171
FXUS61 KPHI 301858
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
258 PM EDT FRI MAY 30 2025
SYNOPSIS
A STRENGTHENING AREA OF LOW PRESSURE WILL CROSS OUR AREA TONIGHT
INTO SATURDAY MORNING WITH A WARM FRONT LIFTING NORTHWARD. A COLD
FRONT THEN SWEEPS ACROSS OUR AREA LATER SATURDAY AFTERNOON AND
EVENING. HIGH PRESSURE BUILDS INTO THE OHIO VALLEY LATER SUNDAY THEN
ARRIVES IN OUR AREA LATER MONDAY THROUGH WEDNESDAY. A SURFACE TROUGH
MAY MOVE THROUGH THURSDAY INTO FRIDAY AS A COLD FRONT APPROACHES
FROM THE WEST.
NEAR TERM /THROUGH SATURDAY/
THE STALLED FRONT TO THE SOUTH WILL REMAIN THERE THIS EVENING AS LOW
PRESSURE MOVES ALONG IT AND STRENGTHENS SHARPLY OVERNIGHT. THE LOW
WILL PASS ACROSS SE PA AND NJ AROUND MIDNIGHT WITH FREQUENT SHOWERS
AND TSTMS AS WELL. HEAVY RAINS AND GUSTY WINDS EXPECTED TOO. OVERALL
RAINFALL TOTALS OF 1 TO 2 INCHES OF RAIN ARE FORECAST, BUT A FEW
SPOTS (IN TSTMS) COULD END UP CLOSER TO 3 INCHES. THE FLOOD WATCH
WILL CONTINUE IN THE SAME AREAS AS BEFORE.
WINDS WILL REMAIN LIGHT INTO THE EVENING, BUT THEN INCREASE SLOWLY
OVERNIGHT AS THE LOW DEEPENS. AROUND MIDNIGHT AS THE LOW CROSSES THE
REGION, THE SOUTHEAST TO EAST WINDS OF 15 TO 20 MPH WILL TURN
WESTERLY AT OF 15 TO 25 MPH WITH GUSTS OF 25 TO 35 MPH DEVELOPING.
THE GREATER WIND GUSTS WILL BE ACROSS SOUTH NJ AND DELMARVA. WINDS
WILL REMAIN GUSTY THROUGH DAWN. LOWS TEMPERATURES WILL DROP INTO THE
MID/UPPER 50S MOST SPOTS.
FOR SATURDAY, THE STRONG LOW PRESSURE AREA WILL BE NORTHEAST OF OUR
CWA AND PULLING AWAY. A DECENT PRESSURE GRADIENT ACROSS THE MIDDLE
ATLANTIC WILL KEEP GUSTY WINDS FROM THE WEST OVER THE AREA MUCH OF
THE DAY. WINDS GUSTS 25 TO 35 MPH ARE EXPECTED FOR THE MORNING FOR
SOUTHERN NJ AND DELMARVA. STEADY RAINS WILL END FROM SW TO NE THRU
THE MORNING WITH SCATTERED SHOWERS INTO THE AFTERNOON. HIGHS TEMPS
WILL MOSTLY BE IN THE UPPER 60S TO LOW 70S, BUT A COUPLE MID 70S
POSSIBLE FOR SRN DELWARE.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/
AN UPPER-LEVEL TROUGH IS FORECAST TO BE IN PLACE ACROSS THE
NORTHEAST AND MID-ATLANTIC THROUGH SUNDAY NIGHT, THEN THIS STARTS TO
WEAKEN DURING MONDAY.
SOME SHOWERS AND THUNDER POSSIBLE SATURDAY EVENING WHICH THEN SHIFT
OFFSHORE OR DISSIPATE AS A COLD FRONT WORKS ACROSS THE AREA AND THEN
OFFSHORE. A MUCH DRIER AIR MASS WILL OVERSPREAD THE REGION IN THE
WAKE OF THE COLD FRONT, AND THE CLOUD COVER IS EXPECTED TO DECREASE.
AN INCREASE IN COLD AIR ADVECTION WILL ALSO DELIVER COOLER AIR, WITH
LOWS SATURDAY NIGHT MOSTLY IN THE MID/UPPER 40S TO LOW 50S.
