Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 170714 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 314 AM EDT Tue Sep 17 2019 .SYNOPSIS... A weak cold front will continue to move south across Delmarva this morning. High pressure across southern Canada will then build southward into New England through Thursday and then across the Middle Atlantic Friday. The high will then push offshore this weekend. Low pressure will move through Canada next week and an associated cold front will approach our area next Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A cold front is making very slow progress south through our area overnight. It is south of NJ/PA and should continue to sink south of DE and NE MD through the morning. In the wake of the front, high pressure will build in from the north. This will keep persistent northeasterly flow for our region through the day. Thanks to the post-frontal cold air advection, temperatures today should be about 5 to 10 degrees lower than Monday, with highs mostly in the 70s across the area. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... The surface high will continue to build south Tuesday night, leading to more tranquil conditions overnight. Overnight lows will be mostly in the 50s, with the possible exception of coastal locations (with lows near 60), and the higher terrain of the southern Poconos and NW NJ which could drop into the 40s. Despite the northeasterly flow, the risk for fog looks to be relatively low as we should also see some dry air advection today into tonight. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Rather uneventful weather during the extended period since high pressure will be across the area much of the time. We have a dry forecast for Wednesday through Sunday and then slight chc or low chc pops for next Monday when a cold front will approach. Temperatures during this period will be below normal Wed/Thu, then close to normal Fri. After that, readings will climb above normal (by almost 10 degrees Sun and Mon). The upper high pressure across the SE will promote the high temperatures while keeping most disturbances away from our area. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...Some MVFR ceilings are possible through about 12Z. Once those clouds dissipate however, there is high confidence that VFR conditions will continue through the day with decreasing mid level clouds through the day. Winds should stay northeasterly 5 to 15 kt through the day. However, in the late afternoon to early evening, winds could veer to more easterly, but speeds by then should be 10 kt or less. Tonight...VFR conditions continue overnight. Winds are expected to be easterly and northeasterly with speeds below 10 kt. OUTLOOK... Wednesday-Saturday...Generally VFR conditions with light winds. && .MARINE... For the Delaware Bay: winds and seas are expected to stay below Small Craft Advisory criteria today and tonight. For the Atlantic coastal waters: seas will continue to build through the morning. Seas above 5 feet are expected for the coastal waters adjacent to Delaware and the Delaware Bay by mid day. SCA starts mid day and continues through at least tonight (but will likely need to be extended later). For the rest of the Atlantic coastal waters, expect the seas to stay just below the 5 ft criteria into tonight. So have held off on an SCA for these areas for now, but will continue to watch closely. Outlook... Wed/Wed night...SCA probable with a NE fetch ahead of the building high. Not sure yet whether winds and seas will climb fast enough yet to justify extending the Tue/Tue night SCA into Wed yet. Seas will climb also with swells assd with Humberto. Fair weather. Thu thru Sat night...Humberto swells will likely force a long term SCA flag for the ocean. Sub-SCA for Delaware Bay. Fair weather. Rip Currents... A moderate risk of rip currents is anticipated through this evening as northeasterly winds increase to 15-20 kts and seas build to 4-5ft. An elevated risk of rip currents (e.g. either moderate or high) will likely persist through much of the week. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 11 AM this morning to 6 AM EDT Wednesday for ANZ454-455. && $$ Synopsis...O`Hara Near Term...Johnson Short Term...Johnson Long Term...Johnson/O`Hara Aviation...Johnson/O`Hara Marine...Johnson/O`Hara

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