Area Forecast Discussion
Issued by NWS Wakefield, VA

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817 FXUS61 KAKQ 190843 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 443 AM EDT Mon Mar 19 2018 .SYNOPSIS... High pressure moves off the Mid Atlantic coast this morning. A pair of low pressure systems will impact the region late today through Wednesday. High pressure builds into the area late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Sfc high pressure moves off the mid-Atlantic coast this morning, then pushes farther offshore this afternoon allowing moisture to overspread the area late. Lower levels remain dry thru about 18Z, but look for skies to become mostly cloudy to overcast before that has mid/high clouds increase. Some overrunning yet spotty light rain (a few hundredths at best) progged to develop across the Piedmont around/after 18Z, then spread east during the afternoon. Highest pops (25-35%) west of the I95 corridor. Highs 45-50 immediate coast, in the 50s west of the Bay. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... A complex weather system will make for an unsettled mid week period. Inland concerns range from moderate to locally heavy rainfall along with sct tstms across the SE tonight, rain mixing with or changing to wet snow Tues night/Wed (with minor accumulations possible). Coastal issues range form gale force wind gusts Tues/Wed to possible coastal flooding thru the mid week period. Stay tuned. First event occurs tonight as a potent shortwave races eastward from the TN Valley late this evening, with a sfc low tracking across NC late tonight/Tues morning before emerging off the mid-Atlantic coast on Tuesday. Rather impressive lift progged with and north of the sfc low to produce a widespread rain across the FA. Will carry categorical pops all areas with some moderate to heavy rainfall possible after midnight. QPF amounts could exceed an inch in some areas. Following a blend of the models, a triple pt low should track ne across ne NC and sern VA late Monday night then out into the VA capes Tue morning. Thus, can`t rule out thunder across those areas early Tues morning. Lows from the mid 30s north to mid-upr 40s SE. The sfc low deepens as it tracks across the VA capes Tues morning, then pushes farther out to sea Tues afternoon as weak high pressure tries to nudge in from the north. Will carry likely to categorical PoPs Tues morning (locally heavy rain early over the Eastern Shore), then likely pops north and NE with chc PoPs south Tues afternoon. Chilly with highs nr 40/low 40s north to 55-60 se coastal areas. Still much uncertainty on how the system evolves Tues night and Wed. The first low progged to pull away from the coast Tue night with the next upr level system crossing the area Wed. This upr level system pulls in enough cold air to allow p-type issues both periods. Chc pops to likely pops Tue evening ramp up to likely everywhere after midnight as the moisture from the upr level system crosses the mountains. Thicknesses suggest a mixed/rain and snow event across the Piedmont Tuesday night with a cold rain elsewhere. There could be a changeover to all snow across Louisa/Fluvanna counties. Temps drop into the lwr 30s NW, mid-upr 30s se. Wed is not looking to be a repeat of last Monday`s event with the location of the sfc low being displaced well offshore and pcpn intensity having to rely solely on forcing aloft to dynamically cool the column to get snow to accumulate with temps above freezing. Will keep likely PoPs for most areas during Wednesday as rain and snow showers will occur. However, given lack of significant lift and ability to keep the column cold enough for predominately snow, and the fact that pcpn will be fighting the late March sun angle, will not show much snow accumulation. Stayed closed to WPC guidance with 0.5-1" accumulations Tues night/Wed limited to Fluvanna/Louisa County and traces amounts along/west of an OXB-JGG-FKN-IXA line. Other than a possible rain/snow mix across far SE VA and coastal NE NC Wed evening, expecting all liquid pcpn for this event. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Deep/anomalous trough aloft will remain near the E coast Thu-Fri before slowly shifting E next weekend. Meanwhile...blocking upper level high will remain invof Hudson Bay. Using a blend of GFS/WPC/ECMWF through the period. Expecting a continuation of (much) below temperatures Wed night/Thu-Sun. Lingering clouds/ISOLD-SCT RA/SN Wed eve (esp toward the coast)...then Dry/cool wx Thu-Fri. Next lo pres system develops invof nrn Plains by Fri...then tracks E (undercutting the upper level high N of the Great Lakes) through the mid-Atlantic/NE CONUS next weekend...bringing increased clouds/PoPs. Lows Wed night in the u20s W to the m30s right at the coast. Highs Thu ranging through the 40s. Lows Thu night in the u20s W...m30s at the coast. Highs Fri around 50F inland...m40s at the coast. Lows Fri night in the l30s inland...u30s-around 40F at the coast. Highs Sat in the u40s-l50s inland...m-u40s at the coast. Highs Sun in the 40s N to m50s S. