064
FXUS61 KPHI 100631
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
231 AM EDT SUN MAY 10 2026
WHAT HAS CHANGED
RAINFALL AMOUNTS ON MONDAY ARE DECREASING.
KEY MESSAGES
1. AREAS OF FOG WILL IMPACT PORTIONS OF THE AREA INTO THIS MORNING.
SOME PATCHY DENSE FOG IS POSSIBLE.
2. A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND FEW THUNDERSTORMS
TO THE AREA THIS AFTERNOON THROUGH TONIGHT.
3. SOME ADDITIONAL OPPORTUNITIES FOR RAINFALL THIS WEEK.
DISCUSSION
KEY MESSAGE 1...AREAS OF FOG WILL IMPACT PORTIONS OF THE AREA INTO
THIS MORNING. SOME PATCHY DENSE FOG IS POSSIBLE.
CALM WINDS, RESIDUAL GROUND MOISTURE, AND A STRONG TEMPERATURE
INVERSION ABOVE THE SURFACE HAVE LED TO THE DEVELOPMENT OF AREAS OF
FOG EARLY THIS MORNING ACROSS MUCH OF EASTERN PA AND NJ. THE FOG
WILL LIKELY BECOME A BIT MORE WIDESPREAD IN COVERAGE ACROSS THESE
AREAS THROUGH SUNRISE. SOME LOCALLY DENSE FOG IS EXPECTED, BUT AT
THIS TIME WIDESPREAD VISIBILITY REDUCTIONS TO DENSE FOG ADVISORY
CRITERIA APPEAR UNLIKELY. FARTHER SOUTH ACROSS THE DELMARVA, LITTLE
TO NO RAINFALL OCCURRED YESTERDAY, BUT SOME PATCHY FOG DEVELOPMENT
IS STILL POSSIBLE GIVEN THE MOIST LOW LEVELS AND LIGHT WINDS.
FOG SHOULD QUICKLY DISSIPATE AFTER SUNRISE AS TEMPERATURES WARM.
KEY MESSAGE 2...A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND FEW
THUNDERSTORMS TO THE AREA THIS AFTERNOON THROUGH TONIGHT.
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. AT THE SURFACE, LOW PRESSURE WILL TRACK WELL TO THE
NORTH OF THE REGION WITH A COLD FRONT PASSING THROUGH THE AREA THIS
AFTERNOON INTO THIS EVENING.
AHEAD OF THE COLD FRONT, WARM WEST-SOUTHWESTERLY FLOW WILL CONTINUE
INTO THIS AFTERNOON, WITH AT LEAST FILTERED SUNSHINE. THIS WILL
ALLOW TEMPERATURES TO CLIMB INTO THE MID 70S TO LOW 80S ACROSS MUCH
OF THE AREA. AS THE COLD FRONT APPROACHES THIS AFTERNOON, SCATTERED
SHOWERS ARE EXPECTED TO DEVELOP AND TRACK FROM NORTHWEST TO
SOUTHEAST ACROSS THE AREA. SOME ELEVATED INSTABILITY WILL BE
PRESENT, WITH MUCAPE VALUES GENERALLY AROUND 500 J/KG, SO A FEW
THUNDERSTORMS WILL BE POSSIBLE. THIS APPEARS MOST LIKELY ALONG AND
SOUTHEAST OF I-95. WITH THE STRONG DAYTIME HEATING, VERTICAL MIXING
APPEARS LIKELY, LIMITING THE EXTENT OF SURFACE BASED INSTABILITY
THAT IS ABLE TO BE REALIZED. THEREFORE, WHILE GUSTY WINDS CAN'T BE
RULED OUT WITH ANY STRONGER STORM, SEVERE WEATHER IS NOT CURRENTLY
ANTICIPATED.
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 3...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 /06Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS...
THROUGH 12Z...MVFR TO IFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH
MUCH OF THE OVERNIGHT PERIOD IN FOG. BRIEF PERIODS OF LIFR
VISIBILITIES LIKELY, WITH THE EXCEPTIONS BEING AT PHL, ILG, AND MIV,
WHERE FOG IS EXPECTED TO BE A BIT LESS EXTENSIVE. WINDS LIGHT AND
VARIABLE WITH PERIODS OF CALM. LOW CONFIDENCE.
TODAY...CONDITIONS LOOK TO IMPROVE TO VFR BY 14Z AS FOG DISSIPATES
AT ALL TERMINALS. SCATTERED SHOWERS ARE POSSIBLE BEGINNING 17-19Z. A
FEW THUNDERSTORMS CAN'T BE RULED OUT FOR PNE, PHL, AND ILG. BRIEF
PERIODS OF VISIBILITY RESTRICTIONS WILL BE POSSIBLE IN HEAVIER
SHOWERS OR STORMS. WINDS BECOMING WEST- SOUTHWEST AND INCREASING TO
AROUND 10 KT WITH A FEW GUSTS 15-20 KT, BECOMING NORTHWEST BETWEEN
21-23Z AT 5-10 KT. MODERATE CONFIDENCE.
TONIGHT...PRIMARILY VFR. LIGHT SHOWERS WILL BE POSSIBLE THROUGH THE
NIGHT, PARTICULARLY FROM PNE SOUTHWARD. BRIEF PERIODS OF MVFR
VISIBILITIES CAN'T BE RULED OUT WITH ANY HEAVIER SHOWERS. NORTHWEST
WINDS BECOMING NORTH-NORTHEASTERLY AT GENERALLY 5 KT OR LESS.
MODERATE CONFIDENCE.
OUTLOOK...
MONDAY...MOSTLY VFR CEILINGS IN THE MORNING WITH SOME SHOWERS,
ESPECIALLY SOUTH AND EAST OF PHL.
TUESDAY...VFR.
WEDNESDAY AND THURSDAY...A PERIOD OF SUB-VFR CONDITIONS POSSIBLE
ALONG WITH SHOWERS. A FEW THUNDERSTORMS POSSIBLE WEDNESDAY AFTERNOON
AND EVENING.
MARINE
NO MARINE HEADLINES ARE ANTICIPATED THROUGH TONIGHT. SOUTHERLY WINDS
WILL INCREASE TO 10-15 KT WITH GUSTS AROUND 20 KT ON THE WATERS THIS
AFTERNOON, SHIFTING TO NORTHERLY AND EVENTUALLY NORTH-NORTHEASTERLY
TONIGHT. SEAS GENERALLY 2-4 FEET THROUGH TONIGHT. SHOWERS WILL BE
POSSIBLE BEGINNING THIS EVENING AND CONTINUING THROUGH THE OVERNIGHT
HOURS TONIGHT.
OUTLOOK...
MONDAY 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...NONE.
DISCUSSION...COOPER/GORSE
AVIATION...COOPER/GORSE
MARINE...COOPER/GORSE
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