860
FXUS61 KPHI 290720
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
320 AM EDT FRI AUG 29 2025
SYNOPSIS
A COLD FRONT WILL SHIFT OFFSHORE TODAY. HIGH PRESSURE WILL THEN
BUILD IN OVER THE WEEKEND AND AND EARLY NEXT WEEK. AN AREA OF LOW
PRESSURE IS FORECAST TO DEVELOP OFF THE SOUTHEAST COAST EARLY NEXT
WEEK, HOWEVER REMAIN WELL AWAY FROM OUR AREA. A COLD FRONT IS
FORECAST TO ARRIVE INTO OUR REGION LATER THURSDAY.
NEAR TERM /THROUGH TONIGHT/
EARLY THIS MORNING, AN APPROACHING COLD FRONT IS LOCATED OVER
NORTHERN AND WESTERN PORTIONS OF NEW YORK AND
PENNSYLVANIA, HEADING SOUTHEASTWARD. THE FRONT WILL CROSS THE
AREA BY LATE THIS AFTERNOON. CLOUDS EARLY THIS MORNING
ASSOCIATED WITH UPPER LEVEL TROUGH WILL BREAK LATER IN THE
MORNING, BUT ADDITIONAL CLOUDS LIKELY DEVELOP, ALONG WITH
PERHAPS A FEW ISOLATED SHOWERS, AS THE FRONT CROSSES MIDDAY AND
AFTERNOON, WITH BEST CHANCE OF ANY SHOWERS BEING ACROSS NORTHERN
NJ AND NORTHEASTERN PA. DURING AND AFTER FRONTAL PASSAGE, WINDS
SHIFT TO WEST NORTHWEST AND BECOME A BIT GUSTY, WITH GUSTS
LIKELY IN THE 20-25 MPH RANGE THIS AFTERNOON. DEW POINTS WILL
LIKELY DROP SIGNIFICANTLY AS WELL BY LATE IN THE DAY, WITH MOST
PLACES LIKELY DOWN INTO THE 40S BY EVENING. WINDS WILL GRADUALLY
DIMINISH TONIGHT AS THE FRONT MOVES FURTHER AWAY AND HIGH
PRESSURE BUILDS IN, ALLOWING FOR SOME RADIATIONAL COOLING LATER
ON. THUS, A DAY WHICH SHOULD SEE MUCH OF THE AREA MAKE A RUN AT
80 WILL BE FOLLOWED BY A NIGHT WHERE MANY RURAL AREAS DROP CLOSE
TO 30 DEGREES, THOUGH URBAN AND MARINE LOCALES WILL STAY MILDER.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
AN UPPER-LEVEL TROUGH, WITH A CLOSED LOW CENTERED TO OUR NORTH AND
NORTHEAST SATURDAY, LINGERS ACROSS THE ENTIRE REGION. DESPITE THIS,
THE PATTERN FAVORS SURFACE HIGH PRESSURE CENTERED INITIALLY ACROSS
THE GREAT LAKES TO BUILD INTO OUR AREA. THIS WILL REINFORCE THE DRY
AND COOL/CHILLY CONDITIONS THROUGH SATURDAY NIGHT. PLENTY OF DRY AIR
IN PLACE WITH SURFACE DEW POINTS IN THE 40S WILL RESULT IN PLENTY OF
SUNSHINE DESPITE THE PRESENCE OF THE TROUGH ALOFT. THE LOW-LEVEL
WINDS SHOULD BECOME LIGHT ENOUGH TO RESULT IN THE DEVELOPMENT OF A
SEA BREEZE IN THE AFTERNOON. LIGHT TO CALM WINDS AND A CLEAR SKY
SATURDAY NIGHT WILL LEAD TO A CHILLY OVERNIGHT WITH LOW TEMPERATURES
IN THE LOW TO MID 50S, WITH SOME AREAS DROPPING INTO THE 40S.
