010
FXUS61 KPHI 170718
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
318 AM EDT FRI APR 17 2026
WHAT HAS CHANGED
THE CHANCE FOR SHOWERS WERE INCREASED SOME TODAY, MOSTLY THIS
AFTERNOON, FOR PORTIONS OF THE AREA.
KEY MESSAGES
1. ABOVE AVERAGE TEMPERATURES CONTINUE TODAY INTO SATURDAY.
SOME SHOWERS AND THUNDER FOR PARTS OF THE AREA TODAY INTO EARLY
THIS EVENING.
2. WIDESPREAD MINOR TIDAL FLOODING IS FORECAST TO OCCUR ALONG
THE ATLANTIC COASTS OF NJ AND DE, DELAWARE BAY, AND THE TIDAL
DELAWARE RIVER WITH THE SATURDAY EVENING/NIGHT HIGH TIDE.
3. A STRONG COLD FRONT WILL CROSS THROUGH THE AREA SUNDAY
MORNING, RESULTING IN A PERIOD OF SHOWERS AND SOME THUNDERSTORMS
ALONG WITH COOLER AND BREEZY CONDITIONS.
4. MUCH COOLER, BELOW NORMAL TEMPERATURES ARE EXPECTED INTO
EARLY NEXT WEEK. WIDESPREAD FROST AND/OR FREEZE APPEARS LIKELY
MONDAY NIGHT INTO TUESDAY MORNING.
DISCUSSION
KEY MESSAGE 1...ABOVE AVERAGE TEMPERATURES CONTINUE TODAY INTO
SATURDAY. SOME SHOWERS AND THUNDER FOR PARTS OF THE AREA TODAY
INTO EARLY THIS EVENING.
AN UPPER-LEVEL TROUGH AXIS IS FORECAST TO SLIDE ACROSS OUR AREA
DURING TODAY. THIS WILL BREAK DOWN THE PATTERN THAT HAS BROUGHT
RECORD WARMTH TO MOST OF THE REGION. WHILE TEMPERATURES TODAY
WILL STILL BE WELL ABOVE AVERAGE, HIGHS WILL BE ABOUT 10 DEGREES
LOWER THAN YESTERDAY. THE PRESENCE OF THE UPPER-LEVEL TROUGH
AND ITS ASSOCIATED COOLING ALOFT WILL ALSO RESULT IN ADDITIONAL
CLOUDS DEVELOPING DURING DAYTIME HEATING. IN ADDITION, ENOUGH
INSTABILITY DEVELOPS FOR SOME SHOWERS TO OCCUR ESPECIALLY FROM
ABOUT THE I-95 CORRIDOR ON EASTWARD ESPECIALLY THIS AFTERNOON.
THE MODEL FORECAST SOUNDINGS SHOW SKINNY INSTABILITY (CAPE)
PROFILES WITH THIS BEING AT AND BELOW 20,000 FEET. THIS WOULD
RESULT IN LOW-TOPPED CONVECTION WHICH MAY PRODUCE LITTLE OR NO
LIGHTNING. THE COVERAGE OF THE SHOWERS THROUGH THE DAY,
ESPECIALLY THIS AFTERNOON, LOOKS TO BE ISOLATED TO SCATTERED AS
THE OVERALL FORCING IS NOT STRONG. THE LOW- LEVEL FLOW IS
FORECAST TO BECOME LIGHTER AS THE AFTERNOON WEARS ON, THEREFORE
A SEA BREEZE CIRCULATION SHOULD DEVELOP AND ONCE AGAIN RESULT IN
IT BEING COOLER ALONG THE COAST.
THE WARMTH CONTINUES INTO SATURDAY, HOWEVER A NORTHEAST TO EAST
LOW- LEVEL FLOW WILL BECOME ESTABLISHED AS A BACKDOOR FRONT
PUSHES SOUTHWESTWARD. THIS WILL RESULT IN MUCH COOLER
TEMPERATURES CLOSEST TO THE COAST WITH THE WARMEST ON SATURDAY
ACROSS OUR WESTERN ZONES. SOME GUIDANCE IS RATHER ROBUST WITH
THE MARINE INFLUENCE, ESPECIALLY AS THE BOUNDARY LAYER WARMS UP
QUITE A BIT INLAND, AND THEREFORE SHOVES THE COOLING FARTHER
INLAND BY LATE AFTERNOON. HIGH TEMPERATURES STILL ABOVE AVERAGE
SATURDAY, HOWEVER THEY WILL CONTINUE TO STEP DOWNWARD AS WE GET
MUCH CLOSER TO A MORE SIGNIFICANT PATTERN CHANGE.
KEY MESSAGE 2...WIDESPREAD MINOR TIDAL FLOODING IS FORECAST TO
OCCUR ALONG THE ATLANTIC COASTS OF NJ AND DE, DELAWARE BAY, AND
THE TIDAL DELAWARE RIVER WITH THE SATURDAY EVENING/NIGHT HIGH
TIDE.
