Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 221019 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 619 AM EDT Sat Oct 22 2016 .SYNOPSIS... A low will lift northeast through the day today, bringing windy and cooler weather to our region on the back side of the low. Another cold front arrives Sunday night, then high pressure gradually builds in through mid week. A warm front is expected to lift north over our area at the end of the work week. && .NEAR TERM /THROUGH TONIGHT/...
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Everyone will notice a big change today. A strong cold front passed through our area overnight and sfc low pres was movg by to the east. An upr low to the w will rotate thru this AM. As a result there will be some showers, mainly in the morning, with precip chcs decreasing thru the day from s to n. As the sfc low moves into New Eng, it will intensify and the pgrad between it and high pres to the sw will keep a gusty nw wind over the area thru the day today. The combination of the cooler temps (Highs only in the 50s) and wind gusting into the 30s will make it feel much cooler. With temps in the 80s just a few days ago, it will seem like its THAT much colder. Based on the latest radar imagery, have adjusted pops over the s (downward) and the north (upward). It appears that there is a back edge to the precip acrs the Delmarva that will slowly work its way nwd. The HRRR and the majority of the mdl guid has a good portion of the srn area precip free by 12Z and then working its way nwd durg the day. Current fcst is on track with that, though the ultimate timing may need to be tweaked.
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&& .SHORT TERM /SUNDAY/... Any lingering precip acrs nrn sections shud come to an end erly tonight, then clouds will decrease as the upr flow becomes more zonal, the sfc low moves away and high pres builds slowly in from the s. The wind will slowly begin to subside but will remain gusty. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Sunday...low will continue to lift NE away from the region. As it does so, we should see the pressure gradient across the region slowly decrease. However, low and mid level height gradients will remain quite large through the day time hours, so depending on how deep the mixing is, we could continue to see windy conditions, though still not as windy as what we are expecting today. Sunday night...A secondary surface cold front slides through the region late (after midnight). As mentioned by the previous shift, a tight band of frontogenetic forcing along and just ahead of this front could lead to some showers. However, limited synoptic scale lift means that coverage should be quite limited across our region. Monday and Tuesday...A robust northwest flow pattern sets up to start the work week, resulting in continued cold air advection. In fact, a few models even depict small QPF values across the NW portions of the area in what looks like a lake effect pattern. However, given that this is still a climatologically unlikely time to see any lake effect precip, have kept the forecast dry. Wednesday and Thursday...though the high associated with the polar air mass builds closer to the region through this time, we should actually see temperatures moderate a bit thanks to low level flow shifting from northwesterly to westerly and possibly southwesterly. Having said that, latest model runs backed off on southerly return flow developing, so think that through the day on Thursday we will continue to see slightly below normal temperatures. Friday and Saturday...there are big differences both between models and run to run with how to handle the next upper level low at the end of the week. The GFS depicts the upper level low digging into the deep South with essentially no reflection of a low in the surface pattern. The ECMWF on on the other hand, shows a well defined extra tropical cyclone sliding across the Great Lakes region resulting in first a warm front lifting over our region and then a cold front sweeping through at the very end of the forecast period. Given the uncertainty, have stayed close to the previous forecast for now. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. TAFS have been more VFR as rain has been steady but not heavy enough to cause widespread MVFR. There have been some pockets of MVFR and that is expected to continue through the mrng as the SHRA move thru. Then, later this mrng all sites will become VFR as the rain moves out from s to n and high pres begins to move in. VFR will then prevail for the remainder of the TAF pd. A gusty NW wind is expected for the balance of the day with speeds in the 25 to 30 kt range and psbly higher. The gusts will subside later tonight but speeds will remain in the 10 to 15 kt range. Outlook... Sunday...VFR conditions expected. Breezy westerly winds continue. Sunday night...Mostly VFR conditions expected but there is a small chance of MVFR with showers after midnight primarily for TAF sites north of KPHL. Monday through Wednesday...Mostly VFR conditions expected.
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&& .MARINE... The Gale Warning for the coastal waters and Delaware Bay will remain in effect unchanged. By late tonight, it is expected that the GLW will come down on the Bay but that can be reassess on later shifts. Outlook... Sunday...winds will diminish slightly on Sunday, and should drop below gale conditions by late afternoon on the coastal waters. However, SCA conditions will continue into Sunday night. Monday and Tuesday...SCA conditions are expected to continue as winds should continue gusting above 25 kt (though seas may drop off below 5 ft. Wednesday...winds are expected to subside below SCA criteria early in the day. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Gale Warning until noon EDT Sunday for ANZ452>455. Gale Warning until 6 PM EDT Sunday for ANZ450-451. Gale Warning until 2 AM EDT Sunday for ANZ430-431. && $$ Synopsis...Gorse/Johnson Near Term...Nierenberg Short Term...Nierenberg Long Term...Johnson Aviation...Johnson/Nierenberg Marine...Johnson/Nierenberg is the U.S. government's official web portal to all federal, state and local government web resources and services.