Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 251831 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 231 PM EDT Tue Oct 25 2016 .SYNOPSIS... High pressure near James Bay Canada will nose down into region Wednesday. 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 early Friday morning. Weak high pressure quickly follows Friday night before low pressure and its associated frontal systems cross the mid Atlantic states this weekend. High pressure will become dominant over our area by next Monday. && .NEAR TERM /THROUGH TONIGHT/... Remainder of this afternoon...Clouds clear late in the day but gusty northwest winds to 20 and 25 mph continue. The sprinkles (first flurries of the season were reported at Lake Harmony and High Point- Wantage this morning). Tonight...Frost Freeze continues as previously advertised. Will repost the NPW around 3PM with only cosmetic changes. 12z GFS and GGEM are steadfast regarding their 2m temp and tsection rh fcst overnight. frost-freeze. 09z/25 SREF PWAT of .25" is even further south than yesterdays modeled guidance for 12z/26. It may take a while for decoupling due to the constant caa but shortly after 05z, am expecting a notably drop in wind and the radiating countryside should soon be done with the growing season, even if the urban centers remain just above freezing. Philly metro and surrounding PA suburbs, Cape May County, and much of Delmarva, have a frost advisory for less risk of damaging near 32F for an hour or two near the approximate 725 am sunrise. The NJ shore and DE beaches, where winds may stay up through much of the night due to heat sink water temperatures in the upper 50s, looking to keep the wind actively drawing cooler land airmass toward the water should prevent frost or a freeze. The growing season has already ended in the poconos and far northwest NJ. Forecast basis: 50 50 blended 12z/25 GFS/NAM MOS then lowered 1 degree in parts of northwest NJ and and eastern PA. These low temps should average 5 to 7 degrees below normal, which means far from a record and its seasonally about the time the growing season ends in a larger section of PA and NJ. Forecasters during the day tomorrow will post a note in this AFD, also via a PNS, about what counties met the requirement of 50 coverage of below freezing temps to end the season. && .SHORT TERM /WEDNESDAY/... Variably thin bands of cirrus will allow plenty of sunshine, however much less wind will also limit mixing potential. Max temps a few degrees cooler than they were this Tuesday afternoon and again about 5 to 7 degrees below normal. Quite a nice fall day. This part of the forecast was based on a 50 50 blend of the 12z/25 GFS/NAM Mos, modified slightly warmer by the 2m temps of the 12z EC. For PHL thats 51F, so that should mean a high of 55 in PHL. && .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 /18Z TUESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of this afternoon...VFR sct-bkn aoa 5000 ft. Northwest wind with gusts 22 to 28 kt, diminishing late with cloud cover thinning and dissipating to scattered cloud or skc by 22z. Tonight...VFR clear. Northwest winds may still be gusting around 20 kt through 04z/26 vcnty KPHL/KACY but will gradually decouple and decrease toward 09z/26. Wednesday...VFR bands of variably thin 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... SCA headline on the Atlantic waters may be extended 2 hours. 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. && .CLIMATE... 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 around 4PM. && .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...Drag/Franck 230 Near Term...Drag/Johnson 230 Short Term...Drag/Johnson 230 Long Term...Franck Aviation...Drag/Franck/Johnson 230 Marine...Drag/Franck/Johnson 230 Climate...230 is the U.S. government's official web portal to all federal, state and local government web resources and services.