Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 231414 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 1014 AM EDT Sat Sep 23 2017 .SYNOPSIS... The remnant low of Jose, currently southeast of Nantucket Island, will continue to weaken and drift offshore through the weekend. Meanwhile, high pressure remains entrenched over the Northeast before moving offshore by the middle of the week. Hurricane Maria will track northward over the Atlantic waters, approaching the Mid-Atlantic coast on Wednesday, then curving out to sea on Thursday as a cold front passes through the region. High pressure builds east to close out the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... No changes needed to the ongoing fcst. The impressively resilient Jose will continue its slow decay southeast of Cape Cod today as a 590+ dam 500-mb ridge continues to build in the Great Lakes region. Meanwhile, Hurricane Maria will continue to be drawn northward toward the weakness in the ridge provided by Jose. More on Maria in the long-term discussion. In the near term, the midlevel ridging will be our region`s dominant player, as Jose will remain well away from the coast. Subsidence downstream of the ridge will generate a nearly cloud-free sky by afternoon, and a northerly to northwesterly surface flow will provide sufficient mixing and downsloping (combined with a notable lack of cold-air advection) to warm temperatures a few degrees more from those seen Friday. The near-surface drying will prevent apparent temperatures/heat indices from separating much from ambient temperatures, which are forecast to reach the 80s across the area (mid to potentially upper 80s in the urban corridor; around 80 in the southern Poconos and along the immediate coast). The surface pressure gradient will diminish somewhat today as Jose drifts a bit more offshore. As such, there is a good chance for the sea breeze to move inland a bit this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... As Jose drifts a bit more offshore tonight, the surface ridge to our west will edge eastward into our region. This will allow winds to relax after dark. Meanwhile, surface dew points will be a few degrees higher than the previous night (perhaps aided to some degree by progression of a vort max across eastern Canada, with subtle moist-air advection occurring southeastward around the Great Lakes/Appalachians ridge). As temperatures nocturnally decline, surface decoupling should allow a bit more patchy fog to develop than that seen Friday night. Have included mention in the grids for the particularly susceptible valley locations northwest of the Fall Line and in the Pine Barrens of New Jersey. Temperatures should be a few degrees warmer than those observed Friday night as well, generally around 60 in the southern Poconos to around 70 in the Philadelphia metropolitan area -- well above average for this time of year. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Surface high pressure will be firmly entrenched over the region on Sunday before lifting to the north and east on Monday. Sunny skies with very warm temperatures will be in place with highs topping off in the upper 80s to low 90s on Sunday, and then slightly cooler on Monday as a northeast flow takes place. This will usher slightly cooler temperatures across the region, especially for right along the coast, where highs will be in the upper 70s to around 80. During this time, Hurricane Maria will lift to the north over the western Atlantic waters. Latest model runs, and the ensembles reflect this as well, show Maria taking a bit more of a western track, possibly approaching the east coast of North Carolina Tuesday into Wednesday. Outer rain bands associated with Maria will lift to the north, and spreading from east to west into the region during this time. Please see the forecast discussion from the National Hurricane Center for the latest information on the track and forecast. A cold front moves across the region Wednesday, followed by another cold front on Thursday. High pressure returns on Friday. During this time, showers and possible thunderstorms will develop with the passage of each cold front. Temperatures drop off to the upper 70s to low 80s Wednesday and Thursday, and then much cooler weather returns for Friday with highs in the low 70s. The week starts off with temperatures well above normal, then closes with temperatures below normal. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. VFR through tonight. Light/variable winds will become northerly around or below 10 kts during the day. Very few clouds are expected by late morning. Patchy fog may occur in more susceptible valley locations tonight (i.e., KRDG, KABE, and KMIV), but confidence is too low and occurrence too transient for mention in the TAFs at this time. Outlook... Sunday through Monday...VFR conditions with NE winds less than 10 KT. Tuesday through Wednesday...Mainly VFR conditions expected, but there may be some showers each day. NE winds as high as 10-15 KT. && .MARINE... Small craft advisory for hazardous seas remains in effect for the Atlantic coastal waters, though conditions may become marginal (i.e., seas may subside slightly below 5 feet for a time), especially for the northern/central New Jersey coastal marine zones, this afternoon and tonight. Winds should remain below advisory criteria through tonight, though northerly breezes may gust 15-20 kts during the day. Winds may become more variable late this afternoon into this evening before re- establishing a primarily northerly direction tonight. Long- period easterly swells should continue through tonight, with components both from Maria (southeast) and the remains of Jose (northeast) potentially generating some undesirably choppy conditions today/tonight. Outlook... Sunday through Wednesday...Elevated seas due to swells associated Hurricane Maria will impact the waters during this time. Seas 4-6 feet Sunday will gradually build to 8-12 feet Tuesday and Wednesday. NE winds will range from 10-15 KT, increasing to 15-20 KT with gusts up to 25 KT for the ocean waters Tuesday-Wednesday. RIP CURRENTS... Swells from the remains of Jose will continue today (generally 4 to 6 feet from the northeast with a period of 9-10 seconds), but with time, swells from Maria will become a bigger player (generally 2-3 feet from the southeast with a period of 13-16 seconds). For today, this could create rather chaotic surf. Though swell heights will likely be lower than seen recently, the combined effects of Jose and Maria will maintain at least a moderate risk of dangerous rip currents today. If entering the surf zone, be especially cautious today. Only swim in the presence of lifeguards/beach patrols, and heed the advice of local officials. Outlook... A prolonged period of moderate to high risk for the development of dangerous and life threatening rip currents is on tap for most of the upcoming week due to swells emanating from Hurricane Maria. && .TIDES/COASTAL FLOODING... Spotty minor flooding may occur with this morning`s high tide thanks to the continued influence from Jose, but any flooding is not expected to be widespread enough or severe enough for issuance of an advisory. Forecasts for this evening`s high tide are even lower. && .CLIMATE... With high temperatures making a run at 90 Sunday and Monday across the region, some record high temperatures may be tied or broken. The highest chances are on Monday where all locations but Georgetown are expected to be within three degrees of a record. Here are the records for both days. Sunday ACY-92(2010) PHL 95(1970) ILG-92(2010) ABE-92(1970) TTN-92(1970) GED-97(2010) RDG-95(1970) MPO-85(2010) Monday ACY-91(1970) PHL-92(1970) ILG-93(1970) ABE-92(1970) TTN-92(1970) GED-92(2010 and 1970) RDG-92(1970) MPO-85(1970) && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory for hazardous seas until 6 AM EDT Sunday for ANZ450>455. && $$ Synopsis...MPS Near Term...CMS Short Term...CMS Long Term...MPS Aviation...CMS/MPS Marine...CMS/MPS Tides/Coastal Flooding... Climate...

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