254
FXUS61 KPHI 142321
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
721 PM EDT TUE JUL 14 2026
WHAT HAS CHANGED
THE CHANCE FOR ISOLATED TO SCATTERED SHOWERS AND STORMS, SOME
OF WHICH COULD BE SEVERE, HAS INCREASED SLIGHTLY FOR WEDNESDAY
AFTERNOON AND EVENING.
AVIATION SECTION UPDATED FOR THE 00Z TAF ISSUANCE.
KEY MESSAGES
1. ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE END OF
THE WEEK. WEDNESDAY WILL BE THE HOTTEST DAY OF THE STRETCH, WHEN
DANGEROUSLY HOT AND HUMID CONDITIONS ARE EXPECTED. EXTREME HEAT
WARNINGS AND HEAT ADVISORIES ARE IN EFFECT FOR OUR ENTIRE
FORECAST AREA.
2. A COLD FRONT WILL PASS THROUGH THE REGION WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT. ISOLATED TO SCATTERED SHOWERS
AND STORMS WILL BE POSSIBLE IN THE AFTERNOON AND EARLY EVENING
HOURS FOR PARTS OF THE AREA, SOME OF WHICH COULD BE SEVERE.
3. THE WEEKEND IS SHAPING UP TO BE ACTIVE AND UNSETTLED WITH
CHANCES FOR SHOWERS AND THUNDERSTORMS EACH DAY. SOME STORMS
COULD BE SEVERE AND ALSO MAY PRODUCE HEAVY RAINFALL LEADING TO
FLASH FLOODING.
DISCUSSION
KEY MESSAGE 1..ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH
THE END OF THE WEEK. WEDNESDAY WILL BE THE HOTTEST DAY OF THE
STRETCH, WHEN DANGEROUSLY HOT AND HUMID CONDITIONS ARE EXPECTED.
EXTREME HEAT WARNINGS AND HEAT ADVISORIES ARE IN EFFECT FOR OUR
ENTIRE FORECAST AREA.
HEAT AND HUMIDITY HAS BEGUN BUILDING OVER THE AREA TODAY AS AN
UPPER LEVEL AREA OF HIGH PRESSURE OVER THE CENTRAL PART OF THE
COUNTRY EXPANDS EASTWARD TOWARDS THE EAST COAST. A LOW PRESSURE
SYSTEM MOVING THROUGH EASTERN CANADA WILL RESULT IN WARM
ADVECTION STRENGTHENING INTO WEDNESDAY.
ON WEDNESDAY, THE HEAT WILL CONTINUE TO BUILD OVER THE AREA.
HIGH TEMPERATURES SHOULD RANGE FROM THE MID 90S TO NEAR 100
DEGREES IN MOST AREAS, HOTTEST ALONG AND SOUTHEAST OF I-95, WITH
INCREASING HUMIDITY. WHILE SOME AREAS WILL LIKELY REACH THE
CENTURY MARK AGAIN, IT WILL NOT BE QUITE TO THE MAGNITUDE THAT
WE EXPERIENCED TO START JULY. HUMIDITY WILL BE A LITTLE LESS AS
WELL, AND THE HOTTEST CONDITIONS WILL ONLY LAST FOR ONE DAY.
HOWEVER, HEAT INDEX VALUES ARE STILL FORECAST TO RANGE FROM
100-109 DEGREES FOR MOST OF THE AREA, AGAIN HOTTEST FROM ALONG
AND SOUTHEAST OF I-95. A MODEST WESTERLY, OFFSHORE WIND NEAR
10-15 MPH SHOULD HELP KEEP THE SEA BREEZE FROM MAKING MUCH
INLAND PROGRESS DURING THE AFTERNOON HOURS. THUS, WE EXPECT HIGH
TEMPERATURES IN THE MID TO UPPER 90S AND HEAT INDICES NEAR
100-105 DEGREES EVEN FOR THE NEW JERSEY SHORE AND DELAWARE
BEACHES. THE LIMITING FACTOR IN HOW MUCH WE HEAT WILL BE SMOKE
FROM CANADIAN WILDFIRES. WE ARE ALREADY SEEING THE FIRST PLUME
OF WILDFIRE SMOKE DROPPING SOUTH INTO THE THE MID-ATLANTIC THIS
AFTERNOON AND THAT WILL INSULATE THE REGION FROM THE HIGHEST
HEAT. THE SMOKE SHOULD AGAIN HELP MITIGATE HOW MUCH HEATING WE
RECEIVE TOMORROW SO WHILE TEMPS ARE GOING TO BE HOT AND THERE
ARE NO CHANGES TO ANY HEAT HEADLINES, WE ARE NOT FULLY
MAXIMIZING THE POTENTIAL HEAT THAT THE THERMAL PROFILE SUGGESTS
WE COULD WARM TO.