AN IMPULSE LOOKS TO MOVE THROUGH SUNDAY WITHIN THE UPPER-LEVEL
TROUGH. MUCH LESS MOISTURE WILL BE IN PLACE, REFLECTED BY DEW POINTS
IN THE 40S TO POTENTIALLY DROPPING INTO THE UPPER 30S IN THE
AFTERNOON. THE MODEL FORECAST SOUNDINGS HOWEVER DO SHOW A WELL MIXED
BOUNDARY LAYER OCCURRING AND THIS SHOULD SUPPORT SOME CUMULUS
DEVELOPMENT. CANNOT RULE OUT A BRIEF LIGHT SHOWER OR A FEW SPRINKLES
IN THE POCONOS AREA. GIVEN THE DEEPER MIXING AND A TIGHTENED
PRESSURE GRADIENT, A NOTABLE WESTERLY BREEZE IS EXPECTED ON SUNDAY.
THE WIND SHOULD THEN QUICKLY DIMINISH SUNDAY EVENING AS THE VERTICAL
MIXING WEAKENS. HIGH TEMPERATURES LOOK TO BE BELOW AVERAGE WITH
HIGHS IN THE 60S TO LOW 70S.
AS WE GO THROUGH MONDAY, THE UPPER-LEVEL TROUGH IS FORECAST TO
WEAKEN AND START TO LIFT OUT. AS HIGH PRESSURE STARTS TO BUILD
CLOSER, THE PRESSURE GRADIENT WEAKENS AND THE COLD AIR ADVECTION
ALSO WEAKENS. THERE IS A WEAK IMPULSE TO OUR SOUTH THOUGH ROUNDING
THE SLOWLY RETREATING TROUGH WHICH COULD TOSS SOME MORE CLOUDS FOR A
TIME ESPECIALLY ACROSS DELMARVA. OTHERWISE, A WARMER AFTERNOON IS
EXPECTED WITH MORE IN THE WAY OF SUNSHINE FOR THE BULK OF THE AREA.
HIGH TEMPERATURES IN THE LOW TO MID 70S FOR MOST.
LONG TERM /TUESDAY THROUGH FRIDAY/
SUMMARY...WARMER AND DRY TO START, THEN MORE HUMID WITH A CHANCE FOR
SOME CONVECTION LATE IN THE WEEK.
SYNOPTIC OVERVIEW...AS AN UPPER-LEVEL TROUGH DEPARTS TO START
TUESDAY, MID TO UPPER LEVEL RIDGING IS FORECAST TO BUILD ACROSS THE
EAST THROUGH WEDNESDAY. THE RIDGE MAY THEN FLATTEN SOME THURSDAY AND
ESPECIALLY FRIDAY. IT SHOULD BE NOTED THAT SOME GUIDANCE SHOWS A
CLOSED LOW ACROSS THE MID-ATLANTIC TO THE NORTHEAST THROUGH ABOUT
THURSDAY. THE ECMWF WAS MOST NOTABLE WITH THIS, WITH ONLY ONE OR TWO
GFS ENSEMBLE MEMBERS SHOWING THIS POTENTIAL.
FOR TUESDAY AND WEDNESDAY...IN THE WAKE OF AN UPPER-LEVEL TROUGH TO
START TUESDAY, MID TO UPPER LEVEL RIDGING IS FORECAST OVERALL TO
BUILD OVER MUCH OF THE EAST. THIS WILL RESULT IN INCREASING
TEMPERATURES, WITH HIGHS GETTING INTO THE LOW 80S FOR MUCH OF THE
AREA TUESDAY FOLLOWED BY MID TO SOME UPPER 80S WEDNESDAY. AS
MENTIONED ABOVE, MUCH OF THE GUIDANCE IS IN FAVOR OF THE RIDGE
HOWEVER A FEW OF THE MODEL GUIDANCE SHOWED A CLOSED LOW MOVING
ACROSS THE AREA. THE GUIDANCE THAT IS SHOWING THE CLOSED LOW SEEMS
TO BE AN OUTLIER WITH A STRONGER SIGNAL IN THE GUIDANCE/ENSEMBLES
MORE TOWARD THE RIDGE. AS A RESULT, THIS FORECAST FOLLOWS THE WARMER
SOLUTIONS (NATIONAL BLEND OF MODELS). THE AIR MASS IS FORECAST TO BE
DRIER TUESDAY THEN THE DEW POINTS INCREASE WEDNESDAY WHICH WILL
START TO MAKE IT FEEL MORE HUMID. THE FLOW IS FORECAST TO BE LIGHT
GIVEN THE PRESENCE OF THE RIDGE ALOFT AND HIGH PRESSURE AT THE
SURFACE, THEREFORE SEA/BAY BREEZE CIRCULATIONS ARE ANTICIPATED BOTH
DAYS. NO PRECIPITATION IS ANTICIPATED GIVEN THE RIDGE SCENARIO.
