458 FXUS61 KPHI 030816 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 316 AM EST Sun Feb 3 2019 .SYNOPSIS... High pressure over the Mid-Atlantic moves offshore today. A warm front lifts north through the region Monday night, and then a cold front moves across the region Tuesday night. Several waves of low pressure will pass through the region later this week, and then a cold front moves through the region Friday night. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As expected, patchy fog has developed across the area. So far, visibilities are generally hovering around 4-7 miles, but expect these to lower locally in the more favored locations, particularly in the Pine Barrens, Delmarva, and the lower valleys northwest of the Fall Line. This should not be too much of an issue through the early morning. However, because temperatures are hovering a few degrees below freezing, denser fog would have some potential to accumulate a thin glaze of ice. We will need to monitor this closely through the early morning hours. Generally, guidance is doing decently with hourly temperatures and dew points, though there are larger errors in the aforementioned more susceptible spots for fog. Slightly lowered temperatures the rest of the night, especially in these locations. The region is just south of a low-level col, with surface highs to the north and southeast and surface lows to the northeast and west. Flow is quite stagnant as a result, so expect some haze for much of the day today, even after the patchy fog slowly dissipates by mid- morning. A weak perturbation will move into the Great Lakes, while a southern-stream vort max will intensify as it approaches the Southeast coast this afternoon. A surface low will be developing off the Florida coast, progressing northeastward to offshore the Carolinas by this evening. Sensible-weather effects will be well to our northwest and south today, in association with these phenomena. Should be a mostly sunny day across the area. Subtle low-level warm advection and slightly rising heights downstream of the perturbation in the Great Lakes should lead to a warmer day, as well. However, suspect that guidance is once again too warm given the remaining snow cover, so have sided with colder guidance and in some cases went below even the coldest guidance for highs. Forecast max temps are in the 40s across the area, with some 30s in the Poconos and vicinity. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... The surface low off the Carolina coast will progress slowly east- northeast to a position farther offshore by 12z Monday. Meanwhile, a weak perturbation will progress from the eastern Great Lakes to New England during the night. Precipitation will remain well north and south of the area as a result, with fairly stagnant surface flow remaining in place. Lows will be warmer than those seen this morning, and surface moisture will continue to increase slowly. Given the fairly clear conditions and light winds, expecting another round of fog overnight. It may be a little worse than the previous night owing to the slightly increased temperatures/dew points. Low temperatures were a blend of somewhat colder statistical guidance, owing to the decent radiational cooling environment expected. In general, this leads to low temperatures around freezing across the area, with slightly lower values in the valleys/rural areas of eastern PA, northern and southeast NJ, and inland Delmarva. && .LONG TERM /MONDAY THROUGH SATURDAY/... Much of the upcoming week will feature zonal flow that will keep the Arctic air bottled up to the north. High pressure offshore will result in return flow that will bring an unseasonably warm airmass for much of the new week. Low pressure meanders off the Carolina coast on Monday. It should stay far enough to the south and east to keep precip associated with it away from Delmarva, but some clouds may rotate around the low and spread into southern Delaware and far southeast New Jersey. High pressure will otherwise be in control. Heights and thicknesses will increase, and highs on Monday climb into the 50s across much of the region. A weak warm front lifts north through the region Monday night. There will not be much upper level support, so will keep PoPs capped at slight chance/chance, and QPF amounts will be light as well. High pressure becomes entrenched over the Mid-Atlantic on Tuesday, and westerly flow results in an even warmer airmass to spread into the Northeast and Mid-Atlantic. Highs will be in the upper 40s in the southern Poconos and generally in the low 50s north and west of the Fall Line. For the southern half of the forecast areas, highs will be well into the 50s, and may even touch 60 in parts of southeast New Jersey and northern Delmarva. Southern Delmarva will be in the lower 60s. Although it will be quite warm for early February, record highs should be safe. High pressure moves offshore Tuesday evening, and a cold front slides south through the region Tuesday night. Much colder air filters to the south, and lows Tuesday night drop into the 20s and 30s. The front should pass through dry, so will not have PoPs with its passage. From there, unsettled weather on tap for the end of the week as several waves of low pressure develop out ahead of a deep trough digging into the Western United States. With high pressure just offshore, it should keep precip to the west until late Wednesday. By the time precip arrives, temperatures should be in the mid and upper 40s, and precip should for the most part be rain, with maybe a rain/snow mix in the Poconos. The first wave of low pressure passes through the region Wednesday night and Thursday. Snow or a rain/snow mix possible for northern zones, and mostly rain expected for the southern half. A stronger area of low pressure moves into eastern Canada on Friday, and this drags a strong cold front south through the region Friday night. Warm air returns for Thursday through Friday, as highs return to the 50s throughout. Colder air arrives Friday night, allowing precip to change to snow before tapering off by Saturday morning, and then temps drop to below normal levels on Saturday. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This morning...Mainly VFR, but patchy fog may produce temporary MVFR VSBYs, generally before 14z. Light and variable winds. Moderate confidence. This afternoon...VFR, though some haze may be present much of the day. Winds generally light with a dominant west or southwest component. High confidence. Tonight...Patchy fog may once again develop. There is a chance it will be somewhat more prevalent than what is observed this morning. Light and variable winds. Moderate confidence. OUTLOOK... Monday...VFR. Light south winds. Monday night...Sub-VFR conditions possible in rain/patchy fog. Light SW winds. Tuesday through Wednesday morning...VFR. W-NW winds around 10 kt. Wednesday afternoon through Thursday...Sub-VFR conditions, primarily in rain, but a rain/snow mix is possible at KRDG/KABE. Light E-SE winds. && .MARINE... Sub-advisory winds/seas are expected through tonight. OUTLOOK... Monday through Thursday: Sub-advisory winds/seas expected. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...MPS Near Term...CMS Short Term...CMS Long Term...MPS Aviation...CMS/MPS Marine...CMS/MPS