004 FXUS61 KPHI 030053 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 753 PM EST Tue Mar 2 2021 .SYNOPSIS... High pressure passes through the region tonight. A weak, but dry, cold front will cross the region Wednesday evening followed by a return to high pressure through early next week. && .NEAR TERM /THROUGH WEDNESDAY/... Cold high pressure centered over the Ohio Valley will slowly build east through tonight and will move off the Mid-Atlantic coast by morning. Zonal flow sets up as the region finds itself in between weak low pressure moving through northern New York State and into northern New England and a stronger area of low pressure passing off the Southeast U.S. coast. The pressure gradient continues to decrease, causing winds to rapidly diminish, if they haven't already. A light southwest flow develops tonight, and WAA will be underway as H8 temps rise from -11C to -8C to 0C to 1C by daybreak Wednesday. Even though skies will be clear and winds will be light, not expecting strong radiational cooling due to that WAA. Lows will range from the teens and 20s north and west of the Fall Line to the 20s to around 30 in southern New Jersey, the Delaware Valley, and Delmarva. With high pressure offshore, and zonal flow over the area, WAA continues on Wednesday, which should be the warmest day of the week. Surface dew points rise from the single digits/low teens today to mid 20s on Wednesday and highs will be in the mid to upper 40s in the northern zones, and in the low to mid 50s in the southern zones with cooler temps along the coasts. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... We are situated between two systems by Wednesday evening with a low passing off the Carolina coast to our south and another low centered near the Canadian maritimes. The low to the northeast drags a weak cold front across the region Wednesday night but it looks to be dry as it crosses our area and we will only really see a wind shift as it moves through. Behind the front we get another push of cold air advection. Northwest winds will move into the region and 850mb temps drop back down into the -5 to -10 C range. With light winds and clear skies expect that we should radiate fairly well. However it may take a while for the cold air to arrive so temps will remain a little more mild overnight. Overnight lows will be in the mid 20s to mid 30s across the forecast area. The low to the northeast makes little to no progress on Thursday or Friday and in fact retrogrades a bit to the west. High pressure moving down through the midwest gets shunted to our southwest. This period should remain dry as the high controls our weather. Daytime highs will drop below normal and into the 30s to 40s, with Friday slightly colder than Thursday. With the low remaining in place, the gradient will tighten up and expect that Thursday and Friday and will be a bit gusty. With the winds remaining up, we will see the atmosphere really dry out and RH values are already starting to show that they drop below 30 percent. A good portion of the region has lost their snow pack and should have the opportunity for the fuels to dry out, too. This could lead to some fire weather concerns on Friday. There is a decent shortwave that crosses the region early Thursday morning which could be accompanied by some flurries or snow showers, mainly across the Poconos and portions of northwest New Jersey. No mention in the forecast yet due to low confidence but something to keep in mind. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... The high strengthens and starts to push down from Canada and through the eastern US through the weekend. The high moves slowly and won't even be overhead until at least Monday, then slides offshore on Tuesday. This will keep us in a nice period of dry weather, albeit a fairly long stretch at that. The airmass modifies through the weekend and into early next week with temperatures gradually warming each day. Temperatures on Saturday and Sunday will be just below to near normal, (generally in the 40s with some 30s across the north) but by Monday we are starting to get back near and above normal with highs reaching into the 50s across much of the region. By Tuesday we are well above normal with highs in the mid to upper 50s through a good portion of the area. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR/SKC. W-SW winds diminishing to 5-10 knots as any remaining wind gusts subside. High confidence. Wednesday...VFR. W winds less than 10 kt. High confidence. Outlook... Wednesday night...VFR. Light westerly winds becoming northwest late. High confidence. Thursday through Friday...VFR. Northwest winds around 10 to 20 knots. Gusts around 25 to 30 knots each day. High confidence. Saturday through Sunday...VFR. West to northwest winds around 10 knots. High confidence. && .MARINE... Winds and seas are diminishing to sub-Small Craft Advisory conditions on Delaware and southern New Jersey ocean waters, as well as Delaware Bay. So will cancel the SCA that was in effect until 4 pm. For northern New Jersey ocean waters, SCA will remain in effect until 7 pm. There may be a surge of SCA conditions for a brief time Wednesday morning. Otherwise, conditions will mainly be sub-SCA criteria. Low tide that is ongoing has come in lower than previously forecast. Therefore, a short fuse low water advisory has been issued through 7 PM on the coastal waters. Since winds should be diminishing further through the night, expect this to be the last low tide to be affected. Outlook... Wednesday night...Sub-advisory conditions expected. Thursday through Friday night. Northwest winds around 10 to 20 knots with gusts around 25 knots. Seas 2 to 4 feet, nearing 5 feet Thursday night. A Small Craft Advisory will likely be needed. Conditions will abate through Friday night. Saturday through Sunday...Sub-advisory conditions expected. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Meola Near Term...Davis/MPS Short Term...Meola Long Term...Meola Aviation...Davis/Meola/MPS Marine...Davis/Johnson/Meola/MPS