502
FXUS61 KPHI 131041
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
641 AM EDT TUE OCT 13 2026
WHAT HAS CHANGED
UPDATED AVIATION SECTION FOR 06Z TAFS.
CANCELLED REMAINING SMALL CRAFT ADVISORIES.
KEY MESSAGES
1. SPOTTY MINOR COASTAL FLOODING WILL BE POSSIBLE WITH THE
TUESDAY MORNING HIGH TIDE CYCLE.
2. SURGE OF WARMTH AND HUMIDITY THROUGH WEDNESDAY AHEAD OF A
COLD FRONT.
3. A STRONG COLD FRONT FRIDAY BRINGS AN END TO THE WARMTH AS
MUCH COLDER AIR ARRIVES FOR THE WEEKEND.
DISCUSSION
KEY MESSAGE 1...SPOTTY MINOR COASTAL FLOODING WILL BE POSSIBLE
WITH THE TUESDAY MORNING HIGH TIDE CYCLE.
THERE WILL BE THE POTENTIAL FOR SOME SPOTTY MINOR COASTAL
FLOODING WITH TUESDAY MORNING'S HIGH TIDE CYCLE FOR PLACES ALONG
THE ATLANTIC COAST AND DELAWARE BAY. NO COASTAL FLOOD ADVISORY
IS IN EFFECT AT THIS TIME.
NO TIDAL FLOODING CONCERNS EXPECTED ALONG THE CHESAPEAKE BAY.
KEY MESSAGE 2...SURGE OF WARMTH AND HUMIDITY THROUGH WEDNESDAY
AHEAD OF A COLD FRONT.
A FRONTAL ZONE DRAPED TO OUR NORTH TUESDAY WILL RESULT IN SURFACE
LOW PRESSURE RIDING ALONG IT TUESDAY NIGHT AND WEDNESDAY. THIS WILL
PULL A COLD FRONT ACROSS OUR AREA BY LATER WEDNESDAY. AHEAD OF THIS
FEATURE, SOUTHERLY FLOW WILL BOOST THE LOW-LEVEL WARM AIR ADVECTION
AND THIS RESULTS IN MUCH WARMER AIR SURGING INTO OUR AREA THROUGH
WEDNESDAY. HIGH TEMPERATURES WILL NEAR 80 DEGREES FOR MANY AREAS ON
TUESDAY, THEN INTO THE LOW TO EVEN SOME MID 80S ON WEDNESDAY. IN
ADDITION, DEW POINTS WILL INCREASE BACK THROUGH THE 60S TUESDAY AND
WEDNESDAY, WITH THEM PEAKING ON WEDNESDAY (NEAR 70F FOR PARTS OF THE
AREA) AHEAD OF THE AFOREMENTIONED FRONT. THIS WILL RESULT IN A MUCH
MORE HUMID FEEL OVER THE NEXT FEW DAYS, WITH IT BEING THE MOST HUMID
ON WEDNESDAY (HEAT INDEX VALUES SHOULD APPROACH 90F FOR AREAS FROM
ABOUT PHILADELPHIA SOUTH AND EAST; AWAY FROM THE COAST). THERE DOES
NOT APPEAR TO BE ALL THAT MUCH IN THE WAY OF FORCING FOR ASCENT WITH
THE FRONT AS IT ARRIVES BY LATER WEDNESDAY, THEREFORE JUST A LOW
CHANCE (20-30 PERCENT) FOR SHOWERS AS OF NOW. THE DEW POINTS WILL
FALL FROM NORTH TO SOUTH LATER WEDNESDAY NIGHT INTO THURSDAY AS THE
FRONT SETTLES SOUTHWARD AND THE WINDS TURN OUT OF THE NORTH AND
NORTHEAST. THE FRONT HOWEVER MAY NOT COMPLETELY CLEAR OUR
REGION.
KEY MESSAGE 3...A STRONG COLD FRONT FRIDAY BRINGS AN END TO THE
WARMTH AS MUCH COLDER AIR ARRIVES FOR THE WEEKEND.
