030
FXUS61 KPHI 200924
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
424 AM EST WED NOV 20 2024
SYNOPSIS
A WARM FRONT WILL PROGRESS NORTH ACROSS PARTS OF THE REGION
TODAY. LOW PRESSURE AND AN ASSOCIATED STRONG COLD FRONT MOVES
INTO OUR REGION TONIGHT AND THURSDAY WITH SOME MUCH NEEDED
RAIN AND, IN THE HIGHER TERRAIN, SNOW. LOW PRESSURE THEN
LINGERS ACROSS THE NORTHEAST INTO THE WEEKEND WITH MUCH COLDER
AIR BEFORE MOVING INTO THE CANADIAN MARITIMES BY THE END OF THE
WEEKEND. HIGH PRESSURE THEN ARRIVES FOR LATER SUNDAY AND
ESPECIALLY MONDAY, FOLLOWED BY A COLD FRONT ON TUESDAY.
NEAR TERM /THROUGH THURSDAY/
OVERALL, THE NEAR TERM FORECAST REMAINS ON TRACK WITH A WARM
FRONT CONTINUING TO DRIFT NORTH TOWARDS THE FORECAST AREA. THE
MAIN AREA OF SHOWERS FROM EARLIER HAS CLEARED THE AREA WITH A
FEW LINGERING LIGHT SHOWERS POSSIBLE FOR THE REMAINDER OF THE
OVERNIGHT HOURS. OTHERWISE, MAINLY OVERCAST SKIES EXPECTED.
DEPENDING ON HOW FAR THE WARM FRONT TRACKS NORTH, PORTIONS OF
THE REGION COULD SEE SOME LATE NIGHT VISIBILITY RESTRICTIONS.
BEST CHANCES FOR THIS RESIDES ACROSS SOUTHERN NEW JERSEY AND THE
DELMARVA. LOWS ARE EXPECTED TO BE IN THE 40S ACROSS MUCH OF THE
AREA.
FOR WEDNESDAY, SAID WARM FRONT WILL LIKELY GET HUNG UP SOMEWHERE
ACROSS THE DELMARVA. WEAK LOW PRESSURE WILL FORM ON THE FRONT ACROSS
THE PANHANDLE OF WEST VIRGINIA, AND AN OCCLUDED FRONT WILL APPROACH
THE REGION FROM THE WEST.
AFTER SOME LIGHT SHOWERS OR DRIZZLE EARLY IN THE MORNING, THE REGION
SHOULD SEE A BRIEF LULL IN PRECIPITATION. CHANCES BEGIN TO RAMP BACK
UP IN THE AFTERNOON AND AS WE APPROACH THE EVENING HOURS. IF THE
WARM FRONT MAKES IT NORTH OF SUSSEX COUNTY, THERE COULD BE A FAIRLY
DECENT TEMPERATURE GRADIENT ACROSS THE FORECAST AREA. HIGHS COULD
APPROACH 70 ACROSS THE FAR SOUTH WITH TEMPERATURES HOLDING AROUND 50
ACROSS THE SOUTHERN POCONOS.
WINDS WILL BE LIGHT AND VARIABLE IN THE MORNING HOURS AND DEVELOP
INTO A LIGHT SE IN THE AFTERNOON.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/
STRONG LOW PRESSURE WILL BE LOCATED NEAR NEW YORK CITY THURSDAY
EVENING, WITH STRONG AND GUSTY NORTHWEST WINDS FUNNELING COOLER
AIR SOUTHEASTWARD ACROSS THE REGION. THE UPPER LOW WIL REMAIN TO
OUR WEST IN THE UPPER OHIO VALLEY, AND AS THAT FEATURE HEADS
EAST, THE SURFACE LOW WILL ACTUALLY RETROGRADE SLIGHTLY, WITH
IT BECOMING "CAPTURED" OVER OUR NORTHERN AREAS EARLY FRIDAY.
