Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 190821 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 321 AM EST Sun Nov 19 2017 .SYNOPSIS... A strong cold front moves across the area this morning then pushes off the coast by midday. High pressure builds into the area this afternoon through Monday, before sliding offshore Monday night through midweek. The next cold front crosses the area on Wednesday. && .NEAR TERM /THROUGH TONIGHT/... Front now just to the west of the local area this morning, with pre-frontal showers now pushing across the piedmont toward the I-95 corridor. With the moisture being pinched off from the south, the expectation is that the rain showers will be diminishing as they move through the area. Still, QPF looks to be on track w/Western sections of the forecast area could see up to a quarter inch of rainfall. By the time the front reaches the coast, the expectation is of just scattered showers. Hi-res models jiving very well with obs thus far, and a period of rather gusty winds (30-40 mph) still anticipated over the next few hours, with winds maxing out immediately behind the frontal passage across the entire area, as some of the cold air surge gets mixed down by strong subsidence behind the front. Winds decrease slightly later this morning, but remain breezy through the day, owing to still-tight pressure gradient and mixing up to 875 mb. NW winds gusting to 25 to 35 mph (strongest far north and MD eastern shore) through the afternoon before they drop off. Temperatures at 08z remain in the low to mid 60s (upper 50s far west) across the local area. Temperatures do fall off quickly behind the front over the piedmont, reaching the upper 40s/low 50s by sunrise. Cold front and sct showers along the coast just after sunrise will push offshore by mid-morning. Subsequent subsidence will allow for quick scouring out of the vertical column, with mostly sunny conditions most zones by late morning. Blustery with gusty W-NW winds and only a slow rise in temps despite the plentiful sunshine. Highs in the mid 50s- lwr 60s. Sfc high settles over the sern states tonight through Monday, sliding offshore Monday night into Tuesday. look for early morning lows in the mid/upper 20s piedmont to mid 30s far SE zones under a mainly clear sky. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Rather benign weather pattern to start the holiday week. Aforementioned high pressure sliding offshore of the southeast coast will maintain dry weather across the Mid-Atlantic and southeast. Model thicknesses recover nicely and should allow for a pair of pleasant late fall days. Highs Mon in the upr 40s to low 50s eastern shore. low to mid 50s west of the bay. Partly to mostly clear Mon night. Not quite as cool as flow turns around to the W-SW, with some increasing mid to high clouds late. Early morning lows in the 30s to near 40 se. Warmer in return flow on Tuesday. Could see a few showers in association with a weak low pressure sliding along the coastal Carolinas, but have kept the daylight hours dry and held to slight/low end chance Tuesday night for now. Highs Tue in the upr 50s to lwr 60s. Lows in the 40s to low 50s SE zones. && .LONG TERM /WEDNESDAY 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 slight 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 /07Z SUNDAY THROUGH THURSDAY/... VFR conditions across area terminals early this morning with lowering/thickening clouds out ahead of approaching cold front. The front crosses the region through 12z this morning, and is bringing some pre-frontal showers to the terminals during this period. Overall, expect VFR conditions through this timeframe, with some short-lived MVFR VSBYs possible in heavier showers. Otherwise, main concerns will be the potential for gusty winds and wind shear this morning. 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 today, 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 Sunday evening through Monday, then tracks off the Southeast coast on 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. && .EQUIPMENT... The fan on the temperature sensor at the Richmond ASOS (KRIC) has likely failed, causing erroneous temperature readings. The contract observer is augmenting the official METAR observations (Hourly METAR and SPECIs). However, the 5-min high resolution data is automated directly from the sensor and is subject to reporting this erroneous data. As such, do not rely on the 5 min temperature data from KRIC until our techs can repair the sensor, likely on Monday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 7 AM EST Monday for ANZ633-635>638. Gale Warning until 3 PM EST this afternoon for ANZ634-656-658. Small Craft Advisory until 10 AM EST Monday for ANZ630>632. Gale Warning until 4 AM EST Monday for ANZ650-652-654. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MPR/MAM LONG TERM...MPR AVIATION...AJB/MAM MARINE...TMG EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.