158
FXUS61 KPHI 101648
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1248 PM EDT SUN MAY 10 2026
WHAT HAS CHANGED
SOME AREAS HAVE A MARGINAL (1 OUT OF 5) RISK FOR SEVERE WINDS
THIS AFTERNOON.
KEY MESSAGES
1. A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND FEW
THUNDERSTORMS TO THE AREA THIS AFTERNOON THROUGH TONIGHT.
2. SOME ADDITIONAL OPPORTUNITIES FOR RAINFALL THIS WEEK.
DISCUSSION
KEY MESSAGE 1...A COLD FRONT WILL BRING A CHANCE FOR SHOWERS
AND FEW THUNDERSTORMS TO THE AREA THIS AFTERNOON THROUGH
TONIGHT.
AS OF NOON, THE SURFACE COLD FRONT IS JUST WEST OF THE REGION
AND SHOULD BE CROSSING OFF SHORE BY LATE THIS EVENING. IN THE
MID AND UPPER LEVELS, A LARGE SCALE TROUGH CENTERED OVER
PORTIONS OF ONTARIO AND QUEBEC WILL SHIFT SLOWLY EASTWARD
THROUGH TONIGHT, WITH THE REGION EMBEDDED IN ENHANCED (45-55 KT)
SOUTHWESTERLY FLOW ALOFT DOWNSTREAM OF THE TROUGH AXIS.
AS THE COLD FRONT GETS CLOSER, A BROKEN LINE OF SHOWERS IS
EXPECTED TO PROGRESS JUST AHEAD OF THE FRONT. SOME ELEVATED
INSTABILITY WILL BE PRESENT, WITH MUCAPE VALUES GENERALLY AROUND
500 J/KG, SO A FEW EMBEDDED THUNDERSTORMS IN THIS LINE ARE
EXPECTED. UPON FURTHER REVIEW OF THE LATEST MODEL SOUNDINGS,
THERE IS INCREASING CONCERN FOR DOWNDRAFTS, PARTICULARLY WEST OF
PHILADELPHIA. THUS FOR A PORTION OF SOUTHEASTERN PA, THERE IS A
MARGINAL (1 OUT OF 5) RISK FOR SEVERE WINDS.
AFTER THE COLD FRONT PASSES, THE BROAD REGION OF ASCENT FROM THE
TROUGH WILL ALLOW FOR CONTINUED SCATTERED SHOWER DEVELOPMENT,
PRIMARILY ALONG AND SOUTHEAST OF I-95, THROUGH THE OVERNIGHT HOURS.
QPF FROM THIS EVENT LOOKS TO BE LOW, GENERALLY AROUND A TENTH OF AN
INCH OR LESS. LOWS WILL BE IN THE MID 40S TO LOW 50S.
KEY MESSAGE 2...SOME ADDITIONAL OPPORTUNITIES FOR RAINFALL THIS
WEEK.
AN UPPER-LEVEL TROUGH IS FORECAST TO BE MORE PRESENT ACROSS MUCH OF
THE EAST THROUGH THIS WEEK. SOME GUIDANCE CONTINUES TO BE MORE
POTENT WITH THE TROUGH AMPLIFICATION LATER THIS WEEK WITH A CLOSED
LOW DEVELOPING IN THE VICINITY OF OUR AREA AND THEN MOVING OFF TO
THE NORTHEAST. THERE ARE OTHER MODELS THAT SHARPEN THIS TROUGH
EASTWARD, HOWEVER KEEP IT MORE PROGRESSIVE AND NOT BECOME CLOSED
OFF. THE OVERALL PATTERN THAT IS FORECAST WILL OFFER SOME
OPPORTUNITIES FOR RAINFALL THROUGH THIS WEEK.
OUR FIRST SYSTEM BRINGS A COLD FRONT THROUGH THE AREA INTO MONDAY
MORNING. THE FRONT ITSELF LOOKS TO SHIFT FARTHER SOUTH AND EAST WITH
IT MOSTLY OFFSHORE TO START MONDAY. MID LEVEL ENERGY MAY RESULT IN
JUST ENOUGH LIFT IN THE WAKE OF THE FRONT FOR A TIME MONDAY TO
PRODUCE ADDITIONAL SHOWERS MAINLY SOUTH AND EAST OF I-95. A MODEL
TREND HAS BEEN TO BE WEAKER WITH THIS OVERALL AND THUS DECREASED
RAINFALL AMOUNTS/COVERAGE. IT TURNS CHILLIER MONDAY NIGHT AS THE
TROUGH AXIS SHIFTS OFFSHORE AND SURFACE HIGH PRESSURE BEGINS TO
BUILD IN. THERE IS SOME FROST POTENTIAL, MOSTLY IN THE SOUTHERN
POCONOS, LATER MONDAY NIGHT INTO EARLY TUESDAY MORNING.
THE ACTIVE PATTERN LOOKS TO RELOAD AS ANOTHER UPPER-LEVEL TROUGH
QUICKLY REPLACES THE FIRST ONE ACROSS MUCH OF THE EAST. THIS FEATURE
MAY BECOME CLOSED OFF IN THE VICINITY OF OUR REGION LATE WEDNESDAY
THROUGH FRIDAY BEFORE IT LIFTS OUT DURING SATURDAY. THE ARRIVAL OF
INCREASED WARM AIR ADVECTION AHEAD OF THIS SYSTEM AND WITH A COLD
FRONT SHOULD DRIVE AN INCREASE IN SHOWER ACTIVITY DURING WEDNESDAY.
