526
FXUS61 KPHI 301051
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
651 AM EDT FRI MAY 30 2025
SYNOPSIS
A STALLED FRONT OVER THE AREA KEEP THINGS UNSETTLED THROUGH
TODAY. A STRONG AREA OF LOW PRESSURE MOVES THROUGH TONIGHT
BRINGING HEAVY RAIN. A SWEEPING COLD FRONT COMES THROUGH LATE
SATURDAY, KICKING THE UNSETTLED PATTERN. HIGH PRESSURE WILL THEN
ARRIVE FOR SUNDAY AND GENERALLY PERSIST THROUGH WEDNESDAY OF
NEXT WEEK, BRINGING MUCH QUIETER WEATHER. ANOTHER FRONT MOVES IN
ON THURSDAY.
NEAR TERM /THROUGH TONIGHT/
THE MAIN CHANGE WITH THIS UPDATE WAS AN ISSUANCE OF A FLOOD
WATCH FOR THE I-95 CORRIDOR AND POINTS NORTH AND WEST (NOT
INCLUDING THE POCONOS).
A WEAK AREA OF LOW PRESSURE IS RIDING A STALLED BOUNDARY OVER
DELMARVA AND SOUTH JERSEY, RESULTING IN SOME RAIN MOVING INTO
THOSE AREAS. SHOULDN'T EXPECT MUCH FROM THIS OTHER THAN PERHAPS
A BRIEF PERIOD OF HEAVY RAIN AND MAYBE A RUMBLE OF THUNDER.
RAINFALL SHOULD BE OFFSHORE BY THE MID TO LATE MORNING WITH QPF
AMOUNTS OF UP TO A QUARTER OF AN INCH. ELSEWHERE, EXPECT SOME
PATCHY FOG THIS MORNING WITH LOW DEW POINT DEPRESSIONS AND LIGHT
WINDS. ALREADY STARTING TO SEE 2 TO 4 MILE VISIBILITIES ACROSS
THE AREA.
QUIET FOR THE MOST PART THROUGH MOST OF THE DAY, WITH THE
DAYTIME HOURS LOOKING MAINLY DRY. WITH THE STALLED FRONT
OVERHEAD, CANNOT RULE OUT A FEW SHOWERS AND THUNDERSTORMS,
MAINLY FOR AREAS ALONG AND SOUTH OF THE STALLED FRONT. A FEW
STORMS COULD END UP ON THE STRONGER SIDE THIS AFTERNOON OVER
DELMARVA (MORE ON THAT BELOW). OUTSIDE OF THAT, LOOKING AT
PARTLY TO MOSTLY CLOUDY SKIES. WITH SOME SUNSHINE BREAKING
THROUGH, TEMPERATURES WILL GET INTO THE MID TO UPPER 70S.
A STRONG AREA OF LOW PRESSURE WILL DEVELOP ALONG THE STALLED
BOUNDARY, AND MOVE THROUGH OUR AREA TONIGHT. MORE HEAVY RAIN
MOVES IN FROM THE SOUTHWEST BY 7-8 PM OR SO, OVERSPREADING THE
REGION THROUGH THE OVERNIGHT HOURS. STRONG FRONTOGENETIC FORCING
WILL RESULT IN A SWATH OF HEAVY RAIN, WHICH THE CAMS HAVE BEEN
PRETTY CONSISTENT ON WHERE THIS HEAVIER AXIS SETS UP. THE LATEST
FORECAST HAS A SWATH OF 1-3" FROM THE I-95 CORRIDOR AND POINTS
NORTH AND WEST, FALLING OVER A 6 TO 12 HOUR PERIOD. WHILE NOT
EXPECTING 1 HOUR FFGS TO BE EXCEEDED, THERE IS CERTAINLY
POTENTIAL FOR 3 TO 6 HOUR FFGS BEING EXCEEDED. 00Z HREF
PROBABILITY OF EXCEEDANCE FOR THOSE TIME FRAMES IS UPWARDS OF
40-70% FROM SE PENNSYLVANIA INTO NORTHERN NJ. GIVEN A SATURATED
SURFACE AS WELL, WENT AHEAD WITH THE FLOOD WATCH BEGINNING AT 7
PM THIS EVENING THROUGH 8 AM SATURDAY FOR THE PHILADELPHIA METRO
AND SURROUNDING NEW JERSEY SUBURBS, NORTHERN DELAWARE, LEHIGH
VALLEY, AND NORTHERN NEW JERSEY. LEFT THE POCONOS OUT FOR NOW AS
THEIR FFG VALUES ARE A BIT HIGHER AND THEY MAY BE A TAD WEST OF
THE HIGHEST AXIS OF PRECIPITATION. BOTH THE HRRR AND NAMNEST
HAVE PERIODS OF INSTANTANEOUS RAINFALL RATES OVER AN INCH PER
HOUR AS WELL. WPC MAINTAINS A SLGT RISK FOR AREAS WITHIN THE
FLOOD WATCH, WITH MRGL FOR THE NJ COAST AND LOWER DELMARVA.
