373
FXUS61 KPHI 111707
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
107 PM EDT SUN OCT 11 2026
WHAT HAS CHANGED
UPDATED THE AVIATION SECTION WITH THE 12Z TAFS.
COASTAL FLOOD ADVISORY HAS EXPIRED FOR KENT COUNTY, DE.
KEY MESSAGES
1. THE REMNANTS OF ISAIAS BRINGS RAIN, SOME POTENTIALLY HEAVY
AT TIMES, GUSTY WINDS AND A LOW RISK FOR AN ISOLATED SEVERE
THUNDERSTORM.
CC
DISCUSSION
KEY MESSAGE 1...THE REMNANTS OF ISAIAS 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 TONIGHT
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. AN EAST TO SOUTHEAST ROBUST LOW-LEVEL JET
(AROUND 925 MB) ON THE ORDER OF 40-60 KNOTS WILL OVERSPREAD OUR
AREA THIS MORNING AND THIS WILL RAPIDLY INCREASE THE WARM AIR
ADVECTION AND MOISTURE ADVECTION ACROSS THE REGION. PWAT VALUES
ARE EXPECTED TO SURGE INTO THE 1.75 TO 2.25 INCH RANGE. AS THIS
COINCIDES WITH STRONG FORCING FOR ASCENT TODAY, 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 TONIGHT INTO EARLY MONDAY MORNING. WPC HAS
MAINTAINED MOST OF THE REGION IN A MARGINAL RISK (LEVEL 1 OUT OF
4) FOR EXCESSIVE RAINFALL FOR TODAY INTO TONIGHT, 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 LATER TODAY, AN EASTERLY WIND WILL
INCREASE AND BECOME GUSTY. WIND GUSTS UP TO 30 MPH ARE
ANTICIPATED INLAND WITH GUSTS UP TO 40 MPH ALONG THE COAST. THE
WINDS SHOULD DIMINISH TONIGHT 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 THIS AFTERNOON INTO EVENING AS THE MAIN RAIN SHIELD STARTS
TO SHIFT NORTH AND EAST OF OUR AREA. DURING THIS TIME, SOME
INSTABILITY MAY TRY TO ADVECT NORTHWARD ACROSS DELMARVA INTO
SOUTHERN NEW JERSEY ESPECIALLY, BUT THE WINDOW OF OPPORTUNITY IS
RATHER SMALL WHERE LINGERING STRONGER DEEP-LAYER SHEAR OVERLAPS
WITH SOME INCREASE IN INSTABILITY. PERHAPS A FEW TRANSIENT LOW-
TOPPED SUPERCELLS WITH AN ISOLATED DAMAGING WIND GUST ARE
POSSIBLE AS A RESULT, BUT CONFIDENCE REMAINS LOW. 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 REMAINS 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. SPOTTY MINOR TIDAL FLOODING EXPECTED MONDAY
MORNING
THE COASTAL FLOOD ADVISORY HAS EXPIRED FOR KENT COUNTY, DE.
WIDESPREAD MINOR TIDAL FLOODING WAS OBSERVED THERE, WITH SPOTTY
MINOR OBSERVED ALONG THE ATLANTIC COASTLINE AND OTHER PARTS OF
DELAWARE BAY.
AS WE GET AWAY FROM THE NEW MOON AND FLOW TURNS MORE
WEST/NORTHWESTERLY, TIDE LEVELS WILL DECLINE. SPOTTY MINOR
FLOODING REMAINS POSSIBLE FOR MONDAY MORNING'S HIGH TIDE ALONG
THE ATLANTIC COASTLINE AND DELAWARE BAY. NO CURRENT ADVISORIES
ARE UP, BUT MAY NEED TO CONSIDER ONE FOR BARNEGAT BAY AS IT MAY
BE A BIT SLOW TO DRAIN.
NO TIDAL FLOODING CONCERNS EXPECTED ALONG THE TIDAL DELAWARE
RIVER OR CHESAPEAKE BAY.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...MVFR CONDITIONS HAVE DEVELOPED AND WILL CONTINUE TO DROP
TO IFR DUE TO LOWERING CEILINGS. WIDESPREAD RAINS CONTINUE THROUGH
THE DAY WITH VISIBILITY RESTRICTIONS. PERIODS OF LIFR CONDITIONS
POSSIBLE. POCKETS OF MODERATE TO HEAVY RAIN AT TIMES WITH VCTS
LATE AFTERNOON. 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.
TONIGHT...SUB-VFR CONDITIONS PREVAIL. RAIN BECOMES MORE SCATTERED
OVERNIGHT WITH VCTS. VIS RESTRICTIONS MAY EASE TO MVFR, BUT
IFR/LIFR CEILINGS REMAIN. WINDS GRADUALLY BACK TO THE NNE AND
EASE TO AROUND 10 KTS. MODERATE CONFIDENCE IN LOW CEILINGS, BUT
LOW CONFIDENCE OVERALL.
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
SMALL CRAFT ADVISORIES FOR THE COASTAL OCEAN WATERS WERE
EXTENDED INTO MONDAY NIGHT.
FOR SUNDAY, EASTERLY WINDS INCREASE FURTHER TO 30 KTS WITH
OCCASIONAL GUSTS UPWARDS OF 35 KTS, PARTICULARLY THIS 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 UNTIL TONIGHT. 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.
WINDS SHIFT MORE SOUTHERLY AND DIMINISH BELOW ADVISORY CRITERIA AS
THE LOW CENTER MOVES ACROSS THE WATERS OVERNIGHT BEFORE SHIFTING
MORE NORTHERLY AS THE LOW BEGINS TO DEPART EARLY MONDAY MORNING.
SEAS WILL BE SLOW TO SUBSIDE, STAYING ELEVATED AROUND 6-8 FEET.
OUTLOOK...
MONDAY...SCA CONDITIONS FOR THE COASTAL OCEAN WATERS DUE TO
LINGERING SEAS OF 6-8 FEET AND NORTHERLY 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...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ430-
431.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT TUESDAY FOR ANZ450>452.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR ANZ453>455.
DISCUSSION...HOEFLICH/MJL/WFO PHI
AVIATION...MJL
MARINE...MJL
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