Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 121200 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 700 AM EST Wed Dec 12 2018 .SYNOPSIS... High pressure will prevail over the Mid-Atlantic through Thursday. Low pressure approaches from the southwest Thursday night into Friday, and tracks across the region Friday afternoon through early Saturday. An upper level trough will remain over the area through Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 400 AM EST Wednesday... Current GOES wv data shows an upper trough pushing off the New England and Mid-Atlantic coasts, ahead of a ridge over Ohio Valley. A nrn stream trough is digging across the Midwest, with a srn stream trough lagging back over the nrn Baja Peninsula and Desert SW. At the surface, 1027mb high pressure is centered over the nrn Gulf coast, with low pressure E of Cape Cod. There was some light mixing earlier in WSW flow, but most locations away from the coast are now decoupling, and temperatures are dropping into the low 20s where snow cover is present under a clear sky. Closer to the coast, temperatures are holding in the low/mid 30s. High pressure gradually slides off the Southeast coast today. Sunny this morning with some high clouds arriving this aftn. High temperatures today range from the low/mid 40s inland, to the mid/upper 40s toward the coast, with a light W or NW wind this morning becoming SE in the aftn. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... As of 400 AM EST Wednesday... A weak trough (the one over the Midwest early this morning) clips the nrn Mid-Atlantic Thursday, with high pressure building across New England in the wake of this system. Temperatures will be slow to moderate Thursday, although dewpoints rising into the low/mid 30s should hasten snow melt. Remaining dry tonight to Thursday with lows in the upper 20s/low 30s Thursday morning, followed by highs in the mid 40s inland, to the low/mid 50s in SE VA/NE NC. The aforementioned srn stream trough will reach ern TX/LA by late Thursday night, with a moist frontal band emerging from the Gulf into the Deep South ahead of the low. Continued dry Thursday night with lows in the low 30s inland to the upper 30s/low 40s at the coast. The upper level system traverses the Deep South Friday into Friday night, as the moist frontal band pushes toward the Mid-Atlantic Friday aftn into Friday night. 12/00z models remain in good agreement with a warm and wet pattern prevailing Friday aftn into Friday night. Storm total QPF of 0.75-1.5" is expected, with up to 2.0" possible through 12z Saturday. This combined saturated ground from snowmelt will bring potential flooding. A Flood Watch will certainly be worth consideration with later forecast packages if current setup remains in place in modeled data, and will continue to make a mention in HWO, given POPs in the 70-90% range. MMEFS still depicts minor river flooding with moderate flooding possible. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 355 PM EST Tuesday... Saturday`s low pressure system departs offshore by Sunday morning with residual showers possible across far southern VA and northeast NC as the upper level low swings across the region. Still some disagreement between the models on this feature, decided to go closer to the ECM/Fv3. ECM is still consistent with showing low pressure redevelop off the NC coast Sunday night into Monday. This would allow for rain showers to linger across the east into Monday morning. The operational GFS is more progressive with the upper level low, thus has dry weather by Sunday afternoon. Introduced chance PoPs across the south and southeast Sunday afternoon into Monday morning to take into account both model solutions. Dry weather Monday and Tuesday as high pressure builds back across the region. Temperatures moderate by this weekend with southerly flow ahead of the next low pressure system, currently have highs in the lower 50s NW to the low/mid 60s across the SE for Saturday. Sunday will feature highs in the low to mid 50s across the region. Temperatures trend cooler early next week as cool high pressure builds across the area. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... As of 700 AM EST Wednesday... High pressure is centered over the Deep South early this morning, and it will gradually slide across the Southeast coast today and move offshore tonight. Localized bkn-ovc cigs at SBY of 5-6kft should persist through about 14z. Otherwise, expect mainly high clouds today. A light WSW wind early will become NW, and then become SSE (locally ENE at ORF) as high pressure slides off the coast later this aftn. High pressure continues to prevail Thursday into Thursday night. Low pressure approaches from the SW Friday and moves across the area Friday night into Saturday bringing rain and degraded flight conditions. An upper level trough lingers over the area into Sunday. && .MARINE... As of 630 AM EST Wednesday... Update: Went ahead and cancelled the SCAs south of Cape Charles as buoy obs continue to show diminishing seas. Previous Discussion: Latest sfc analysis indicates low pressure well offshore of the Mid-Atlantic/Northeast coast, with weak sfc troughing over wrn VA. Winds are out of the NW/NNW at 10-15 kt over the bay/15-20 kt over the ocean. Since buoy 44009 is reporting ~4 ft seas ~20 nm offshore of the MD/DE border (w/ only 3.3 ft seas at the Wallops buoy), opted to cancel all SCAs north of Cape Charles. A weak shortwave trough aloft will be passing just to our NE from now through around mid-morning. This will bring weak cold advection to the region (mainly north), but wind gusts will likely stay just below SCA thresholds over the bay and ocean zones. Cannot rule out a few gusts to SCA thresholds in elevated areas (mainly N of Parramore Island), but these will be infrequent/short-lived. Tranquil marine conditions are in store from this afternoon through Thursday night as high pressure will dominate our local weather. Longer term model guidance shows low pressure (sfc- aloft) approaching the area on Friday. The latest 00z/12 GFS/ECMWF/GEM are in relative agreement that sfc low pressure develops near or just south of the region late Fri- Sat as an upper low slowly moves eastward across the deep South. This first area of sfc low pressure likely moves offshore by late in the day on Sat. The upper low may approach the region late this weekend as a secondary area of low pressure deepens offshore. However, the timing/placement of the upper low vary substantially among the latest GFS/ECMWF/GEM. Will continue to show increasing winds/seas beginning Friday with the potential for SCA conditions (most likely across offshore zones) through Sunday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ/MAM LONG TERM...AJB AVIATION...AJZ MARINE...ERI

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