STRONG FORCING OVER OUR NORTHERN ZONES RELATIVELY CLOSE TO THE
SURFACE LOW AND NORTHEAST OF THE UPPER LOW WILL RESULT IN
CONTINUED PRECIPITATION THROUGH THE NIGHT, WITH PRECIPITATION
TAPERING OFF FURTHER SOUTH AND MOSTLY DRY CONDITIONS IN THE
DELMARVA. WITH THE COLD ADVECTION AT THE SURFACE AND ALOFT, ODDS
FAVOR A TRANSITION TO HEAVY WET SNOW ACROSS THE HIGHER TERRAIN,
ESPECIALLY ABOVE 1500 FEET ON THE POCONO PLATEAU AND POSSIBLY A
FEW HIGHER RIDGES ELSEWHERE IN EASTERN PA AND NORTHERN NJ. WITH
THE BEST ODDS OF HEAVY WET SNOW BEING ACROSS THE POCONOS, HAVE
ISSUED THE FIRST WINTER STORM WATCH OF THE SEASON FOR CARBON AND
MONROE COUNTIES, SPECIFICALLY FOR AT AND ABOVE 1500 FEET. LOWER
ELEVATIONS MAY SEE FAR LESS SNOWFALL, IN FACT THE LOWEST VALLEYS
EVEN UP THERE MAY FAIL TO GET AN ENTIRE INCH OF ACCUMULATION
WITH THIS ELEVATION-DEPENDENT SYSTEM. AS THIS WILL BE A HEAVY
WET SNOW WITH SIGNIFICANT WIND IN THE 20-30 MPH RANGE, A BIG
POTENTIAL IS DOWNED TREES AND POWER LINES. TRAVEL THURSDAY NIGHT
IN PARTICULAR IS DISCOURAGED.
THERE ARE A FEW SIMULATIONS WHICH IMPLY SNOW COULD REACH
SIGNIFICANTLY FURTHER SOUTH ACROSS OUR REGION, EVEN DOWN TO THE
I-95 CORRIDOR AND PHILLY METRO, PARTICULARLY THE CANADIAN
MODELS. FOR THE MOMENT WE'VE MOSTLY DISCOUNTED THAT GUIDANCE AS
BEING OUTLIERS, BUT WILL BE KEEPING IT IN MIND AS WE WATCH
FURTHER PROGRESS WITH THIS SYSTEM. HAVE ALLOWED FOR SOME MIXING
ACROSS AREAS JUST NORTH AND WEST OF THE I-95 CORRIDOR THURSDAY
NIGHT INTO EARLY FRIDAY, BUT LITTLE TO NO ACCUMULATION IS
CURRENTLY EXPECTED OUTSIDE THE POCONOS. EITHER WAY, BRISK AND
COLD WILL BE THE THEM FOR THURSDAY NIGHT, WITH LOWS IN THE 30S
FOR MOST, UPPER 20S PERHAPS IN THE HIGHER TERRAIN OF THE
POCONOS.
FOR THE BULK OF FRIDAY, THE SURFACE LOW WILL REMAIN CAPTURED
UNDER THE UPPER LOW OVER OUR REGION, RESULTING IN CONTINUED
SHOWERS. ENOUGH INSOLATION LIKELY DEVELOPS TO ALLOW A TRANSITION
FROM A RAIN/SNOW MIX TO JUST PLAIN RAIN AT THE LOWER ELEVATIONS,
WITH SIGNIFICANTLY LESS ACCUMULATION IN THE HIGHER TERRAIN AS
WELL, WITH PRECIPITATION STARTING TO TAPER OFF TOWARDS THE END
OF THE DAY AS WE START TO SEE SOME MOVEMENT EASTWARD AND THE
SURFACE LOW BEGINS TO SLOWLY FILL. REGARDLESS, A CHILLY, RAW
DAY WILL BE HAD BY MOST WITH TEMPS GENERALLY NO HIGHER THAN THE
40S REGION-WIDE, WITH TEMPS NOT STRAYING FAR FROM FREEZING IN
THE POCONOS.
PRECIP SHOULD MOSTLY END DURING THE EVENING FRIDAY AS THE
SURFACE AND UPPER LOWS BEGIN MOVING FURTHER EAST, BUT THE BRISK
CONDITIONS CONTINUE. LOWS IN THE 30S FOR MOST, UPPER 20S
POCONOS.
