Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000 FXUS61 KPHI 050141 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 841 PM EST Thu Mar 4 2021 .SYNOPSIS... High pressure dominates our weather through the middle of next week. A cold front will approach the region later in the week. && .NEAR TERM /THROUGH FRIDAY/...
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A tight northwest pressure gradient remains over the Northeast and down into the Mid-Atlantic as the region is caught between low pressure over eastern Canada and high pressure building in to the Northern Plains and upper Great Lakes region. A deep upper trough will be over the region as well, and strong CAA will be underway tonight through Friday. A weak LLJ of 35-40 kt winds will be over the area as well, and while most of the winds will mix down, winds will not be strong enough to warrant a Wind Advisory. Northwest winds will diminish a bit during the overnight due to loss of mixing from diurnal heating, however gustiness will remain with the robust cold air advection. By late Friday morning, winds increase back up to 15-20 mph with 25-35 mph gusts, diminishing again towards evening. Lows tonight will drop into the teens across the northern zones, and otherwise in the low to mid 20s. On Friday, highs will range from the mid 20s in the southern Poconos to the mid and upper 30s. Wind chills late tonight and early Friday morning will range from as low as 10 below in the southern Poconos, to otherwise in the single digits to low teens. For reference, highs on Friday will be around 10 degrees below normal, and more similar to the seasonal highs around mid-January. Low temperature records tonight and record low high temperatures on Friday will not be challenged.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... The high builds overhead through the weekend keeping our weather nice and dry. An upper trough digs down through the Great Lakes and deepens as it crosses our area late Saturday. This trough will be the reason our temperatures remain on the colder side through Sunday. Temperatures on Saturday and Sunday will be pretty similar with highs in the mid 30s to lower 40s. The southern Poconos and the higher elevations of northwest New Jersey may struggle to reach 30 both days. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... The upper trough pushes to the east of the region Sunday night as the surface high shifts overhead. As the trough exits the region we will start to see the airmass modify and warm. Temperatures on Monday start to get back near and above normal with highs reaching into the upper 40s to near 50 across much of the region. The high settles just south of our area and keeps us in the southwest flow with strong warm air advection taking place. Each day will warm appreciably with highs on Tuesday reaching into the upper 50s to lower 60s. Wednesday looks to be in the 60s for most of the area and by Thursday we are even warmer with highs possibly nearing 70 in some areas. The next chance for precipitation at this point looks to be later in the week. Low pressure starts to move through the Great Lakes on Wednesday. The attendant cold front will slowly drop down into the Mid-Atlantic on Thursday. Low pressure may develop along the front, which would help to pull it through our forecast area, possibly late Thursday or Friday. Obviously, this is at the tail end of the period and has plenty of uncertainty associated with it as the energy associated with this system may not move onshore until early next week. One thing for certain is that the temperatures ahead of the system will be exceedingly warm, leaving us with an all rain event. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/...
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The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR. Lingering stratocu around 6000 feet will continue dissipating and moving south through 06Z. SKC conditions thereafter. NW winds around 10-15 kt with gusts up to 20 kt. High confidence. Friday...VFR/SKC. NW winds 15-20 kt with 25-30 kt gusts. High confidence. Outlook... Friday night through Saturday...VFR. Northwest winds around 10 to 15 knots with gusts around 25 knots. High confidence. Sunday...VFR. West to northwest winds around 10 knots. High confidence. Monday and Tuesday...VFR. West to southwest winds less than 10 knots. High confidence.
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&& .MARINE...
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A tight pressure gradient remains on the waters through at least Friday. NW winds will range from 15-20 kt with 25-30 kt gusts during this time, and seas will build to 3 to 5 feet on the ocean. An SCA remains in effect for all waters during this time. Cannot rule out a few gale force gusts through the early overnight, but do not think gales will be widespread enough nor long lived enough to warrant a Gale Warning. There is a chance for freezing spray late tonight through Friday morning due to the strong NW flow and sea surface temps in the upper 30s to low 40s. Outlook... Friday night through Saturday...Northwest winds around 10 to 20 knots with gusts around 25 to 30 knots. Seas 2 to 4 feet. Winds expected to fall below SCA conditions on Saturday. Saturday night through Tuesday...Sub-advisory conditions expected.
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&& .FIRE WEATHER... A prolonged period of dry weather will last into the middle of next week. Strong northwest winds will be in place tonight through Friday. A cold and dry airmass will spread over the region starting tonight, and min RH values on Friday will range from around 20 to 25 percent across southeast Pennsylvania, much of New Jersey, the eastern shores of Maryland, and Delaware. Afternoon wind gusts will be as high as 25 to 35 mph. Conditions will somewhat abate on Saturday, with min RH values generally 35 to 40 percent and afternoon wind gusts as high as 20 mph. Based on coordination with fire-weather partners, there will neither be a Special Weather Statement nor a Red Flag Warning for Friday, as fuels are not sufficiently dry enough. Though winds will be lighter this weekend, dew points will remain unusually low, so conditions may be close to fire-weather thresholds several days in a row. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EST Saturday for ANZ430-431- 450>455. && $$ Synopsis...Meola Near Term...MPS/Staarmann Short Term...Meola Long Term...Meola Aviation...Meola/MPS/Staarmann Marine...Meola/MPS Fire Weather...WFO PHI

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