A COLD FRONT LOOKS TO PASS SOMETIME LATE WEDNESDAY WHICH WILL
KNOCK DOWN TEMPERATURES AND DEWPOINTS A BIT. HOWEVER, THURSDAY
WILL STILL BE QUITE HOT, WITH MAXIMUM HEAT INDICES IN THE UPPER
90S TO LOW 100S ALONG AND SOUTHEAST OF I-95. IT IS POSSIBLE SOME
ADDITIONAL HEAT ADVISORIES COULD BE NEEDED ON THURSDAY FOR OUR
SOUTHERN ZONES. FRIDAY LOOKS TO BRING MORE RELIEF FROM THE
HUMIDITY AT LEAST, AS DRIER DEWPOINTS ADVECT IN FROM THE NORTH
DESPITE HIGHS IN THE LOW TO MID 90S REMAINING FOR SOME AREAS.
KEY MESSAGE 2...A COLD FRONT WILL PASS THROUGH THE REGION
WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. ISOLATED TO SCATTERED
SHOWERS AND STORMS WILL BE POSSIBLE IN THE AFTERNOON AND EARLY
EVENING HOURS FOR PARTS OF THE AREA, SOME OF WHICH COULD BE
SEVERE.
MOST OF THE DAY WEDNESDAY IS STILL EXPECTED TO BE DRY, WITH
INCREASINGLY HOT AND HUMID CONDITIONS AHEAD OF AN APPROACHING
COLD FRONT. HOWEVER, CONCERN HAS INCREASED SOMEWHAT THAT
ISOLATED TO SCATTERED STORMS COULD FORM ACROSS THE NORTHERN HALF
OF THE AREA DURING THE AFTERNOON HOURS AND CONTINUE INTO THE
EVENING.
WHILE MID-LEVEL RIDGING WILL BE IN PLACE TO START THE DAY, IT
WILL SLOWLY BECOME SUPPRESSED TO THE SOUTH OF THE REGION THROUGH
THE AFTERNOON HOURS. A SHORTWAVE LOOKS TO DIG SOUTHEASTWARD
NORTH OF THE REGION ACROSS PORTIONS OF NEW ENGLAND. WHILE THE
SHORTWAVE APPEARS LIKELY TO REMAIN MOSTLY NORTH OF THE REGION,
IT WILL STILL CAUSE HEIGHT FALLS THROUGH THE AFTERNOON AND INTO
THE EVENING, WITH H5 FLOW ON THE ORDER OF 50-55 KT OVERSPREADING
THE AREA. THE ENVIRONMENT DURING THE AFTERNOON AND EARLY
EVENING HOURS AHEAD OF THE COLD FRONT WILL BECOME STRONGLY
UNSTABLE, WITH SBCAPE VALUES OF 2000-2500 J/KG. WITH SOME MIXING
TAKING PLACE, SURFACE DEWPOINTS WILL LIKELY FALL INTO THE UPPER
60S F. LOW-LEVEL LAPSE RATES WILL BE QUITE STEEP, WITH 0-3 KM
LAPSE RATES NEAR DRY ADIABATIC. WITH THE ENHANCED MID-LEVEL FLOW
OVERSPREADING THE REGION, EFFECTIVE SHEAR WILL RANGE FROM 40-50
KT, GREATEST ACROSS NORTHERN PORTIONS OF THE AREA. ALL OF THIS
BEING SAID, THE ENVIRONMENT IN PLACE WILL BE CONDITIONALLY
SUPPORTIVE OF SEVERE WINDS, AND PERHAPS SOME MARGINALLY SEVERE
HAIL AS WELL.
FORCING IS STILL EXPECTED TO BE SOMEWHAT WEAK, SO STORM
COVERAGE IS EXPECTED TO BE LIMITED. WE HAVE INCREASED POPS FROM
THE PHILLY METRO NORTHWARD TO AROUND 20%, AND TO AROUND 30%
NEAR AND JUST NORTH OF I-78. ANY ISOLATED STORMS THAT DEVELOP
SHOULD TRACK SOUTHEASTWARD INTO THE EVENING HOURS BEFORE RUNNING
INTO INCREASING INHIBITION AND DECREASING INSTABILITY,
THEREFORE, IT CURRENTLY APPEARS UNLIKELY THAT ANY CONVECTION
WOULD MAKE IT MUCH FARTHER SOUTH THAN THE PHILLY METRO AREA.
