675
FXUS61 KPHI 102327
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
727 PM EDT SAT OCT 10 2026
WHAT HAS CHANGED
UPDATED THE AVIATION SECTION WITH THE 00Z TAFS.
KEY MESSAGES
1. THE REMNANTS OF ISAIAS SUNDAY AND SUNDAY NIGHT BRINGS RAIN, SOME
POTENTIALLY HEAVY AT TIMES, GUSTY WINDS AND A LOW RISK FOR AN
ISOLATED SEVERE THUNDERSTORM.
2. MINOR TIDAL FLOODING POSSIBLE WITH SUNDAY MORNING'S HIGH
TIDE, MAINLY FOR COASTAL AREAS WITHIN DELAWARE BAY. A COASTAL
FLOOD ADVISORY IS IN EFFECT FOR KENT COUNTY, DE.
DISCUSSION
KEY MESSAGE 1...THE REMNANTS OF ISAIAS SUNDAY AND SUNDAY NIGHT
BRINGS RAIN, SOME POTENTIALLY HEAVY AT TIMES, GUSTY WINDS AND A LOW
RISK FOR AN ISOLATED SEVERE THUNDERSTORM.
A CLOSED MID LEVEL LOW AND SURFACE LOW, THE REMNANTS OF FORMER
HURRICANE ISAIAS, IS FORECAST TO SLIDE ACROSS THE MID-ATLANTIC
REGION SUNDAY NIGHT INTO EARLY MONDAY MORNING. AS THIS OCCURS, IT IS
FORECAST TO WEAKEN FURTHER WITH THE CLOSED MID LEVEL LOW OPENING UP
MORE INTO A TROUGH. THE MAIN IMPACTS FOR OUR AREA WILL BE WIDESPREAD
RAINFALL AND SOME GUSTY WINDS.
LARGE SCALE ASCENT WILL START TO INCREASE FROM THE SOUTH LATE
TONIGHT AS THE SYSTEM APPROACHES. AN EAST TO SOUTHEAST ROBUST LOW-
LEVEL JET (AROUND 925 MB) ON THE ORDER OF 40-60 KNOTS WILL
OVERSPREAD OUR AREA SUNDAY MORNING AND THIS WILL RAPIDLY INCREASE
THE WARM AIR ADVECTION INITIALLY ABOVE A MARINE STABLE LAYER. THIS
WILL ENHANCE THE LIFT (STRONG 700-850 MB FRONTOGENESIS) AS THE LOW
TO MID LEVEL FLOW VEERS WITH HEIGHT. IN ADDITION, DEEPER MOISTURE
WILL BE ADVECTED NORTHWARD INTO OUR AREA WITH THIS PEAKING SUNDAY
AFTERNOON INTO THE EVENING AS A WARM SECTOR GRADUALLY ADVECTS
NORTHWARD. THE PRECIPITABLE WATER VALUES ARE FORECAST TO QUICKLY
INCREASE FROM SOUTH TO NORTH LATE TONIGHT THROUGH SUNDAY TO 1.75-
2.25 INCHES. AS THIS COINCIDES WITH STRONG FORCING FOR ASCENT
SUNDAY, SOME PERIODS OF HEAVIER RAIN SHOULD OCCUR. TOTAL RAINFALL
AMOUNTS STILL LOOK TO BE 1-2 INCHES ACROSS THE ENTIRE AREA, HOWEVER
UP TO 3 INCHES WILL BE POSSIBLE WHERE SOME ENHANCEMENT AND/OR
EMBEDDED CONVECTIVE ELEMENTS OCCUR. THIS EVENT SHOULD INITIALLY BE
IN THE FORM OF STRATIFORM RAIN BEFORE TRANSITIONING TO MORE
CONVECTIVE/SHOWERY SUNDAY NIGHT INTO EARLY MONDAY MORNING. WPC HAS
MAINTAINED MOST OF THE REGION IN A MARGINAL RISK (LEVEL 1 OUT OF 4)
FOR EXCESSIVE RAINFALL FOR SUNDAY INTO SUNDAY NIGHT, WHICH MEANS
ISOLATED INSTANCES OF FLASH FLOODING WILL BE POSSIBLE. THERE ARE
CURRENTLY NO RIVER GAUGES FORECAST TO REACH MINOR FLOOD STAGE,
HOWEVER IF EVEN HEAVIER RAIN OCCURS INTO NORTHERN NJ (ESPECIALLY
2.5+ INCHES), THIS COULD CAUSE SOME GAUGES IN THE RARITAN BASIN (THE
MILLSTONE RIVER) TO RISE TO MINOR FLOOD STAGE. IF RAINFALL RATES
BECOME HIGH ENOUGH FOR A TIME, THEN SOME URBAN/ROADWAY FLOODING WILL
ALSO BE POSSIBLE.
