Area Forecast Discussion
Issued by NWS Sterling, VA

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393 FXUS61 KLWX 140135 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 835 PM EST Tue Feb 13 2018 .SYNOPSIS... High pressure will move offshore tonight into Wednesday. A warm front will then cross the region during midweek, followed by a cold front late in the week. Another wave of low pressure may affect the area over the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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High pressure will remain along the east coast tonight. A light southerly flow will allow for tonight to be milder compared to last night. However...there will be breaks in the clouds overnight as isentropic lift subsides behind a warm front in the low-levels (925-850mb). Light winds and breaks in the clouds will allow for colder valleys and rural areas to drop into the mid and upper 20s. Min temps will be in the 30s for most other locations. A westerly upslope flow in the low-levels will lead to some showers/drizzle after midnight for locations along and west of the Allegheny Front. Temps may be close to freezing briefly...but temps should rise overnight across these areas and be well above freezing by early Wednesday morning. Therefore...any chance for freezing rain will be limited and most areas will get just some light rain.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Southerly flow will increase across the region on Wednesday, and with it will come warming temperatures. Most locations are expected to remain dry, but as a surface low passes well north of the region, dragging a warm front near the area, and a weak disturbance moves towards the region, showers become more likely along and west of the Allegheny Front during the day, and possibly as far east as the Blue Ridge by the evening. Highs should reach into the 50s area- wide, possibly near 60F across portions of central/western Virginia. More widespread showers will then push eastward and across the remainder of the region Wednesday night. Temperatures will be quite mild, with lows in the 40s to around 50F, so no mixed precipitation issues are expected. Southwest flow and warm conditions will be the story for Thursday on the warm side of the boundary. High temperatures from the mid 60s to low 70s are likely. A cold frontal system will then begin its approach from the northwest late in the day, and some showers become more likely by the afternoon north/west over western Maryland and eastern West Virginia. The cold front will continue its approach and be on the doorstep by Friday morning. Rain will become increasingly widespread Thursday night from northwest to southeast, although downsloping on strong westerly flow will initially limit coverage/intensity. A very mild night is expected with lows only in the 50s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A cold front will be moving through our region on Friday which will bring rain over our CWA. High temperatures will be above normal, reaching the 50s and 60s. Conditions should be drying out in the evening and will continue into the overnight hours with near normal temperatures and breezy conditions. The front will stall south of us and a wave of low pressure will move through it. Some guidance keep the front close enough where we could get additional precipitation on Saturday. Latest GFS keeps our CWA dry through Monday as high pressure builds in, while most GEFS, Euro and the Canadian support a wetter solution for Saturday and into Sunday, maybe Monday. Temperatures will be marginal in the overnight hours, so cannot rule out snow at this moment. Guidance suggests that another frontal system could bring unsettled weather for early next week. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
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VFR is expected through at least Wednesday with mainly dry conditions and BKN-OVC variable VFR cloud decks. Sub-VFR potential becomes higher Wednesday night as a disturbance moving through bringing some showers. Conditions will then improve on Thursday, accompanied by southwest wind gusting 20-30 knots. Sub-VFR conditions become possible once again Thursday night as showers move across the region ahead of a cold front. Sub-VFR conditions possible over the terminals on Friday as front moves through our region. Conditions could improve on Friday night to VFR but is uncertain how close will this front stall into the weekend, therefore sub-VFR/unsettled weather is possible during this time. Gusts up to 20 kts on Friday.
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&& .MARINE... Sub-SCA conditions expected through Wednesday as high pressure gradually slides eastward and winds remain relatively light. By Wednesday night, southerly flow will be on the increase and SCA conditions become possible across portions of the waters from Wednesday night through Thursday night. SCA conditions expected Friday into Friday night as front moves through the region. Winds will be decreasing on Saturday and remain below SCA criteria into Sunday. && .CLIMATE... Unseasonably warm weather is expected on Thursday. While temps will be over 20 degrees above normal, it will be difficult to top the record highs in Baltimore and Washington. However, the record highs at Dulles could be smashed. Below are the current record highs for Thursday February 15: SITE RECORD MAX RECORD MIN DCA 77 in 1949 52 in 1909 BWI 77 in 1949 51 in 1949 IAD 68 in 1982 44 in 1984 and 1967 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...MM NEAR TERM...BJL/MM SHORT TERM...MM LONG TERM...IMR AVIATION...BJL/MM/IMR MARINE...BJL/MM/IMR CLIMATE...RCM

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