Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 181210 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 710 AM EST Sat Nov 18 2017 .SYNOPSIS... High pressure slides offshore this morning, ahead of a cold front approaching the region from the west. The cold front moves across the area late tonight into Sunday morning, producing scattered showers. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Latest surface analysis features ~1021mb surface high pressure centered over the Virginia and Carolina coastal plain early this morning. To the west, a large, positively-tilted upper trough continues to drop across the Mississippi River Valley this morning, with the surface low centered over MO/IL at 10z. Quiet/benign weather lingers through the first part of the day, as surface high pressure nudges offshore, with resultant low- level return flow increasing around the offshore high. Tightening pressure gradient due to the approaching front will allow for breezy conditions through the afternoon with gusts of 25 to 35 mph (highest immediate coast and Eastern Shore). Took down forecast highs slightly, but still expect temps to rebound nicely w/compressional warming and out ahead of the approaching cold front. highs today into the mid/upper 60s SE zones...upper 50a to mid 60s farther inland. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... Surface low will lift across the eastern Great Lakes toward southern Quebec tonight into Sunday morning. Trailing cold front will push across the area after midnight tonight, reaching the coast around/just after dawn Sunday morning. Ahead of the front, expect quick dewpoint surge as the warm front lifts across the area Sat aftn/night. Low level S-SW flow quickly increasing PW values into the 1"-1.25" range after 00z/Sun. Still anticipate 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. Aforementioned increasing PW, along with a narrow axis of low-level convergence/forcing, will lead to a broken line of scattered to numerous showers through the overnight period. Accordingly, have pushed pop into high end likely/categorical range, highest over western sections. CAPE is nearly nil through this period, some have again held thunder wording out. Breezy conditions persist 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. A wind advisory was considered but has not been issued with this package, with winds likely to be just below criteria. That said, expect a small window of windy conditions Sunday morning (especially north), with blustery and chilly conditions continuing through Sunday. Temperatures remain mild tonight before dropping off late tonight. Temperatures struggle to rise Sunday morning, aided in small measure by clear sky and sunshine, but remain steady/drop off Sunday afternoon. Winds diminish late afternoon as the gradient slackens. Cooler with highs in the 50s...to near 60 SE coast. One last surge of wind possible with another passing disturbance Sunday night. Blustery conditions ease through the night as cool sfc high pressure centered over the TN Valley expands east into the Mid-Atlantic late Sunday and Monday. We can expect a clear sky and below normal temperatures. Lows Sunday night in the mid/upr 20s Piedmont to the mid/upr 30s coast. Highs Monday in the upr 40s to low 50s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... High pressure moves offshore of the region during the day on Tuesday allowing for a warming trend. Highs on Tuesday will climb into the upper 50s to lower 60s and lows fall into the upper 30s to low 40s inland (mid to upper 40s at the coast). Temperatures remain near normal during the day on Wednesday before a mainly dry cold front crosses the area Wednesday late afternoon/evening. Introduced a slight chance of PoPs with the passage of the front, but moisture appears fairly limited at this time. A cooler airmass moves into the region for Thanksgiving and the end of the work week behind the front. Temperatures are expected to be below normal for Thanksgiving Day with highs in the upper 40s to low 50s and lows dropping into the lower 30s away from the coast. An offshore trough develops on Friday which will bring a chance of rain for coastal areas. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... VFR conditions across area terminals will persist through the 12z TAF period. Surface high pressure over the Mid-Atlantic coast will slide offshore through this afternoon. Clouds will gradually thicken/lower this afternoon and tonight as a strong cold front approaches the region through tonight. Winds will be gusty ahead of the front Saturday afternoon, gusting out of the southwest between 20-25kt. Outlook: The cold front crosses the area late tonight into Sunday morning, with the possibility of some short-lived MVFR ceilings with sct/numerous rain showers with the frontal passage. LLWS will be a concern tonight into Sunday morning just ahead of the front, 35-45kt at 2kft AGL. Winds quickly swing around to the W-NW post-frontal and will be highest within a few hours of frontal passage, but will remain gusty through Sunday. High pressure builds back over the local area Sunday morning, allowing for a return to VFR conditions through the remainder of the weekend. High pressure gradually slides off the Southeast coast Monday and Tuesday with VFR conditions prevailing. && .MARINE... High pressure slides off the Carolina coasts today as a strong cold front approaches the area from the west today. Winds a tad slower to increase through this morning. By this aftn, SW winds will increase to 15-20kt as the pressure gradient tightens significantly with the high offshore and the cold front passing through the Ohio Valley. 00Z model guidance shows impressive pressure falls of 6-9mb occurring this aftn into this evening ahead of the front. Expect SW winds to increase to 20-30kt with gusts ranging from 25-35kt. The pressure gradient tightens up more after midnight tonight with gusts increasing to 40kt all coastal waters...mainly due to a strong temperature gradient associated with this low pressure system. In addition, gusts could reach up to 35kt over Currituck Sound between 200 AM to 900 AM. Will need to monitor gale gust potential here and possibly the mouth of Ches Bay. Seas build to 3-5ft north/3-4ft south this aftn...then build to 5-8ft north/5-6ft south after midnight tonight. Waves build to 3-4ft this aftn...then build to 4-5ft late this evening. Cold front crosses the waters around sunrise Sunday morning. Strong cold air advection, a very persistent tight pressure gradient, and rapid pressure rises (5-9mb) behind the front will all contribute to a continuation of strong NW winds 20-30kt with gusts of 25-40kt through Sunday. Windy conditions will be common everywhere on Sunday (including over land areas) and generally uniform with slightly stronger winds occurring over the warmer waters. Winds should remain generally unchanged Sunday night with NW winds averaging 15-25kt with gusts averaging 30kt. A secondary surge in NW winds may be possible Sunday night as coldest part of airmass swings across the area. However, relaxing pressure gradient with high pressure building over the Southeast States may prevent a surge from happening. High pressure continues to build over the Southeast States into the srn Mid Atlantic Region Mon/Mon night... sliding offshore on Tuesday. Adverse boating conditions to subside during Monday with more benign/quiet sub- SCA conditions anticipated through Wednesday. Gale warnings now in effect for all coastal waters from this evening through early Monday morning. SCA flags begin on Ches Bay by mid morning today through mid morning Monday morning. River/Sound begin this aftn and persist through roughly sunrise Monday morning. For specific details, please visit www.weather.gov/wakefield/marinebrief. && .TIDES/COASTAL FLOODING... Gusty SW winds may push a few areas into the action stage during Saturdays high tide cycle. Nuisance type flooding may be possible...especially in vicinity of Bishops Head this afternoon and overnight. && .EQUIPMENT... KDOX remains down until further notice due to a pedestal fault. Updates will be provided here and in FTMDOX as they become available. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 7 AM EST Monday for ANZ633-635>638. Small Craft Advisory from 10 AM this morning to 10 AM EST Monday for ANZ630>632-634. Small Craft Advisory from 10 AM this morning to 7 PM EST this evening for ANZ650-652-654. Gale Warning from 7 PM this evening to 4 AM EST Monday for ANZ650-652-654. Small Craft Advisory from 1 PM this afternoon to 7 PM EST this evening for ANZ656-658. Gale Warning from 7 PM this evening to 3 PM EST Sunday for ANZ656-658. && $$ SYNOPSIS...MAM NEAR TERM...AJZ/MAM SHORT TERM...JDM/MAM LONG TERM...AJB AVIATION...AJB/MAM MARINE...BMD TIDES/COASTAL FLOODING... EQUIPMENT...

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