245
FXUS61 KPHI 231927
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
327 PM EDT WED APR 23 2025
SYNOPSIS
HIGH PRESSURE ACROSS THE AREA THIS EVENING WILL SHIFT OFFSHORE
OVERNIGHT INTO THURSDAY, WITH A WARM FRONT LIFTING NORTHWARD
ACROSS THE AREA FRIDAY NIGHT. A COLD FRONT WILL FOLLOW FOR FRIDAY
NIGHT INTO SATURDAY AS LOW PRESSURE LIFTS TO THE NORTHEAST OUT
OF THE OHIO VALLEY FRIDAY AND INTO NEW ENGLAND THROUGH SATURDAY.
HIGH PRESSURE RETURNS FOR SUNDAY INTO MONDAY.
NEAR TERM /THROUGH THURSDAY/
THOUGH SOME SHORTWAVE ENERGY MAY PROPAGATE THROUGH, THE REGION
WILL EXPERIENCE MAINLY ZONAL FLOW ALOFT DURING THE DURATION OF
THE NEAR TERM. WEAK HIGH PRESSURE LOOKS TO CONTROL THE REGION AT
THE SURFACE LEVEL DURING THE TERM; A BIT OF A WARM FRONT LOOKS
TO LIFT THROUGH EITHER TONIGHT OR THURSDAY.
SHORTWAVE ENERGY AND WARM FRONT REMAIN WEAK WITH SURFACE HIGH
PRESSURE MAINLY IN CONTROL; DRY FORECAST EXPECTED WITH NOT MUCH
TO WRITE HOME ABOUT. FOR THE REST OF TODAY, EXPECT MOSTLY SUNNY
TO PARTLY CLOUDY SKIES WITH HIGHS MAINLY IN THE MID 70S. WITH
WEAK FLOW DUE TO SURFACE HIGH PRESSURE IN PLACE, SEA-BREEZE HAS
ALREADY DEVELOPED AND IS PENETRATING INLAND. EXPECT HIGHS NEAR
THE COAST BEING COOLER IN THE 60S AND LOW 70S.
FOR TONIGHT, SKIES WILL BE MOSTLY CLEAR TO PARTLY CLOUDY WITH
LIGHT AND VARIABLE AND/OR CALM WINDS. THIS WILL RESULT IN
RADIATIONAL COOLING; LOWS WILL BE IN THE UPPER 40S TO LOW 50S.
FOR THURSDAY, MOSTLY CLEAR TO PARTLY CLOUDY SKIES WITH
TEMPERATURES MAINLY IN THE MID TO UPPER 70S FOR MOST INTERIOR
LOCATIONS. HIGHER ELEVATIONS AND AREAS NEAR THE COAST SHOULD
EXPECT HIGHS IN THE 60S TO LOW 70S.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
HIGH PRESSURE WILL BE EAST OF THE AREA THURSDAY NIGHT AND EARLY
FRIDAY. WE'LL CONTINUE WITH THE FAIR WEATHER THOSE PERIODS, BUT
MOISTURE AND WARMTH WILL BE INCREASING OVER THE AREA FRIDAY AS THE
RETURN FLOW BEHIND THE HIGH SETS UP OVER OUR AREA. DEPENDING ON HOW
THE WINDS SET-UP THERE COULD BE SOME LOW CLOUDS CLOSE TO THE SHORE
FRI MORNING.
THE NEXT DISTURBANCE ARRIVES LATER FRIDAY AND WILL AFFECT THE
WEATHER INTO SATURDAY EVENING. AN UPPER TROUGH ACROSS THE GREAT
LAKES PROMOTES SURFACE CYCLOGENESIS ACROSS IN/OH AREA. THIS LOW THEN
DEEPENS AND MOVES ACROSS LAKE ERIE/ONTARIO AND ACROSS SOUTHERN
CANADA. AN ASSOCIATED COLD FRONT CROSSES THE AREA LATER SAT. WE'LL
BRING CHANCE POPS (30-50) ACROSS MOST AREAS FRI NIGHT AND LIKELY POPS
(70-80) FOR SATURDAY. THUNDERSTORMS ARE POSSIBLE TOO BUT SEVERE
WEATHER IS NOT. LOWS WILL REMAIN MILD FRI NIGHT/SAT MORNING WITH
MOSTLY 60S. HIGHS WILL BE A LITTLE ABOVE NORMAL SAT WITH LOW/MID 70S
S/E AND MID 60S N/W.
