211
FXUS61 KPHI 231815
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
215 PM EDT WED APR 23 2025
SYNOPSIS
HIGH PRESSURE BUILDS DOWN OUT OF CANADA AND INTO THE MID-
ATLANTIC REGION THROUGH WEDNESDAY. THE HIGH THEN SHIFTS OFFSHORE
WEDNESDAY NIGHT 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 FRIDAY/
NO REAL CHANGES TO THE FORECAST THROUGH THE REST OF THE WEEK AS
HIGH PRESSURE WILL KEEP THE AREA UNDER DRY CONDITIONS WITH
TEMPS RUNNING A FEW DEGREES ABOVE NORMAL. ENSEMBLE MEANS AND
ENSEMBLE CLUSTER ANALYSIS SHOW NO APPRECIABLE DIFFERENCES
THROUGH FRIDAY.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
HIGH PRESSURE STARTS MOVING OFFSHORE FRIDAY NIGHT AS HIGHS
START FALLING ALOFT AND A WARM FRONT MOVES THROUGH AT THE
SURFACE. THE WARM FRONT WILL LEAD TO TEMPS STAYING IN THE 60S
OVERNIGHT FRIDAY NIGHT AND WILL LEAD TO AN INCREASE IN LOW LEVEL
MOISTURE WITH PWATS APPROACHING 1.5 INCHES. MID LEVEL PVA WILL
TRACK THE REGION AS CONSENSUS GUIDANCE BRINGS A POSITIVELY
TILTED TROUGH WITH SEVERAL IMPULSES. AT THE SURFACE THIS WILL
FEATURE A COLD FRONT THAT WILL BE THE SURFACE TRIGGER FOR
SHOWERS WITH SOME ISOLATED THUNDERSTORMS.
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.
THE COLD FRONT PUSHES OFFSHORE SATURDAY NIGHT, BEFORE HIGH
PRESSURE BUILDS INTO THE MID ATLANTIC REGION SUNDAY INTO MONDAY,
BEFORE SHIFTING OFFSHORE MONDAY NIGHT AND OUT TO SEA TUESDAY.
DRY WEATHER WILL RETURN FOR SATURDAY NIGHT THROUGH TUESDAY, AND
AFTER A BRIEF PERIOD OF NEAR NORMAL TEMPERATURES SATURDAY NIGHT
INT SUNDAY, ABOVE NORMAL TEMPERATURES RETURN FOR SUNDAY NIGHT
THROUGH TUESDAY.
AVIATION /18Z 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...VFR.
FRIDAY...VFR WITH INCREASING CLOUD COVER.
FRIDAY NIGHT-SATURDAY NIGHT...SUB VFR CONDITIONS AS SHOWERS
IMPACT THE REGION WITH A SMALL CHANCE (10%-15%) OF THUNDERSTORMS
DURING THE DAY SATURDAY.
SATURDAY NIGHT-SUNDAY...VFR.
MARINE
SUB-SCA CONDITIONS EXPECTED THROUGH THURSDAY. WINDS LESS THAN
15 KNOTS. SEAS MAINLY 2 FEET OR LESS.
OUTLOOK...
THURSDAY NIGHT THROUGH FRIDAY...SUB SCA WITH SEAS 2-3 FEET AND
WINDS LESS THAN 20KTS.
FRIDAY NIGHT-SUNDAY...SUB-SCA WINDS BUT SEAS WILL BUILD TO 4-5
FEET WITH SCA ANTICIPATED ON SATURDAY. SHOWERS EXPECTED ON
SATURDAY.
FIRE WEATHER
RELATIVE HUMIDITY VALUES WILL BE LOWER THAN YESTERDAY, AROUND
20-25%, BUT WINDS WILL BE LIGHT AND UNDER 10 MPH. SEA/BAY
BREEZES TODAY SHOULD RESULT IN A RECOVERY OF THE RELATIVE
HUMIDITY NEAR THE COAST AND ALSO BRING A SWITCH IN WIND
DIRECTION TO 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...GORSE
NEAR TERM...HOEFLICH/WUNDERLIN
SHORT TERM...DEAL
LONG TERM...DEAL
AVIATION...DEAL/HOEFLICH/WUNDERLIN
MARINE...DEAL/HOEFLICH/WUNDERLIN
FIRE WEATHER...
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