Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 082051 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 351 PM EST Thu Dec 8 2016 .SYNOPSIS... An area of low pressure will continue to slowly drift across eastern Canada through Friday, and offshore by Saturday. With high pressure to our west, strong west to northwest flow will remain through Saturday. A warm front is expected to lift across the area Sunday night, before an area of low pressure moves north of the region around Monday. This system will pull a cold front across the area Monday, then another quick moving frontal boundary may move across the area around Tuesday night. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Morning summary: had a smattering-scattering of .01 rainfall this morning southern 2/3rds De and a ptn of Md E shore. Remainder of this afternoon...west wind will continue increasing to 22-28 kt around 21z then should decrease after sunset but PHL may gust 18-20 kt all night. Note: tonights low temp fcst at PHL will be the coldest of the season so far at PHL and remember last winter, it didnt drop into the 20s until January 4th 2016! Tonight...mostly clear with a light west-northwest breeze except PHL may gust 18-20 kt all night as well as adjacent all bodies of water as boundary layer temps show increasing land-sst differential and resultant enhanced land breeze effect, near the water. Exception to the mostly clear skies: near the Poconos where lake effect clouds arrive and then flurries should eventually develop there sometime tonight. Fcst was a 50 50 blend of the 12z GFS/NAM mos guidance. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Cold air advection and lake effect streamers of moisture, flurries and snow showers from the Great Lakes combined with the cold trough aloft increase the snow squall probabilities tomorrow and so at least sct flurries to near I-95 (not expecting flurries or sprinkles along the coast) and suspect small accumulation in parts of Poconos Friday afternoon. A snow map will post shortly followed by snow probs around 5PM for this first little terrain related accumulation event. Otherwise...mostly sunny skies to start (mo cloudy Poconos) becomes considerable cloudiness everywhere during the afternoon. Breezy with west northwest wind gusts 25 to possibly 30 mph. Forecast basis was a 50 50 blend of the 12z gfs/nam MOS and added a degree to the max T per the 12z/8 EC 2m temps. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Strong nwly flow will continue Fri night into Saturday a large area of high pres builds to the w and a departing low moves away to the e. This will keep things relatively dry but cold and breezy. There could be a passing flurry or snow shower but that should be the extent of any precip. The high then moves over us Sat night and the wind will decrease. We should be in for a cold night, before the high moves ewd. As the high moves away, low pres will take shape over the plains and head toward the Oh vly on Sun and drag a wmfnt thru the region Sun night. Precip will begin acrs the area later Sun into Sun night. There are still some disagreements in the mdls as to the timing and path of the low, which will ultimately impact what type of precip falls and where. However, it does appear that the bulk of the precip will fall Sunday night into early Monday. Temps will be cold enough Sunday night n and w for pretty much all snow and a plowable event which would impact the Monday mrng commute. Further s, there may be some low accumulations before a changeover to rain on Monday. Acrs srn and ern areas, we shud expect mainly rain. The cdfnt assocd with the low will move thru on Mon and end the precip. Then, dry wx is expected for later Mon into Tue. Then, twd the end of the pd, there is the potential for another mixed precip event. The GFS is faster bringing this sys in as early as erly Wed, while the GFS holds off until later Wed. Again, temps will be warm enough s and e for mainly rain, while n and w it would likely be wintry precip. Again, the timing and track of the sys will determine ultimately who gets what and it is a week away but clearly we are entering a more active wx patn. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Remainder of this afternoon...VFR sct clouds aoa 4000 ft. West wind with gusts increasing 22 to 28 kt by 21z. Already 25 kt PHL. Tonight...VFR mostly clear. wnw wind with scattered gusts 15-20 kt, mainly PHL area. Friday...Generally VFR sct-bkn aoa 4000 ft, although CIGS may briefly lower to MVFR in scattered snow showers e PA higher terrain. An afternoon flurry or sprinkle is possible southeastward to ILG- PHL-TTN. Gusty west to northwest winds 22-30 knots. OUTLOOK... Fri night - Sat...Generally VFR, although cigs may occasionally lower to MVFR. Scattered showers or flurries/sprinkles are possible during the daytime of each day which may temporarily lower conditions. Gusty w to nw wind 15-25 kts. High confidence. Sun...VFR early, possibly lowering to MVFR by the afternoon. Rain or snow psbl late in the day. Moderate confidence. Sun night-Mon...Conds lower to MVFR then IFR. RA and SN becoming likely, best chc for SN n. Most of DE and MD will stay all rain. Any SN over srn NJ and sern PA will change to RA durg Mon. Accumulating snow over nrn and wrn areas. Mdt confidence. && .MARINE... Gale warning posted for lower De Bay and adjacent DE, Cape May waters. A gale watch is posted for Fri-Fri eve per collab with OKX. Many reports 29kt upstream mid afternoon. The wind orientation down De Bay, steep lapse rates possibly manufactures several more kts of wind than modeled in the caa pattern. NAM sounding indicates mid 30s gales possible. For Friday...the winds should ease 3 kts or so on DE bay but some of the guidance is suggesting increasing wind NJ coast, especially NNJ later in the day. Therefore the gale watch. OUTLOOK... Fri night-Sat...Gale watch much of NJ coast early Fri night. SCA in effect upper De Bay through Friday night, which may need to be extended into Saturday. Atlc De and Cape May Atlc waters will probably be SCA Fri night. Saturday night...Winds expected to drop below SCA levels, but pick up again late Sunday. Sunday-Sunday night...Winds may increase and approach SCA levels. Monday...SCA conds psbl. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Gale Watch from Friday morning through late Friday night for ANZ450>452. Small Craft Advisory until 6 AM EST Friday for ANZ450>452. Gale Warning until 6 AM EST Friday for ANZ453>455. Small Craft Advisory until 6 AM EST Saturday for ANZ430. Gale Warning until 6 AM EST Friday for ANZ431. && $$ Synopsis...Nierenberg Near Term...Drag Short Term...Drag Long Term...Nierenberg Aviation...Drag/Nierenberg Marine...Drag/Nierenberg 351P is the U.S. government's official web portal to all federal, state and local government web resources and services.