Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 222022 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 322 PM EST Thu Feb 22 2018 .SYNOPSIS...
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A stalled front across south-central Virginia will return northward as a warm front Friday. The next low pressure system will move along the Mason-Dixon region late Friday and Friday night. The low`s associated cold front will drag across the northern half of our region Saturday, before stalling then retreating northward as a warm front by Saturday night. A stronger cold front will push across the region Sunday. High pressure will evolve Sunday night through Tuesday.
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&& .NEAR TERM /THROUGH FRIDAY/...
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A stalled front lies just south of Staunton, Virginia to just north of Richmond, Virginia. Temperatures on the north side of the front are in the lower 50s, while temperatures on the south side of the front are in the lower 70s. This is a big temperature contrast. Radar imagery shows a weak line of rain showers pushing east across our western and northern zones and extending from Highland County, Virginia to Carroll County, Maryland. Rain amounts are generally light with reduced visibility in areas of rain, drizzle and fog across central and northeast Maryland. A persistent north to northeast light wind will continue into tonight to allow for cooler air to remain in place on the north side of the front. Additional rain showers and patchy drizzle is expected to develop later this afternoon and tonight because of the cool air undercutting the milder air aloft. There will be pockets of freezing rain in parts of western Maryland and northern West Virginia in the higher terrain. Current temperatures range from 33 degrees to 36 degrees in these areas, as of 230 pm, and are expected to drop to near 30 in a couple of locations by the overnight. Ice accumulation will be light and probably only amount to a few hundredths of an inch, nonetheless, be cognizant of icy roads and sidewalks. If the roads and sidewalks look wet, they are probably icy. Tonight`s low temperatures will range from the lower 30s in the northwestern areas to the lower 40s in central Virginia. While the northern Appalachian Mountains will be encountering some icy roads in spots due to freezing rain or drizzle Friday morning, the remainder of the region will have periods of rain and drizzle Friday as the stalled front moves north as a warm front. Additional rain amounts will be light with slightly higher amounts across the Mason-Dixon region. Highs Friday will range from the middle 40s in the north to the middle 50s in the south.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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A warm front will shift along our northern zones as an area of low pressure connects to its western end and moves east Friday night. While the rain chances decrease in our southern zones, we will still hang on to rain chances in our northern zones as the low pressure slides to our east. High pressure will swing across New England Saturday into Saturday night. An affiliated cold front with the low pressure will also stall. Temps in the 40s and 50s are expected Saturday on the cool side of the front but temps in the 60s and perhaps 70s are expected on the warm side of the front. Shortwave energy will also pass through the area...bringing the chances for showers. The best chance for rain will be along and north of the front. The stationary front will be in place into Saturday night. Showers are possible with min temps ranging from the 40s north and east of the front to the 50s and perhaps lower 60s south of the front.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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A low pressure system will be moving northeast from the Great Lakes on Sunday while its associated warm front lifts north away from our region. A cold front will then move through on Sunday afternoon allowing for some showers... maybe a thunderstorm. The front will then stall to our south on Monday, but it is unclear how close to our CWA it will be... this may cause additional showers into Monday for parts of our area. A high pressure system will build on Monday into Monday night and be overhead on Tuesday bringing dry conditions over our area. The high pressure will then shift eastward over western Atlantic waters as a return flow settles over us. Guidance then disagrees on the development of a low pressure system over the western Gulf states and its associated boundary. The Euro keeps Wednesday conditions dry, while GFS/GEFS are bringing showers over us as early as Wednesday afternoon as this boundary and the low pressure system approaches us and continue into Thursday. Temperatures will be around 20 degrees above normal on Sunday, with high temperatures reaching the 60s and 70s. Then high temperatures will be mainly in the 50s maybe 60s, with 40s at higher elevations for the rest of the period.
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&& .AVIATION /21Z THURSDAY THROUGH TUESDAY/...
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A stalled front extending from the central Shenandoah Valley to near Richmond, Virginia will linger into tonight. Milder air will overrun surface chilly air that will result in additional periods of rain and drizzle to develop through Friday night. Places that are currently MVFR with low clouds and patchy fog will likely become IFR late this afternoon and continue through Friday. The front may lift further north Saturday and Saturday night. Most terminals should still be on the cool side of the boundary which means more low clouds along with areas of fog...light rain and drizzle. Perhaps KCHO will have improving conditions with the boundary setting up just to their north. Sub-VFR conditions possible Sunday with a frontal boundary affecting our area. VFR conditions should return on Monday into Tuesday with high pressure building over us.
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&& .MARINE...
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A stalled front just to our south will allow for persistent light north to northeast winds through tonight. A Small Craft Advisory remains in effect for Maryland Chesapeake Bay and lower Tidal Potomac River through this evening. The front will likely remain to the south through Saturday night. As of now...it appears that the gradient will be light enough for winds to remain below SCA criteria. On Sunday the winds will be on the increase and come close to criteria, so it should be monitored in case a SCA is needed. Winds will decrease on Sunday night and remain below criteria into Tuesday.
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&& .CLIMATE... From Wednesday February 21st the following records were broken. For IAD: A monthly record high minimum temperature of 59 degrees occurred. This breaks the old record of 55 degrees set on February 17th 1976. The high of 80 degrees was also a monthly record, breaking the old record of 79 degrees set on February 24th 1985 and February 25th 2000. For DCA: A daily record high minimum temperature of 56 degrees occurred. This breaks the old record of 51 degrees set in 1954. The high of 82 degrees was also a daily record, breaking the old record of 75 degrees set in 1953. For BWI: A daily record high minimum temperature of 52 degrees occurred. This breaks the old record of 49 degrees set in 1981. The high of 79 degrees was also a daily record, breaking the old record of 74 degrees set in 1930. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Winter Weather Advisory until 8 AM EST Friday for MDZ501. VA...None. WV...Winter Weather Advisory until 8 AM EST Friday for WVZ501-503. MARINE...Small Craft Advisory until midnight EST tonight for ANZ530>534- 537>543.
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&& $$ SYNOPSIS...KLW NEAR TERM...KLW SHORT TERM...KLW LONG TERM...IMR AVIATION...IMR/KLW MARINE...IMR/KLW CLIMATE...KLW

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