413
FXUS61 KPHI 221744
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
144 PM EDT SUN MAR 22 2026
WHAT HAS CHANGED
THE RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND THIS
EVENING HAS INCREASED TO OUR WEST.
SOME ADJUSTMENTS MADE TO THE SMALL CRAFT ADVISORY START TIMES.
KEY MESSAGES
1. ISOLATED TO SCATTERED SEVERE THUNDERSTORMS POSSIBLE LATE THIS
AFTERNOON AND THIS EVENING, THEN TURNING MUCH COOLER WITH GUSTY
WINDS ON MONDAY.
DISCUSSION
KEY MESSAGE 1...ISOLATED TO SCATTERED SEVERE THUNDERSTORMS POSSIBLE
LATE THIS AFTERNOON AND THIS EVENING, THEN TURNING MUCH COOLER WITH
GUSTY WINDS ON MONDAY.
AN UPPER-LEVEL TROUGH ACROSS CENTRAL CANADA IS FORECAST TO AMPLIFY
SOME INTO MONDAY ON ITS SOUTH SIDE FROM THE GREAT LAKES AND
NORTHEAST. THIS WILL DRIVE SURFACE LOW PRESSURE EASTWARD FROM THE
GREAT LAKES AND INTO SOUTHERN NEW ENGLAND LATE THIS AFTERNOON AND
THIS EVENING ALONG A FRONTAL ZONE. HOWEVER, ANOTHER WEAK LOW
DEVELOPS ALONG THE FRONT AND WITHIN THE ELONGATED PRESSURE TROUGH.
THIS SECONDARY WEAK LOW MAY BECOME CONVECTIVELY ENHANCED AS IT
SLIDES EAST-SOUTHEAST ALONG THE FRONT LATE THIS AFTERNOON AND THIS
EVENING. OUR AREA WILL REMAIN WITHIN THE WARM SECTOR AHEAD OF THE
ADVANCING COLD FRONT, THEN THE ACTUAL STRONG COLD FRONT WILL MOVE
ACROSS OUR AREA LATER TONIGHT BRINGING COLDER AIR ACROSS OUR AREA
MONDAY THROUGH TUESDAY. THIS AFTERNOON WILL FEATURE TEMPERATURES
WELL INTO THE 60S TO LOW/MID 70S FOR MOST OF THE REGION. A MORE
SOUTHERLY WIND COMPONENT THOUGH WILL KEEP IT MUCH COOLER ALONG THE
COAST DUE TO THE WIND OFF THE COLD OCEAN AND SOME LINGERING STRATUS.
THE MODEL FORECAST SOUNDINGS INDICATE INSTABILITY DEVELOPING WITHIN
THE WARM SECTOR, ESPECIALLY WEST OF OUR AREA INTO CENTRAL PENNSYLVANIA
WHERE THE GREATER INSTABILITY IS EXPECTED. IT IS THERE WHERE THUNDERSTORMS
ARE TO INITIATE THIS AFTERNOON WITH A GREATER CHANCE FOR SOME TURNING
SEVERE AS LAPSE RATES ARE STEEP THROUGH THE LOW AND MID LEVELS AND
THE SHEAR AND WIND FIELDS ARE VERY STRONG. THE SHOWERS AND THUNDERSTORMS
WILL THEN MOVE EAST AND SOUTHEASTWARD INTO OUR AREA LATE THIS
AFTERNOON AND THIS EVENING, WITH INITIALLY DISCRETE CELLS BECOMING
MORE LINEAR. THERE LESS INSTABILITY FORECAST ACROSS OUR AREA
WITH A CAP/INVERSION, ALTHOUGH SOME GUIDANCE ERODES THE CAP INTO
EARLY THIS EVENING MOSTLY ACROSS OUR WESTERN ZONES. WE WILL HAVE
TO SEE HOW CONVECTION UPSTREAM EVOLVES AND THE ACTUAL TIMING OF
IT. THE OVERALL SEVERE THUNDERSTORM RISK ACROSS OUR AREA LOOKS
TO BE FOCUSED ACROSS PORTIONS OF OUR WESTERN ZONES THROUGH EARLY/MID
EVENING. IT IS POSSIBLE THAT A LINE SEGMENT OR BOWING SEGMENT
ARRIVES BEFORE WEAKENING AND PRODUCE LOCALLY DAMAGING WINDS. IF
CONVECTION DOES REACH OUR AREA EARLY ENOUGH AND REMAINS MORE DISCRETE,
THEN LARGE HAIL IS ALSO POSSIBLE. THE TORNADO RISK CONTINUES TO
LOOK VERY LOW GIVEN THE LARGER TEMPERATURE-DEW POINT SPREADS LEADING
TO HIGHER LCL HEIGHTS. THE TIMING FOR ANY SEVERE THUNDERSTORMS LOOKS
TO BE FROM APPROXIMATELY 4 PM TO 10 PM.
