Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260810 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 410 AM EDT Fri Aug 26 2016 .SYNOPSIS... High pressure remains off the coast through tonight. A weak cold front will cross the region this morning. High pressure will return for the weekend. Another front may slowly slide southward into the area by the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... At present...a large ridge of upper-level high pressure is centered over the southern Appalachians. Over the course of today and tnoight the ridge will slowly slide east-northeast and end up centered directly over Virginia by late tnoight. At the surface...a cold front is stretched from near St. Louis to the Adirondacks and is slowly pushing southeast. The front will gradually slide southward into our area today but there just does not appear to be enough of a trigger to cause any thunderstorms to develop for most of the region...with the possible exception of west-central Virginia...and in fact the northwest flow developing today will likely suppress convection despite the higher humidity now in place. This humidity has allowed patchy fog to develop but it should not become dense enough to warrant any advisories early this morning. By this afternoon...warm air surging north ahead of the front combined with the high humidity will allow temps to sruge to the mid-upper 90s with heat indices in the low 100s. However...most of the moisture is at the surface and stong mixing should allow dew pionts to lower a bit later today...so think we should stay just below heat advisory criteria. Nevertheless...it will be substantially hotter and more humid than yesterday so anyone outdoors should use caution. This part of August has relatively weak record highs...and those records may topple...see climate section below for details. Tonight...drier air will gradually slide southward from the north as high pressure builds in. There may still be a little patchy fog in the favored spots. Lows will not be quite as warm as this morning`s...but it will still be warm for this time of year. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Upper level ridge basically sits over Virginia through Sunday night. Surface high pressure gradually shifts eastward to our north allowing winds to shift to northeast...then southeast by the end of the weekend. This may bring some low clouds into the area but not sure of this at all. Otherwise...the front will dissipate just to our south over the weekend and only slight cooling and drying of the air mass is expected. Basically...not as bad as today...but still hotter than normal. Thunderstorms look to be suppressed by the ridge and lack of a trigger...with any risk confined to the highest ridges to our west. && .LONG TERM /MONDAY THROUGH THURSDAY/... Continued warmth expected for much of next week as high pressure remains over the east coast to end the month of August. Highs should be in the upper 80s/around 90. Precipitation chances look to be in the chance range at best for much of the week - things will primarily be dry. But as September begins it does appear that a change will be in store..actually beyond the scope of this forecast. Both Euro and GFS show and upper level low deepening near Nova Scotia next Friday which would bring a halt to the above average temperatures. In addition a cold front would likely be moving through the Mid Atlantic next Thursday or Friday...giving region a better chance for convection. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... Patchy fog possible early this morning mainly CHO and MRB. Could be a little around IAD as well but think it should stay VFR with just some patchy ground fog. VFR today with only a slight risk of a t-storm down near CHO. More of the same fog-wise tonight and Saturday night. Otherwise VFR thru the weekend with no significant t-storm risk. Winds mainly light with gusts mostly 15 knots or less...starting W to WNW today...then NE Saturday..and shifting to the SE Sunday. VFR conditions expected during the first part of next week. Isolated thunderstorms will be possible in the afternoon/evening. && .MARINE... Southerly channelling is diminishing as the front approaches so current SCA drops off soon. Front sliding southward into the area today may bring af ew NW gusts close to 20 knots. However...am not confident about SCA conditions occurring so have held off on SCA for later today. Should be relatively light winds over the weekend as high pressure slides past to the north...with winds mostly NE on Saturday shifting more SE by later Sunday. No significan risk of t-storms thru Sunday night. Winds expected to remain below SCA values Monday and Tuesday. && .CLIMATE... Record highs are not out of the question today. Here are the records for today: Site Record Date(s) Washington (Reagan National) 97 1948 Baltimore (BWI/Marshall) 101 1948 Washington (Dulles) 95 1998/1993/1975 Ranking of summer 2016 in terms of average temperature (JUN 1 - AUG 25) Site RankAverage Temperature DC 3 (tie with 2012)80.4 Balt 19 (tie with 2 other years) 77.2 IAD 3 77.2 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 AM EDT early this morning for ANZ534-543. && $$ SYNOPSIS...ABW NEAR TERM...RCM SHORT TERM...RCM LONG TERM...ABW AVIATION...RCM/ABW MARINE...RCM/ABW CLIMATE...RCM/ABW

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