A POTENT UPPER-LEVEL TROUGH IS FORECAST TO ARRIVE ACROSS THE EAST
DURING FRIDAY, THEN GRADUALLY LIFT OUT OVER THE WEEKEND. THIS WILL
DRIVE SURFACE LOW PRESSURE JUST NORTH OF OUR AREA FRIDAY WITH AN
ASSOCIATED STRONG COLD FRONT SWEEPING THROUGH.
A MILD AND INCREASINGLY MOIST AIR MASS AHEAD OF THIS FEATURE WILL
PROVIDE SOME INSTABILITY AS THE STRONG COLD FRONT ARRIVES ON FRIDAY.
LARGE SCALE FORCING FOR ASCENT WILL INCREASE WITH THE ARRIVAL OF THE
ROBUST UPPER-LEVEL TROUGH AND COLD FRONT, THEREFORE SHOWERS WILL
INCREASE FOR A TIME (PEAKING ON FRIDAY). SOME SHOWERS THOUGH LOOK TO
DEVELOP THURSDAY NIGHT AHEAD OF THE MAIN COLD FRONT. SOME
THUNDERSTORMS CANNOT BE RULED OUT GIVEN THE STRENGTH OF THE SYSTEM,
HOWEVER THIS WILL ULTIMATELY DEPEND ON THE MAGNITUDE OF THE
INSTABILITY AND TIMING OF THE COLD FRONT. IN THE WAKE OF THE COLD
FRONT, STRONG COLD AIR ADVECTION OCCURS AND THIS WILL RESULT IN MUCH
COLDER TEMPERATURES FOR THE WEEKEND. AS OF NOW, HIGH TEMPERATURES
BOTH SATURDAY AND SUNDAY LOOK TO STRUGGLE TO GET OUT OF THE 50S
(COLDER IN THE HIGHER TERRAIN). A GUSTY WIND SATURDAY DUE TO COLD
AIR ADVECTION AND A TIGHTENED PRESSURE GRADIENT WILL ADD TO THE
CHILL. IF THE WIND DROPS OFF ENOUGH SATURDAY NIGHT, SOME FROST OR
FREEZING TEMPERATURES WILL BECOME A CONCERN FOR PORTIONS OF OUR
AREA. THE AIR MASS THEN STARTS TO MODIFY EARLY NEXT WEEK.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TUESDAY... VFR EXPECTED FOLLOWING ANY LINGERING MORNING FOG.
SOUTHWEST WINDS INCREASING 5 TO 10 KNOTS. HIGH CONFIDENCE.
TUESDAY NIGHT...VFR. A PERIOD OF LLWS POSSIBLE AS A FRONTAL
BOUNDARY APPROACHES THE REGION. HIGH CONFIDENCE IN CATEGORY, BUT
LOW CONFIDENCE IN LLWS IMPACTS.
OUTLOOK...
WEDNESDAY AND WEDNESDAY NIGHT...VFR. SLIGHT CHANCE FOR BRIEF
PERIOD OF SUB-VFR CONDITIONS WEDNESDAY NIGHT FROM SHOWERS.
THURSDAY AND FRIDAY...A PERIOD OF SUB-VFR CONDITIONS POSSIBLE WITH
SHOWERS. GUSTY SOUTHWEST TO WEST WINDS ON FRIDAY.
SATURDAY...VFR. GUSTY NORTHWEST WINDS.
MARINE
ALL REMAINING SMALL CRAFT ADVISORIES WERE CANCELLED.
FAIR WEATHER TUESDAY AND TUESDAY NIGHT. SSW TO SW WINDS AROUND
15 KTS WITH GUSTS AROUND 20 KTS POSSIBLE IN THE AFTERNOON AND
OVERNIGHT. SEAS 2 TO 4 FEET.
OUTLOOK...
WEDNESDAY THROUGH THURSDAY...NO MARINE HAZARDS ARE ANTICIPATED.
FRIDAY AND SATURDAY...SMALL CRAFT ADVISORY CONDITIONS PROBABLE, WITH
A PERIOD OF GALE-FORCE WIND GUSTS POSSIBLE.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...MJL/WFO PHI
AVIATION...MJL
MARINE...MJL
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