169
FXUS61 KPHI 241916
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
316 PM EDT THU APR 24 2025
SYNOPSIS
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC OCEAN. A
WARM FRONT LIFTS NORTH THE REGION FRIDAY NIGHT, FOLLOWED BY A
COLD FRONT ON SATURDAY AS LOW PRESSURE LIFTS NORTH OF THE
REGION. HIGH PRESSURE WILL THEN BE IN CONTROL FOR THE FIRST HALF
OF THE NEW WEEK. ANOTHER FRONTAL SYSTEM APPROACHES LATE NEXT
WEEK.
NEAR TERM /THROUGH FRIDAY NIGHT/
HIGH PRESSURE HAS SHIFTED OFFSHORE AND REMAIN WELL OFF THE
COAST TONIGHT THROUGH FRIDAY. THE HIGH WILL STILL HAVE ENOUGH OF
AN EFFECT ON THE REGION TO KEEP THE AREA DRY TONIGHT THROUGH
THE DAYTIME HOURS FRIDAY. WITH THE HIGH BEING OFFSHORE, RETURN
FLOW WILL BE IN PLACE ACROSS THE AREA, WHICH WILL KEEP
TEMPERATURES ABOVE NORMAL, AND BEGIN TO LEAD TO AN INCREASE IN
MOISTURE ACROSS THE AREA.
SHORT TERM /SATURDAY THROUGH SUNDAY/
LOW PRESSURE WILL BE OVER THE GREAT LAKES AND OHIO VALLEY
FRIDAY EVENING. A WARM FRONT WILL EXTEND OUT FROM THAT LOW AND
WILL LIFT NORTH THROUGH THE REGION FRIDAY NIGHT. AS THE LOW
PASSES NORTH OF THE REGION AND INTO EASTERN CANADA ON SATURDAY,
IT WILL DRAG A COLD FRONT THROUGH THE REGION DURING THE DAY, AND
THE FRONT WILL CLEAR THE AREA SATURDAY EVENING. SHOWERS WILL
DEVELOP FRIDAY NIGHT, AND THEN SHOWERS CONTINUE THROUGHOUT THE
DAY SATURDAY, TAPERING OFF LATE AND ENDING IN THE EVENING. THE
SURFACE LOW LOOKS TO STRENGTHEN SOMEWHAT FRIDAY NIGHT AS IT
LIFTS NORTH OF LAKE ONTARIO, AND THIS MAY RESULT IN SOME LOCALLY
HEAVY RAIN ACROSS THE SOUTHERN POCONOS, NORTHERN NEW JERSEY,
AND THE LEHIGH VALLEY. SCATTERED THUNDERSTORMS ARE POSSIBLE FROM
TIME TO TIME, BUT NOT LOOKING AT A SEVERE THREAT. OVERALL,
BETWEEN 3/4 INCHES AND 1 INCH OF RAIN IS EXPECTED FOR THE
SOUTHERN POCONOS AND FAR NORTHWEST NEW JERSEY, OTHERWISE,
BETWEEN 1/3 AND 1/2 INCH OF RAIN FOR MOST OF THE AREA, AND 1/4
INCH OR SO FOR DELMARVA. FLASH FLOODING IS ALSO NOT EXPECTED.
THIS WILL BE A BENEFICIAL RAIN.
CANADIAN HIGH PRESSURE BUILDS INTO THE GREAT LAKES AND OHIO
VALLEY ON SUNDAY. SUNNY, DRY AND SEASONABLE CONDITIONS WITH A
BREEZY NORTHWEST WIND.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
HIGH PRESSURE BUILDS EAST AND WILL BE CENTERED OVER THE MID-
ATLANTIC ON MONDAY, THEN SLIDES OFFSHORE AND BECOMES A BERMUDA
HIGH THROUGH AT LEAST WEDNESDAY. MID-LEVEL RIDGING BUILDS OVER
THE EAST COAST AS WELL. UNSEASONABLY WARM AIR BUILDS INTO THE
REGION WITH HIGHS IN THE 70S ON MONDAY, AND THEN IN THE 80S ON
TUESDAY AND WEDNESDAY.
