National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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-- Discussion containing changed information from previous version are highlighted. --690FXUS61 KPHI 040122AFDPHIArea Forecast DiscussionNational Weather Service Mount Holly NJ922 PM EDT Tue Sep 3 2024.SYNOPSIS...High pressure remains in control through Thursday. An area oflow pressure approaches from the Gulf coast with a cold frontapproaching from the northwest, bringing some rain for the endof the week/first half of the weekend. Cold front moves throughby Sunday with high pressure building in for early next week.&&.NEAR TERM /THROUGH WEDNESDAY/...
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High pressure will remain in place across the region, with itscenter passing overhead tonight and offshore into Wednesday.This will provide below normal temperatures, very dry air, andgenerally very pleasant conditions for early September.Temperatures have plummeted quickly so far this evening thanksto an ideal radiational cooling setup under mostly clear skies.Winds will be mainly 5 mph or less favoring a north tonortheast direction, locally calm. Went much lower thandeterministic guidance for low temperatures, with forecast lowsmainly in the 40s to low 50s. Areas near the immediate coast andwithin this Philly urban corridor will likely stay closer tothe mid 50s.By Wednesday, the high pressure will be shifting offshore, whichwill shift the surface flow more easterly. This will supportdewpoints rebounding slightly with more marine influence,though still keeping very comfortable humidity levels. Afternoontemperatures will be a few degrees warmer as the airmass beginsmodifying as well. Forecast highs are mainly in the mid 70s tonear 80 degrees. We should see some cirrus throughout the daymixed with some wildfire smoke aloft, though should remain mostlysunny.
-- End Changed Discussion --&&.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...The mid-week period through Thursday night will be a quiet oneoverall. High pressure settling near Nova Scotia on Thursday. Asurface low tries to develop off the coast of the Outer Banks onThursday along a stalled boundary. With the high to thenortheast, and the low to the south, an onshore flow willdevelop, increasing moisture and cloud cover.In terms of sensible weather, expecting a set of nice days tocontinue. Temperatures will climb into the upper 70s both dayswith some spots hitting the 80 plateau. Some clouds willinfiltrate into areas south of Philadelphia as the area of lowpressure along the stalled front off to the south meanders, butall spots should be partly to mostly sunny. Overnight lows onWednesday night will be in the upper 40s/low 50s for most withupper 50s in Delmarva and around the Philly metro. Increasingcloud cover on Thursday Night associated the low off to thesouth gradually pushing north will keep things warmer, withupper 50s/low to mid 60s.&&.LONG TERM /FRIDAY THROUGH TUESDAY/...An unsettled end of the week and first half of the weekendlooks on tap, especially for Saturday. A digging trough movesthrough the upper Midwest, with a surface cold front approachingon Saturday. Further south, an area of low pressure looks tocome up out of the Gulf Coast, interacting with the northernstream trough, and moving up the East Coast. Guidance in generalstill remains spread in how these two features interact,although it is appearing more likely that much of the area willget some form of rainfall sometime Saturday. A few showers maydevelop late Friday or Friday night, but the main show stilllooks to be during the daytime Saturday. Given lack ofconfidence in coverage of any heavier amounts, opted to keepPoPs mainly near 50-60% for now.Some deterministic guidance and ensembles show the surface lowejecting off the coast near the Hampton Roads/Norfolk area andsliding up the coast, while other members show the low pushingeastward off the Outer Banks and out to sea, with only the coldfront bringing some showers. With PWATs getting near 2 inchesthis weekend, there is the concern for some heavy rain if theGulf Coast low rides up the coast. However, given the dryconditions of the past few weeks, the flooding concern isoverall low at this time. NBM Probabilities of 24 hour rainfall> 1 inch remains near 10-30% as of this writing for Saturday.The cold front should sweep through rather quickly by Sunday,with drier air working in. High pressure looks to settle inafter the front passes.Temperatures look to be near/just above normal ahead of theincoming frontal system, with near/slightly below normaltemperatures taking over in the wake of the front that passes onSunday.&&.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,KILG, KMIV, KACY and surrounding areas.Tonight...VFR/SKC with winds mainly less than 5 kt, favoring anortheast direction. High confidence.Wednesday...VFR with few to scattered high clouds at times.Easterly winds around 5-10 kt. High confidence.Outlook...Wednesday night through Thursday Night...VFR. No significantweather.Friday through Friday Night...Primarily VFR. Some scatteredlight showers around.Saturday...sub-VFR conditions possible with showers andscattered thunderstorms around.&&.MARINE...The Small Craft Advisory was extended through 1 AM Wednesdayfor the coastal waters from Cape May to Fenwick Island due toseas lingering around 5-6 feet. Elsewhere, the SCA has beenallowed to expire.For tonight, northeast to east winds near 10-15 kt with gustsaround 20 kt possible. Seas ranging between 3-5 feet.For Wednesday, fair weather is anticipated. Similar windconditions are expected to continue with seas around 2-4 feet.Outlook...Wednesday night through Wednesday Night...No marine headlinesanticipated.Thursday through Saturday...SCA conditions likely (60%) on thecoastal waters as seas around 5 feet expected. Showers possibleon Friday/Saturday.Rip Currents...Wednesday...Winds turn more easterly but decrease to 10 to 15mph. Breaking waves should also decrease a foot or so and willbe generally in the 1 to 3 foot range, though lower across theJersey Shore and higher at the Delaware Beaches. For thesereasons, will go with a LOW risk for the development ofdangerous rip currents for the Jersey shore and MODERATE for theDelaware beaches.Thursday...Winds turn more back a little more northeasterly andincrease to 15 to 20 mph. Breaking waves should also increase afoot or so and will be generally in the 2 to 3 foot range. Swellperiod will increase to 8 seconds. For these reasons, will gowith a HIGH risk for the development of dangerous rip currentsfor both the Jersey shore and the Delaware beaches.For specific beach forecasts, visit weather.gov/beach/phi&&.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...None.NJ...None.DE...None.MD...None.MARINE...Small Craft Advisory until 1 AM EDT Wednesday for ANZ454-455.
-- End Changed Discussion --&&$$SYNOPSIS...HoeflichNEAR TERM...DeSilva/StaarmannSHORT TERM...Hoeflich/StaarmannLONG TERM...Hoeflich/StaarmannAVIATION...DeSilva/Hoeflich/StaarmannMARINE...DeSilva/Hoeflich/MJL/RCM/Staarmann