Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 251554 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1154 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 /THROUGH TONIGHT/...
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930 AM ESTF: adjusted dewpoints higher through this evening based on current trends and some model guidance. temps adjusted for a slightly faster rise this morning. otherwise, no changes from 840 am. TEWR tdwr is showing the bands of sewd moving sprinkles into our area except flurries highest terrain near High Point - Vernon with High Point 36F at 9 am and a report of flurries). 840 AM ESTF update: fcst sct light pcpn nw zones this morning and increased pop 10 pct for more extensive wording and delayed drying of pcpn til 17z (early afternoon). no change in the max temps from our 330 am fcst. increased gusts 2-4 kts through this evening per 06z/25 gfs/nam transfer. Should be or become a mostly cloudy breezy day. The continued northwesterly flow and cold air advection will result in highs 5 to 10 degrees lower than what we saw yesterday (about 4-5F below normal). 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... Tonight...12z GFS is steadfast on its 2m temp and tsection rh fcst. PWAT of .25" is even further south than yesterday. So cold it is. 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.
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&& .SHORT TERM /WEDNESDAY/... 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. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... 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 /16Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...VFR cigs aoa 5000 ft. nw wind with gusts increasing to between 22 kt and 28 kt this aftn with steepening low level lapse rates during midday. Tonight...becoming VFR clear by 03z/26. NW winds may still be gusting around 20 kt through 03z/26 vcnty KPHL/KACY but will gradually decouple and decrease toward 09z/26. Wednesday...VFR bands of variably thick cirrus aoa 20000 ft. Northwest wind becoming north late in the day. Outlook... 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. marine headlines anticipated. Outlook... SCA likely Thursday into Friday, otherwise sub-SCA. && .FIRE WEATHER... 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. && .CLIMATE...
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Our forecast indicates October should average 2 to 3.5 degrees above normal for PHL and ABE. Forecasts are trending warmer beyond Thursday. This should result in average temperatures ranking between 15 and 20th warmest Octobers on record. This is only noteworthy in that the excessive monthly warmth of July, August, September eased in October. Will reevaluate late this afternoon.
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&& .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...Drag/Johnson 1153 Short Term...Drag/Johnson Long Term...Franck Aviation...Drag/Franck/Johnson Marine...Drag/Franck/Johnson Fire Weather... Climate...1153 is the U.S. government's official web portal to all federal, state and local government web resources and services.