FOR THURSDAY AND FRIDAY...THE MID/UPPER LEVEL RIDGE LOOKS TO FLATTEN
SOME THURSDAY AND ESPECIALLY ON FRIDAY AS SHORTWAVE ENERGY SLIDES
ACROSS CANADA TO THE MIDWEST AND GREAT LAKES. THIS WILL SEND A
SURFACE COLD FRONT TOWARD OUR AREA, HOWEVER IT MAY END UP SLOWING OR
STALLING TO OUR WEST. IT IS FORECAST TO STILL BE VERY WARM, AND ON
THE HUMID SIDE, DURING THIS TIME FRAME WITH PERHAPS SOME COOLING
FRIDAY GIVEN THE RIDGE FLATTENING MORE. SOME MOSTLY DIURNALLY DRIVEN
CONVECTION CANNOT BE RULED OUT EACH DAY, ESPECIALLY TIED TO ANY
SURFACE TROUGHS THAT DEVELOP, HOWEVER COVERAGE AND INTENSITY THIS
FAR OUT IS LESS CERTAIN.
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...MVFR EARLY THEN IFR/LIFR WIDESPREAD BEGINNING 01Z-03Z
AND REMAINING OVERNIGHT WITH FREQUENT SHOWERS AND TSTMS. TIMING
IN THE TAFS ISN'T MUCH DIFFERENT FROM EARLIER. GENTLE SOUTH TO
SOUTHEAST WINDS THIS EVENING THEN SHIFTING SHARPLY TO WEST AFTER
MIDNIGHT AND SHARPLY INCREASING TO 15 TO 25 KTS WITH GUSTS OVER
30 KTS. LOW/MEDIUM CONFID.
SATURDAY...GUSTY WINDS CONTINUE THRU DAYBREAK THEN DECREASE
SLOWLY THROUGH THE MORNING. CLOUDY MUCH OF THE DAY WITH MOSTLY
MVFR CONDITIONS AND SHOWERS SATURDAY MORNING WITH VFR POSSIBLE
LATER IN THE AFTERNOON. MEDIUM CONFID.
OUTLOOK...
SATURDAY NIGHT AND SUNDAY...VFR. WEST-NORTHWEST WINDS DIMINISHING
SATURDAY EVENING, THEN WESTERLY WIND GUSTS TO AROUND 20 KNOTS
SUNDAY.
MONDAY THROUGH WEDNESDAY...VFR.
MARINE
THE LOW PRESSURE SYSTEM WHICH WILL BE AFFECTING THE WATERS TONIGHT
AND SATURDAY HAS TRENDED STRONGER TODAY AND AS A RESULT, WE HAVE
CHANGED THE MARINE FLAGS FOR THESE PERIODS. A GALE WARNING HAS BEEN
ISSUED FOR DELAWARE BAY AND THE NJ/DE WATERS (SOUTH OF GREAT EGG
INLET) FOR TONIGHT AND SATURDAY MORNING. A SMALL CRAFT ADVISORY
CONTINUES FOR THE WATERS NORTH OF THAT WITH A NEW SCA FLAG FOR THE
NORTH-MOST NJ ZONE ADDED. WIND GUSTS IN THE SCA AREA WILL AVERAGE
AROUND 30 KTS AND CLOSER TO 35 TO 40KTS FOR THE GALE AREA. THE
PERIODS OF GALES WILL NOT LAST AS LONG AS THE WARNING, BUT WE'VE
ADDED TIME ON BOTH SIDES DUE TO NORMAL FORECAST VARIATIONS WHICH MAY
DEVELOP. SHOWERS AND TSTMS TONIGHT AND INTO SATURDAY.
SATURDAY...SCA FLAGS WILL BE NEEDED AFTER THE GALE IS TAKEN DOWN.
WEST WINDS LATE TONIGHT AND SATURDAY WITH SHOWERS OR A FEW TSTMS
MOSTLY THROUGH NOON.
OUTLOOK...
SATURDAY NIGHT...THE CONDITIONS IMPROVE AS WINDS AND SEAS DIMINISH.
SUNDAY THROUGH WEDNESDAY...THE CONDITIONS ARE ANTICIPATED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
RIP CURRENTS...
FOR THIS AFTERNOON, 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 REMAINS IN PLACE FOR NORTHERN DELAWARE, THE PHILADELPHIA
METRO AREA AND SURROUNDING SUBURBS IN NEW JERSEY, THE LEHIGH VALLEY,
AND NORTHWEST NEW JERSEY. THE WATCH IS VALID FROM 7 PM TONIGHT
THROUGH 8 AM SATURDAY.