KEY MESSAGE 3...THE WEEKEND IS SHAPING UP TO BE ACTIVE AND
UNSETTLED WITH CHANCES FOR SHOWERS AND THUNDERSTORMS EACH DAY.
SOME STORMS COULD BE SEVERE AND ALSO MAY PRODUCE HEAVY RAINFALL
LEADING TO FLASH FLOODING.
WE ARE STILL SEVERAL DAYS OUT, BUT ARE MONITORING THE SEVERE
WEATHER SETUP AS WE GET INTO THE WEEKEND.
ANOTHER COLD FRONT WILL APPROACH ON FRIDAY. SOME MODELS ARE
TRENDING STORMIER WITH THIS PERIOD. FOR NOW THOUGH, THE
CONSENSUS BLEND OF GUIDANCE IS STILL MOSTLY DRY THROUGH THIS
PERIOD, BUT WILL BE WATCHING TRENDS WITHIN THIS PERIOD CLOSELY.
REGARDLESS, MOST MODELS ARE STILL FOCUSING STORM CHANCES WHEN
THE FRONT FINALLY SINKS INTO THE REGION SATURDAY. THE FRONT WILL
STAY OVER OR AT LEAST NEAR THE REGION INTO SUNDAY. AS IS OFTEN
THE CASE WITH THESE PATTERNS FOLLOWING A BUILDING HEAT PATTERN
MID WEEK, THERE IS SOME POTENTIAL FOR BOTH SEVERE THREATS AND
HEAVY RAIN/FLASH FLOODING THREAT. AT THIS EARLY VANTAGE POINT
THE SHEAR LOOKS TO BE MODERATE TO POTENTIALLY STRONG WITH THE
MAIN QUESTION BEING HOW UNSTABLE IT WILL GET. THIS WILL
DETERMINE THE EXTENT OF ANY SEVERE WEATHER THREAT BUT AT THIS
POINT WE SEE AT LEAST SOME POTENTIAL FOR SEVERE THREATS.
PRECIPITABLE WATER VALUES WILL ALSO BE INCREASING TO AROUND 2+
INCHES. THAT IS WELL ABOUT THE 90TH PERCENTILE FOR THIS TIME OF
YEAR, INCREASING THE RISK FOR HEAVY RAIN/FLASH FLOODING.
THERE'S UNCERTAINTY THOUGH REGARDING HOW FAST THIS FRONT PUSHES
THROUGH AND ALSO WHETHER IT MAY GET HUNG UP NEAR THE AREA INTO
EARLY NEXT WEEK. IF IT MOVES THROUGH FASTER AS THE GFS IS
INDICATING, THINGS COULD START TO CLEAR OUT BY LATER SUNDAY
AFTERNOON WITH FAIR WEATHER TO FOLLOW FOR MONDAY. HOWEVER THE
ECMWF HANGS UP THE FRONT OVER THE AREA INTO NEXT MONDAY WITH
CONTINUING CHANCES FOR SHOWERS AND STORMS.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR. SOUTHWEST WINDS TRENDING MORE WEST WITH TIME AT
5-10 KT. LLWS OUT OF THE NORTHWEST AT RDG AND ABE AT AROUND 35
KT. HIGH CONFIDENCE.
WEDNESDAY...PRIMARILY VFR. SMOKE COULD BRIEFLY BRING DOWN
VISIBILITY BELOW 6 MILES. ISOLATED STORMS ARE POSSIBLE AFTER
AROUND 20Z FOR RDG/ABE/TTN/PNE/PHL, WHICH COULD LEAD TO BRIEF
RESTRICTIONS, BUT CONFIDENCE IS NOT CURRENTLY HIGH ENOUGH TO
INCLUDE IN THE TAFS. WEST WINDS INCREASING TO AROUND 10 KT WITH
GUSTS 15-20 KT. MODERATE CONFIDENCE OVERALL.
OUTLOOK...
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MAINLY VFR, HOWEVER
SOME SMOKE MOVING IN FROM THE WILDFIRES IN WESTERN ONTARIO COULD
RESULT IN SOME MVFR VISIBILITY AT TIMES. OTHERWISE, NO
SIGNIFICANT WEATHER.
FRIDAY THROUGH SUNDAY...RESTRICTIONS WILL BE POSSIBLE IN
ISOLATED TO SCATTERED SHOWERS AND STORMS. THE CHANCE FOR IMPACTS
TO TERMINALS CURRENTLY APPEARS GREATEST SATURDAY AFTERNOON AND
EVENING.