LONG TERM /SATURDAY THROUGH TUESDAY/
THE PATTERN QUIETS DOWN THROUGH THE LONG TERM. AS THE STORM
PULLS FURTHER AWAY TO OUR NORTHEAST ON SATURDAY, A GUSTY
NORTHWEST WIND WILL CONTINUE AND CLOUDS WILL LINGER, WITH SOME
SPOTTY SHOWERS IN THE POCONOS, BUT OVERALL, SIGNIFICANTLY
IMPROVED COMPARED TO FRIDAY. HIGHS MOSTLY IN THE LOWER 50S, A
SIGNIFICANT REBOUND. CLOUDS AND WIND LIKELY CONSPIRE TO KEEP
TEMPS FROM DROPPING TOO MUCH SATURDAY NIGHT, WITH LOWS MOSTLY
30S AGAIN.
WINDS GRADUALLY RELAX A BIT MORE ON SUNDAY WITH MORE SUNSHINE AS
HIGH PRESSURE BUILDS TO OUR SOUTHWEST. THE WARMING TREND WILL
CONTINUE WITH MID 50S BECOMING MORE LIKELY FOR MUCH OF THE AREA.
SOUTHWESTERLY WINDS PICK UP A BIT AHEAD OF AN APPROACHING FRONT
FOR MONDAY, WHICH WILL HELP BRING A BIT MORE WARMER AIR INTO THE
REGION, ELEVATING HIGHS IN SOUTHERN AREAS INTO THE 60S, WITH
MID-UPPER 50S FURTHER NORTH.
THAT FRONT SLIDES INTO THE REGION BY TUESDAY, WHICH WILL START
TO INCREASE THE CHANCE OF SHOWERS WHILE ALSO STARTING TO NUDGE
TEMPS BACK DOWN IN THE NORTH. SOUTH OF THE FRONT, ACROSS
SOUTHERN AREAS, MID 60S STILL LOOK LIKELY.
AVIATION /09Z WEDNESDAY THROUGH SUNDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
EARLY THIS MORNING...VFR CIGS FOR MOST. MVFR CIGS POSSIBLE
BUT HAVE REMOVED FROM THE TAFS AS CONFIDENCE HAS DECREASED IN
PREVAILING SUB-VFR CONDITIONS BEING OBSERVED. ISOLATED TO
SCATTERED SHOWERS THROUGHOUT THE OVERNIGHT HOURS. LIGHT AND
VARIABLE WINDS. MODERATE CONFIDENCE AT BEST.
WEDNESDAY...MAINLY VFR. A BRIEF BREAK IN PRECIPITATION CHANCES
IS EXPECTED WITH SMALL CHANCES DEVELOPING ONCE AGAIN LATE IN THE
DAY. WINDS OUT OF THE SOUTHEAST AROUND 5 KNOTS. MODERATE
CONFIDENCE AT BEST.
WEDNESDAY NIGHT AND THURSDAY...A PERIOD OF MVFR/IFR CONDITIONS WITH
A PERIOD OF RAIN, THEN CONDITIONS IMPROVE THURSDAY MORNING. SOME
LINGERING SHOWERS CONTINUE THROUGH THURSDAY NIGHT, WITH SOME SNOW
POSSIBLE NEAR AND NORTH/WEST OF KABE. A PERIOD OF WIND GUSTS UP TO
30 KNOTS AND AN ABRUPT WIND SHIFT TO WEST OR NORTHWEST LATER
WEDNESDAY NIGHT. GUSTY WEST-NORTHWEST WINDS CONTINUE THURSDAY.
OUTLOOK...
SUB-VFR, WITH POTENTIAL IFR, THURSDAY NIGHT AND FRIDAY WITH
WIDESPREAD SHOWERS, WHICH MAY MIX WITH SNOW AT KRDG AND KABE. NO
ACCUMULATIONS CURRENTLY EXPECTED AT THE TERMINALS. WINDS WILL
ALSO BE GUSTY FROM THE NORTHWEST. IMPROVEMENT TO MOSTLY VFR
SATURDAY BUT STILL WITH A GUSTY NORTHWEST WIND. LIGHTER WINDS
AND SOLIDLY VFR BY SUNDAY.
MARINE
TONIGHT...SUB-SCA CONDITIONS EXPECTED.
