348
FXUS61 KPHI 091728
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
128 PM EDT FRI OCT 9 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 18Z TAFS.
KEY MESSAGES
1. TRANQUIL, DRY WEATHER WILL PREVAIL THROUGH SATURDAY WITH NO
SIGNIFICANT WEATHER HAZARDS ANTICIPATED.
2. THE REMNANTS OF WHAT IS NOW HURRICANE ISAIAS WILL APPROACH
THE AREA LATE THIS WEEKEND BRINGING RAIN AND A FEW THUNDERSTORMS
BACK TO THE REGION SUNDAY AND SUNDAY NIGHT.
DISCUSSION
KEY MESSAGE 1...TRANQUIL, DRY WEATHER WILL PREVAIL THROUGH
SATURDAY WITH NO SIGNIFICANT WEATHER HAZARDS ANTICIPATED.
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH TONIGHT. THIS
WILL LEAD TO CONTINUED TRANQUIL WEATHER CONDITIONS, THOUGH IT
WILL BE A BIT BREEZY UNTIL THIS EVENING. CIRRUS ASSOCIATED WITH
THE OUTFLOW FROM ISAIAS WILL CONTINUE TO SPREAD ACROSS SOUTHERN
PORTIONS OF THE REGION, SLOWLY LIFTING NORTHWARD. TONIGHT, WINDS
SHOULD QUICKLY DIMINISH, ALLOWING FOR TEMPERATURES TO COOL
FAIRLY QUICKLY IN AREAS WHERE CLOUD COVER HAS NOT YET MOVED IN.
OVERNIGHT LOWS WILL LIKELY BE IN THE LOW 40S ACROSS THE POCONOS,
LEHIGH VALLEY, AND ADJACENT AREAS OF FAR NORTHERN NJ, THE MID
TO UPPER 40S ACROSS MUCH OF SOUTHEASTERN PA AND MOST OF NJ, AND
LOW 50S ACROSS DELMARVA.
ON SATURDAY, THE HIGH IS EXPECTED TO BEGIN SHIFTING SLOWLY
EASTWARD AWAY FROM THE AREA. IT WILL REMAIN DRY, BUT CLOUD COVER
SHOULD STEADILY INCREASE THROUGH THE DAY. AS A RESULT,
AFTERNOON HIGHS WILL BE A COUPLE OF DEGREES COOLER ON SATURDAY
THAN TODAY, BUT STILL IN THE LOW 70S FOR MOST. HOWEVER, AS THE
HIGH PRESSURE CENTER SHIFTS NORTHEASTWARD, WINDS WILL SETTLE OUT
OF THE EAST-NORTHEAST. THE ONSHORE FLOW WILL KNOCK TEMPERATURES
DOWN EVEN FURTHER FOR LOCATIONS NEAR THE COAST.
KEY MESSAGE 2...THE REMNANTS OF WHAT IS NOW HURRICANE ISAIAS
WILL APPROACH THE AREA LATE THIS WEEKEND BRINGING RAIN AND A FEW
THUNDERSTORMS BACK TO THE REGION SUNDAY AND SUNDAY NIGHT.
THE PRIMARY FORECAST CONCERN FOR THE LATTER PART OF THIS
WEEKEND INTO EARLY NEXT WEEK WILL BE THE REMNANTS OF WHAT IS
CURRENTLY HURRICANE ISAIAS IN THE GULF. IT MAY INTENSIFY
FURTHER BEFORE MAKING LANDFALL SOMEWHERE ALONG THE NORTHERN GULF
COAST TONIGHT AS IT BEGINS INTERACTING WITH AN UPPER TROUGH.
FROM THERE, IT IS EXPECTED TO UNDERGO EXTRATROPICAL TRANSITION
AND CONTINUE NORTHWARD TOWARDS PORTIONS OF THE OHIO VALLEY
THROUGH SATURDAY NIGHT, AND THEN NORTHEASTWARD IN THE DIRECTION
OF OUR AREA ON SUNDAY.