IN ADDITION TO THE HYDRO THREAT, WHICH COMES MORE AT NIGHT, THERE
IS A THREAT FOR SEVERE WEATHER, WHICH COMES MORE THIS AFTERNOON
AND EVENING, MAINLY FOR AREAS SOUTH AND EAST OF THE STALLED
FRONT. PART OF THE EASTERN SHORE IS IN A SLIGHT (2/5) RISK,
WITH THE REST OF DELMARVA, SOUTH JERSEY, AND SOUTHEASTERN PA IN
A MARGINAL (1/5) RISK. VERY CONDITIONAL THREAT, ESPECIALLY IN
THE MARGINAL RISK AS INSTABILITY IS MEAGER AND LAPSE RATES
UNIMPRESSIVE. IF ENOUGH INSTABILITY BUILDS THIS AFTERNOON,
PERHAPS THE SETUP GETS MORE INTERESTING. BUT, THERE IS SOME
CONCERN IN DELMARVA AS SOME MULTI-CELL CLUSTERS LOOK TO DEVELOP
OVER IN NORTHERN VIRGINIA AND PUSH EASTWARD. THERE WILL BE MORE
INSTABILITY AVAILABLE OVER THE EASTERN SHORE, WHICH COULD
RESULT IN LINEAR CLUSTERS MAINTAINING STRENGTH AS THEY MOVE OVER
THE CHESAPEAKE BAY. THE TIMING FOR THE SEVERE WEATHER POTENTIAL
COMES FROM AROUND 4 TO 10 PM OR SO.
SHORT TERM /SATURDAY THROUGH SUNDAY/
SATURDAY STARTS OUT WITH THE LAST OF THE HEAVY RAIN MOVING OUT
OF THE NORTHERN AREAS AS AN AREA OF LOW PRESSURE PULLS AWAY.
WHILE THERE SHOULD BE A BREAK IN PRECIPITATION, THE BREAK WILL
NOT BE LONG. ANOTHER SHORTWAVE ROTATES AROUND THE BASE OF THE
UPPER LEVEL LOW POSITIONED OVER QUEBEC/ONTARIO. AT THE SURFACE,
A COLD FRONT APPROACHES FROM THE WEST. THE RESULT WILL BE
SUFFICIENT FORCING TO PRODUCE SOME SHOWERS AND THUNDERSTORMS.
THE QUESTION REMAINS HOW MUCH INSTABILITY WILL BE ABLE TO BUILD
BUT STEEPENING LOW AND MID-LEVEL LAPSE RATES AND AROUND 20-30
KT OF BULK SHEAR COULD RESULT IN SOME STRONGER THUNDERSTORMS.
MAIN HAZARD WOULD BE DAMAGING WIND GUSTS IN THE AFTERNOON AND
EVENING WITH THE POTENTIAL FOR SOME SMALL HAIL AS WELL WITH
COLDER TEMPERATURES ALOFT. ANY HEAVIER DOWNPOURS COULD ALSO
PRODUCE SOME URBAN AND POOR DRAINAGE FLOODING, GIVEN IT WON'T
TAKE MUCH TO CAUSE FLOODING ISSUES WITH THE HEAVY RAIN MOVING
THROUGH TONIGHT. SPC MAINTAINS A MARGINAL (1/5) RISK FOR SEVERE
WEATHER FROM CENTRAL JERSEY AND SOUTHEASTERN PA SOUTHWARD.