WEDNESDAY...SUB-SCA CONDITIONS EXPECTED, ALTHOUGH EAST/SOUTHEAST
WINDS WILL INCREASE IN THE AFTERNOON.
WEDNESDAY NIGHT AND THURSDAY...SMALL CRAFT ADVISORY CONDITIONS,
HOWEVER A PERIOD OF GALE FORCE WIND GUSTS POSSIBLE WEDNESDAY NIGHT
INTO EARLY THURSDAY MORNING. A GALE WATCH REMAINS IN EFFECT FOR
NEARLY ALL OF OUR ZONES.
OUTLOOK...
POTENT LOW PRESSURE WILL CERTAINLY RESULT IN HIGH END SMALL
CRAFT ADVISORY CONDITIONS AND IN FACT MAY RESULT IN LOW-END
GALES THURSDAY NIGHT THROUGH FRIDAY NIGHT. FOR THE TIME BEING
HAVE HELD OFF ON ANY GALE WATCHES/WARNINGS AS THE FIRST PUSH OF
GALE WINDS IS EXPECTED TONIGHT AND EARLY THURSDAY, BUT THIS MAY
BE REVISED IN FUTURE UPDATES. CONDITIONS SHOULD SUBSIDE TO SCA
LEVELS FOR SATURDAY AND START DROPPING BELOW SCA LEVELS ON
SUNDAY.
HYDROLOGY
SIGNIFICANT RAINFALL IS FORECAST ACROSS THE REGION FOR THE FIRST
TIME IN MONTHS, WITH WIDESPREAD TOTALS IN EXCESS OF 2 INCHES
EXPECTED ACROSS NORTHERN PARTS OF THE FORECAST AREA. WITH THE
GROUND RELATIVELY DRY AND HARD, WE COULD END UP WITH SOME MINOR
FLOODING ISSUES DUE TO EXCESSIVE RUNOFF, DESPITE HOW LOW WATER
LEVELS ARE PRESENTLY. THESE WOULD MAINLY BE FOR THE FLASHIER
SMALL STREAMS. IN ADDITION, ACCUMULATION OF LEAVES AROUND STORM
DRAINS MAY RESULT IN LOCALIZED ROADWAY ISSUES. THAT ALL HAVING
BEEN SAID, GIVEN THE EXCESSIVE DRYNESS ACROSS THE REGION
PRESENTLY, THERE ARE NO PLANS FOR A FLOOD WATCH AT THIS TIME.
CLIMATE
DRIEST AUTUMN (SEP-NOV) ON RECORD, AND ANY 3-CALENDAR MONTH
PERIOD ON RECORD, PLUS CURRENT STATUS:
9/1-11/18 DRIEST DRIEST 3 YEAR/
SITE 2024 PRECIP AUTUMN YEAR CALENDAR MONTHS MONTHS
ALLENTOWN (ABE) 1.61 3.81 1922 3.58 OCT-DEC 1928
A.C. AIRPORT (ACY) 0.99 3.34 2001 2.35 OCT-DEC 1946
A.C. MARINA (55N) 0.79 2.89 1941 2.52 AUG-OCT 1895
GEORGETOWN (GED) 0.85 2.67 2001 2.20 AUG-OCT 2024
MOUNT POCONO (MPO) 3.17 4.21 1931 3.36 OCT-DEC 1928
PHILADELPHIA (PHL) 1.08 2.37 1922 2.37 SEP-NOV 1922
READING (RDG) 1.40 2.89 1922 2.89 SEP-NOV 1922
TRENTON (TTN) 0.67 3.18 1922 2.66 JUN-AUG 1966
WILMINGTON (ILG) 0.86 3.17 1922 3.17 SEP-NOV 1922
PHI WATCHES/WARNINGS/ADVISORIES
PA...WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY
AFTERNOON FOR PAZ054-055.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING FROM 11 PM THIS EVENING TO 7 AM EST THURSDAY FOR
ANZ430-431-453>455.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 6 AM EST
FRIDAY FOR ANZ450>452.
SYNOPSIS...GORSE/RCM
NEAR TERM...AKL
SHORT TERM...RCM
LONG TERM...RCM
AVIATION...AKL/RCM
MARINE...AKL/RCM
HYDROLOGY...PHI
CLIMATE...PHI
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