118
FXUS61 KPHI 131316
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
ISSUED BY NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
916 AM EDT TUE OCT 13 2026
WHAT HAS CHANGED
PATCHY FOG CENTRAL NEW JERSEY AND THE NORTHERN AND WESTERN
SUBURBS OF PHILADELPHIA WILL BURN OFF BY 11 AM.
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 THIS MORNING'S HIGH TIDE CYCLE.
THERE WILL BE THE POTENTIAL FOR SOME SPOTTY MINOR COASTAL
FLOODING WITH THIS 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 TODAY WILL RESULT IN SURFACE
LOW PRESSURE RIDING ALONG IT TONIGHT 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 TODAY, 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
COUPLE 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. A RUMBLE OF
THUNDER IS POSSIBLE ALONG THE EASTERN SHORE INTO DELAWARE WHERE
THERE MAY BE A LITTLE MORE INSTABILITY, BUT ANY COVERAGE SHOULD
BE ISOLATED AT MOST. 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 /13Z TUESDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TUESDAY... VFR EXPECTED. 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
FAIR WEATHER THROUGH TONIGHT. 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 AND LWX
AVIATION...MJL/LWX
MARINE...MJL
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