EVEN WITH ALL THE RAIN THIS SPRING, GROUNDWATER RECHARGE HAS BEEN
SLOW. AND THAT'S WHY STATE DROUGHT DECLARATIONS REMAIN IN PLACE. BUT
AREA CREEKS, STREAMS, AND RIVERS HAVE FULLY REBOUNDED AND ARE RUNNING
NORMAL TO ABOVE NORMAL. THE UPPER LEVELS OF OUR SOILS ARE ALSO
MOIST/SATURATED. AND THE LATTER ITEMS SUPPORT THE FLOOD WATCH.
AS A RESULT OF THE RECENT RAINS AND SATURATED SOILS, WE'VE SEEN OUR
FFG VALUES DROP. SO THERE IS A CONCERN TONIGHT IF A QUICK 1 TO 3
INCHES OF RAIN MATERIALIZES, ESPECIALLY IF THE MAJORITY OF IT FALLS
IN THE 3 TO 6 HOUR TIMEFRAME.
NO RIVER FLOODING IS CURRENTLY FORECAST, BUT KEEP AN EYE ON OUR
SE PA CREEKS AND STREAMS, AS WELL AS NORTHERN NEW CASTLE COUNTY
IN DELAWARE. BODIES OF WATER LIKE BRANDYWINE CREEK, THE NESHAMINY
CREEK, THE PERKIOMEN CREEK, RED AND WHITE CLAY CREEKS, AND THE
CHRISTINA. THIS IS NOT AN ALL INCLUSIVE LIST.
AS FOR THE MAINSTEMS, WE'RE BASICALLY LOOKING AT 1/2 TO 3/4
BANKFULL, ALTHOUGH THE PASSAIC RIVER AT PINE BROOK COULD COME CLOSE
TO BANKFULL. MOST OF OUR FORECAST POINTS WILL CREST SOMETIME ON
SATURDAY, ALTHOUGH THE PASSAIC WON'T CREST UNTIL SUNDAY.
UNTIL RECENTLY, IT'S BEEN QUITE DRY ACROSS THE REGION, GOING BACK TO
LAST FALL. AND WE HAVEN'T BEEN DEALING WITH A LOT FLOODING. SO IT'S
TIME AGAIN TO REMAIN VIGILANT. MOST FLOODING INJURIES AND FATALITIES
OCCUR IN VEHICLES. SO IF YOU'RE OUT ON THE ROAD TONIGHT AND
ENCOUNTER A FLOODED ROAD, TURN AROUND. FLOODING AT NIGHT, AND THE
SEVERITY OF IT, IS HARDER TO PICK UP VS. DURING THE DAY. AND CHECK
YOUR CELL PHONE TO MAKE SURE YOUR WIRELESS EMERGENCY ALERT FEATURE
IS TURNED ON. THIS IS ONE OF THE BEST WAYS TO GET FLASH FLOOD
WARNINGS.
YOU CAN ALSO VISIT OUR WEBSITE FOR THE LATEST WARNINGS:
WEATHER.GOV/PHI
TO STAY ON TOP OF THE FLOODING POTENTIAL, VISIT THE 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
IF YOU WANT TO SEE THE FLOODING THREAT IN TERMS OF PROBABILITIES,
CHECK OUT THIS HYDROLOGIC ENSEMBLE FORECAST LINK:
WEATHER.GOV/ERH/MMEFS
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 7 PM EDT THIS EVENING THROUGH SATURDAY
MORNING FOR PAZ060>062-070-071-101>106.
NJ...FLOOD WATCH FROM 7 PM EDT THIS EVENING THROUGH SATURDAY
MORNING FOR NJZ001-007>010-012-015>019.
DE...FLOOD WATCH FROM 7 PM EDT THIS EVENING THROUGH SATURDAY
MORNING FOR DEZ001.
MD...NONE.
MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 11 AM EDT SATURDAY FOR
ANZ430-431-453>455.
SMALL CRAFT ADVISORY FROM 1 AM TO 6 PM EDT SATURDAY FOR
ANZ450>452.
SYNOPSIS...GORSE
NEAR TERM...OHARA
SHORT TERM...GORSE/HOEFLICH
LONG TERM...GORSE
AVIATION...GORSE/OHARA
MARINE...GORSE/OHARA
HYDROLOGY...KRUZDLO
TIDES/COASTAL FLOODING...HOEFLICH
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