Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 251011 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 611 AM EDT Tue Oct 25 2016 .SYNOPSIS... High pressure near Hudson Bay Canada will build closer to our region through mid week. A warm front on Thursday will be followed by a cold front Thursday night as low pressure redevelops from near Lake Erie Thursday to Long Island Friday morning. Weak high pressure quickly follows Friday night before low pressure and its associated frontal systems cross the mid Atlantic states Saturday. High pressure will become dominant over our area by next Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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The northwest flow pattern has resulted in a narrow band of light precip (mostly sprinkles) that has stayed just to our northwest through the overnight hours. High resolution models continue to depict that this band could move into the far NW corner of our region, so continued the mention of sprinkles and flurries through the mid morning. Otherwise, only mid level clouds are expected across the region today. the clouds moved in a bit earlier than previously anticipated, so adjusted sky grids to match current satellite trends. The continued northwesterly flow and cold air advection will result in highs 5 to 10 degrees lower than what we saw yesterday. The northwesterly flow will also result in dry air advection/decreasing dew points through the day, which will set the stage for what is to come tonight...
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... Surface high will move closer to the region overnight. This will result in two things. First, skies are expected to clear quickly through the evening hours, leading to clear skies overnight. Secondly the decreasing pressure gradient will help winds decouple quickly after sunset. In addition, the previously mentioned dry air advection will mean that by this evening dew points will already be in the mid 20s to lower 30s. All of this sets the stage for prime radiational cooling conditions across the region. As such, expect widespread frost and freeze across the region. The freeze watch was converted to a warning, and includes all of the region with the following exceptions: the Philly metro and surrounding PA suburbs, Cape May County, and much of Delmarva, which have a frost advisory; the NJ shore and DE beaches, where winds may stay up through the evening hours enough to prevent frost formation; and the southern Poconos and NW NJ where the growing season has already ended. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Wednesday...Temps will rebound nicely from what is forecast to be one of the coldest mornings thus far this fall, but still around 10 degrees below normal for highs. Some high and even mid-level clouds later in the day in advance of an approaching warm front. Wednesday night and Thursday...Still model disagreement at this time with regard to precip amounts, thermal profile, and precip type across northern NJ and the Poconos. The NAM continues its trend of keeping the bulk of the precip northwest of the CWA, while the GFS and ECMWF are in good agreement, indicating a band of overrunning precip, focused north of the I-78 corridor. We adjusted the precip starting time later, just after midnight on Thursday morning. The column is below freezing to start, and with the addition of wet bulb cooling, this will initially favor light snow. Model soundings indicate the lack of a warm nose aloft, so a gradual changeover to rain and even some spotty freezing rain is likely by Thursday morning, although cannot rule out a period of sleet. Any accumulation of snow and slippery travel will be more confined to Sussex and Monroe counties, generally less than one inch at this time. Otherwise, locally heavy rain showers for the remainder of the area, with southerly winds gusty at times. Thursday night and Friday...Precipitation ending from west to east Thursday night with a blustery northwest flow to follow. Friday will feature fair weather. Saturday through Monday...Still considerable uncertainty, with model timing differences, taking low pressure across the area this weekend. Fair weather will return by Monday. Temperatures are expected to rebound closer to normal during this time frame. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions are expected through the TAF period. Scattered to Broken mid level clouds (between 4000 and 6000 ft AGL) are possible through 21Z, but then few, if any clouds are expected overnight. Northwesterly winds will be breezy during the day today, with gusts above 20kt possible, but winds should drop off quickly by 00Z and remain light through the rest of the TAF period. Outlook... Wednesday...VFR. Wednesday night and Thursday...MVFR at times with a gusty south wind on Thursday. Friday and Saturday...VFR. Gusty northwest winds at times. && .MARINE... Winds will continue to gust near or just above 25 kt on all the waters through the afternoon. On the ocean waters, SCA conditions, primarily for winds could linger into late this evening, and even after midnight we could continue to see winds gusting above 20 kt. Outlook... SCA likely Thursday into Friday, otherwise sub-SCA. && .FIRE WEATHER...
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Minimum relative humidity values could be near or below 35 percent for portions of the region today and frequent northwesterly wind gusts above 20 mph are expected from late morning through late afternoon. However, at this time we are not expecting red flag criteria to be met at this time.
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&& .CLIMATE... Our forecast indicates October should average at least 2 to 3 degrees above normal for PHL and ABE. Some of the recent forecasts have been colder and that may mean PHL and ABE slip to around 20th warmest October on record, which is only noteworthy in that the excessive monthly warmth of July, August, September eased in October. Will reevaluate this afternoon and Tuesday. The colder scenario than a week ago still has doubt and so we`ll try to be more definitive late Tuesday regarding around 15th or around 20th warmest October. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Freeze Warning from midnight tonight to 9 AM EDT Wednesday for PAZ060>062-101>103-105. Frost Advisory from midnight tonight to 9 AM EDT Wednesday for PAZ070-071-104-106. NJ...Freeze Warning from midnight tonight to 9 AM EDT Wednesday for NJZ008>010-012-013-016>022-027. Frost Advisory from midnight tonight to 9 AM EDT Wednesday for NJZ015-023. DE...Freeze Warning from midnight tonight to 9 AM EDT Wednesday for DEZ001. Frost Advisory from midnight tonight to 9 AM EDT Wednesday for DEZ002-003. MD...Freeze Warning from midnight tonight to 9 AM EDT Wednesday for MDZ008. Frost Advisory from midnight tonight to 9 AM EDT Wednesday for MDZ012-015-019-020. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ450>455. Small Craft Advisory until 6 PM EDT this evening for ANZ430- 431. && $$ Synopsis...Franck Near Term...Johnson Short Term...Johnson Long Term...Franck Aviation...Franck/Johnson Marine...Franck/Johnson Fire Weather... Climate... is the U.S. government's official web portal to all federal, state and local government web resources and services.