TEMPERATURES WILL BE IN THE UPPER 60S/LOW 70S.
SOME SHOWERS LINGER FOR THE FIRST HALF OF SUNDAY NIGHT AS THE
COLD FRONT MOVES OFFSHORE, THOUGH MOST AREAS DRY OUT. SKIES
CLEAR OUT QUICKLY AS WELL WITH COLD AIR ADVECTION SETTING UP.
LOWS ON SATURDAY NIGHT END UP IN THE MID TO UPPER 40S AND LOW
50S.
IMPROVING WEATHER FOR SUNDAY AS DRY AIR CONTINUES TO WORK IN.
ONE LAST IMPULSE MOVES THROUGH AS THE UPPER LEVEL LOW PULLS
AWAY, THOUGH WITH NOT A LOT TO MOISTURE TO WORK WITH, THINKING
THE ONLY IMPACT IS SOME SCATTERED CUMULUS CLOUDS. CANNOT RULE
OUT A FEW SPRINKLES IN THE POCONOS, BUT NOT EXPECTING ANYTHING
IMPACTFUL. CLOSING OUT THE WEEKEND A BIT BREEZY AS WELL IN THE
WAKE OF THE FRONT AND A TIGHT GRADIENT, WITH GUSTS 20-30 MPH
ANTICIPATED. TEMPERATURES WILL BE A FEW DEGREES BELOW NORMAL,
GETTING INTO THE MID TO UPPER 60S AND LOW 70S.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
QUIET WEATHER EXPECTED THROUGH THE MIDDLE OF THE WEEK AS UPPER
LEVEL RIDGING BUILDS IN. A STRONG AND EXPANSIVE AREA OF HIGH
PRESSURE SLOWLY MOVES IN FROM THE TENNESSEE RIVER VALLEY, MOVING
OFF THE MID-ATLANTIC COAST ON WEDNESDAY. THE RESULT WILL BE
MODERATING TEMPERATURES, STARTING OUT WITH SEASONABLE
TEMPERATURES MONDAY AND TUESDAY. THIS TRANSITIONS TO A PERIOD OF
ABOVE NORMAL TEMPERATURES WEDNESDAY-THURSDAY AS THE HIGH MOVES
OFFSHORE, AND RETURN FLOW SETS UP. LOOKING LIKELY THAT HIGHS GET
INTO THE MID TO UPPER 80S BOTH WEDNESDAY AND THURSDAY BEFORE A
COLD FRONT COMES IN ON THURSDAY, POTENTIALLY BRINGING A FEW
SHOWERS AND THUNDERSTORMS, AND USHERING IN A MORE SEASONABLE
AIRMASS.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...IFR/MVFR CONDITIONS GRADUALLY IMPROVE THROUGH THE
MORNING, THEN VFR BY THE AFTERNOON. KACY COULD HANG ON TO LOWER
CIGS THROUGH ABOUT 18Z, BUT THINKING EVERYONE ELSE IS VFR BY
16Z. SOME SHOWERS AT KACY/KMIV THIS MORNING. ANOTHER ROUND OF
SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE (20-30%) THROUGH
THE AFTERNOON, BUT THE BULK OF THE RAINFALL SHOULD COME IN AFTER
00Z. WINDS OUT OF THE SOUTH/SOUTHWEST AROUND 5-10 KT. MODERATE
CONFIDENCE IN TIMING OF IMPROVEMENT OF RESTRICTIONS.
TONIGHT...MVFR/IFR CONDITIONS EXPECTED AT ALL SITES WITH PERIODS
OF RAIN, SOME OF WHICH COULD BE HEAVY AT TIMES. HEAVIEST RAIN
EXPECTED FROM 00Z-06Z AT THE I-95 AND LEHIGH VALLEY TERMINALS.
