Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 181152 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 652 AM EST Mon Dec 18 2017 .SYNOPSIS... The Mid Atlantic region will reside in between weak low pressure along the Gulf coast and strong low pressure over Canada today and Tuesday as high pressure becomes centered off the southeast coast. A cold front pushes through the region Tuesday night then stalls over the Carolinas on Wednesday. Low pressure moves along the front Wednesday and pushes off the southeast coast Wednesday night. high pressure returns for Thursday. && .NEAR TERM /THROUGH TONIGHT/... Latest wx analysis indicating a strong area of low pressure W of Hudson Bay Canada, with a sfc trough extending south into the Great Lakes. A westerly fairly fast moving/progressive flow is in place aloft. Skies have now cleared out except acrs portions of the eastern shore and NE NC. High pressure will be centered off the SE coast today, with sfc troughing pushing east from the Great lakes. Skies are expected to be mostly sunny later this morning with only a few high clouds streaming through far southern areas and some SCT cumulus possible in the aftn. Milder with highs in the mid/upper 50s N to the low 60s S. High pressure continues to prevail in vicinity of FL/GA tonight, with a weak/sheared out shortwave passing through the local area bringing a period of partly cloudy skies this evening especially over the N. Some low level moisture and fairly light flow depicted on Bufkit soundings could bring some patchy fog/low stratus after midnight through Tue morning. Forecast lows tonight range from the upper 30s/around 40 F well inland to the lower-mid 40s SE coast. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Northern stream upper trough passing by the northern Great Lakes to New England on Tue will increase the westerly flow aloft, and with the approach of a sfc cold front from the NW, low level WSW flow will increase and become somewhat breezy by aftn. This should make for a rather warm day on Tuesday with highs well into the 60s, and potentially close to 70F over srn half of the area if enough mixing occurs. Progressive split zonal flow will continue over the central and ern Conus Tuesday night and Wednesday. A nrn stream wave passes across New England Tuesday night, which will push a cold front through the Mid-Atlantic. Meanwhile, a srn stream wave will track across the Tennessee Valley Tuesday night and across the Carolinas Wednesday. Consensus among the 18/00z GFS/NAM/ECMWF/CMC has trended a bit farther N with the deeper moisture reaching to around the VA/NC border and have adjusted PoPs up to likely over the southern zones, mainly for late wed morning through Wed aftn, and have extended the chc/30% PoPs to about metro Richmond. The GFS looks a bit overdone with higher QPF amounts well into VA, but the NAM is probably too dry. Overall looks like ~0.50" of rain for NE NC zones tapered to 0.10" or less for VA zones (except for higher values near the NC border). Lows Tuesday night are generally in the low/mid 40s (upper 30s far NE) and highs Wednesday range from the upper 40s to lower 50s most areas. Think with the clouds/rain and limited mixing the MAV numbers are too warm and went close to the MET. Drier air pushes in from the NW late Wednesday night into Thursday as high pressure builds N of the region. Lows Wednesday night range from the upper 20s/around 30F N to the mid/ upper 30s SE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... High pressure centered over eastern Canada will ridge south into the mid-Atlc and carolinas on Thu. Low level NNE flow to bring a seasonably cool day with highs mainly ranging from the mid/upper 40s to around 50 F. The large scale trend by Friday/Saturday is for a trough over the Great Lakes and a ridge off the Southeast coast. Only a gradually warming trend is expected Friday with limited mixing and forecast highs range from the low 50 NW to low 60s SE after morning lows in the 30s. The 12z model consensus keeps a cold front well NW of the area Saturday with high pressure off the Southeast coast and southerly flow over the region. Forecast highs are in the upper 50s to mid 60s at this time, but there is the potential for higher values if enough sun and mixing occur. For the Christmas eve/Christmas day timeframe there remains run-to-run differences with respect to the location of the cold front. Temperatures could be well above normal if the front remains to the NW, while near to slightly above normal temperatures along with a chc of rain would be expected if the front settles over the region. PoPs are trended toward or slightly above climo for this time period. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... VFR conditions prevail at all sites, a few cigs mainly from ~5000 to 6000 feet still linger in NE NC and in MD and may affect KECG/KSBY through about 13Z. Skies will be partly/mostly sunny for the rest of today with W/SW winds 5-10 mph. There is some potential for low clouds and/or patchy fog late tonight/early Tue morning given somewhat high dew pts for the time of year and light winds but do not have these conditions in any of TAFS at this point. Outlook: High pressure remains near the Southeast coast Tuesday with VFR conditions prevailing along with occasional high clouds and WSW winds of 10-15 mph. Low pressure passes south of the region Wednesday, and some flight restrictions and rain is likely across southern VA and NE NC, cloudy but cigs will be higher farther north. High pressure builds north of the region Wednesday night and Thursday. High pressure slides offshore by Friday. && .MARINE... No headlines necessary with this forecast package. Latest sfc analysis shows ~1025 mb high pressure centered well off the SE coast with a stationary frontal bndry just north of the local area. This front stays north of the area today into tonight as strong low pressure pushes east across Canada. Weak pressure gradient over the local area will allow for light winds (aob 10 kt) today and tonight with just 1-2 ft waves/seas. The low over Canada will drop a cold front through the wtrs Tue night/Wed morning, with low pressure passing just south of the area along the front Wed/Wed night. At this point sub-SCA conditions appear likely mid week, but marginal SCA conditions are psbl should the sfc low and associated pressure gradient end up stronger than currently predicted. High pressure then builds in from the north Wed night and Thu, and pushes into the Atlc late Thu night and Fri. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...AJZ/LKB LONG TERM...AJZ AVIATION...AJB/LKB MARINE...MAS

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