Area Forecast Discussion
Issued by NWS Wakefield, VA

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349 FXUS61 KAKQ 190021 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 721 PM EST Sat Feb 18 2017 .SYNOPSIS... A weak area of low pressure moves through the Carolinas tonight with high pressure returning by Sunday afternoon. A backdoor cold front pushes through the Eastern Shore Sunday night as high pressure builds well north of the region and slides off the coast by Tuesday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... The latest analysis depicts a split flow pattern across the Central and Ern Conus, with a srn stream trough moving into the Tennessee Valley upstream of a ridge pushing off the Mid- Atlantic coast. The nrn stream is well to the N with a trough SE of James Bay. Upper level moisture is increasing ahead of the trough to the WSW with high clouds thickening across the region. Very mild inland W of the Bay this afternoon with temperatures in the low/mid 70s, with mid 60s for the interior Ern Shore, and upper 50s/low 60s for areas of the Ern Shore adjacent to the ocean/Bay. The upper system dampens tonight as it lifts into the central Appalachians, with the main forcing shifting off the Southeast coast. Becoming mostly cloudy to overcast across the area tonight. PoPs have been lowered to less than 15% for the CWA tonight, but there will likely be a few radar echoes, and there could be some very isolated light rain out of an 8-10kft cloud deck. Overnight lows range from the upper 40s to around 50. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Low pressure ambles offshore Sunday as weak high pressure builds in from the west. 850mb temperatures drop to around +6-8C, but will be offset by downsloping albeit light NW flow. Above normal temperatures continue (+1.5-2.0 st dev) with decreasing clouds. Forecast highs range from the upper 60s to low 70s west of the Bay and for the interior Ern Shore, with locally cooler temperatures at the immediate coast. High pressure builds into the Ern Great Lakes Sunday night and pushes a backdoor cold front through the Ern Shore. This high (1030+ mb) will continue to build ewd Monday resulting in onshore flow along the coast, which will result in cooler (but still above normal) temperatures along the coast, while the Piedmont will remain mild. Lows Sunday night/Monday morning range from 40-45F. Forecast highs range from the low/mid 50s for the Ern Shore, to the low/mid 60s in the I-95 corridor, to the low 70s over the Piedmont. Mostly clear/sunny Sunday night into Monday. Surface high pressure will prevail over the region Monday night with low temperatures dropping into the low/mid 30s NE to the upper 30s/around 40 W under a mostly clear sky. The high gradually slides offshore Tuesday as a weakening cold front approaches from the W. Mixing will be limited, only to about 950-925mb, with high temperatures ranging from the low/mid 50s NE to the low 60s SW. Mainly clear early with increasing high clouds by aftn. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... High pressure slides off the Mid Atlantic Coast Tue night and settles over the Southeast coastal waters on Wed. The area continues to sit in the middle of split flow aloft (primarily westerly flow) with active systems passing well north and well south. Models still struggling in regard to how far south to bring precip associated with nrn system. However, available shortwave moisture/energy is still being sheared apart. Have maintained ongoing precip forecast by keeping a slight chance for showers mainly across nwrn half of CWA during Tue night with dry conditions for Wed as aforementioned shortwave moves offshore. Otherwise, expect a dry forecast through Thu night with temperatures running anywhere from 15-20 degrees above seasonal normals. Lows generally mid 40s to mid 50s. Highs generally mid-upper 60s to lower 70s inland/low-mid 60s immediate coast. Next big system to potentially impact the Mid Atlantic Region exits the Plains Thu night and tracks northeast into the Great Lakes on Fri. Increasing south winds and decent warming ahead of a strong cold front is anticipated for Fri/Fri night. Scattered showers will be possible Fri aftn/evening and maybe even some thunder...but only if the timing of the frontal passage doesn`t change (i.e. the arrival of the front will likely slow down its ewd progression as upper level troughing digs behind the sfc low). Forecast highs for Fri are currently in the low-mid 70s inland/low-mid 60s beaches, however they could easily end up being several degrees warmer due to a tightening pressure gradient and subsequent well-mixed environment, ample warm air advection occurring ahead of the front, and longer daytime hours as we approach meteorological spring. Lows Fri night will be highly dependent on when the frontal passage occurs. Warm temps should be anticipated through most of the night with readings falling in the Piedmont and far nw counties closer to sunrise. For now, lows Fri night will be around 50F (+/- a few degrees). && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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Weak low pressure moves through the Carolinas overnight and then off the coast in the morning. High pressure slowly strengthens over the Mid Atlantic States Sunday and Monday then slides off to the east and south Tuesday. A southwest flow prevails during midweek. Mid level moisture will produce a band of mid level clouds over most of the TAF sites overnight which will diminish Sunday morning. VFR conditions will prevail through the 00Z TAF period. Southwest winds veer to northwest and north on Sunday. OUTLOOK...Mainly dry weather is expected through Thursday.
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&& .MARINE... Sfc pressure gradient has tightened up a bit this aftn and a slight uptick in winds has been observed. Winds generally south 10-15kt. Wind speeds will hold steady around 10-15kt through tonight while veering to the sw overnight as a weak trough crosses the waters late tonight/early Sun morning. The trough is expected to push ewd the rest of Sun as a more defined sfc low develops well of the Southeast Coast. The end result will be winds becoming light (10kt or less) from the nw. Sub-SCA conditions will prevail Mon through Thu. Wind speeds aob 15kt, seas 2-3ft, and waves 1-2ft. Wind direction n on Mon, becoming onshore ne-se Mon night through Tue, then s-sw Tue night through Thu. && .CLIMATE...
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No records were set on Saturday. Listed below are the records and actual highs for Saturday. Also listed are the records for Sunday. Forecast high temperatures fall short of records but come rather close at SBY. * Site Sat 2/18 High Sat Sun 2/19 Forecast Sun highs * RIC: 77 (2011) 74 78 (1961) 72 * ORF: 77 (1937) 7673 (1907) 67 * SBY: 75 (1976) 68 72 (1961)71 * ECG: 80 (1976) 71 77 (1939) 67
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...AJZ/MPR NEAR TERM...AJZ SHORT TERM...AJZ/MPR LONG TERM...BMD AVIATION...LSA MARINE...BMD CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.