MARINE
SOUTH TO SOUTHWEST WINDS INCREASING AS THE DAY PROGRESSES TO
NEAR 15-25 KTS, STRONGEST NORTH OF ATLANTIC CITY. SEAS BUILDING
3-5 FEET. A SMALL CRAFT ADVISORY IS IN EFFECT FROM 2PM THROUGH
2AM ISSUED FOR THE NEW JERSEY ATLANTIC COASTAL WATERS NORTH OF
GREAT EGG INLET. WINDS AND SEAS DIMINISHING OVERNIGHT.
OUTLOOK...
WEDNESDAY THROUGH FRIDAY...NO MARINE HAZARDS EXPECTED. A FEW
THUNDERSTORMS POSSIBLE WEDNESDAY EVENING.
SATURDAY THROUGH SATURDAY NIGHT...SOUTH TO SOUTHWESTERLY WINDS
COULD APPROACH SCA CRITERIA, WITH 10-15 KT WINDS AND GUSTS 20-25
KT. SEAS GENERALLY UNDER 5 FEET.
SUNDAY...NO MARINE HEADLINES CURRENTLY ANTICIPATED WITH WINDS
UNDER 25 KT AND SEAS UNDER 5 FEET.
RIP CURRENTS...
ON WEDNESDAY, WEST WINDS WILL AVERAGE 10 TO 15 MPH WITH A LIGHT
SOUTHEAST SWELL WITH A PERIOD OF 6 TO 8 SECONDS. BREAKING WAVES
WILL AVERAGE 1 TO 2 FEET. AS A RESULT, THERE IS A LOW RISK FOR
THE DEVELOPMENT OF DANGEROUS AND LIFE THREATENING RIP CURRENTS
AT THE JERSEY SHORE AND AT DELAWARE BEACHES.
ON THURSDAY, SOUTH TO SOUTHWEST WINDS WILL AVERAGE 10 TO 15 MPH
WITH A LIGHT SOUTHEAST SWELL WITH A PERIOD OF 6 TO 8 SECONDS.
BREAKING WAVES WILL AVERAGE 1 TO 2 FEET. AS A RESULT, THERE IS A
LOW RISK FOR THE DEVELOPMENT OF DANGEROUS AND LIFE THREATENING
RIP CURRENTS AT THE JERSEY SHORE AND AT DELAWARE BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
CLIMATE
A BRIEF 1-DAY SPIKE IN TEMPERATURES IS EXPECTED, WITH HIGHS
LIKELY TO APPROACH RECORDS. HERE ARE THE RECORDS FOR WEDNESDAY,
JULY 15:
ALLENTOWN/ABE 98 IN 1995
AC AIRPORT/ACY 100 IN 1995
AC MARINA/55N 99 IN 1995
GEORGETOWN/GED 96 IN 2024 AND 1993
MOUNT POCONO/MPO 92 IN 1954
PHILADELPHIA/PHL 103 IN 1995
READING/RDG 100 IN 1995
TRENTON/TTN 101 IN 1995
WILMINGTON/ILG 99 IN 1997 AND 1995
PHI WATCHES/WARNINGS/ADVISORIES
PA...EXTREME HEAT WARNING FROM 10 AM TO 8 PM EDT WEDNESDAY FOR
PAZ070-071-104-106.
HEAT ADVISORY FROM 10 AM TO 8 PM EDT WEDNESDAY FOR PAZ054-055-
060>062-101>103-105.
NJ...EXTREME HEAT WARNING FROM 10 AM TO 8 PM EDT WEDNESDAY FOR
NJZ010-012>015-017>020-027.
HEAT ADVISORY FROM 10 AM TO 8 PM EDT WEDNESDAY FOR NJZ001-
007>009-016-021>026.
DE...EXTREME HEAT WARNING FROM 10 AM TO 8 PM EDT WEDNESDAY FOR
DEZ001.
HEAT ADVISORY FROM 10 AM TO 8 PM EDT WEDNESDAY FOR DEZ002>004.
MD...HEAT ADVISORY FROM 10 AM TO 8 PM EDT WEDNESDAY FOR MDZ012-015-
019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT WEDNESDAY FOR ANZ450>452.
DISCUSSION...COOPER/DEAL/FITZSIMMONS/HOEFLICH/JOHNSON/STAARMANN
AVIATION...COOPER/DEAL/STAARMANN
MARINE...AKL/COOPER/DEAL/MPS/STAARMANN
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