Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 131750 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ Issued by National Weather Service Baltimore MD/Washington DC 1250 PM EST Tue Nov 13 2018 .SYNOPSIS... Low pressure is moving into New England this afternoon. High pressure will gradually build in from the west through Wednesday night, before moving across to the north of our area on Thursday. An area of low pressure will develop off of the southeast coast late Wednesday, then track up through the Mid Atlantic Thursday into Friday. High pressure will then return later Friday through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Latest analysis puts low pressure near Long Island at present. The center of the low should reach Cape Cod during the early afternoon. The feature is forecast to be in the Gulf of Maine around sunset. Rain and drizzle has ended, though lingering back end energy could still bring a couple stray showers through the rest of the day. As the low moves across the coastal waters of New England this afternoon, the circulation around the system will cause the wind in our region to become northwesterly. Dry air is slowly but surely building into eastern Pennsylvania, New Jersey and the upper Delmarva, and it will continue doing so through the afternoon. The cloud cover may begin to break a bit toward dusk. Temperatures rose into the lower 60s this morning in southern Delaware and New Jersey. Readings have dropped back into the 50s in those areas now that the low has passed. Otherwise, high temperatures are anticipated to range from the 40s in northwestern New Jersey, the Poconos, the Lehigh Valley and Berks County, to the 50s in the rest of our forecast area. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/... The axis of a mid level trough should pass overhead late tonight. Surface high pressure is forecast to nose into our region from the west. However, high clouds may linger overhead. Also, a deck of stratocumulus to our northwest may affect parts of eastern Pennsylvania and northern New Jersey. The stratocumulus is expected to be trapped under a temperature inversion. The wind should remain out of the northwest around 10 MPH. Low temperatures are anticipated to be mainly in the upper 20s and lower 30s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Wednesday...High pressure will move from the midwest states on Wednesday up into Wednesday night. Overall, we should see quiet weather across the area as the north to northwest flow brings dry air to the region. With skies remaining clear, we should another cold night across the forecast area. Thursday through Friday...The main event of the extended is slated for Thursday into Friday. High pressure slides across to the north of the area on Thursday as low pressure starts to organize itself off the South Carolina coast. The system looks to start off as a double barreled low with the second low located inland across the southeast. As the coastal low starts to deepen, it becomes the more dominant surface low. This low will track up the Mid-Atlantic coast Thursday, passing off the New Jersey coast Friday morning before heading off and reaching the Canadian Maritimes later Friday. Above the surface, a strong, closed off low in the mid levels will move up through the Ohio Valley before starting to open up a bit and then moves across our area late Thursday into Friday. This system looks to have plenty of moisture available with it. The real variable will be just how much cold air remains across the region as the low tracks northward and where the rain/snow/ice line may set up. There is an indication that a TROWAL may be present so expect some areas to see some sleet or freezing rain through the event. Have added a mention of sleet and freezing rain to the forecast in areas north and west of I-78 based on the current forecasted temperatures. Precipitation will start to move into the area on Thursday and then continue through the overnight and into Friday morning. Some lingering showers on Friday through the afternoon are possible. Temperatures at the onset of the event will vary across the region with sub freezing temps expected north and west of the I-95 corridor and temps in the mid 30s to lower 40s south and east of I-95. As the precipitation moves northward on Friday, there won`t be too much of an opportunity for much warming to occur at the surface so some mixed precipitation may be possible even across our southern areas. However, the more likely locations for any type of mixed precip (rain/snow/sleet/freezing rain) will be across the northern areas, generally north of the I-78 corridor. As the low tracks northward, it will bring some warmer air into the lower levels and temperatures are likely to rise Thursday night, at least up through the I-95 corridor, which will help to keep the precip rain. Lots of variables in play with this event and it will really depend on the track and timing. As is usually the case with coastal lows, a shift in the track (east/west) or timing (faster/slower) will have an impact on ptype. One thing that looks pretty consistent though is that we will see some decent precipitation fall across the region (~1-2 inches of liquid), but whether it is dominantly rain (more likely across the south) or snow (more likely across the north and higher elevations) still needs to be worked out. As we get closer, it seems likely that some sort of advisory will be needed in parts of our forecast area. Friday night through Monday...High pressure will start to nose up into the region late Friday and last through the weekend. A weak cold front may approach from the west on Saturday but seems to have limited moisture associated with it, Current guidance shows the front dissipating before it reaches our area but we might some flurries or light snow showers as it near the area. Sunday and Monday look to be fairly nice days as high pressure moves across the region. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Today...Conditions should gradually improve to VFR through 20Z. Mainly VFR from 20Z through 23Z. Northwest wind 8 to 12 knots gusting around 18 to 22 knots. While the improving trend is a high confidence forecast, the exact timing of the improvement is not. Tonight...VFR. Northwest wind 8 to 12 knots gusting around 18 to 22 knots. Outlook... Wednesday...Mainly VFR conditions expected. Northwest winds around 10 to 15 knots with gusts around 20 to 25 knots. High confidence. Thursday through Friday...Mainly VFR conditions expected early with deteriorating conditions through the day. Precipitation will overspread the terminals from south to north with MVFR or lower conditions expected. Mostly rain expected with mixed precipitation possible, especially at KRDG and KABE. Precip will continue through Thursday night, gradually ending from south to north Friday afternoon. Northeast winds around 10 to 20 knots (strongest towards KACY) with gusts of 25 to 30 knots possible through Thursday night becoming northwest around 10 knots with gusts up to 20 knots possible on Friday. Wind shear likely Thursday night into Friday. Low confidence. Friday night through Saturday...Improving conditions Friday night with a return to VFR expected to occur late. West to northwest winds around 5 to 10 knots. && .MARINE... Low pressure is moving up across the coastal waters of New England. Winds northwest for this afternoon and tonight. Wind gusts will increase to 25 to 30 knots. As a result, a Small Craft Advisory remains in effect for our coastal waters and for Delaware Bay. Waves on our ocean waters are expected to build to 5 to 7 feet. Waves on Delaware Bay should increase to 2 to 4 feet. Outlook... Wednesday...Small Craft Advisory conditions continue through Wednesday. Northwest winds will diminish later in the day. Seas are expected to drop below 5 feet Wednesday afternoon. Thursday through Friday...Winds and seas will increase as a coastal storm develops to our south and starts to move up over our waters. Seas will build on Thursday becoming 6 to 12 feet. East to northeast winds will increase during the day Thursday, increasing to 20 to 30 knots overnight with higher gusts. Winds will turn to the northwest on Friday, remaining around 15 to 25 knots. Gale Warnings seem likely for later Thursday through Friday. Friday night...Gale force gusts are expected to end before Friday night but Small Craft Advisory conditions will continue. The northwest winds will start to diminish overnight and lose their gustiness by early Saturday morning. Seas are expected to drop below 5 feet Friday night. Saturday...Sub-Small Craft Advisory conditions expected. Northwest winds around 10 to 15 knots. Seas around 2 to 4 feet. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EST Wednesday for ANZ450>455. Small Craft Advisory until noon EST Wednesday for ANZ430-431. && $$ Synopsis...Meola/RCM Near Term...Iovino/RCM Short Term...Iovino Long Term...Meola Aviation...Iovino/Meola/RCM Marine...Iovino/Meola/RCM

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