791
FXUS61 KPHI 021629
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1229 PM EDT WED SEP 2 2026
WHAT HAS CHANGED
A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR THE EASTERN
SHORE OF MARYLAND THROUGH 5 PM TODAY.
KEY MESSAGES
1. TODAY INTO TONIGHT, A SHORTWAVE TROUGH COULD SPARK ANOTHER
ROUND OF SHOWERS AND STORMS, BUT IT WILL BE WORKING AGAINST A
RELATIVELY STABLE BOUNDARY LAYER.
2. HOT AND HUMID CONDITIONS ARE FORECAST ACROSS THE REGION ON
THURSDAY.
3. UNSETTLED CONDITIONS WILL CONTINUE ON THURSDAY WITH THE
POTENTIAL FOR SEVERE THUNDERSTORMS. SCATTERED THUNDERSTORMS ARE
AGAIN POSSIBLE ON FRIDAY, MAINLY SOUTH OF PHILADELPHIA.
4. THE LABOR DAY WEEKEND WILL FEATURE MOSTLY DRY WEATHER WITH
AT OR BELOW NORMAL TEMPERATURES AND LOWER HUMIDITY.
DISCUSSION
KEY MESSAGE 1...TODAY INTO TONIGHT, A SHORTWAVE TROUGH COULD
SPARK ANOTHER ROUND OF SHOWERS AND STORMS, BUT IT WILL BE
WORKING AGAINST A RELATIVELY STABLE BOUNDARY LAYER.
A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR THE EASTERN
SHORE OF MARYLAND TODAY UNTIL 5 PM.
A COLD FRONT CONTINUES TO REMAIN SITUATED ACROSS CENTRAL
PORTIONS OF THE REGION. THIS HAS LEFT A LARGE PORTION OF OUR
REGION IN THE RELATIVELY COOLER MARINE LAYER AND MORE STABLE AIR
MASS NORTH OF THE FRONT. THE NET RESULT IS THAT OUR REGION
SHOULD BE IN NORTHEAST TO EASTERLY FLOW, AND CLOUDY CONDITIONS
FOR MUCH OF THE DAY. AS A RESULT, SURFACE BASED INSTABILITY IS
EXPECTED TO BE VERY LIMITED, WITH MOSTLY ELEVATED INSTABILITY
PRESENT.
THE RISK FOR SEVERE STORMS STILL REMAINS QUITE CONDITIONAL AND
UNCERTAIN FOR A LARGE PORTION OF OUR AREA. THERE IS CURRENTLY A
LINE OF THUNDERSTORMS SINKING TO THE SOUTHEAST. THE AREAS THAT
HAVE THE CURRENT BEST POTENTIAL TO SEE THIS CONVECTION IS INTO
DELMARVA, PARTICULARLY THE EASTERN SHORE OF MARYLAND WHICH IS
UNDER THE SEVERE THUNDERSTORM WATCH THROUGH 5 PM. GIVEN HOW
SHARP OF A MID LEVEL SHORT WAVE TROUGH THAT IS APPROACHING,
THERE WILL BE AMPLE FORCING, BUT IT IS A QUESTION OF IF THE
ELEVATED INSTABILITY WILL BE ENOUGH TO SUSTAIN STORMS THROUGH
PARTS OUR REGION.
WITH THAT SAID, SOME CAMS DO FEATURE ADDITIONAL SCATTERED
STORMS MOVING INTO PARTS OF THE AREA BY LATE THIS
AFTERNOON/EARLY EVENING AND INTO TONIGHT. CONFIDENCE IN DETAILS
REGARDING THIS REMAINS RELATIVELY LOW, BUT SHOULD THE REGION
EXPERIENCE MORE DESTABILIZATION AND EROSION OF THE MARINE LAYER
THAN IS CURRENTLY ANTICIPATED, STORMS WILL BE CAPABLE OF
DAMAGING WINDS, SOME HAIL, AND PERHAPS AN ISOLATED TORNADO. THE
GREATER RISK OF ANY SEVERE STORMS WILL BE TOWARD OUR SOUTHERN
AND WESTERN ZONES. LOCALLY HEAVY RAINFALL WILL ALSO BE A THREAT
WITH ANY TRAINING SHOWERS AND STORMS, EVEN IF A SEVERE
THUNDERSTORM THREAT DOES NOT MATERIALIZE. PORTIONS OF EASTERN PA
HAVE BEEN HIGHLIGHTED IN A SLIGHT RISK FOR EXCESSIVE RAINFALL,
WHICH COULD LEAD TO LOCALIZED FLASH FLOODING.
SPC MAINTAINS A SLIGHT RISK (LEVEL 2 OUT OF 5) FOR SEVERE
THUNDERSTORMS FOR MUCH OF OUR AREA, BUT AGAIN, THIS RISK IS
HIGHLY CONDITIONAL AND LOW CONFIDENCE FOR TODAY INTO TONIGHT.