A COLD FRONT APPROACHES LATE NEXT WEEK. THERE IS UNCERTAINTY
AMONG THE MODELS AS TO TIMING AND STRENGTH. BASED ON NBM POPS,
CHANCES FOR SHOWERS ARRIVE SOMETIME WEDNESDAY, BUT IT MAY NOT
CLEAR UNTIL WEDNESDAY NIGHT OR THURSDAY. WILL CARRY SLIGHT
CHANCE-CHANCE POPS DURING THIS TIME. COOLING OFF FOR THE END OF
THE WEEK.
AVIATION /19Z THURSDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. SOUTH TO SOUTHWEST WINDS 5-10 KNOTS, WITH
OCCASIONAL GUSTS 15-20 KNOTS; GUSTS DROP OF BY SUNSET. HIGH
CONFIDENCE.
TONIGHT...VFR. SOUTH-SOUTHWEST WINDS 5-10 KNOTS, BECOMING LIGHT
AND VARIABLE MOST PLACES OVERNIGHT. HIGH CONFIDENCE.
FRIDAY... VFR.
OUTLOOK...
FRIDAY NIGHT THROUGH SATURDAY...MVFR/IFR IN SHRA AND SCATTERED
TSRA.
SUNDAY THROUGH TUESDAY...VFR. NSW. GUSTY NW WINDS LIKELY ON
SUNDAY.
MARINE
REST OF TODAY-FRIDAY...CONDITIONS WILL REMAIN BELOW SMALL CRAFT
ADVISORY LEVELS, ALTHOUGH WINDS WILL GUST AROUND 20 KNOTS THIS
AFTERNOON AND EVENING, AND AGAIN FRIDAY AFTERNOON.
OUTLOOK...
FRIDAY NIGHT THROUGH SATURDAY...OVERALL, SUB-SCA CONDITIONS
EXPECTED, ALTHOUGH SEAS MAY BUILD CLOSE TO 5 FEET LATE SATURDAY.
VSBY RESTRICTIONS IN SHOWERS AND SCATTERED THUNDERSTORMS.
SATURDAY NIGHT THROUGH SUNDAY...SCA CONDITIONS POSSIBLE, MAINLY
FOR SEAS BUILDING TO 5 FEET. A PERIOD OF 25 TO 30 KT GUSTS
POSSIBLE SATURDAY NIGHT AND SUNDAY MORNING.
MONDAY THROUGH TUESDAY...SUB-SCA CONDITIONS.
FIRE WEATHER
RH VALUES ON THURSDAY DROPPED INTO THE LOW TO MID 20S, WHILE
WINDS INCREASED AND GUSTED TO AROUND 20 MPH AT TIMES. FRIDAY
WILL SEE SIMILAR WIND GUSTS, HOWEVER, RH VALUES ARE NOT EXPECTED
TO BE AS LOW. THE LOWEST RH VALUES ARE EXPECTED ACROSS EASTERN
PENNSYLVANIA AND INLAND PORTIONS OF NEW JERSEY WHERE RH VALUES
COULD DROP INTO THE MID TO UPPER 20S. RH VALUES FOR DELAWARE,
MARYLAND, AS WELL AS COASTAL PORTIONS OF NEW JERSEY WILL LIKELY
SEE RH VALUES IN THE 35-45% OR GREATER RANGE. DEPENDING ON HOW
MUCH FUELS HAVE DRIED IN THE LAST COUPLE OF DAYS, WE MAY NEED TO
ISSUE A SPECIAL WEATHER STATEMENT FOR PORTIONS OF NEW JERSEY
AND PENNSYLVANIA.
RAIN WILL IMPACT THE AREA FRIDAY NIGHT THROUGH SATURDAY
EVENING. OVERALL, BETWEEN 1/3 AND 1/2 INCH OF RAIN WILL FALL
ACROSS MOST OF THE AREA, THOUGH UP TO AN INCH OF RAIN IS
POSSIBLE IN THE SOUTHERN POCONOS AND FAR NORTHWEST NEW JERSEY,
AND 1/4 INCH OR SO IS POSSIBLE IN DELMARVA.
ON SUNDAY, NORTHWEST WINDS WILL INCREASE TO 15 TO 20 MPH WITH
30 TO 35 MPH GUSTS POSSIBLE. IN ADDITION, MIN RH VALUES ON
SUNDAY WILL BE 30 TO 35 PERCENT.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MDZ012-015.
MARINE...NONE.
SYNOPSIS...MPS
NEAR TERM...ROBERTSON
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...MPS/ROBERTSON
MARINE...MPS/ROBERTSON
FIRE WEATHER...PHI
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