298
FXUS61 KPHI 101916
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
316 PM EDT SUN MAY 10 2026
WHAT HAS CHANGED
THE COLD FRONT IS SLOWLY PROGRESSING THROUGH THE REGION.
KEY MESSAGES
1. A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND FEW
THUNDERSTORMS TO THE AREA THIS AFTERNOON THROUGH TONIGHT.
2. 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 MID AFTERNOON, THE SURFACE COLD FRONT IS SLOWLY
PROGRESSING THROUGH 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.
OVER THE NEXT FEW HOURS, A BROKEN LINE OF SHOWERS IS EXPECTED
TO DEVELOP AND 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. THAT BEING SAID, LATEST TRENDS OF THICK CLOUDS
DEVELOPING AHEAD OF THE FRONT DO APPEAR TO BE LIMITING
INSTABILITY, AS TEMPERATURES IN THE DELAWARE VALLEY HAVE
DECREASED A FEW DEGREES FROM 2 TO 3 PM. THAT BEING SAID, THERE
REMAINS A CONCERN FOR DOWNDRAFTS, PARTICULARLY WEST OF
PHILADELPHIA WHERE A NARROW CORRIDOR OF CLEARING HAS PERSISTED.
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...ADDITIONAL OPPORTUNITIES FOR RAINFALL THIS WEEK.
IN THE UPPER-LEVELS THIS WEEK, THERE WILL BE TROUGHING IN PLACE
ACROSS THE REGION FOR A MAJORITY OF THIS WEEK. ONE TROUGH MOVES OUT
INTO TUESDAY WITH ANOTHER UPPER-LEVEL TROUGH MOVING IN WEDNESDAY
THROUGH FRIDAY NIGHT. THIS SECOND TROUGH BECOMES MORE AMPLIFIED AND
MAY TRY TO CLOSE OFF ON FRIDAY. RECENT GUIDANCE HAS TRENDED AWAY
FROM THE TROUGH FULLY CLOSING OFF INTO AN UPPER LOW NEAR THE MID-
ATLANTIC REGION, BUT SOME DO STILL SHOW THE CLOSED LOW FORMING JUST
OFF TO OUR NORTHEAST. REGARDLESS, WITH ALL OF THIS SAID, THERE WILL
BE MORE OPPORTUNITIES FOR UNSETTLED WEATHER THIS WEEK.
OUR FIRST TROUGH MOVES OUT MONDAY NIGHT INTO TUESDAY WITH A SURFACE
HIGH PRESSURE SYSTEM BUILDING IN. MONDAY NIGHT IS A CHILLER NIGHT AS
WINDS AND CLOUD COVER DECREASE WHICH ALLOWS FOR RADIATIONAL COOLING.
THERE IS SOME FROST POTENTIAL IN THE POCONOS MONDAY NIGHT INTO
TUESDAY MORNING.
ONCE THE HIGH PRESSURE SYSTEM EXITS ON TUESDAY NIGHT AND ANOTHER
UPPER-LEVEL TROUGH MOVES INTO THE REGION WEDNESDAY, WE SEE MORE
ACTIVE WEATHER. AT THE SURFACE, A LOW PRESSURE SYSTEM MOVES INTO THE
NORTHEAST FROM THE GREAT LAKES REGION WEDNESDAY INTO THURSDAY. THIS
LOW PRESSURE SYSTEM DRAGS A WARM FRONT THROUGH THE AREA ON WEDNESDAY
WHICH IS FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT INTO THURSDAY.
RAIN SHOWERS DEVELOP LATE TUESDAY NIGHT INTO WEDNESDAY MORNING WITH
COVERAGE INCREASING ACROSS THE AREA DURING THE DAY WEDNESDAY. DURING
WEDNESDAY AFTERNOON INTO EARLY WEDNESDAY NIGHT, THERE IS THE
POTENTIAL FOR SOME ISOLATED THUNDERSTORMS. THE EXTENT OF
DESTABILIZATION IS A BIT MORE UNCERTAIN, BUT GUIDANCE DOES SHOW SOME
INSTABILITY PRESENT TO SUPPORT ISOLATED THUNDERSTORMS. SHOWERS
LINGER INTO THURSDAY AS OUR LOW PRESSURE SYSTEM DEPARTS.
BEYOND THURSDAY, THERE IS SOME UNCERTAINTY FOR FRIDAY WHICH
CORRESPONDS TO IF THE UPPER-LEVEL TROUGH IS MORE PROGRESSIVE OR
CLOSES OFF INTO A CLOSED LOW NEAR THE AREA. RECENT TRENDS HAVE BEEN
A BIT DRIER FOR FRIDAY. HOWEVER, IF THE CLOSED LOW DOES FORM NEAR
THE AREA, IT WOULD LEAD TO MORE POTENTIALS FOR SHOWERS. INTO THE
WEEKEND, WE FEEL THE INFLUENCE OF A SURFACE HIGH OFF TO OUR
SOUTHEAST WHICH ALLOWS FOR DRIER CONDITIONS AND TEMPERATURES TO WARM
UP.
AVIATION /19Z 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.
FRIDAY...VFR.
MARINE
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...SMALL CRAFT ADVISORY CONDITIONS EXPECTED WITH WINDS OF
25-30 KT AND SEAS OF 4-6 FEET.
THURSDAY AND FRIDAY...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/GUZZO/JOHNSON
AVIATION...COOPER/GORSE/GUZZO/JOHNSON
MARINE...GORSE/GUZZO/JOHNSON
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