Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 190011 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 711 PM EST Sat Nov 18 2017 .SYNOPSIS... A strong cold front moves across the area late tonight then pushes off the coast Sunday morning. High pressure builds into the area Sunday afternoon through Tuesday. The next cold front crosses the area early Wednesday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Latest MSAS has a warm front located ivof the Mason-Dixon line. The main low lifts across the Gt Lakes and into southern Canada late tonight with the trailing cold front not progged into the area until after midnight. Latest data supports a dry evening across the fa with pcpn not moving east of mts until around 04Z. Expect rising dewpoint temps as the low level S-SW flow quickly increases PW`s into the 1"-1.25" range. Thus, temps not falling much this evening with readings between 55-60. Latest data continues to support a quick-moving band of showers along and ahead of the cold front just after midnight out in the piedmont, reaching the coast by Sunday morning. The increasing PW, along with a narrow axis of low-level convergence/forcing, will lead to a broken line of showers through the overnight period. Thus have maintained likely to categorical pops, highest across the north. No CAPE to speak of, so kept thunder out of the grids. Breezy to windy conditions continue through the night. H92-850 winds increase to 40-50 kt as gradient tightens just ahead of the front. Expect strongest winds to be within a few hours of frontal passage as subsidence behind the departing boundary mixes down some of that wind. Mild most of the night east cooling off late across the west. Lows upr 40s west to mid-upr 50s along the coast. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Cold front and any lingering shwr activity along the coast arnd 12Z quickly moves offshore by 15Z. Tsctns show rather quick drying of the column so expect skies to become mstly sunny. Blustery with gusty W-NW winds and only a slow rise in temps despite the sun. Winds diminish towards sunset. Highs in the mid 50s-lwr 60s. Sfc high settles over the sern states Sun night and Mon then drifts off the coast Tues. Passage of an upr level system will usher in one last surge of CAA Sun night. Otw, dry with a slow warming trend. Lows Sun night in the upr 20s NW to mid 30s SE. Highs Mon in the upr 40s-lwr 50s. Lows Mon night in the 30s to near 40 se. Highs Tue in the upr 50s to lwr 60s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Model differences make for a challenging mid week and holiday fcst. The next cold front progged to cross the area Tues nite. Challenge comes from just how much moisture gets entrained ahead of the front from a trof off the Carolina coast and weak low progged to move ne along it? GFS much more aggressive with the moisture than the ECMWF. For now, elected to keep measurable rainfall east of I95 Tue nite and Wed with slght chc pops across the east Thurs. Lows Tue nite in the 40s to near 50 se. Highs Wed 55-60. Lows Wed nite in the 30s to lwr 40s se. Cool Thurs with highs mid 40s-lwr 50s. Dry and cool Fri and Sat as high pressure builds into the area. Highs Fri 50-55. Lows mid 30s-lwr 40s. Highs Sat 55-60. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR conditions to start the TAF period with only mid/high level clouds overspreading the region. A cold front crosses the region overnight, impacting the TAF sites mainly after 06Z, bringing some lower ceilings and a chance for showers. Am expecting ceilings to primarily remain VFR with the passage of the front, but a few pockets of MVFR ceilings cannot be ruled out. Otherwise, the main concerns of the forecast will be the potential for gusty winds and wind shear tonight. Models continue to show 35 to 50 knots at 2000 feet, thus continued the mention of wind shear ahead of the cold front in the forecast. The front exits the region by or shortly after sunrise on Sunday with winds becoming W-NW post frontal. VFR conditions are expected through the day on Sunday, but winds will remain gusty out of the W/NW with gusts as high as 30 to 35 knots. Outlook: High pressure builds over the region later Sunday through Monday and then tracks off the Southeast coast Tuesday. VFR conditions are expected during this time frame. && .MARINE... Late this aftn, sfc high pressure was cntrd off the Mid Atlc coast, while sfc low pressure was cntrd over extrm wrn OH. A cold front extended SW fm the low thru srn IN and down into the lower MS valley. SSW winds were 10-20 kt with gusts into the upper 20s (kt) late this aftn over the waters. The pressure gradient between the high offshore and the approaching cold front will tighten this evening into early Sun morning, resulting in SW winds increasing to 20-30 kt with gusts ranging from 25-40 kt. The cold front will cross the waters generally between 11Z-14Z Sun morning, with winds then shifting to the NW behind the front. On the late this aftn fcst, have decided to go ahead and hoist the Gale warning (one headline) for the entire coastal waters, due to gale conditions (gusts) expected within the next 12 hrs. Also, for now, have kept SCA`s in effect for all the other waters, even though there could be isolated gusts to 35 kt at the mouth of the Ches Bay or the Currituck Snd. Decent cold air advection, a persistent tight pressure gradient, and rapid pressure rises (5-9mb) behind the front will all contribute to a continuation of strong NW winds 20-30 kt with gusts of 25-40 kt through Sun. Breezy to windy conditions will prevail over much of the area on Sun, and generally uniform with slightly stronger winds occurring over the warmer waters. Winds should remain generally unchanged Sun night with NW winds averaging 15-25 kt with gusts averaging 30 kt. Will still have to monitor for possible gale gusts at the mouth of the Ches Bay or the Currituck Snd during Sun. A secondary surge in NW winds may be possible Sun night, as the coldest part of the airmass swings across the area. However, relaxing pressure gradient with high pressure building over the Gulf coast States into the TN valley will likely prevent a very strong surge from happening. High pressure continues to build over the Southeast States into the srn Mid Atlc region Mon/Mon night, then sliding out to sea on Tue. Calmer sub-SCA conditions anticipated Mon aftn into Wed. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ633-635>638. Small Craft Advisory until 10 AM EST Monday for ANZ630>632-634. Gale Warning until 4 AM EST Monday for ANZ650-652-654. Gale Warning until 3 PM EST Sunday for ANZ656-658. && $$ SYNOPSIS...MPR NEAR TERM...AJZ/MPR/MAM SHORT TERM...MPR LONG TERM...MPR AVIATION...AJB MARINE...TMG is the U.S. government's official web portal to all federal, state and local government web resources and services.