION WITH THE FRONT. AS A
RESULT, ANY SEVERE STORMS WILL BE ISOLATED, BUT STILL POSSIBLE.
IMPORTANT TO NOTE THAT FOR AREAS WHERE THE GROUND BECOMES
SATURATED DUE TO HEAVY RAIN, IT WILL NOT TAKE SEVERE LEVEL GUSTS
TO BRING DOWN TREES.
KEY MESSAGE 2...LOW PRESSURE SOUTH OF THE AREA WILL PUSH A WARM
FRONT NORTH THROUGH THE REGION TUESDAY NIGHT THROUGH WEDNESDAY.
THE COLD FRONT WORKS ITS WAY THROUGH THE REGION TONIGHT, THEN
WASHES OUT OVER THE AREA ON TUESDAY. HIGH PRESSURE BUILDS IN
FROM THE NORTH AND WEST ON TUESDAY BEFORE DEPARTING TUESDAY
NIGHT. A PLEASANT DAY ON TAP FOR TUESDAY WITH HIGHS IN THE LOW
TO MID 80S AND DEW POINTS GENERALLY IN THE LOW 60S.
A WARM FRONT THEN LIFTS NORTH THROUGH THE REGION TUESDAY NIGHT,
ALLOWING SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP LATE
TUESDAY NIGHT AND INTO WEDNESDAY MORNING. LOW PRESSURE
DEVELOPING OVER THE SOUTHEAST LIFTS NORTH ALONG THE EASTERN
SEABOARD, BUT THERE IS CONSIDERABLE UNCERTAINTY AS TO ITS TRACK.
12Z GFS TAKES IT OUT TO SEA WITH MINIMAL IMPACTS TO THE AREA,
WHILE THE 12Z ECMWF AS IT INLAND ACROSS PENNSYLVANIA, WHERE THE
HEAVIEST RAIN WILL FALL, AND THE 12Z NAM BRINGS IT RIGHT OVER
THE I-95 CORRIDOR. HEAVY RAIN WILL RESULT IN FLASH FLOODING, BUT
IT IS UNCERTAIN AS TO WHERE THAT HEAVY RAIN WILL FALL. THE
WEATHER PREDICTION CENTER HAS A MARGINAL RISK FOR EXCESSIVE
RAINFALL, WHICH IS A 1 OUT OF 4. FOR NOW, WILL FOLLOW THE NBM
AND CARRY HIGH CHANCE TO LOW END LIKELY POPS FOR MOST OF THE
REGION. THERE IS THE POTENTIAL FOR ANOTHER 1/2 INCH TO 1 INCH OF
RAIN WEDNESDAY AFTERNOON AND EVENING.
KEY MESSAGE 3...FOR THE LATER HALF OF THE WEEK, WE WILL HAVE A
HOT, HUMID, AND AT TIMES STORMY PATTERN IN PLACE.
EXPECT A PROLONGED PERIOD OF SOUTHWESTERLY FLOW AS OUR REGION
WILL BE IN BETWEEN A BERMUDA HIGH WELL TO OUR EAST, AND A MID
LEVEL LONG WAVE TROUGH THAT WILL BE SLOWLY SLIDING EAST OVER THE
NORTHERN TIER OF THE U.S./SOUTHERN CANADA. AS SUCH, HEAT AND
HUMIDITY WILL BE BUILDING THROUGHOUT THE LATER HALF OF THE WEEK.
AT THIS POINT, FRIDAY AND SATURDAY APPEAR TO BE THE WARMEST
DAYS, WITH HIGHS RANGING FROM THE UPPER 70S TO NEAR 90. THAT IN
AND OF ITSELF IS PRETTY CLOSE TO NORMAL. HOWEVER, WITH DEWPOINTS
IN THE MID 70S POSSIBLE, WE COULD GET HEAT INDEX VALUES AT OR
ABOVE 100 DEGREES FOR MUCH OF THE AREA. ALL THAT BEING SAID,
THIS STILL DOESN'T LOOK NEARLY AS IMPACTFUL AN EXTREME HEAT
SETUP AS WHAT WE SAW EARLIER THIS SUMMER DURING THE FIRST WEEK
OF JULY.