SOME MODEST TIMING DISCREPANCIES REMAIN AMONGST MODEL GUIDANCE
THIS MORNING, BUT THERE IS STRONG AGREEMENT THAT THE REMNANTS OF
ISAIAS WILL BRING SOME IMPACTS TO THE REGION BEGINNING SUNDAY
AND PERHAPS LINGERING INTO EARLY MONDAY. AT THIS POINT IN TIME,
IT APPEARS THAT WIDESPREAD RAIN WILL BE THE PRIMARY IMPACT. IT
SHOULD BE NOTED THAT PWATS ARE MODELED TO BE IN THE 1.5-2+ INCH
RANGE, SO SOME PERIODS OF HEAVY RAINFALL WILL BE POSSIBLE. OUR
CURRENT FORECAST IS FOR STORM TOTALS IN THE 1.0 TO 2.0 INCH
RANGE. SOME AREAS COULD SEE OVER 2.0 INCHES, WITH THE BEST
CHANCE OF HIGHER TOTALS PRESENTLY LOCATED IN THE DELMARVA AND
SOUTHERN NEW JERSEY. WPC HAS PLACED MOST OF THE REGION IN A
MARGINAL RISK (1 OF 4) EXCESSIVE RAINFALL OUTLOOK FOR SUNDAY
MEANING AT LEAST ISOLATED INSTANCES OF FLOODING WILL BE
POSSIBLE. WE WILL CONTINUE TO MONITOR TRENDS OVER THE COMING
DAYS.
ASIDE FROM THE RAIN POTENTIAL, WITH THE SYSTEM LIFTING OVER OUR
REGION, SHEAR AND CAPE MAY REACH VALUES JUST HIGH ENOUGH TO
SUPPORT SOME ISOLATED SEVERE STORMS SUNDAY/SUNDAY NIGHT, SO OUR
SOUTHERN ZONES HAVE BEEN PLACED IN A MARGINAL RISK (1 OF 5)
SEVERE THUNDERSTORM OUTLOOK FOR SUNDAY.
FINALLY, THE EASTERLY AND SOUTHEASTERLY SURFACE FLOW PRECEDING
AND DURING THE PASSAGE OF THE SYSTEM MAY RESULT IN MINOR TIDAL
FLOODING SUNDAY INTO MONDAY.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. WEST-NORTHWEST WINDS 10-15 KT WITH GUSTS
AROUND 20 KT. HIGH CONFIDENCE.
TONIGHT...VFR WITH INCREASING HIGH CLOUDS. WEST-NORTHWEST WINDS
IN THE EVENING AROUND 5 KT WILL BECOMING LGT/VRB OVERNIGHT.
CALM PERIODS LIKELY. HIGH CONFIDENCE.
SATURDAY...VFR WITH SCT/BKN HIGH CLOUDS. LIGHT WINDS IN THE
MORNING WILL EVENTUALLY SETTLE OUT OF THE EAST AT 5-10 KT. HIGH
CONFIDENCE.
OUTLOOK...
SATURDAY NIGHT...VFR. NO SIGNIFICANT WEATHER.
SUNDAY THROUGH MONDAY...SUB-VFR CONDITIONS ARE LIKELY IN RAIN
AND LOW CLOUDS.
MONDAY NIGHT THROUGH TUESDAY...PRIMARILY VFR. ISOLATED SHOWERS
ARE POSSIBLE TUESDAY AFTERNOON, WHICH COULD LEAD TO BRIEF
PERIODS OF SUB-VFR CONDITIONS.
MARINE
WEST- NORTHWEST WINDS AROUND 10 KT INTO THIS EVENING, BECOMING
NORTHERLY OVERNIGHT AT 5-10 KT. WINDS WILL INCREASE OUT OF THE
EAST ON SATURDAY TO 10-15 KT WITH GUSTS UP TO 20 KT. SEAS 1-3
FEET. FAIR WEATHER.
OUTLOOK...
SATURDAY NIGHT...NO MARINE HEADLINES CURRENTLY ANTICIPATED WITH
WINDS UNDER 25 KTS AND SEAS BELOW 5 FEET.
SUNDAY THROUGH MONDAY...ADVISORY CONDITIONS ARE POSSIBLE WITH
WIND GUSTS IN EXCESS OF 25 KTS AND SEAS IN EXCESS OF 5 FEET AS
THE REMNANTS OF HURRICANE ISAIAS MOVE THROUGH. VISIBILITY
RESTRICTIONS ARE POSSIBLE IN RAIN AND PERHAPS SPRAY.
TUESDAY...CONDITIONS RETURN TO BELOW SMALL CRAFT ADVISORY
LEVELS WITH WEST TO SOUTHWEST WINDS AROUND 10-15 KNOTS AND SEAS
2-4 FEET.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...COOPER/FITZSIMMONS/RCM
AVIATION...COOPER/MPS/RCM
MARINE...COOPER/FITZSIMMONS/RCM
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