EMBEDDED THUNDERSTORMS POSSIBLE (20-30%) BETWEEN 02Z-08Z, BUT
CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN THE TAF. AN AREA OF
LOW PRESSURE WILL MOVE PRETTY MUCH RIGHT ALONG THE I-95 CORRIDOR
RESULTING IN SHIFTING WINDS THROUGH THE NIGHT STARTING OUT OF
THE SOUTH/SOUTHEAST AND COMING AROUND TO THE NORTH/NORTHWEST BY
DAYBREAK SATURDAY. WINDS WILL BE AROUND 10 KT OR SO. LOW
CONFIDENCE IN TIMING OF RESTRICTIONS, MODERATE CONFIDENCE IN
EXTENT.
SATURDAY...PRIMARILY VFR THOUGH RESTRICTIONS POSSIBLE (40-60%)
WITH SCATTERED SHOWERS AND THUNDERSTORMS MOVING THROUGH.
CONDITIONS AS LOW AS IFR POSSIBLE IN ANY THUNDERSTORMS.
OUTLOOK...
SATURDAY NIGHT...PRIMARILY VFR, THOUGH SOME LINGERING SHOWERS
COULD RESULT IN RESTRICTIONS.
SUNDAY...VFR. WIND GUSTS 20-25 KT OUT OF THE NORTHWEST EXPECTED.
SUNDAY NIGHT THROUGH TUESDAY...VFR. NO SIGNIFICANT WEATHER.
MARINE
SUB-SCA CONDITIONS EXPECTED THROUGH THE REST OF TODAY ON ALL
WATERS. WINDS TURN SOUTHERLY, AROUND 10-20 KT, WITH SEAS 2 TO 3
FEET.
A SMALL CRAFT ADVISORY COMES IN AT 2 AM FOR COASTAL WATERS SOUTH
OF GREAT EGG INLET AND DELAWARE BAY, AND AT 4 AM FOR COASTAL
WATERS NORTH OF GREAT EGG INLET UP TO MANASQUAN INLET AS WINDS
25 TO 30 KT ARE EXPECTED FOR THE SECOND HALF OF THE NIGHT.
NORTH OF MANASQUAN INLET, WINDS WILL HOVER AROUND 20 KT, WITH NO
MARINE HEADLINES IN PLACE. SEAS 3 TO 4 FEET ON THE OCEAN.
OUTLOOK...
SATURDAY...A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH 4 PM FOR
DELAWARE BAY AND COASTAL WATERS SOUTH OF MANASQUAN INLET. WIND
GUSTS OF 25-30 KT EXPECTED WITH SEAS NEARING 5 FEET, MAINLY ON
THE OUTER WATERS. SUB-SCA CONDITIONS EXPECTED NORTH OF MANASQUAN
INLET.
SATURDAY NIGHT THROUGH TUESDAY...NO MARINE HEADLINES EXPECTED.
RIP CURRENTS...
FOR TODAY, A MODERATE RISK FOR RIP CURRENTS IS IN PLACE FOR THE
JERSEY SHORE AS SOUTH/SOUTHWEST WINDS WILL EITHER BE SHORE-
PARALLEL OR HAVE AN ONSHORE COMPONENT. SWELL DIRECTION REMAINS
PERPENDICULAR TO THE SHORELINE, AND WHILE THE PERIOD WILL ONLY
BE 6 TO 8 SECONDS, THERE ARE MULTIPLE SWELL GROUPS. FLOW IS MORE
OFFSHORE AT THE DELAWARE BEACHES, RESULTING IN A LOW RISK FOR
RIP CURRENTS. BREAKING WAVES OF 2 TO 4 FEET EXPECTED.
FOR SATURDAY, A LOW RISK FOR RIP CURRENTS IS IN PLACE AT ALL
BEACHES AS THE ONSHORE SWELL WEAKENS AND FLOW TURNS OFFSHORE.
