Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 230157 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 857 PM EST Thu Feb 22 2018 .SYNOPSIS...
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A front will remain nearly stationary across southern Virginia through tonight, then begin to move northward as a warm front on Friday before stalling again across the area on Saturday. A stronger cold front will clear the area on Sunday. High pressure builds over the region for the early part of next week.
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&& .NEAR TERM /THROUGH FRIDAY/...
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Front continues to push south this evening and is now located along the NC/VA border. Thin line of showers and gusty winds that crossed the area earlier has pretty much exited the fcst area. Overnight, it doesn`t appear there will be much forcing to generate precip with drizzle likely to be the main p-type due low level convergence and upslope component, although some higher/thicker clouds are seen west of the Appalachians moving eastward that could result in more rain than drizzle at times. Question is what to do with winter wx advisory over the far NW. Currently 2G4 is the only site aob below freezing with basically all guidance except NAM keeping temps abv freezing. Model trends show temps slowly rising overnight with any ice accumulation looking marginal at best. Any ice would probably occur on elevated surfaces and not on road surfaces. Will continue to monitor obs, but it is likely that the advzy will be cancelled early especially for western Mineral and Grant counties where there are no obs showing sub-freezing air.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... 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. && .LONG TERM /SUNDAY THROUGH THURSDAY/... 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. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/...
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MVFR cigs being observed at eastern terminals will gradually lower to IFR category overnight and remain like that through Fri and likely through the weekend. Expect also periods of light rain or drizzle. 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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North to northeast winds will persist through tonight with winds expected to gradually decrease overnight. A Small Craft Advisory remains in effect for Maryland Chesapeake Bay and lower Tidal Potomac River through tonight. 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>532- 538>540. Small Craft Advisory until 6 AM EST Friday for ANZ533-534-537- 541>543. Small Craft Advisory until 9 PM EST this evening for ANZ535- 536.
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&& $$ SYNOPSIS...KLW NEAR TERM...LFR SHORT TERM...KLW LONG TERM...IMR AVIATION...IMR/KLW MARINE...IMR/KLW CLIMATE...

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