Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 051729 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1229 PM EST Mon Dec 5 2016 .SYNOPSIS... Low pressure passes south of the region this morning. A complex area of low pressure crosses the region Tuesday. A strong cold front crosses the area Thursday. && .NEAR TERM /THROUGH TONIGHT/... Given current radar trends, went ahead and dropped all pops as the pcpn has pushed offshore. Adjusted cloud grid a bit to account for a few hour period of ST/SC late this morning before partial clearing from the NNW this afternoon. Downslope flow and subsidence behind the departing wave will allow temps to warm into the low-mid 50s. PVS DSCN: Rain chances ramp back up late tonight, as wind fields back to the SSW as sfc low pressure deepens over the Gulf Coast. Isentropic lift similarly ramps back up late this evening through the overnight hours, and rain chances increase from SW to NE during this period. Meanwhile, sfc high pressure builds across the Interior northeast, with weak CAD setting up as sfc high noses down into the piedmont. CAMS indicating increase in pops after 06z but have increased pop after midnight, as deterministic models generally underestimate just how fast pcpn breaks out in and overrunning scenario. Clouds thicken/lower once again in the evening with rain overspreading the fa SW-NE after midnight. Lows upr 30s north to upr 40s SE. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... Tuesday remains a challenge as low pressure rides NE along the Southern Appalachians with a secondary low pressure tracking NE along the Carolina coast. Given the current temp/dp temp scheme, it is not out of the question to see a few sleet pellets mix in with the rain at the beginning across northern most zones early Tuesday morning before the column wet bulbs out above freezing. While this won`t result in any significant impacts, have allowed mention for potential brief period of sleet across far NW tier of counties late tonight and early Tuesday morning. Deterministic models and majority of NCAR ensembles indicating period of moderate rainfall Tuesday morning through afternoon as Gulf/Atlantic moisture become entrained and track across the region. 00z/05 models consistent in tracking the triple point low across the northern outer banks keeping the center ivof eastern Albemarle sound. This track will likely keep pcpn type mainly stratiform across the fa but may become convective across the extreme sern zones for a few hours during the afternoon. Temp forecast tricky due to a strong in-Situ- wedge holding readings arnd 40 most of the day across the nwrn most zones (LKU) ranging to the low-mid 60s ivof the northern outer banks (ONX). Forcing strong enough for a several hour period of mdt to psbly heavy rainfall with widespread rainfall amounts between 1/2 to 1 inch. Pcpn slowly ends SW-NE Tuesday night as the best lift moves NE. Lows 35-40 west, 40s east. The low slowly pulls away from the region Wednesday with deep layered SW flow behind it. Decreasing clouds in the morning bcmg mostly sunny in the aftn. Highs in the mid-upr 50s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Upper trough tracks into the Northeast states Thursday, with an associated cold front quickly pushing across the local area Thursday. Medium range guidance now in better agreement with the frontal timing and evolution of the upper wave. Moisture will be limited along the front as the best dynamics lag behind. As a result, have maintained only a slight chance to low end chance POP Thursday morning for the Piedmont into central Virginia, and then pushing toward the coast Thursday afternoon. Highs Thursday in the mid/upper 40s northwest to the mid 50`s southeast. Better chances expected in the north/northeast forecast area nearest the deepest moisture. Front and moisture quickly push offshore late Thursday as a cold and dry arctic air mass surges into the region. Lows drop into the 20`s Thursday night. Cool, breezy, and dry Friday as surface high pressure builds in from the west. Latest GEFS still indicates 850mb temperatures of -10 to -12C (-2 standard deviations). Highs are expected to warm only into the upper 30`s to low 40`s. Add in a breezy northwest wind and wind chills will struggle to reach the mid 30`s. High pressure centers over the area Friday night as temperatures drop into upper teens to low 20`s inland to mid/upper 20`s near the coast. 850Mb temperatures progged to moderate slightly Saturday (-6 to -8C) as cold high pressure centers over the region. Less mixing will result in another cool day, with highs back around 40 under a mostly sunny sky. High pressure slides offshore Sunday as return flow and quasi zonal flow aloft results in moderating temperatures. Highs Sunday forecast in the mid to upper 40`s to low 50`s southeast. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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Stubborn IFR Stratus hanging on a bit longer than expected today, however the sat trends are noting this quickly burning off allowing the IFR ST to dissipate with vfr conditions over the next 1-2 hours. High level moisture will begin to increase after 00Z as the moisture from the approaching storm from the south moves NE. Rain will quickly overspread the region around 12Z Monday with lowering cigs and vsbys. IFR conditions along with areas of fog and MDT pcpn expected just before the end of the forecast period. Outlook: IFR conditions continue into Tuesday night as the storm slowly pulls away to the NE. Improving conditions to VFR behind the system on Wednesday. A strong cold front crosses the area Thursday with sct shwrs.
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&& .MARINE... High pressure located just offshore this morning, with an area of weak low pressure along the Southeast coast. Observations indicate a light south to southeast wind over the waters, generally at or below 10 knots. Waves 1-2 feet and seas 2-3 feet. The low lifts off the Outer Banks early to mid morning as high pressure builds in from the northwest. Winds in the southern waters become north to northwest 10- 15 knots early morning, then northwest 10-18 knots all waters by late morning. With a brief period of increasing onshore flow in the southern waters, seas will build to 3-4 feet, possibly reaching 5 feet briefly out 20nm. High pressure builds into the region this afternoon as the low slowly pushes offshore. A northwest wind around 15 knots in the coastal waters expected to keep seas in the 2-4 ft range. High pressure centers over the Northeast tonight through Tuesday as another area of low pressure lifts along the Southeast coast. Flow becomes onshore late tonight and Tuesday. Pressure gradient strengthens as height falls spread northward over the coastal waters. Seas expected to build to 4-5 feet in the southern waters, then 4-6 ft all waters Tuesday afternoon as east winds increase to 15 to 25 knots. Waves 2-3 feet in the north and 3-4 feet in the lower Bay. SCA headlines have been issued for the Bay, Atlantic waters, and Sound. The low lifts northeast away from the coast Tuesday evening with flow becoming northerly. Speeds remain 10 to 20 knots and seas 4-6 feet. SCA headlines for the Atlantic waters run through 4th period. The low pushes farther offshore Wednesday with northwest winds decreasing to 10-15 knots in the afternoon. Seas subside to 3-4 feet late. A strong cold front pushes across the waters Thursday, with strong SCA conditions (or low end Gale conditions) possible Thursday night. SCA conditions expected to linger into the weekend. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 AM to 6 PM EST Tuesday for ANZ630>634. Small Craft Advisory from 1 PM Tuesday to 6 AM EST Wednesday for ANZ650-652-654. Small Craft Advisory from 10 AM Tuesday to 6 AM EST Wednesday for ANZ656-658. && $$ SYNOPSIS...MAM NEAR TERM...MPR/MAM SHORT TERM...MPR/MAM LONG TERM...SAM AVIATION...MPR MARINE...SAM is the U.S. government's official web portal to all federal, state and local government web resources and services.