587
FXUS61 KPHI 291812
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
212 PM EDT FRI AUG 29 2025
SYNOPSIS
A COLD FRONT WILL MOVE ACROSS THE AREA THROUGH THIS AFTERNOON.
HIGH PRESSURE WILL THEN BUILD IN OVER THE WEEKEND AND EARLY NEXT
WEEK. AN AREA OF LOW PRESSURE IS FORECAST TO DEVELOP OFF THE
SOUTHEAST COAST EARLY NEXT WEEK BUT REMAIN WELL AWAY FROM OUR
AREA. A COLD FRONT IS FORECAST TO ARRIVE INTO OUR REGION LATER
THURSDAY.
NEAR TERM /THROUGH SATURDAY/
A COLD FRONT WILL CONTINUE MOVING ACROSS THE AREA THROUGH THIS
AFTERNOON AS AN UPPER LEVEL LOW CONTINUES TO DEEPEN OVER
SOUTHERN QUEBEC. WITH THE UPPER LEVEL LOW AND ASSOCIATED COLDER
AIR ALOFT COMBINED WITH SURFACE HEATING AND THE FORCING FROM THE
COLD FRONT, THERE WILL CONTINUE TO BE CONSIDERABLE CLOUDINESS
AROUND AT TIMES THIS AFTERNOON. WE ALSO MAINTAIN CHANCES FOR
SOME ISOLATED SHOWERS OR SPRINKLES BUT WITH ANY OF THESE BEING
CONFINED MAINLY TO NE PA INTO NORTHERN NJ. EVEN HERE THOUGH,
MOST PLACES WON'T SEE ANYTHING. EXPECT NW WINDS AROUND 10
GUSTING 15 TO 20 MPH. AFTERNOON HIGHS WILL BE IN THE 70S TO NEAR
80 WITH COMFORTABLE HUMIDITY LEVELS AS DRIER AIR MOVES IN.
FOR TONIGHT, THE FRONT MOVES OFFSHORE WITH HIGH PRESSURE
BUILDING IN OVER THE GREAT LAKES REGION. THIS SET UP WILL
CONTINUE TO ADVECT COOL, DRY AIR INTO THE AREA DUE TO CONTINUING
NW WINDS. AS A RESULT, IT WILL BE A CHILLY NIGHT BY LATE AUGUST
STANDARDS. LOWS IN THE URBAN AREAS AS WELL AS ALONG THE COAST
AND THE DELAWARE BAY WILL BE MAINLY IN THE MIDDLE TO UPPER 50S.
MEANWHILE THE NORMALLY COLDER SPOTS SUCH AS THE PINE BARRENS,
EASTERN PA, AND NW NJ WILL SEE LOWS GENERALLY GETTING DOWN INTO
THE UPPER 40S TO LOW 50S. ACROSS THE POCONOS, IT COULD EVEN GET
DOWN CLOSE TO 40 IN SPOTS.
FOR SATURDAY, HIGH PRESSURE WILL CONTINUE TO BE CENTERED TO OUR
WEST AND WILL DOMINATE OUR WEATHER LEADING TO MAINLY SUNNY
SKIES, COOL TEMPERATURES (AGAIN, BY LATE AUGUST STANDARDS), AND
LOW HUMIDITY. EXPECT HIGHS MOSTLY IN THE 70S WITH EVEN SOME
UPPER 60S OVER THE POCONO PLATEAU. GENERALLY EXPECT NW WINDS
AROUND 5 TO 10 MPH.
SHORT TERM /SATURDAY NIGHT 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. 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 40-50% ACROSS THE AREA.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THIS AFTERNOON...A FEW BRIEF SHOWERS OR SPRINKLES POSSIBLE BUT
IT SHOULD REMAIN VFR WITH A SCATTERED TO AT TIMES BROKEN CLOUD
DECK AROUND 5 KFT. NW WINDS AROUND 8-10 KTS WITH SOME GUSTS UP
TO 20 KTS.
TONIGHT...VFR. NORTHWEST WINDS DROPPING TO AROUND 5 KTS LATE.
HIGH CONFIDENCE.
SATURDAY...VFR UNDER MAINLY CLEAR SKIES AND NW WINDS AROUND
5-10 KNOTS. HIGH CONFIDENCE.
OUTLOOK...
SATURDAY NIGHT THROUGH WEDNESDAY...PREVAILING VFR. NO
SIGNIFICANT WEATHER.
MARINE
GENERALLY EXPECT WINDS SHIFTING TO NW AND INCREASING TO 10-15
WITH SOME GUSTS UP TO 20 KNOTS BY EARLY THIS EVENING CONTINUING
THROUGH MOST OF TONIGHT. THE CONDITIONS SHOULD REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS BOTH THROUGH TONIGHT AND SATURDAY
THOUGH WITH SEAS 2-3 FEET.
OUTLOOK...
SATURDAY NIGHT THROUGH WEDNESDAY...THE CONDITIONS ARE
ANTICIPATED TO BE BELOW SMALL CRAFT ADVISORY CRITERIA. FAIR
WEATHER.
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...FITZSIMMONS
NEAR TERM...FITZSIMMONS
SHORT TERM...GORSE/STAARMANN
LONG TERM...GORSE/STAARMANN
AVIATION...FITZSIMMONS/GORSE
MARINE...FITZSIMMONS/GORSE
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