THE PREVIOUS SHIFT NOTED THAT THE PRIMARY IMPACT OVER THE WEEKEND
WILL BE ROUNDS OF MODERATE TO HEAVY RAINFALL ON SATURDAY. TALL SKINNY
CAPE PROFILES WITH WARM CLOUD DEPTHS APPROACHING 10,000FT SUGGEST
FAIRLY EFFICIENT RAINFALL. NBM PROBS SUGGEST GENERALLY A 20%
CHANCE OF GREATER THAN 1" FOR MOST OF THE FORECAST AREA.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
A COLD FRONT COMPLETES ITS TRANSIT ACROSS NJ AND DELMARVA SATURDAY
NIGHT WITH DECREASING POPS AFTER SAT EVENING. AS HIGH PRESSURE
ARRIVES FROM THE NORTHWEST SUNDAY, THE WEATHER WILL BE NICE FOR THE
LAST HALF OF THE WEEKEND AND INTO NEXT WEEK. AFTER THAT, LOW
PRESSURE WILL MOVE NORTH OF THE AREA BRINGING MILDER AIR AND A
CHANCE FOR SHOWERS/TSTMS LATER TUE AND INTO WED.
TEMPERATURES WILL START OUT THE PERIOD CLOSE TO NORMAL, BUT THEN THE
MILDER AIR GETS ADVECTED INTO THE REGION WITH WARMER TEMPS EACH DAY
INTO NEXT WEEK. BY THE MIDDLE OF HE WEEK, TEMPS WILL BE MUCH ABOVE
NORMAL WITH LOW/MID 80S IN MANY AREAS AND LOW 70S NEAR THE SHORE.
NORMAL HIGH TEMPERATURES FOR LATE APRIL ARE UPPER 60S TO LOW 70S FOR
PHILADELPHIA AREA AND LOW 60S FOR THE FAR NW AREAS. LOWS GENERALLY
ARE IN THE 40S, BUT CLOSER TO 50 NEAR THE HIGHLY URBAN AREAS.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. W AND NW WINDS 5-10 KNOTS BACKING WITH
TIME BECOMING S OR SW BY LATE AFTERNOON AND EARLY EVENING. SEA-
BREEZE LOOKS TO MOVE FURTHER INLAND WITH TIME SHIFTING WINDS OUT
OF THE S AND SE FOR SOME SITES. HIGH CONFIDENCE IN VFR
CONDITIONS, LOW CONFIDENCE IN SEA-BREEZE WIND SHIFT TIMING AND
LOCATION.
TONIGHT...VFR. LIGHT AND VARIABLE AND/OR CALM WINDS. HIGH
CONFIDENCE.
THURSDAY...VFR. S/SSW WINDS 5-10 KNOTS. HIGH CONFIDENCE.
OUTLOOK...
THURSDAY NIGHT/FRIDAY... VFR. INCREASING CLOUDS FRIDAY.
FRIDAY NIGHT... LOWERING CIGS WITH SHOWERS AND SUB-VFR POSSIBLE.
SAT/SAT EVENING...MVFR OR IFR PROBABLE WITH SHOWERS AND A CHANCE OF
TSTMS.
SUNDAY/MONDAY... VFR EXPECTED.
MARINE
SUB-SCA CONDITIONS EXPECTED THROUGH THURSDAY. WINDS LESS THAN
15 KNOTS. SEAS MAINLY 2 FEET OR LESS.
OUTLOOK...
THURSDAY NIGHT/FRIDAY ... SUB-SCA EXPECTED. FAIR.
FRIDAY NIGHT THRU SAT. EVENING... SCA POSSIBLE ACROSS THE OCEAN WITH
SHOWERS AND A FEW TSTMS.
SAT NIGHT THRU MONDAY... SUB-SCA. FAIR.
FIRE WEATHER
RELATIVE HUMIDITY VALUES ARE AROUND 20-25% THIS AFTERNOON, BUT
WINDS OVERALL ARE RATHER LIGHT. WE HAVE SEEN SEA/BAY BREEZES
DEVELOP WHICH HAVE RESULTED IN A RECOVERY OF THE RELATIVE
HUMIDITY NEAR THE COAST AND A SWITCH IN WIND DIRECTIONS FROM
THE SOUTH/SOUTHEAST. SIMILAR CONDITIONS EXPECTED ON THURSDAY,
WITH RHS NEAR 25-35% AND LIGHT WINDS.
RELATIVE HUMIDITY RECOVERS MORE THIS WEEKEND. GIVEN LIGHTER
WINDS, THERE ARE NO FIRE WEATHER CONCERNS EXPECTED REGARDING
RAPID FIRE SPREAD.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR NJZ020-
022>027.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...OHARA/GORSE
NEAR TERM...HOEFLICH/WUNDERLIN
SHORT TERM...DEAL/OHARA
LONG TERM...OHARA
AVIATION...OHARA/WUNDERLIN
MARINE...OHARA/WUNDERLIN
FIRE WEATHER...STAFF
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