Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 191923 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 223 PM EST Fri Jan 19 2018 .SYNOPSIS... High pressure to the south will dominate the weather through the weekend. A cold front will approach the region Monday before passing through Monday night into Tuesday. High pressure will return for Wednesday through Thursday of next week before moving offshore Friday. && .NEAR TERM /THROUGH TONIGHT/... High pressure extends from the southeastern CONUS to the Mid Atlantic. Wave clouds still reside across southern Pennsylvania into western Maryland; otherwise the forecast area is mostly sunny aside from a few cirrus. Winds never fully decoupled last night. Tonight`s setup will be quite similar aside from a lack of an offshore coastal cyclone. Nonetheless, in light of good model agreement, am hesitant to undercut low temperatures. Will therefore leave lows in the upper 20s to near 30. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... While the high pressure ridge remains in place through the weekend, there will be a couple of transitory features in the mean westerly flow: southern stream 500 mb shortwave/cyclone along the Gulf coast, and northern stream low pressure across southern Canada with weak attendant boundary emanating west/southwest from it. While neither will have a direct impact locally, warm advection in the wake of the former disturbance will spread moisture north Saturday-Saturday night. Saturday will still be sunny. At this time, it appears as though any precip will be confined to mountains Saturday night. Further, it is looking more likely that temperatures will remain above freezing through this time, so have removed mention of freezing rain. Sunday will be cloudier, in part due to the pressure weakness. But forcing will be too meager for anything but clouds. Thermally, the cloud cover likely will lead to slightly cooler temperatures, but highs will still be at-or-above 50 degrees. && .LONG TERM /MONDAY THROUGH FRIDAY/... A cold front will approach from the west Monday before passing through Monday night into Tuesday. Showers are expected ahead of the boundary...especially Monday night into Tuesday. A southerly flow ahead of the boundary will allow for mild conditions Monday...but low clouds and fog are possible and if this develops it would cause temps to be a bit cooler than currently forecasted. The cold front will move off to the east later Tuesday and high pressure will return for Wednesday and Thursday. Dry and seasonably chilly conditions are expected during this time. The high will move offshore late in the week and milder conditions will return due to a southerly flow. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... VFR conditions will prevail through the weekend with high pressure positioned just southwest of the terminals. A cold front will approach from the west Monday. Low clouds and fog are possible ahead of the cold front due to warm and moist air overrunning cooler air near the surface...but confidence is low at this time. The cold front will pass through Monday night into Tuesday... bringing showers and subVFR conditions. High pressure will return for later Tuesday and Wednesday with VFR conditions likely. && .MARINE... Winds will be 10 kt or less through the weekend with high pressure positioned southwest of the waters. Flow will have a primary southwest component, but will veer west/northwest by Sunday as a front approaches. A cold front will approach the waters Monday before passing through Monday night or Tuesday. High pressure will return for the middle portion of next week. A Small Craft Advisory may be needed for portions of the waters Monday night through Wednesday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...BJL NEAR TERM...HTS SHORT TERM...HTS LONG TERM...BJL AVIATION...HTS/BJL MARINE...HTS/BJL

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