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... VFR conditions prevail across the region as of 06z as high pressure along the coast slowly moves offshore. High level clouds overspread the area this morning into afternoon ahead of the next system approaching from the SW. Any pcpn with this system will hold off until after 18Z Mon. Rain will overspread the region Mon night into Tue morning, and could be heavy for a time. Ceilings and visibilities will generally decrease to MVFR conditions during the overnight. Brief IFR conditions are possible in the heaviest rain. Outlook: Another window of flight restrictions late Tues thru Wed. Rain for the most part may mix with or change to wet snow by Wed at RIC and SBY. Gusty winds buffet the coast Tue and Wed as a coastal storm develops. && .MARINE... Sub-SCA conditions to prevail today into this evening as sfc high pressure along the NC coast gradually slides offshore later this morning as low pressure across the TN Valley begins to move east towards the region. Initially, will see the flow turn E/SE and still remain rather light in the 10-15 kt range with seas averaging 2-3 ft and waves 1-2 ft. By tonight, the pressure gradient will tighten in between the approaching sfc low from the W, and ~1030mb sfc high centered over ontario but ridging SE into the northern mid-Atlc region. Have converted the Gale watch for the coastal waters N of Cape Charles into a Gale Warning, and raised SCA headlines for the remainder of the marine area. NE winds will ramp up significantly after midnight, as the initial sfc low stalls over eastern KY and transfers energy to a developing sfc low across the NC coastal Plain. The exact position of this will be critical as to how strong the winds get in southern portions of the marine area. A slight southward shift in the track of this low would lead to Gales farther south than what is currently forecast (i.e spreading into the lower Bay and coastal waters to the VA/NC border). For now, the consensus has been to rapidly intensify the sfc low in the vicinity of the VA/NC border Tue morning, then lift it NE and this would support Gales staying a little farther north. Did mention gusts to 35 kt in much of the marine area in the MWW and will continue to monitor closely. This initial low will head out farther to sea Tue aftn/Tue evening. As the upper level low enters the region late Tue night/Wed, a new surface low will develop along/off the Carolina coast and lift it NE off the Virginia coast during the day Wed. Another round of Gale force conditions are likely across the northern coastal waters while SCA conditions with 25 to 30 kt winds are likely over the remainder of the area. Seas will build pretty quickly as well on Tuesday into Wednesday with seas getting up to 8 to 12 ft on the coastal waters. By Wed night/Thu morning, the sfc low will be moving well off the coast and this will allow conditions to begin to relax with NW flow continuing into Friday when high pressure finally moves over the area. Seas likely to remain elevated for the coastal waters such that SCA headlines will continue through at least Thu aftn. && .TIDES/COASTAL FLOODING... Low pressure approaches from the TN Valley later today, and intensifies just off the coast on Tue before pulling off to the NE. Secondary area of low pressure lags back off the Carolina coast and tracks NE off the mid-Atlc coast Wed/Wed night. This pattern will allow for a strong and persistent NE flow into much of the local area from late tonight into Tue night, then winds shift more to the NNW on Wed. Building tidal departures and the potential for at least minor coastal flooding over locations adjacent to the lower Bay and the Atlc coast from Ocean City to Currituck NC. Current forecast projections give the greatest chance for flooding Late Tue night into midday Wed as the anomalies will take awhile to build tonight through Tue. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 AM Tuesday to 6 AM EDT Wednesday for ANZ630>632-634>638. Small Craft Advisory from 4 AM Tuesday to 6 AM EDT Wednesday for ANZ633-656-658. Gale Warning from 4 AM Tuesday to 6 AM EDT Wednesday for ANZ650-652-654. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM/MPR LONG TERM...ALB AVIATION...JDM MARINE...LKB TIDES/COASTAL FLOODING...AKQ is the U.S. government's official web portal to all federal, state and local government web resources and services.