AS THE LOW-LEVEL JET MOVES ACROSS THE AREA AND THE WARM SECTOR
GRADUALLY SPREADS NORTHWARD ON SUNDAY, AN EASTERLY WIND WILL
INCREASE AND BECOME GUSTY. WHERE THE BETTER WARM SECTOR GETS, THE
SURFACE WINDS WILL VEER MORE OUT OF THE SOUTHEAST TO SOUTH WITH
TIME. THE SURFACE WIND SPEEDS WILL BE DRIVEN BY HOW MUCH MIXING
OCCURS WITHIN THE BOUNDARY LAYER, AND THIS LOOKS TO BE GREATEST
ALONG THE COAST GIVEN THE ONSHORE WIND AND WARMER OCEAN ALLOWING FOR
A BIT MORE MIXING ONTO THE ADJACENT LAND. THERE IS A ROBUST WIND
FIELD FORECAST TO BE IN PLACE NOT TO FAR ABOVE THE SURFACE, HOWEVER
A MOIST/STABLE LAYER SHOULD KEEP THIS FROM FULLY MIXING DOWN. WIND
GUSTS UP TO 30 MPH ARE ANTICIPATED INLAND WITH GUSTS UP TO 40 MPH
ALONG THE COAST. THE WINDS SHOULD DIMINISH SUNDAY NIGHT AS THE
REMNANT SURFACE LOW SLIDES ACROSS OUR AREA AND THE LOW-LEVEL JET
SHIFTS AWAY FROM OUR REGION.
WHILE THIS IS THE REMNANTS OF A TROPICAL SYSTEM, IT HAS HAD PLENTY
OF TIME BEING A POST-TROPICAL SYSTEM PRIOR TO REACH OUR AREA.
NEVERTHELESS, LOW-LEVEL SHEAR PROFILES INCREASE QUITE A BIT FOR A
TIME SUNDAY INTO SUNDAY EVENING. FOR AWHILE THERE WILL BE A MARINE
INFLUENCE GIVEN THE ONSHORE FLOW AND WITH A PERIOD OF STRATIFORM
RAIN THIS WILL KEEP THE INSTABILITY LIMITED TO NEAR ZERO. HOWEVER,
AS THE MAIN RAIN SHIELD STARTS TO SHIFT NORTH AND EAST OF OUR AREA
EITHER LATER SUNDAY AFTERNOON AND/OR SUNDAY EVENING, SOME
INSTABILITY MAY TRY TO ADVECT NORTHWARD ACROSS DELMARVA INTO
SOUTHERN NEW JERSEY ESPECIALLY. MODEL FORECAST SOUNDINGS SHOW THE
FLOW VEERING WITH TIME AND THIS WOULD WEAKEN THE LOW-LEVEL
SHEAR/HELICITY (SPIN). THERE APPEARS TO BE A VERY SMALL WINDOW OF
OPPORTUNITY THOUGH IN DELMARVA WHERE LINGERING STRONGER DEEP-LAYER
SHEAR OVERLAPS WITH SOME INCREASE IN INSTABILITY FOR PERHAPS A FEW
TRANSIENT LOW-TOPPED SUPERCELLS WITH AN ISOLATED DAMAGING WIND GUST
POSSIBLE. THE SEVERE SCENARIO HOWEVER IS HIGHLY CONTINGENT ON HOW
MUCH HIGHER DEW POINTS ADVECT NORTHWARD WITH ENOUGH LOW-LEVEL
INSTABILITY, AND THIS LOOKS TO BE GREATER TO OUR SOUTH AND
SOUTHWEST. THE RISK FOR A WEAK/BRIEF TORNADO IN OUR AREA IS
THEREFORE VERY LOW.
SOME SHOWERS LINGER EARLY MONDAY MORNING, ESPECIALLY FROM ABOUT THE
I-95 CORRIDOR ON SOUTH AND EAST, THEN DRYING SHOULD QUICKLY OCCUR
DURING MONDAY AS A NORTH TO NORTHWEST WIND INCREASES FOR A TIME AND
THE ENTIRE WEAKENING SYSTEM EXITS TO OUR EAST AND NORTHEAST.
KEY MESSAGE 2...MINOR TIDAL FLOODING POSSIBLE WITH SUNDAY MORNING'S
HIGH TIDE, MAINLY FOR COASTAL AREAS WITHIN DELAWARE BAY. A COASTAL
FLOOD ADVISORY IS IN EFFECT FOR KENT COUNTY, DE.
WITH A PERIOD OF EAST/SOUTHEASTERLY FLOW EXPECTED AND THE
UPCOMING NEW MOON, INCREASED TIDAL LEVELS ARE EXPECTED LATER
THIS WEEKEND. THIS WILL RESULT IN SPOTTY TO WIDESPREAD MINOR
TIDAL FLOODING, MAINLY FOR COASTAL COMMUNITIES ALONG DELAWARE
BAY. THE ONLY FORECAST POINT CURRENTLY FORECAST TO REACH
WIDESPREAD MINOR IS BOWERS BEACH. AS A RESULT, WENT AHEAD AN
ISSUED A COASTAL FLOOD ADVISORY FROM 7 AM TO 1 PM FOR KENT
COUNTY, DE.
