Area Forecast Discussion
Issued by NWS Wakefield, VA

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414 FXUS61 KAKQ 091649 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1149 AM EST Sat Dec 9 2017 .SYNOPSIS...
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A frontal boundary remains nearly stationary off the Mid Atlantic coast through tonight. Low pressure will track northeast along this boundary today. Cold high pressure builds into the area tonight into early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Latest wx analysis indicates elongated ~1002 mb sfc low pressure from off Cape Hatteras NC NNE to well off the Delmarva as of late this morning. Precipitation has been rather light over the past few hrs with either light snow or a light mix along and west of the I-95 corridor and over the interior MD eastern shore...with mainly rain farther SE. However, latest radar is beginning to fill back in and a more prominent band of snow is now situated from between Farmville and South Hill on NNE through Goochland/western Hanover and Caroline Counties. This band is expected to persist and likely become enhanced through the next few hrs as the forcing increases with RRQ of ~175 KT upper Jet streak and 500 mb shortwave moves into the region. Latest RAP/NAM 12 approximate the changeover to all snow with the 1295 m 1000-850mb thickness and 32F sfc wet bulbs. Initially, there is enough of a warm nose aloft and higher 850-700mb thicknesses to support some sleet or a light mix through 18Z, but after that P-type should become just rain vs. snow. Made some minor adjustments to the forecast to lower additional snow amts slightly/mainly to 1-2" for much of central and eastern VA, though will maintain higher amts of 2-3" (locally up to 4") over the northern Neck and interior MD eastern shore as the band will tend to pivot and slow down a bit late this aftn and into the early evening in these areas. Also, models shows the cold air aloft/1000-850 mb thicknesses crashing below the critical 1295-1300 m over interior SE VA between 19-22Z and reaching the coast after about 22-23Z. Thus, increased snow amts for up to an inch of snow by late aftn in the SE. Confidence not high enough to add any advisories there, but will continue to monitor for a potential winter wx advy over some of SE VA where there is currently no headline in effect if the band were to expand more to the SE. Otherwise, no changes necessary to going winter weather headlines, with warnings bounding a South Hill to Richmond to Salisbury MD line, flanked by Advisories on either side. Highs today remaining steady in the low to mid 30s inland...upper 30s to lower 40s SE coast.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
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By this evening, sky will gradually clear out in subsidence behind the departing upper trough, though some clouds will persist through 06-09Z on the ern shore. The clearing combined with the strong cold advection will allow temps to drop into the 20s late this evening/overnight. Roads may become slick and any snow that remains on the ground will become quite compacted. Sunday should be a cool day with temps only in the upper 30s/lower 40s even with mostly sunny skies.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/... The long term period will be characterized by below normal temperatures and mainly dry wx 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 especially over eastern areas as the upper trough pivots through Tuesday night/Wednesday. Highs Mon/Tues from the mid 40s to around 50. Highs Wed in the mid to upper 30s. Highs next Thurs in the low to mid 40s. Similar into Fri. 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. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Have noted widespread IFR conditions across area terminals this morning. Conditions will deteriorate once again across terminals over the next few hours this morning, as precipitation moves back in over the next few hours. FZDZ/very light snow at RIC will transition back to a period of RASN then SN by 15z before ending late afternoon/early evening. Snow continues at SBY, possibly mixed with PL at times. RA at PHF/ORF/ECG today before ending tonight. Quieter wx returns behind the departing system from Saturday night through early next week. && .MARINE... An active period expected for the next several days with sfc low pressure currently along a frontal boundary from the eastern gulf of Mexico to off the NE FL Atlc coast. N/NE winds currently range from 15 to 25 knots over the waters with waves of 3-5 feet and seas of 4- 7 feet. Small Craft Advisories remain in effect for all of the waters minus the upper rivers through Sunday. A strong cold front passes through tonight, shifting winds to the WNW, and allowing for Small Craft conditions to prevail for all zones (including the upper rivers). Small Craft Advisories have been extended for much of Sunday with the passage of the front. While there may be a brief gust to near gale force Sunday morning it will be limited and Gales are not expected. Elevated westerly flow of 15-20 kt to continue Mon- Tue and will increase to 20-30 kt late Tue night and Wed. && .TIDES/COASTAL FLOODING... Water levels in the lower Bay and NC Outer Banks may approach minor flood thresholds during late morning/early aftn Sat high tide, but do not anticipate headlines being needed attm. && .CLIMATE... Avg 1st Date 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 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Winter Weather Advisory until 4 PM EST this afternoon for MDZ024. Winter Storm Warning until 7 PM EST this evening for MDZ021>023. NC...None. VA...Winter Weather Advisory until 4 PM EST this afternoon for VAZ048-078>083-085-509-510-514-516-518-520-522. Winter Storm Warning until 4 PM EST this afternoon for VAZ060>062-064>069-075>077-511>513-515-517-519-521. Winter Weather Advisory until noon EST today for VAZ099. MARINE...Small Craft Advisory until 6 PM EST Sunday for ANZ650-652-654. Small Craft Advisory until 1 PM EST Sunday for ANZ633-638-656- 658. Small Craft Advisory until 4 PM EST Sunday for ANZ630>632-634. && $$ SYNOPSIS...MAM NEAR TERM...LKB SHORT TERM...ALB/MAM/MRD LONG TERM...MAS AVIATION...ALB MARINE...AJB/LKB TIDES/COASTAL FLOODING... CLIMATE...

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