Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 260017 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 817 PM EDT Mon Sep 25 2017 .SYNOPSIS... High pressure across our region will gradually lift northeast as it weakens through midweek. Hurricane Maria will remain offshore the outer banks of North Carolina through Wednesday, then finally move out to sea, in advance of a cold front moving through our area on Thursday. Another fast moving cold front treks through our region on Friday, followed by a large dome of high pressure settling over our area early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Another sunny day across the region with high pressure continuing to influence the weather. High temperature are near daily records with readings presently in the upper 80s inland and low 70s to low 80s along the shore. There might be just enough of an onshore flow to keep the records from being reached however. An area of low clouds and light fog has been moving Wward offshore the cntrl an srn NJ and DE shore areas so far this afternoon. The clouds are `melting` as they arrive over the well heated lands areas. These clouds should resume the W motion as we approach dusk. Winds will remain light from the E/SE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... There will be more clouds and patchy fog across the area Tuesday morning. The greater concentration will be S/E if I-95 corridor, but areas N/W of that will still have some fog and low clouds. Guidance is showing a rather stubborn area of low level moisture remaining across most areas thru the day. It is therefore difficult to get too optimistic with regards to how much sun will be over the area Tue. Mostly cloudy skies S/E and partly sunny N/W will probably describe the situation best. High temperatures will be only in the low 80s S/E and mid 80s N/W. Winds will continue to be rather gentle from the SE or E. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... The main forecast challenges will be midweek temperatures, PoPs Wednesday into Thursday, a clipper-type system over the weekend, and some uncertainty with the larger scale features by early next week. Direct impacts from Hurricane Maria are expected to remain offshore. Indirect impacts will continue through at least Thursday, including a high risk for the formation of dangerous rip currents, high surf, and beach erosion. We have increased temperatures a couple of degrees on Wednesday, especially given the low bias exhibited by guidance recently. This is with the expectation that low clouds will burn off early in the day. These temperatures may still be a bit conservative, especially given the low-level temperature profile per model soundings. We have trended a bit drier with the forecast Tuesday night and focused PoPs Wednesday into Wednesday night, which is in better agreement with the ensembles, confining chance PoPs to the coastal plain in the latter time frame. A drying trend is expected to take hold Thursday and continue into Friday, with a PoPless forecast at this time. The only exception may be down the shore on Thursday with the potential for some lingering showers. Temperatures slightly above average (~5 degrees) on Thursday are forecast to trend average to slightly below average into early next week. There is some uncertainty with a clipper-type system over the weekend. Forecast reflects slight chance PoPs across the entire area on Saturday, when ensembles indicate the greatest chance of precip, then trending downward by Sunday, with PoPs confined to the coastal plain. There is quite a bit of uncertainty early next week with regard to the large scale features, with a lack of model run to run consistency. For now, we have not strayed far from the previous forecast, bringing PoPs in again for Tuesday. But low confidence at best. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR conditions will continue at the terminals for the afternoon as high pressure remain across the area. Low level onshore flow will continue and this will result in the arrival of low clouds later tonight and Tuesday. You can see the low clouds/fog just offshore of ACY-WWD on the most recent satellite pics. This moisture is having a difficult time moving inland with the sunshine today, but when it approaches dusk, the clouds should resume a NW motion. We have tried to time the arrival of the IFR conditions according to guidance and climatological trends. There may be some fog developing before the low clouds arrive. The arrival times will be earlier and departure times later into Tue morning for the S/E sites. The timing for improvement Tuesday for all sites is rather low confid attm. Winds thru the period will be light E or SE. Outlook... Tue night and Wed...Low clouds Tue night into Wed morning will likely result in IFR conditions from the I-95 terminals (TTN- PNE-PHL-ILG) and points southeast, with greatest confidence in IFR at ACY and MIV. Cannot rule out some fog as well, but it looks predominantly like a low cloud issue. Expect improving conditions to VFR at all terminals Wednesday. Northeast winds may gust up to 25 knots at times along the coast. Wednesday night through Friday...Predominantly VFR conditions expected. Winds shifting to the northwest Wed night and cannot rule out MVFR in a passing shower into Thursday. Some patchy fog is possible at the normally more prone locations by Thursday night. Saturday and Sunday...Predominantly VFR conditions expected at this time. && .MARINE... Seas across the nrn NJ waters are closer to 5 ft than further to the south. Nonetheless, we expect the the seas will rise overnight and the SCA for Haz seas will continue. Patchy/ares of low clouds and fog are occurring across the central/southern waters attm and this will continue overnight and Tuesday. Winds will remain mostly under 10 knots from the E or SE. Outlook... SCA conditions likely to persist over the waters with the combination of swells from Hurricane Maria and occasional wind gusts to 25 knots through at least Thursday night. By Friday, winds and seas are expected to begin subsiding, but there is a renewed opportunity for SCA conditions over the weekend with low pressure developing offshore. Rip Currents... A HIGH risk for dangerous rip currents is expected for the rest of today and into Tuesday. The rip current risk remains high as long-period southeasterly swells continue to build thanks to Hurricane Maria. Given the observed rip currents this weekend along much of the NJ/DE surf zone, swimming is not recommended, especially in the absence of lifeguards/beach patrols. The rip current fatality in Long Branch, NJ on 9/23 brings the total number to 8 this year - all in NJ. This office has compiled these statistics since 1998, and this is the greatest number of fatalities in any one year, followed by 2008 with 6 fatalities. Dangerous surf conditions will continue for much of the new week. A HIGH risk for the development of dangerous rip currents is expected from Tuesday through at least Thursday. High surf conditions and beach erosion likely to develop Tuesday and Wednesday. && .CLIMATE... Allentown tied the record high temperature for today of 92 degrees, last set in 1970. Two other sites came within a degree of their record highs: Philadelphia and Mount Pocono. Here are the record highs for September 25: ACY...91(1970) PHL...92(1970) ILG...93(1970) ABE...92(2017 and 1970) TTN...92(1970) GED...92(2010 and 1970) RDG...92(1970) MPO...85(1970) && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...High Rip Current Risk until 6 AM EDT Tuesday for NJZ014- 024>026. DE...High Rip Current Risk until 6 AM EDT Tuesday for DEZ004. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ452>455. Small Craft Advisory for hazardous seas until 6 AM EDT Wednesday for ANZ450-451. && $$ Synopsis...Franck Near Term...O`Hara Short Term...O`Hara Long Term...Franck Aviation...Franck/O`Hara Marine...Franck/O`Hara Climate...

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