KEY MESSAGE 2...HOT AND HUMID CONDITIONS ARE FORECAST ACROSS
THE REGION ON THURSDAY.
A STRONG MARINE LAYER INFLUENCE TODAY WILL KEEP HIGHS MAINLY IN
THE 70S TO LOW 80S IN MOST AREAS. FOLLOWING THE BRIEF COOL DOWN
IN THE MARINE LAYER TODAY FOR MOST AREAS, HOT AND HUMID
CONDITIONS ARE ONCE AGAIN EXPECTED ACROSS THE REGION ON THURSDAY
AS THE FRONTAL BOUNDARY LIFTS NORTH AGAIN. WITH THE FRONT TO
THE NORTH, HIGH TEMPERATURES ARE FORECAST TO CLIMB INTO THE
UPPER 80S TO MID 90S FOR MANY AREAS (LOW TO MID 80S FAR NORTH).
THESE TEMPERATURES COMBINED WITH DEWPOINTS IN THE LOW TO MID
70S WILL AGAIN RESULT IN HEAT INDICES WELL INTO THE 90S TO LOW
100S SOUTH OF I-78, PERHAPS EVEN AS HIGH AS 105 DEGREES FOR
DELMARVA.
A NEW HEAT ADVISORY WAS ISSUED FOR PORTIONS OF SOUTHEASTERN PA
AND NJ. THIS ADVISORY MAY NEED TO BE EXPANDED INTO DELMARVA IF
THE FORECAST FOR HEAT INDICES NEAR 105 DEGREES HOLDS. NORTH OF
THE CURRENT ADVISORY AREA, MAXIMUM HEAT INDICES ARE FORECAST TO
TOP OUT IN THE LOW TO MID 90S, THUS THE ADVISORY IS UNLIKELY TO
NEED TO BE EXPANDED FARTHER NORTH.
KEY MESSAGE 3...UNSETTLED CONDITIONS WILL CONTINUE ON THURSDAY
WITH THE POTENTIAL FOR SEVERE THUNDERSTORMS. SCATTERED
THUNDERSTORMS ARE AGAIN POSSIBLE ON FRIDAY, MAINLY SOUTH OF
PHILADELPHIA.
ANOTHER ROUND OF SEVERE THUNDERSTORMS ARE POSSIBLE ON THURSDAY.
FRIDAY COULD ALSO EXPERIENCE A FEW SEVERE STORMS ACROSS
DELMARVA, DEPENDING ON HOW QUICKLY THE FRONTAL BOUNDARY PUSHES
SOUTH.
SPC HAS A SLIGHT RISK (LEVEL 2 OUT OF 5) FOR SEVERE
THUNDERSTORMS ON THURSDAY FOR DELMARVA AND A MARGINAL RISK
(LEVEL 1) TO AS FAR NORTH AS THE I-78 CORRIDOR.
THE NORTHWEST FLOW PATTERN WILL REMAIN IN PLACE ON THURSDAY AND
WILL CONTINUE TO BE SUPPORTIVE OF ALL SEVERE THREATS, INCLUDING
DAMAGING WINDS, LARGE HAIL, AND A FEW TORNADOES, DEPENDING ON
HOW ALL THE MESOSCALE DETAILS PAN OUT. THE THREAT FOR FLASH
FLOODING IS TYPICALLY LOWER WITH THESE PATTERNS, BUT NOT ZERO.
TRAINING CAN STILL OCCUR AND A SINGLE LOCALE COULD HAVE MULTIPLE
DAYS WITH HEAVY RAINFALL.
FRIDAY'S SPC OUTLOOK ONLY INCLUDES GENERAL THUNDERSTORMS (NO
SEVERE RISK), THOUGH THERE IS STILL SOME UNCERTAINTY WITH THIS.
OUR LATEST FORECAST HAS ABOUT A 30-40% CHANCE OF SHOWERS AND
THUNDERSTORMS NEAR AND SOUTH OF PHILADELPHIA.
KEY MESSAGE 4...THE LABOR DAY WEEKEND WILL FEATURE MOSTLY DRY
WEATHER WITH AT OR BELOW NORMAL TEMPERATURES AND LOWER HUMIDITY.
BY SATURDAY, CURRENT MODEL CONSENSUS INDICATES THE FRONTAL
BOUNDARY WILL BE PUSHING WELL SOUTH OF OUR REGION, WITH
CANADIAN HIGH PRESSURE BUILDING ACROSS THE NORTHEAST AND MID-
ATLANTIC. THIS WILL LARGELY END ANY SHOWER AND THUNDERSTORM
POTENTIAL. THUS, LABOR DAY WEEKEND IS STILL SHAPING UP TO
FEATURE NICE WEATHER, WITH TEMPERATURES TRENDING AT OR SLIGHTLY
BELOW NORMAL AND LOWER HUMIDITY. THE ONLY ROAD BUMP AT THE
MOMENT, COULD BE A COLD FRONT THAT APPROACHES THE FORECAST AREA
VERY LATE ON MONDAY.