THE OTHER ASPECT OF THIS ARE THE DAILY STORM CHANCES, PRIMARILY
CONFINED TO THE AFTERNOON AND EVENING WITH A TYPICAL DIURNAL
PATTERN. GIVEN THE HOT AND HUMID CONDITIONS THAT WILL BE IN
PLACE, WE CAN'T RULE OUT THE MORE COMMON THUNDERSTORM HAZARDS OF
DAMAGING WINDS AND HEAVY RAIN/FLOODING, BUT IN GENERAL, I DON'T
SEE ANY ONE DAY THAT HAS AN ESPECIALLY HIGH THREAT OF ANY OF
THESE AT THIS TIME. IF AN EMBEDDED SHORT WAVE TROUGH CROSSES OUR
REGION AS THE LARGER TROUGH AXIS APPROACHES, THAT COULD
INCREASE THE RISK, PARTICULARLY FOR SEVERE THREATS, BUT TRYING
TO TIME THAT OUT AT THIS POINT WOULD BE VERY DIFFICULT, GIVEN
THAT WE ARE STILL SEEING SOME DIFFERENCES BETWEEN THE MODELS
WITH THE LARGER PATTERN.
AVIATION /21Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...GENERALLY MVFR TO IFR IN SHRA AND TSRA,
BECOMING VFR AFTER 21Z. KRDG/KABE ALREADY VFR. THERE MAY BE SOME
BRIEF VFR CONDS UNTIL THE COLD FRONT PASSES THROUGH PRIOR TO
21Z. S TO SW WINDS AROUND 10 KT, VEERING TO THE W BEHIND THE
FRONT. LOW CONFIDENCE.
TONIGHT...GENERALLY VFR, BUT THERE IS THE POTENTIAL FOR REDUCED
VSBYS IN BR. LIGHT N WINDS. LOW CONFIDENCE ON BR FORMATION.
TUESDAY...VFR. NE TO E WINDS 5 TO 10 KT. HIGH CONFIDENCE.
OUTLOOK...
TUESDAY NIGHT...MVFR OR LOWER POSSIBLE LATE IN SHRA.
WEDNESDAY THROUGH WEDNESDAY NIGHT...MVFR OR LOWER POSSIBLE IN
SHRA AND TSRA.
THURSDAY THROUGH SATURDAY...PERIODS OF MVFR OR LOWER IN
AFTERNOON AND EVENING SHRA/TSRA.
MARINE
A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL 6 AM TUESDAY,
PRIMARILY FOR ELEVATED SEAS ON THE OCEAN OF 6 TO 9 FEET. SEAS
WILL SUBSIDE THIS EVENING, AND THE SCA MAY BE ABLE TO BE
CANCELLED PRIOR TO THAT. SOUTH WINDS GENERALLY 15 TO 20 KT,
HOWEVER, GUSTS OF 30 TO 35 KT POSSIBLE IN THUNDERSTORMS. WINDS
VEER TO THE NORTHEAST TONIGHT AT 10 TO 15 KT, AND THEN TURN EAST
ON TUESDAY.
OUTLOOK...
TUESDAY NIGHT THROUGH SATURDAY...OVERALL, A PROLONGED PERIOD OF
SUB-SCA CONDITIONS, HOWEVER THERE IS A CHANCE FOR 25+ KT WIND
GUSTS THURSDAY NIGHT AND FRIDAY NIGHT. AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS POSSIBLE AS WELL.
RIP CURRENTS...
THERE IS A HIGH RISK FOR THE FORMATION OF DANGEROUS RIP
CURRENTS ALONG THE NJ COAST TODAY DUE TO LONG PERIOD SWELLS WITH
SURF HEIGHTS NEAR OR ABOVE 3 FEET. FOR THE DELAWARE BEACHES,
THERE IS A MODERATE RISK FOR THE FORMATION OF DANGEROUS RIP
CURRENTS.
FOR TUESDAY, SURF HEIGHTS SHOULD DECREASE SOME. HOWEVER, THERE
WILL BE A NORTHEAST (ONSHORE) BREEZE AND SOUTHEASTERLY SWELLS
WITH BREAKING WAVES OF 2-3 FEET IN MOST AREAS. THIS WILL RESULT
IN A MODERATE RISK FOR THE FORMATION OF DANGEROUS RIP CURRENTS
ALONG THE NJ SHORE AND DELAWARE BEACHES.
FOR WEDNESDAY, SURF HEIGHTS AND SWELLS WILL CONTINUE TO LESSEN
SOME, AND SURFACE WINDS WILL SHIFT SOUTH TO SOUTHEASTERLY. THIS
WILL RESULT IN A MODERATE RISK FOR THE FORMATION OF DANGEROUS
RIP CURRENTS ALONG THE NJ SHORE, AND A LOW RISK FOR THE
DELAWARE BEACHES.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...HIGH RISK FOR RIP CURRENTS UNTIL 8 PM EDT THIS EVENING FOR NJZ014-
024>026.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ450>455.
DISCUSSION...JOHNSON/MPS/STAARMANN
AVIATION...MPS
MARINE...MPS/STAARMANN
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