HIGH ASTRONOMICAL TIDES ASSOCIATED WITH THE NEW MOON OCCURRING
TODAY AND PERSISTENT ONSHORE FLOW DEVELOPING TONIGHT AND
ESPECIALLY SATURDAY IS FORECAST TO RESULT IN WIDESPREAD MINOR
TIDAL FLOODING WITH THE SATURDAY EVENING/NIGHT HIGH TIDE ALONG
THE ATLANTIC COASTS OF NJ AND DE, DELAWARE BAY, AND THE TIDAL
DELAWARE RIVER. SOME SPOTTY MINOR TIDAL FLOODING MAY OCCUR IN
SOME AREAS WITH THE HIGH TIDE THIS EVENING/TONIGHT, THOUGH ANY
IMPACTS WILL BE LIMITED ENOUGH TO PRECLUDE AND ADVISORY. AS
SOUTHEAST WINDS PERSIST ON SATURDAY, SURGE VALUES WILL INCREASE
TO NEAR 1 FOOT ABOVE NORMAL, WHICH WILL PUT MOST TIDAL AREAS
INTO MINOR FLOOD STAGE DURING HIGH TIDE SATURDAY EVENING/NIGHT.
THIS MAY WARRANT AN ADVISORY WITH A FUTURE UPDATE.
A MODEST OFFSHORE WIND WILL DEVELOP IN THE WAKE OF A COLD FRONT
ON SUNDAY, WHICH SHOULD LIMIT THE THREAT OF ANY ADDITIONAL
FLOODING FOR SUNDAY NIGHT'S HIGH TIDE.
NO TIDAL FLOOD IS FORECAST FOR THE EASTERN SHORE OF CHESAPEAKE
BAY.
KEY MESSAGE 3...A STRONG COLD FRONT WILL CROSS THROUGH THE AREA
SUNDAY MORNING, RESULTING IN A PERIOD OF SHOWERS AND SOME
THUNDERSTORMS ALONG WITH MUCH COOLER AND BREEZY CONDITIONS.
A DEEP UPPER TROUGH WILL APPROACH THE REGION SATURDAY NIGHT. A
STRONG COLD FRONT WILL PRECEDE THIS TROUGH AND SLIDE ACROSS THE
REGION LATE SATURDAY NIGHT INTO SUNDAY MORNING. A WEAK AREA OF
LOW PRESSURE MAY ALSO DEVELOP ALONG THE FRONT IN OUR VICINITY.
AS THE MAIN TROUGH AXIS HANGS BACK FARTHER TO THE WEST, MUCH OF
THE SHOWER ACTIVITY MAY OCCUR BEHIND THE ACTUAL FRONT. GIVEN THE
STRENGTH OF THE INCOMING UPPER-LEVEL TROUGH, FORCING FOR ASCENT
SHOULD BE STRONG ENOUGH TO RESULT IN WIDESPREAD SHOWER
COVERAGE, OR EVEN STRATIFORM RAIN FOR A TIME. THE THUNDER RISK
AT THIS TIME LOOKS RATHER LOW GIVEN THE TIMING OF THE FRONT,
HOWEVER SOME RUMBLES OF THUNDER CANNOT BE RULED OUT.
THIS WILL BE BENEFICIAL RAIN, AND IT WILL ALSO USHER IN A
SIGNIFICANT COOL DOWN INTO EARLY NEXT WEEK. RAINFALL AMOUNTS
LOOK TO BE AROUND 0.10-0.25" ALONG AND SOUTHEAST OF I-95, AND
PERHAPS AS MUCH AS 0.50" TOWARD I-78 AND POINTS NORTH OF THERE.
A GUSTY NORTHWEST WIND WILL ALSO OCCUR IN THE WAKE OF THE COLD
FRONT ON SUNDAY, WITH GUSTS OF 25-35 MPH POSSIBLE ACROSS THE
AREA. HIGHS SUNDAY WILL ONLY BE IN THE 50S TO LOW 60S IN MOST
AREAS. SKIES WILL BE MOSTLY CLOUDY. HOWEVER, IF SOME SUN CAN
BREAK THROUGH THE CLOUDS LATE IN THE DAY, TEMPERATURES MAY WARM
SOME BEFORE DARK.
KEY MESSAGE 4...MUCH COOLER, BELOW NORMAL TEMPERATURES ARE
EXPECTED INTO EARLY NEXT WEEK. WIDESPREAD FROST AND/OR FREEZE
APPEARS LIKELY MONDAY NIGHT INTO TUESDAY MORNING.