AS WE GO THROUGH SUNDAY, THE UPPER-LEVEL TROUGH FROM THE CANADIAN
MARITIMES BACK ACROSS THE NORTHEAST TO OHIO VALLEY IS FORECAST TO
GRADUALLY WEAKEN. THIS RESULTS IN SURFACE HIGH PRESSURE SHIFTING
EASTWARD AND SOUTHWARD SOME MORE INTO AND ACROSS OUR AREA. OUR
SENSIBLE WEATHER LOOKS TO BE CONTROLLED BY THIS AREA OF HIGH
PRESSURE AND THEREFORE DRY CONDITIONS CONTINUE. LITTLE IN THE WAY OF
CLOUDS ARE ANTICIPATED DUE TO THE PRESENCE OF SURFACE HIGH PRESSURE
AND THE TROUGH ALOFT WEAKENING. TEMPERATURES ARE FORECAST TO REMAIN
BELOW AVERAGE, AND WITH WEAK LOW-LEVEL FLOW A SEA BREEZE SHOULD
DEVELOP DURING THE AFTERNOON HOURS.
LONG TERM /MONDAY THROUGH THURSDAY/
SUMMARY...TEMPERATURES BELOW AVERAGE OVERALL, AND DRY WEATHER
CONTINUES UNTIL LATE IN THE WEEK WHEN SOME SHOWERS WILL BECOME
POSSIBLE.
SYNOPTIC OVERVIEW...AN EXPANSIVE UPPER-LEVEL TROUGH IS FORECAST TO
REMAIN ACROSS THE EAST EARLY NEXT WEEK BEFORE A POTENTIALLY STRONG
TROUGH DEVELOPS ACROSS THE MIDWEST THAT THEN SHIFTS EASTWARD THROUGH
THURSDAY. THE GUIDANCE HAS VARIED QUITE A BIT WITH EMBEDDED
SHORTWAVE ENERGY, WHICH HAS OFFERED TIMING AND AMPLITUDE DIFFERENCES
WITH THE OVERALL TROUGH AS IT DEVELOPS AND SHIFTS EASTWARD. THIS HAS
ALSO BEEN RESPONSIBLE FOR SOME OF THE GUIDANCE STRENGTHENING A
COASTAL LOW AS IT SHIFTS NORTH AND NORTHEASTWARD. WHILE THERE STILL
REMAINS SIGNALS AMONG THE GUIDANCE/ENSEMBLES THAT A LOW PRESSURE
SYSTEM DEVELOPS OFF THE SOUTHEAST U.S. COAST NEXT WEEK, IT MAY END
UP REMAINING WEAK AND DISORGANIZED AND BE SLOW TO MOVE. ITS
NORTHWARD MOTION MAY BE HALTED FOR A WHILE GIVEN HIGH PRESSURE TO
THE NORTH, UNTIL A STRONGER INCOMING TROUGH AND COLD FRONT ARRIVES
LATER THURSDAY.
FOR MONDAY THROUGH WEDNESDAY...AN UPPER-LEVEL TROUGH IN THE EAST IS
FORECAST TO WEAKEN SOME AND LIFTING NORTHEASTWARD WHILE ANOTHER
UPPER-LEVEL TROUGH AMPLIFIES ACROSS THE NORTHERN PLAINS AND MIDWEST.
MUCH OF THE GUIDANCE HAS FAVORED MORE OF SEPARATION OF THE
SHORTWAVES AND THEREFORE DELAYS THE EASTWARD SHIFT IN THE AMPLIFYING
UPPER-LEVEL TROUGH LATER IN THE WEEK. THIS RESULT INS SURFACE HIGH
PRESSURE ACROSS OUR AREA GRADUALLY SHIFTING EASTWARD WHILE IS ALSO
WEAKENS. WHILE SOME RAIN IS NEEDED, THE OVERALL PATTERN LOOKS TO
FAVOR THE SURFACE HIGH PROTECTING OUR AREA FROM SYSTEMS. SURFACE LOW
PRESSURE DEVELOPING ALONG A LINGERING BAROCLINIC ZONE FROM OFF THE
SOUTHEAST U.S. COAST TO THE NORTHERN GULF SHOULD BE SLOW TO ORGANIZE
AND ALSO SHOW LITTLE NORTH OR NORTHEAST MOTION GIVEN HIGH PRESSURE
TO ITS NORTH. OUR DRY WEATHER PATTERN LOOKS TO CONTINUE, WITH THE
EXCEPTION OF A SLIGHT CHANCE FOR SOME SHOWERS WEDNESDAY NIGHT AS
SOME MOISTURE STARTS TO INCREASE FROM THE SOUTH ASSOCIATED WITH
PERHAPS A WEAK SURFACE TROUGH EXTENDING NORTHWARD. TEMPERATURES
MOSTLY BELOW AVERAGE.
