Area Forecast Discussion
Issued by NWS Sterling, VA

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392 FXUS61 KLWX 251443 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 943 AM EST Sun Feb 25 2018 .SYNOPSIS... A stationary boundary draped across southern Virginia will lift northward today as a warm front. A cold front will approach from the west and cross the area by this evening. High pressure will then build in over the region, migrating off the Mid Atlantic coast by midweek. A broad area of low pressure will approach the Great Lakes region on Thursday, bringing unsettled weather to our region through weeks end. && .NEAR TERM /THROUGH TONIGHT/... Dense Fog Adv was extended for S MD and adjacent waters until 11am. Main channel of showers moving through the forecast area today... mainly this morning. Have adjusted the forecast based on the latest models and trends. Went with a combo of the models that have been doing best most recently for high temps today, including NAM, NAMNest, Euro, Hi_Res ARW...those which you would expect would do best in damming situations. Improving conditions today. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... High pressure continues to move eastward over the Mid Atlantic on Monday, with a shortwave trough crossing overhead and pressing off to our east by Monday evening. This will help skies to finally start to clear by Monday afternoon, bringing a welcome return of some sunshine. Did keep slight chance POPs in the gridded forecast for the first half of Monday for our extreme southern zones as some guidance wants to keep the frontal boundary just close enough to have the possibility of light shower activity for these areas. Temperatures remain above normal on Monday, with highs in the middle to upper 50s. High pressure will settle overhead Monday night, coupled with light winds, this allow temperatures a good chance to radiate under mostly clear skies. Middle to upper 30s will be prevalent in the metro areas, with lows at or slightly below freezing along and west of the Blue Ridge. Clear and dry conditions continue Tuesday and Tuesday night as high pressure dominates the region, migrating off the Mid Atlantic coast by Tuesday night. Highs on Tuesday will be in the upper 50s to near 60 degrees, with lows Tuesday night in the upper 30s to near 40 degrees. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The extended portion of the forecast will start out with high pressure moving offshore. Warm advection in the return flow will provide enough lift for scattered showers to arrive during the day Wednesday. The warm front will approach the forecast area Wednesday night, and arrive on Thursday as mid level energy runs through rather fast flow. Therefore, PoPs will spread from central Virginia across the entire area by Thursday. Temperatures will be mild for the period. A deep cyclone will be developing in the Great Lakes/Midwest Thursday, which will be sending a moisture-rich cold front across the area Thursday night, with some precip likely lingering into Friday. Believe that rain will be the dominant type with this system; cold air will be rushing in Friday PM on gusty northwest winds after the precip departs. This could provide some upslope snow showers to the Appalachians Friday night. High pressure will be building across the area Saturday as the deepening cyclone continues northeast. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... Challenge between fluctuations between all flight categories of restrictions this morning, but the trend is up for both visby and cigs today. A cold front will approach the terminals midday, moving east of the area by around 26/00z. As a result, winds will veer from the south this morning, to the west southwest this afternoon, and out of the northwest by this evening. Ahead and along of the front, winds will gust to around 20 knots during the day, along with MVFR/IFR conditions as -SHRA moves over the terminals. VFR conditions return in the wake of the front this evening, continuing through the first half of the work week as high pressure builds over the region, promoting light winds and only mid to high level clouds. Scattered showers will be near the terminals Wednesday, mainly to the west. While flight restrictions will be possible, confidence is low. The chances increase sharply Thursday as a warm front heads north toward the terminals. && .MARINE... Areas of dense fog over the adjacent waters to southern Maryland this morning. Also some wind gusts of 15 to 20 kt with a leading edge of showers moving through the same area this morning. SCA conditions expected this afternoon as a warm front lifts northward in to the area and a cold front approaches from the west. Have left the upper portion of the Bay out of the SCA at this time as not expecting the warm front to travel this far north, thus keeping wind gusts down in these areas. The cold front will sweep through the waters this afternoon, potentially accompanied by some gusty showers. High pressure builds over the waters through the first half of the work week, resulting in light winds over the waters with no headlines anticipated. Small Craft Advisories not anticipated Wed or Thu either, due mainly to poor mixing in vicinity of a warm front and complex storm system. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Dense Fog Advisory until 11 AM EST this morning for MDZ016>018. VA...Dense Fog Advisory until 11 AM EST this morning for VAZ057. WV...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ532>534-536-537-540>543. && $$ SYNOPSIS...BKF NEAR TERM...STRONG SHORT TERM...BKF LONG TERM...HTS AVIATION...BKF/HTS/CS MARINE...BKF/HTS/CS

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