Area Forecast Discussion
Issued by NWS Sterling, VA

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230 FXUS61 KLWX 300131 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 831 PM EST Tue Nov 29 2016 .SYNOPSIS... An area of low pressure will move across the area Wednesday with a cold frontal passage Wednesday night. High pressure will return to the region Friday and Saturday. Low pressure will approach the region Sunday. && .NEAR TERM /THROUGH WEDNESDAY/... A Dense fog advisory is in effect across much of the outlook area tonight and into Wednesday morning. Widespread fog with visibilities around a quarter mile or less are expected tonight. High pressure is centered across the Potomac Highlands this evening. Recent rainfall and low dewpt depressions have resulted in fog across the area. A pressure gradient exists across the Tidewater region and southern MD tonight. This will limit fog development in these locations. A cold front located near the Mississippi River Valley will progress eastward overnight. Another round of showers is expected to enter the Mid-Atlantic by Wednesday morning. Rainfall and a tightening pressure gradient should break up dense fog around sunrise Wednesday. Showers spread northeast across the northern half Wed morning while southern areas remain mostly dry but cloudy. Model soundings indicate sufficient elevated instability and high equilibrium temperatures during the morning hours suggesting there could be a few rumbles of thunder early in the day. Cold frontal bdry begins to enter western areas around 21Z with a narrow line of showers moving from Higland county east to southern MD during the late afternoon and early evening hours. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... Cdfnt clears the fcst area by 03Z Thu with showers ending. A half to an inch of rain is expected. Drying and turning colder on Thu under NW flow. && .LONG TERM /FRIDAY THROUGH TUESDAY/... High pressure centered to our southwest will keep dry conditions Friday into Saturday... it will then move overhead into early Sunday. High temperatures will be in the 40s and 50s in most place, could reach the low 30s at higher elevations. Sunday into Monday guidance diverges in the timing of a low pressure/upper level short wave that will move from the Gulf states to the northeast sometime between Sunday afternoon and Monday night. Precipitation associated to this system could be approaching the Mid- Atlantic region as early as Sunday evening -based on the Euro. Warm front moves through followed by a cold front. High pressure/dry conditions for Tuesday. GFS has a similar scenario but happening almost 24 hours later... with drier conditions Monday. Low temperatures Sunday and Monday nights could allow for some snow showers, mainly at higher elevations. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... Dense fog and low cigs are expected at the terminals tonight. LIFR conditions expected under light winds. -SHRA will move across the region Wednesday morning. Some showers may result in vsbys dropping but main impact will be IFR cigs through the morning hours. S winds will increase by Wed afternoon and another round of showers is expected to move through. Some showers may be heavy resulting in restrictions and gusty winds. Cdfnt crosses the area by 06Z Thu with shifting winds and showers ending improving flying conditions. Dry conditions expected for Friday into part of Sunday with high pressure dominating weather conditions... there VFR conditions expected. On Sunday possible storm system could bring showers to the terminals, allowing for conditions to become sub-VFR... but there is still uncertainty on the timing of this system. && .MARINE... S winds continue on the waters overnight. Stronger winds will be across the lower tidal potomac and adjacent bay zones. Small craft advisory is in effect these locations including the tangier sound. S winds increase on all the waters Wednesday and SCA is in effect. A cold front will cross the waters Wed evening and there is a potential for gale force winds ahead of the frontal passage. Confidence is low at this time. Dry conditions expected for Friday into part of Sunday with high pressure dominating weather conditions. Gusty winds possible Friday into Sunday... so a small craft advisory could be possible during this period. && .TIDES/COASTAL FLOODING... Anomalies have dropped to near a foot above normal. Coastal flood advisories are no longer in effect. Southerly flow will continue on the waters through Wednesday however water levels should stay below flood stage. A cold front cross the waters Wed evening. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Dense Fog Advisory until 7 AM EST Wednesday for DCZ001. MD...Dense Fog Advisory until 7 AM EST Wednesday for MDZ003>006-011- 013-014-016-502>508. VA...Dense Fog Advisory until 7 AM EST Wednesday for VAZ025>031- 036>040-050>057-501-502-505>508. WV...Dense Fog Advisory until 7 AM EST Wednesday for WVZ050>053-055- 502-504. MARINE...Small Craft Advisory from 6 AM to 6 PM EST Wednesday for ANZ530>532-535-538>540. Small Craft Advisory until 6 PM EST Wednesday for ANZ533-534- 536-537-541>543. && $$ SYNOPSIS...LFR NEAR TERM...HSK/LFR SHORT TERM...LFR LONG TERM...IMR AVIATION...HSK/IMR/LFR MARINE...HSK/IMR/LFR TIDES/COASTAL FLOODING...HSK is the U.S. government's official web portal to all federal, state and local government web resources and services.