FOR THURSDAY...AN AMPLIFYING UPPER-LEVEL TROUGH GRADUALLY APPROACHES
FROM THE WEST. THIS SHOULD DRIVE A COLD FRONT INTO OUR AREA BY LATER
IN THIS TIME FRAME. SOME MOISTURE RETURN AHEAD OF THIS FRONT
COMBINED WITH AT LEAST SOME LARGE SCALE ASCENT WILL BRING THE CHANCE
FOR SHOWERS AND PERHAPS A THUNDERSTORM. THE TIMING OF THIS WILL
ULTIMATELY DEPEND ON THE AMPLITUDE OF THE INCOMING UPPER-LEVEL
TROUGH AND AN ASSOCIATED COLD FRONT. THIS SYSTEM SHOULD ALSO PULL
WHATEVER LOW PRESSURE SYSTEM IS OFF THE SOUTHEAST U.S. COAST
NORTHEASTWARD AND KEEP IT OFFSHORE, ALTHOUGH PERHAPS SOME MOISTURE
COULD BE ENHANCED INTO OUR AREA FROM IT. GIVEN THE TYPICAL
UNCERTAINTY AT THIS TIME RANGE, DID NOT DEVIATE FROM THE NATIONAL
BLEND OF MODELS (NBM) OUTPUT WHICH SHOWS POPS INCREASING TO 30-40
PERCENT ACROSS THE AREA.
AVIATION /07Z FRIDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THRU 12Z THIS MORNING...VFR. WINDS OUT OF THE SOUTHWEST 5 KT OR
LESS. HIGH CONFIDENCE.
TODAY...A FEW BRIEF SHOWERS POSSIBLE, OTHERWISE VFR.
WEST/NORTHWEST WINDS AROUND 5-10 KT IN THE MORNING INCREASE TO
AROUND 10-15 KT LATE MORNING/EARLY AFTERNOON WITH GUSTS 20 KT
AT SOME TERMINALS. HIGH CONFIDENCE.
TONIGHT...VFR. NORTHWEST WINDS DROPPING TO AROUND 5 KTS LATE.
HIGH CONFIDENCE.
OUTLOOK...
SATURDAY THROUGH TUESDAY...VFR.
MARINE
WINDS START TODAY 5-10 KNOTS, BUT WITH COLD FRONTAL PASSAGE THIS
AFTERNOON, INCREASE TO 10-15 KTS WITH SOME GUSTS UP TO AROUND
20 KNOTS. WINDS START THE DAY SOUTHWESTERLY AND THEN SHIFT WEST
THEN NW LATE DAY INTO THE NIGHT AS A COLD FRONT MOVES THROUGH.
SEAS 3-4 FEET EARLY IN THE DAY DIMINISHING TO 2-3 FEET TONIGHT.
OUTLOOK...
SATURDAY THROUGH TUESDAY...THE CONDITIONS ARE ANTICIPATED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
RIP CURRENTS...
FOR TODAY, WINDS WILL BE OFFSHORE 5-10 MPH EARLY, INCREASING TO
10-15 MPH LATER IN THE DAY WITH A FEW GUSTS TO 25 MPH. BREAKING
WAVE HEIGHTS REMAIN AROUND 1 TO 2 FEET. COMBINED WITH A WEAK
EASTERLY SWELL AROUND 1-2 FEET EVERY 7 TO 8 SECONDS, THIS WILL
ALLOW FOR A LOW RISK FOR RIP CURRENTS ACROSS ALL BEACHES.
FOR SATURDAY, WINDS TURN TO BE ONSHORE/SHORE PARALLEL, OUT OF
THE NNE BUT WILL ONLY BE AROUND 10 MPH. EASTERLY SWELL OF AROUND
2 FEET WITH A 6-8 SECOND PERIOD WILL RESULT IN BREAKING WAVES OF
1-2 FEET IN THE SURF ZONE. AS A RESULT, A LOW RISK FOR THE
DEVELOPMENT OF RIP CURRENTS IS FORECAST FOR ALL BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...GORSE
NEAR TERM...RCM
SHORT TERM...GORSE
LONG TERM...GORSE
AVIATION...GORSE/RCM
MARINE...GORSE/RCM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page