THE PRECIPITABLE WATER IS FORECAST TO INCREASE TO 1+ INCHES AS WE
GET INTO THIS EVENING. THIS ALONG WITH SOME POTENTIAL FOR A TIME OF
TRAINING SHOWERS/THUNDERSTORMS COULD RESULT IN SOME CORRIDORS OF
HEAVIER RAINFALL (1+ INCHES). IF HEAVIER RAINFALL RATES OCCUR OVER
THE MORE URBAN AREAS, LOCALIZED FLASH FLOODING IS POSSIBLE.
OTHERWISE, THE RAINFALL IS MUCH NEEDED. THERE COULD BE A LESSENING
OF THE CONVECTION BY LATER THIS EVENING, THEN ANOTHER WAVE RIDES
ALONG AND NORTH OF THE ADVANCING FRONT AND THIS SHOULD ENHANCE THE
SHOWERS OR RESULT IN A PERIOD OF RAIN. SOME LINGERING THUNDER COULD
OCCUR ALONG THE LEADING EDGE OF THIS AS SOME ELEVATED INSTABILITY
REMAINS.
AS WE GO THROUGH MONDAY, THE COLD ADVECTION PATTERN BEHIND THE FRONT
WILL RESULT IN HIGH TEMPERATURES OCCURING IN THE EARLY MORNING HOURS
WITH TEMPERATURES HOLDING FAIRLY STEADY OR FALLING SOME THROUGH THE
AFTERNOON. SHOWERS TAPER OFF WEST TO EAST EARLY TO MID MORNING,
POSSIBLY ENDING AS A LITTLE WET SNOW IN THE POCONOS. THE PRESSURE
GRADIENT TIGHTENS IN THE WAKE OF THE DEPARTING LOW TO OUR EAST AND
NORTHEAST AS HIGH PRESSURE BUILDS TOWARD THE GREAT LAKES. THIS
COMBINED WITH STRONGER COLD AIR ADVECTION WILL STEEPEN THE LOW-LEVEL
LAPSE RATES AND RESULT IN DEEPER MIXING. A GUSTY NORTHWEST WIND WILL
RESULT DURING MONDAY, ESPECIALLY IN THE AFTERNOON INTO THE EVENING,
WITH PEAK WIND GUSTS OF 25-35 MPH. BELOW AVERAGE TEMPERATURES ARE
FORECAST FOR TUESDAY WITH LESS WIND.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR SHOULD PREVAIL REST OF TODAY. SHOWERS AND A FEW
STORMS, PERHAPS STRONG, MAY BEGIN TO IMPACT RDG AND ABE AS EARLY AS
22Z, BUT WILL LIKELY HOLD OFF THROUGH 00Z FOR ALL OTHER TERMINALS.
SOUTH-SOUTHWESTERLY WINDS GENERALLY 5-10 KT WITH A FEW GUSTS UP TO
20 KTS. MODERATE CONFIDENCE.
TONIGHT...CIGS LOWERING TO MVFR AT ALL TERMINALS, WITH IFR POSSIBLE
LATE. SHOWERS AND A FEW STORMS, SOME PERHAPS STRONG, ARE EXPECTED TO
MOVE THROUGH THE TERMINALS THROUGH 04Z. THEREAFTER, LINGERING
SHOWERS ARE EXPECTED THROUGH MOST OF THE NIGHT. WINDS BECOMING
NORTHERLY AT 5-10 KT WITH THE PASSAGE OF A COLD FRONT BETWEEN 03-
06Z. MODERATE CONFIDENCE.
MONDAY...GRADUAL IMPROVEMENT TO VFR. NORTHWEST WIND 10-20 KTS WITH
GUSTS 20-30 KT. MODERATE CONFIDENCE.
OUTLOOK...
MONDAY NIGHT THROUGH WEDNESDAY...VFR. NORTHWEST WIND GUSTS TO 20
KNOTS MONDAY EVENING DIMINISH.
THURSDAY AND FRIDAY...PERIODS OF SUB-VFR CONDITIONS POSSIBLE WITH
SOME RAIN.
MARINE
THE CONDITIONS REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH
TONIGHT. NORTHERLY WINDS WILL INCREASE FROM NORTH TO SOUTH NEAR
DAYBREAK MONDAY, WITH AN ADDITIONAL INCREASE DURING THE DAY MONDAY.
GIVEN WIND GUSTS 25-30 KNOTS AND SEAS BUILDING TO AROUND 5 FEET
MONDAY, THE SMALL CRAFT ADVISORY IS IN EFFECT FOR MONDAY AND MONDAY
NIGHT. THE CONDITIONS HOWEVER SHOULD START SUBSIDING LATER MONDAY
NIGHT INTO EARLY TUESDAY.
OUTLOOK...
TUESDAY AND WEDNESDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW
SMALL CRAFT ADVISORY CRITERIA.
THURSDAY AND FRIDAY..A PERIOD OF SMALL CRAFT ADVISORY CONDITIONS MAY
DEVELOP STARTING THURSDAY NIGHT.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM MONDAY TO 3 AM EDT TUESDAY FOR
ANZ430-431.
SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 6 AM EDT TUESDAY FOR
ANZ450>455.
DISCUSSION...FITZSIMMONS/GORSE
AVIATION...GORSE/RCM
MARINE...GORSE
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