Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 190733 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 333 AM EDT Thu Oct 19 2017 .SYNOPSIS... A dry frontal boundary will move toward the area tonight into early Friday. Otherwise, high pressure remains in control of the weather for much of the rest of the week into the weekend. A frontal boundary is forecast to affect the area early next week, bringing a return of unsettled weather. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Broad high pressure lies from the Southeast U.S. across the Mid- Atlantic region and then into the western Atlantic. The high will sink southward today as an upper trough and several mid-level shortwaves pass through the region. After some patchy early morning fog, conditions will clear out late this morning and through today. Some cirrus is possible with the passage of the trough, but conditions will otherwise be dry and sunny. Meanwhile, a weak cold front currently over the Great Lakes will continue to track east throughout the day. WAA will be underway today with rising heights/thicknesses, and highs today should end up a degree or so warmer than Wednesday, with highs in the low to mid 70s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... Weak surface cold front passes through the region tonight. With a lack of moisture and no upper level support, conditions will be dry with its passage. Outside of some evening cirrus, skies should clear out after midnight. Surface high pressure reestablishes itself over the Appalachians after midnight. Some patchy ground fog is possible prior to the passage of the cold front. Dew points will fall behind the passage of the front. Lows tonight will be in the upper 40s to around 50. Lows in the Philly metro area will be in the low 50s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Quiet weather is expected for the end of this week into the weekend as high pressure will be in control of the weather through the end of the week before moving offshore for Sunday and Monday. Ridging aloft builds across the area late this week into the weekend, which will help keep temperatures several degrees above normal. As the surface high and ridge aloft moves offshore Sunday, return flow and southwest flow aloft develops. This will help increase clouds, but no precipitation is expected through Sunday. As we go into Sunday, an area of low pressure is forecast to develop near the Lower Mississippi Valley along a frontal boundary located across the central part of the country. It is then expected to strengthen as it moves northward along the frontal boundary and toward the Great Lakes Monday night into Tuesday. The front is expected to move toward our area Tuesday into Tuesday night, although there is some timing differences between the GFS and ECMWF. The GFS pushes the front through quicker, moving the precip through Tuesday into Tuesday night. The ECMWF slowly moves the front through slower, keeping precip across the area Tuesday night through Wednesday night. For now, we have the greatest chances for precipitation Tuesday and Tuesday night. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Some patchy ground fog with MVFR VSBY is possible from 09-12Z at KABE/KMIV/KACY. Otherwise, VFR through the TAF period. Patchy ground fog with brief MVFR VSBY is possible once again from around 02-10Z Friday. SW winds less than 10 KT, becoming less than 5 KT tonight. OUTLOOK... Friday-Monday...VFR conditions expected. Winds may gust around 15 knots Friday, Sunday, and Monday. && .MARINE... SW winds 5-10 KT, increasing to 10-15 KT with gusts to 20 KT this afternoon on the Atlantic coastal waters. Winds shift to the NW tonight after the passage of a cold front. Seas will generally be around 3 ft on the coastal waters and 2 ft or less in the Delaware Bay...mostly a se swell of 9 or 10 seconds. OUTLOOK... Friday-Monday...Conditions expected to remain below Small Craft Advisory levels through the period. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...MPS Short Term...MPS Long Term...Robertson Aviation...Robertson/MPS Marine...Robertson/MPS is the U.S. government's official web portal to all federal, state and local government web resources and services.