THIS WON'T BE A SIGNIFICANT EVENT FOR THE ATLANTIC OCEAN COASTLINE,
WHERE ONLY SPOTTY MINOR TIDAL FLOODING IS EXPECTED FROM
BARNEGAT BAY ON SOUTH. THIS INCLUDES THE DELAWARE BEACHES AND
BACK BAY COMMUNITIES IN SUSSEX COUNTY, DE.
THE EASTERN SIDE OF DELAWARE BAY IN NJ AND NORTHERN PART OF THE
BAY NEAR REEDY POINT ARE ALSO ONLY EXPECTED TO REACH SPOTTY
MINOR. OVERALL THOUGH, THIS EVENT WILL BE NOTHING LIKE LATE
SEPTEMBER.
THE CURRENT FORECAST HAS NO TIDAL FLOODING FOR AREAS ALONG THE
ATLANTIC COASTLINE NORTH OF BARNEGAT BAY. THE FORECAST FOR THE
TIDAL DELAWARE RIVER AND CHESAPEAKE BAY ALSO HAS TIDE LEVELS
STAYING BELOW FLOOD STAGE AT THIS TIME.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR. CEILINGS LOWER OVERNIGHT. WINDS REMAIN OUT OF
THE EAST AT 5-10 KTS. GUSTS OF 15-20 KTS DEVELOP AT KMIV AND
KACY AFTER 08Z. HIGH CONFIDENCE.
SUNDAY...MVFR CONDITIONS DEVELOP AROUND DAYBREAK AND QUICKLY
DROP TO IFR TOWARDS MID-MORNING DUE TO LOWERING CEILINGS.
WIDESPREAD RAIN MOVES IN AROUND DAYBREAK AND CONTINUES THROUGH
THE DAY WITH VISIBILITY RESTRICTIONS. POCKETS OF MODERATE TO
HEAVY RAIN ARE POSSIBLE AT TIMES. WINDS ALSO REMAIN OUT OF THE
EAST BUT INCREASE TO 10-15 KT WITH GUSTS TO 20-25 KT. A FEW
GUSTS UP TO 30 KTS POSSIBLE AT KMIV AND KACY. MODERATE
CONFIDENCE.
OUTLOOK...
MONDAY...SUB-VFR POSSIBLE IN THE MORNING DUE TO LOW CLOUDS.
CONDITIONS GRADUALLY TREND TOWARDS VFR THROUGHOUT THE DAY.
MONDAY NIGHT THROUGH TUESDAY...PRIMARILY VFR. NO SIGNIFICANT
WEATHER.
WEDNESDAY...VFR. GUSTY WNW WINDS POSSIBLE.
THURSDAY...VFR. NO SIGNIFICANT WEATHER.
MARINE
WINDS CONTINUE TO INCREASE WITH GUSTS UP TO 20 KT BY THIS
EVENING. WIND GUSTS BEGIN TO REACH 25 KTS BY LATE TONIGHT INTO
EARLY SUNDAY MORNING. SEAS 1-3 FEET, INCREASING TO 3-5 FEET
OVERNIGHT. FAIR WEATHER.
ON SUNDAY, WINDS INCREASE FURTHER TO 30 KTS WITH OCCASIONAL
GUSTS UPWARDS OF 35 KTS, PARTICULARLY SUNDAY MORNING. SEAS
CONTINUE TO BUILD TO 7-10 FEET BY SUNDAY AFTERNOON. A SMALL
CRAFT ADVISORY IS IN EFFECT FOR THE DELAWARE BAY AND ALL OF THE
ATLANTIC COASTAL WATERS FROM EARLY SUNDAY MORNING INTO SUNDAY
NIGHT. DUE TO THE OCCASIONAL NATURE OF GALE FORCE GUSTS, THE
GALE WATCH HAS BEEN CANCELLED FOR THE OFFSHORE WATERS.
VISIBILITY RESTRICTIONS ARE LIKELY IN RAIN WHICH COULD BE
MODERATE TO HEAVY AT TIMES.
OUTLOOK...
MONDAY...SCA CONDITIONS PROBABLE DUE TO LINGERING SEAS OF 6-8
FEET AND WIND GUSTS UPWARDS OF 25 KTS THAT GRADUALLY DIMINISH
INTO MONDAY NIGHT.
TUESDAY THROUGH THURSDAY...NO MARINE HAZARDS EXPECTED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...COASTAL FLOOD ADVISORY FROM 7 AM TO 1 PM EDT SUNDAY FOR DEZ002.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TO 10 PM EDT SUNDAY FOR ANZ430-
431.
SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR
ANZ450.
SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 6 AM EDT MONDAY FOR
ANZ451.
SMALL CRAFT ADVISORY FROM 5 AM SUNDAY TO 6 AM EDT MONDAY FOR
ANZ452>455.
DISCUSSION...GORSE/GUZZO/HOEFLICH
AVIATION...AKL/GUZZO/MJL
MARINE...AKL/GUZZO/MJL
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