AVIATION /16Z WEDNESDAY THROUGH SUNDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...IFR CEILINGS LIFTING TO MVFR, WHERE THEY MAY REMAIN
THROUGH MUCH OF THE DAY. THERE IS A 20 TO 40% CHANCE FOR SHOWERS
AND STORMS THROUGH THE DAY TIME THAT COULD ALSO RESULT IN
RESTRICTIONS, HOWEVER, THERE IS CONSIDERABLE UNCERTAINTY TO THE
EXTENT OF STORM DEVELOPMENT. TWO MAIN PERIODS FOR TSRA WILL BE
BETWEEN 15-20Z AND 22-06Z. EAST TO SOUTHEAST WINDS 5-10 KTS.
LOW CONFIDENCE.
TONIGHT...MVFR OR IFR CEILINGS. SCATTERED SHOWERS AND STORMS
ARE POSSIBLE, BUT THERE IS LOW CONFIDENCE IN COVERAGE AND
INTENSITY. VISIBILITY RESTRICTIONS ARE LIKELY IN ANY STRONGER
STORMS. SOUTHEAST TO SOUTH WINDS AROUND 5 KTS. LOW CONFIDENCE.
OUTLOOK...
THURSDAY AND FRIDAY...SUB-VFR CONDITIONS ARE POSSIBLE IN
SHOWERS AND THUNDERSTORMS EACH DAY (20-40% CHANCE), MAINLY
DURING THE AFTERNOON TO EVENING HOURS.
SATURDAY AND SUNDAY...PRIMARILY VFR CONDITIONS EXPECTED.
MARINE
WINDS AND SEAS ARE EXPECTED TO STAY BELOW SMALL CRAFT ADVISORY
CONDITIONS. HOWEVER, GUSTY AND ERRATIC WINDS ARE POSSIBLE IN THE
VICINITY OF ANY STORMS, PARTICULARLY TONIGHT.
OUTLOOK...
THURSDAY THROUGH SUNDAY...SUB-SCA CONDITIONS ARE EXPECTED
THROUGH THE PERIOD. THERE IS A CHANCE (40 TO 50%) FOR
THUNDERSTORMS THURSDAY, MAINLY IN THE AFTERNOON AND EVENING
HOURS. FOR FRIDAY, THE CHANCE OF THUNDERSTORMS (30 TO 40%)
SHIFTS SOUTH A BIT, BASICALLY EXTENDING FROM MANASQUAN INLET, NJ
DOWN TO FENWICK ISLAND, DE.
RIP CURRENTS...
FOR TODAY, NORTHEAST FLOW WILL RANGE FROM 10 TO 15 MPH WITH
GUSTS UP TO 20 MPH ALONG THE NEW JERSEY COAST. THERE WILL BE
SOUTHEAST SWELLS WITH A PERIOD AROUND 10 SECONDS AND BREAKING
WAVES OF 2 TO 3 FEET. AS A RESULT, THERE IS A MODERATE RISK FOR
THE DEVELOPMENT OF DANGEROUS AND LIFE THREATENING RIP CURRENTS
FOR THE JERSEY SHORE ALONG MONMOUTH, OCEAN, AND ATLANTIC
COUNTIES, AND A LOW RISK FOR THE DEVELOPMENT OF DANGEROUS AND
LIFE THREATENING RIP CURRENTS FOR THE JERSEY SHORE IN CAPE MAY
COUNTY AND DELAWARE BEACHES.
FOR THURSDAY, WINDS BECOME SOUTHWEST AT 10 TO 15 MPH WITH GUSTS
UP TO 20 MPH ALONG THE JERSEY SHORE. BREAKING WAVES WILL RANGE
FROM 1 TO 3 FEET WITH LIGHT EASTERLY SWELLS WITH A PERIOD AROUND
6 SECONDS. AS A RESULT, THERE IS A MODERATE RISK FOR THE
DEVELOPMENT OF DANGEROUS AND LIFE THREATENING RIP CURRENTS FOR
THE JERSEY SHORE ALONG MONMOUTH, OCEAN, AND ATLANTIC COUNTIES,
AND A LOW RISK FOR THE DEVELOPMENT OF DANGEROUS AND LIFE
THREATENING RIP CURRENTS FOR THE JERSEY SHORE IN CAPE MAY COUNTY
AND DELAWARE BEACHES.
PHI WATCHES/WARNINGS/ADVISORIES
PA...HEAT ADVISORY FROM 11 AM TO 8 PM EDT THURSDAY FOR PAZ060-070-
071-101>104-106.
NJ...HEAT ADVISORY FROM 11 AM TO 8 PM EDT THURSDAY FOR NJZ013>015-
017>020-027.
DE...HEAT ADVISORY FROM 11 AM TO 8 PM EDT THURSDAY FOR DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...COOPER/STAARMANN
AVIATION...COOPER/STAARMANN
MARINE...MPS/STAARMANN
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