THE CHANCE FOR THUNDER REMAINS LESS CERTAIN AS IT WILL DEPEND ON HOW
MUCH DESTABILIZATION CAN OCCUR. IF THE SYSTEM CLOSES OFF AS IT
ARRIVES THURSDAY INTO FRIDAY, THEN SURFACE LOW PRESSURE MAY END UP
DEVELOPING OFF THE NORTHERN MID-ATLANTIC COAST. THIS WOULD INCREASE
THE INTENSITY AND COVERAGE OF SHOWERS/RAIN AND RESULT IN MORE OF AN
ONSHORE FLOW AND THEREFORE EVEN COOLER TEMPERATURES. THIS WOULD ALSO
TEND TO RESULT IN A MORE STABLE AIR MASS AND THUS LITTLE TO NO RISK
OF THUNDER. THE UPPER AIR PATTERN EVOLVING DURING THE SECOND HALF OF
THIS WEEK IS LESS CERTAIN, AS THE AMOUNT AND COVERAGE OF
PRECIPITATION WILL DEPEND ON WHETHER WE END UP WITH A CLOSED LOW OR
JUST A SHARPER UPPER-LEVEL TROUGH THAT IS MORE PROGRESSIVE. AS THE
TROUGH OR CLOSED LOW MOVES AWAY TO START THE WEEKEND, A MUCH WARMER
AIR MASS WILL START TO ARRIVE.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
TODAY...A BROKEN LINE OF SHOWERS IS EXPECTED TO CROSS THROUGH
THE REGION THROUGH 00Z. WITHIN THIS LINE, A FEW EMBEDDED
THUNDERSTORMS ARE POSSIBLE, PARTICULARLY FOR KPHL, KPNE, KTTN,
KILG, AND KMIV. BRIEF PERIODS OF VISIBILITY RESTRICTIONS WILL
BE POSSIBLE IN HEAVIER SHOWERS OR STORMS. WEST- SOUTHWEST WINDS
INCREASING TO AROUND 10 KT WITH A FEW GUSTS 15-20 KT THIS
AFTERNOON, BECOMING NORTHWEST BETWEEN 21-23Z AT 5-10 KT.
MODERATE CONFIDENCE.
TONIGHT...PRIMARILY VFR. LIGHT SHOWERS WILL BE POSSIBLE THROUGH
THE NIGHT, PARTICULARLY FOR THE I-95 TERMINALS, MIV AND ACY.
BRIEF PERIODS OF MVFR VISIBILITIES CAN'T BE RULED OUT WITH ANY
HEAVIER SHOWERS. WIND SPEEDS SHOULD DECREASE TO 6 KT OR LESS,
AND WIND DIRECTION MAY VARY BETWEEN NORTHWESTERLY AND
NORTHEASTERLY. MODERATE CONFIDENCE.
MONDAY...KACY MAY SEE SOME LINGERING SHOWERS THROUGH 18Z WHICH
MAY LEAD TO BRIEF REDUCTIONS IN CEILINGS. OTHERWISE, VFR
CONDITIONS ARE EXPECTED. WINDS WILL START LIGHT AND VARIABLE,
BUT SETTLE OUT OF THE WEST AROUND 18Z.
OUTLOOK...
TUESDAY...VFR.
WEDNESDAY AND THURSDAY...A PERIOD OF SUB-VFR CONDITIONS POSSIBLE
ALONG WITH SHOWERS. A FEW THUNDERSTORMS POSSIBLE WEDNESDAY AFTERNOON
AND EVENING.
MARINE
A MARINE DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE NEAR COASTAL
AREAS FROM MANASQUAN INLET TO SANDY HOOK THROUGH 3 PM. SATELLITE
IS SHOWING THE SOUTHERN END OF THE FOG/LOW CLOUD BANK STARTING
TO ERODE, SO IT IS LIKELY TO DISSIPATE BY THE LATE AFTERNOON.
WINDS AND SEAS SHOULD STAY BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH MONDAY. A FEW AREA ARE CURRENTLY SEEING WAVE HEIGHTS
NEAR 5 FT, BUT EXPECT WAVE HEIGHTS TO CONTINUE TO SUBSIDE. A
BRIEF PERIOD OF NORTHWESTERLY WIND GUSTS AT OR ABOVE 20 KT IS
POSSIBLE VERY LATE TONIGHT INTO TUESDAY MORNING, BUT IT IS
LIKELY TO REMAIN BELOW 25 KT.
OUTLOOK...
MONDAY NIGHT AND TUESDAY...THE CONDITIONS ARE ANTICIPATED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
WEDNESDAY...A PERIOD OF SMALL CRAFT ADVISORY CONDITIONS POSSIBLE.
THURSDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL
CRAFT ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ450.
DISCUSSION...COOPER/GORSE/JOHNSON
AVIATION...COOPER/GORSE/JOHNSON
MARINE...GORSE/JOHNSON
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