PERIOD OF 4 TO 6 SECONDS IS EXPECTED, WITH BREAKING WAVES OF 2
TO 3 FEET ARE EXPECTED.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
HYDROLOGY
A FLOOD WATCH WAS ISSUED FOR NORTHERN DELAWARE, THE PHILADELPHIA
METRO AREA AND SURROUNDING SUBURBS IN NEW JERSEY, THE LEHIGH
VALLEY, AND NORTHERN NEW JERSEY, VALID FROM 7 PM TONIGHT THROUGH
8 AM SATURDAY. HEAVY RAIN MOVES IN DURING THAT TIME, DROPPING A
QUICK 1 TO 3 INCHES OF RAIN, OVER AN ALREADY SATURATED SURFACE.
LOW FFG VALUES, MAINLY IN THE 3 TO 6 HOUR TIMEFRAME COULD BE
EXCEEDED WITH RAINFALL RATES PUSHING 1+" PER HOUR AT TIMES.
WHILE NO RIVER FLOODING IS CURRENTLY FORECAST, IT IS CERTAINLY
POSSIBLE. THE RIVERS/CREEKS THAT LOOK TO BE HARDEST HIT BY THIS
UPCOMING HEAVY RAIN LOOK TO BE THE BRANDYWINE CREEK, NESHAMINY
CREEK, PERKIOMEN CREEK AND SCHUYLKILL RIVER IN PENNSYLVANIA,
RARITAN AND PASSAIC RIVERS IN NEW JERSEY, AND THE BRANDYWINE
CREEK AND WHITE CLAY CREEK IN NORTHERN DELAWARE. THIS COULD
RESULT IN QUICK RISES AND RIVER FLOODING OVERNIGHT.
TO STAY ON TOP OF THE FLOODING POTENTIAL, VISIT THESE WEBSITES.
IF YOU WANT TO SEE THE FLOODING THREAT IN TERMS OF PROBABILITIES,
CHECK OUT THIS HYDROLOGIC ENSEMBLE FORECAST LINK:
WEATHER.GOV/ERH/MMEFS
NATIONAL WATER PREDICTION SERVICE (NWPS) WEBSITE: WATER.NOAA.GOV
TO VIEW RIVER OBSERVATIONS AND OUR FORECASTS IN TABLE FORM,
CHECK OUT OUR DASHBOARD: WEATHER.GOV/PHI/HYDRODASHBOARD
TIDES/COASTAL FLOODING
ONE MORE TIDAL CYCLE OF SPOTTY MINOR FLOODING COMES TONIGHT.
WITH ONSHORE FLOW SETTING UP LATER THIS EVENING AS A SURFACE LOW
CROSSES THE HEART OF OUR AREA, HIGH TIDE TONIGHT MAY BE A BIT
HIGHER THAN THE PREVIOUS TWO NIGHTS. THIS MAY RESULT IN MORE
WIDESPREAD MINOR TIDAL FLOODING. CANNOT RULE OUT A COASTAL FLOOD
ADVISORY BEING NEEDED FOR SOUTH JERSEY, COASTAL DELAWARE, WITHIN
THE DELAWARE BAY, AND THE TIDAL DELAWARE RIVER, BUT WILL HOLD
OFF FOR NOW. TIDAL LEVELS FINALLY LOOK TO DECLINE FROM SATURDAY
NIGHT ONWARD AND COASTAL FLOODING CONCERNS CEASING.
FOR THE CHESAPEAKE BAY, NO TIDAL FLOODING IS EXPECTED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
PAZ060>062-070-071-101>106.
NJ...FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
NJZ001-007>010-012-015>019.
DE...FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
DEZ001.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 4 PM EDT SATURDAY FOR ANZ430-
431-453>455.
SMALL CRAFT ADVISORY FROM 4 AM TO 4 PM EDT SATURDAY FOR ANZ451-
452.
SYNOPSIS...HOEFLICH
NEAR TERM...HOEFLICH
SHORT TERM...HOEFLICH
LONG TERM...HOEFLICH
AVIATION...HOEFLICH
MARINE...HOEFLICH
HYDROLOGY...HOEFLICH
TIDES/COASTAL FLOODING...HOEFLICH
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