Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 072100 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 400 PM EST Thu Dec 7 2017 .SYNOPSIS... A frontal boundary remains nearly stationary off the Mid Atlantic coast through Saturday. A series of low pressure systems will track northeast along this boundary through Saturday. Cold high pressure builds into the area Saturday night into Monday. && .NEAR TERM /THROUGH FRIDAY/... A quiet early evening across the area with the frontal boundary/baroclinic zone well south of the area. Will cut back on any precipitation across the area until late this evening into the overnight hours until the upper southern stream disturbance over the deep south moves across the area. Best forcing and moisture generally along and south of the VA/NC border tonight into Friday and this is where the highest PoPs are located. Am forecasting a sharp cut off in PoPs to the NW with only small chance PoPs in the RIC metro. On the northwest edge of the precipitation late tonight into early Friday morning, could see a few wet snow flakes mixed into the rain but overall the precip type should remain liquid Overall, temperatures will drop into the low-mid 30s west and upper 30s/lower 40s east. Highs on Friday will rise into the upper 30s/lower 40s. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
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Attention turns to the southern stream system currently over the Four Corners region - for Friday Night into Saturday. The operational models have come into better agreement with a slightly more amplified system, allowing more precipitation to be thrown back to the northwest especially during the day on Saturday when the models suggest a weak deformation axis band of precipitation developing on the NW side of the low. However, this better amplification will also cause more warm air to be thrown further inland. With really no cold wedge in place, it will be tough to keep any low level cold air in place and as such with only a marginal thermal profile to support snow, we will be relying on any potential heavier snowfall rates to support any snow accumulations across the interior. Still, as of right now, there seems to be an improved chance for some measurable snow across much of central VA including the RIC metro...extending N-NE into the MD eastern shore. As such, will go with accumulations around an inch late Friday night into Saturday morning for central VA, and around 2 inches for interior MD eastern shore including SBY and Cambridge (where there actually is potential for cold air to get locked into place). Most likely, there will be a narrow band of locally higher snowfall (perhaps 2 inches) somewhere across central VA. However, given the complexity of the thermal profiles and where the best precipitation will set up, it is nearly impossible to pinpoint at this time. Otherwise, precipitation diminishes from west to east late Saturday into Saturday Night. Cold but dry Sunday with temperatures only topping out in the upper 30s. Lows Saturday night in the mid-upper 20s.
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&& .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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The long term period will be characterized by below normal temperatures as a long wave trough sets up over the eastern CONUS. A vigorous shortwave is shown to rotate through the mean trough and pivot across the local area late Tuesday into Wednesday. This feature will reinforce the already chilly air in place and probably bring our coldest readings so far this season. In addition, widely scattered snow showers may occur as the upper trough pivots through Tuesday night/Wednesday. Will introduce slight chc pops at this time. Highs Mon/Tues from the mid 40s to around 50. Highs Wed in the 30s to around 40. Highs next Thurs mainly in the 40s. Low temps Sunday night in the 20s, to near 30 coast. Lows Mon night from the upr 20s Piedmont to the mid 30s coast. Lows Tues/Wed nights from around 20 Piedmont to nr 30 coast.
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&& .AVIATION /21Z THURSDAY THROUGH TUESDAY/... Frontal boundary remains (well) S and E of the local area through the 12Z/07 TAF forecast period. BKN-OVC VFR CIGS (mainly aoa 10kft) continuing. Area of -RA has settled just SE of NE NC. Winds mainly VRB blo 10 kt. The frontal boundary remains off the coast through Sat with a series of weak low pressure areas tracking ENE along it but remaining offshore. BKN-OVC CIGS/occasional pcpn expected at KORF/KECG...and possibly KPHF (by late) tonight/Fri. Pcpn may trend NWWD Fri afternoon/night and reach KRIC/KSBY. Pcpn...possibly as a mix of rain/snow...is expected to move offshore by 18Z Sat. VFR conditions are expected for the upcoming weekend after Saturday morning. && .MARINE...
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Light winds/sub-SCA conditions prevail this aftn with seas 2-4 ft and waves of 1-2 ft. Low pressure progged to develop along a stalled frontal boundary pushing N from Florida late tonight/Fri. Expect winds to shift to N by Fri morning, but with a weak pressure gradient, conditions winds will remain below Small Craft Advisory criteria through Friday. As the sfc low gradually moves NNE off the coast Fri night and intensifies on Sat, expect SCA conditions to develop over the southern VA and NC coastal waters (seas to 5-6 ft) and possibly the lower Bay and Currituck Sound. Strong cold front passes through Sat night and SCA conditions look to prevail for all zones Sunday (potential for a few brief gusts to Gale force Sun morning). Elevated westerly flow of 15-20 kt to continue Mon-Tue.
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&& .CLIMATE...
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Avg 1st Data with Measurable Snowfall at Sites (Data based on 1981-2010): * Richmond: Dec 25th * Norfolk: Jan 12th * Salisbury: Dec 25th * Wallops: Dec 26th * Louisa: Dec 18th * Farmville: Dec 24th
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...ALB/MAS/MRD NEAR TERM...MRD SHORT TERM...MRD LONG TERM...JDM AVIATION...MRD MARINE...LKB CLIMATE...AKQ

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