LINGERING GRADIENT WIND AND COLD ADVECTION SUNDAY NIGHT INTO
MONDAY MORNING SHOULD LIMIT FROST FORMATION, DESPITE
TEMPERATURES DROPPING INTO THE 30S IN MANY AREAS. TEMPERATURES
WILL LIKELY FALL TO NEAR OR JUST BELOW FREEZING NORTH OF I-78,
WHICH MAY WARRANT FREEZE HEADLINES FOR THESE AREAS (SAVE FOR
THE SOUTHERN POCONOS, WHERE THE GROWING SEASON HAS NOT BEGUN).
TEMPERATURES MONDAY WILL BE QUITE CHILLY COMPARED TO OUR RECENT
RECORD BREAKING WARMTH, WITH HIGHS ONLY IN THE MID 40S TO MID
50S. THIS WILL BE ABOUT 10-15 DEGREES BELOW NORMAL. BREEZY
NORTHWEST WINDS WILL CONTINUE AS WELL, WITH GUSTS UP TO 30 MPH
POSSIBLE UNDER PARTLY CLOUDY SKIES.
MUCH LIGHTER WINDS AND A COLDER AIRMASS WITH HIGH PRESSURE
SETTLING OVERHEAD SHOULD SET THE STAGE FOR WIDESPREAD FROST
AND/OR FREEZE CONDITIONS MONDAY NIGHT INTO EARLY TUESDAY
MORNING. FORECAST LOW TEMPERATURES BY TUESDAY MORNING RANGE FROM
THE MID 20S TO MID 30S. TEMPERATURES WILL BEGIN TO REBOUND
TUESDAY AS AIRMASS MODIFICATION BEGINS WITH HIGHS IN THE MID 50S
TO LOW 60S. TEMPERATURES TUESDAY NIGHT SHOULD BE MILD ENOUGH TO
PRECLUDE ANY FROST/FREEZE CONCERNS, WITH LOWS MAINLY IN THE
40S.
TEMPERATURES WILL REBOUND SLIGHT ABOVE NORMAL BY THE MIDDLE TO
END OF THE WEEK WITH LIMITED CHANCES OF CONVECTION.
AVIATION /07Z FRIDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR OVERALL WITH A CEILING BETWEEN ABOUT 5,000-10,000
FEET AGL. NORTHWESTERLY WINDS DIMINISH TO NEAR 5 KNOTS EARLY
THIS MORNING THEN INCREASE TO 8-12 KNOTS. SOME WIND GUSTS UP TO
20 KNOTS POSSIBLE LATER THIS MORNING INTO THIS AFTERNOON. A FEW
SHOWERS DEVELOPING THROUGH THE DAY WITH ISOLATED THUNDER
POSSIBLE (PROB30 INCLUDED AT MOST TERMINALS). LOW CONFIDENCE ON
TIMING/COVERAGE DETAILS OF SHOWERS.
TONIGHT...VFR WITH INCREASING CLOUDS. MVFR CEILINGS SHOULD
DEVELOP OVERNIGHT FROM EAST TO WEST. NORTH-NORTHWEST WINDS 5-10
KNOTS, BECOMING NORTHEAST NEAR 5 KNOTS. LOW CONFIDENCE REGARDING
MVFR CEILING DETAILS AND IF ANY LOCAL FOG DEVELOPS.
OUTLOOK...
SATURDAY...MVFR CEILINGS POSSIBLE TO START, THEN VFR.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...RESTRICTIONS LIKELY AT
TIMES. WIDESPREAD SHOWERS DEVELOPING BY EARLY SUNDAY MORNING,
WITH PERHAPS AN ISOLATED THUNDERSTORM. NORTHWEST WINDS WILL
BECOME INCREASINGLY GUSTY BY SUNDAY AFTERNOON WITH GUSTS UP TO
30 KTS POSSIBLE.
MONDAY THROUGH TUESDAY...VFR. WIND GUSTS UP TO 25 KT POSSIBLE
ON MONDAY, OTHERWISE NO SIGNIFICANT WEATHER EXPECTED.
MARINE
THE CONDITIONS ARE ANTICIPATED TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA THROUGH TONIGHT. A WIND SHIFT TO THE NORTHWEST
THEN NORTH AND EVENTUALLY FROM THE NORTHEAST IS EXPECTED TODAY
INTO TONIGHT.
OUTLOOK...
SATURDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL
CRAFT ADVISORY CRITERIA.
SATURDAY NIGHT THROUGH MONDAY...SMALL CRAFT ADVISORY CONDITIONS
LIKELY DUE TO WIND GUSTS AROUND 25-30 KT. OTHERWISE, NO MARINE
HEADLINES ARE EXPECTED.
MONDAY NIGHT THROUGH TUESDAY...NO MARINE HAZARDS EXPECTED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...GORSE/STAARMANN
AVIATION...GORSE/STAARMANN
MARINE...GORSE/STAARMANN
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