Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 270009 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 809 PM EDT Fri May 26 2017 .SYNOPSIS... High pressure will build overhead this evening before moving offshore toward morning. A warm front will stall out over the area Saturday through Sunday before a cold front moves into the area Monday. High pressure may return during the middle portion of next week. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... Weak ridging will move overhead for much of the night, leading to dry weather and slackening winds. Strato-cu from earlier today should also tend to dissipate, although mid/high clouds will be on the increase ahead of a developing MCS currently located over Indiana at 8 PM. Moving along a frontal zone, remnants of that MCS, although weakening, will move into the region during the late night/early morning hours with increased chances for rain showers and possibly some rumbles of thunder. No severe threat anticipated. Highest rain chances prior to 8am will be from the Allegheny and Potomac Highlands into eastern West Virginia and northern Maryland. There may also be some patchy fog in a few areas. Lows tonight generally in the 50s, except 60s in the urban centers and along the immediate shorelines of the Chesapeake and Potomac. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Low pressure will pass through the area on the stalled boundary Saturday. The boundary will separate cooler marine air to the north vs. warm and humid air to the south. To the north and east of the boundary...mostly cloudy skies along with a few showers are possible due to the low passing through. Showers and thunderstorms are possible to the south and west of the boundary. Some thunderstorms have the potential to be severe due to moderate shear profiles. However...latest guidance suggest the boundary will be a bit farther south across the Potomac Highlands into central Virginia. This is where the best chance for stronger storms are possible Saturday afternoon and evening. The boundary will remain stalled over our area through Sunday night. Most places will turn out dry Saturday night after any evening convection dissipates. More popup showers and thunderstorms are possible Sunday near the boundary. The best chance for showers and thunderstorms will be in the Potomac Highlands into the central Shenandoah Valley...where the boundary is most likely to set up. A cold front will approach from the west Sunday night. More showers and a few thunderstorms are possible. Rain may be locally heavy...especially over the Allegheny and Potomac Highlands where instability may be a bit higher. && .LONG TERM /MONDAY THROUGH FRIDAY/... A cold front slowly moves away from our region Monday into Monday night with some showers, and maybe a thunderstorm, mainly in the first part of the day. Conditions become drier into Tuesday before a weak cold front moves through Tuesday night into early Wednesday... which could bring some scattered showers to our area. Another boundary moves through Wednesday night into Thursday before it stalls south of our CWA into Friday. High temperatures will be in the 70s and 80s... some 60s at higher elevations. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected through tonight. A few showers and thunderstorms are possible Saturday as low pressure passes through. Marine and rain cooled air behind a boundary that will stall out overhead will likely cause sub-VFR ceilings as early as late morning Saturday at MRB, mid afternoon at BWI/MTN, and Saturday night elsewhere. Position of boundary and progression of morning rainfall will greatly influence likelihood/position of reduced ceilings. Low clouds will continue well into Sunday with the boundary likely being off to the south and west. Showers and a few thunderstorms are possible Sunday night as a cold front approaches from the west. Sub-VFR conditions expected at times on Monday with some showers and thunderstorms over us as cold front moves through our area. Conditions become drier/VFR Monday night and into Wednesday. && .MARINE... Gusty west to northwest winds will continue through this evening. Winds will quickly diminish around sunset. A Small Craft Advisory remains in effect through this evening. Gusts around 20-30 knots are likely...especially across the northern waters. A boundary will stall near the waters Saturday through Sunday night. Winds should remain below SCA criteria for most of the time...but it will be close Sunday night as the pressure gradient strengthens just a bit ahead of an approaching cold front. Periods of showers and thunderstorms move through at times on Monday as front moves across our region. Conditions become drier Monday night into Wednesday. Winds will be below the SCA threshold Monday into Tuesday night, increasing slightly on Wednesday to near 16 kt. && .TIDES/COASTAL FLOODING... Tidal anomalies have dropped off this afternoon and evening in the gusty westerly flow, but still likely high enough to produce another round of minor flooding at Straits Point overnight and into early Saturday morning. Annapolis may also approach its flood stage. The offshore flow will quickly diminish tonight and an onshore flow will develop for Saturday through Monday. Elevated water levels are expected and minor flooding is likely. Minor flooding may occur during the high tide cycles Saturday, although confidence is higher for Saturday night into Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Coastal Flood Advisory from midnight tonight to 6 AM EDT Saturday for MDZ017. VA...None. WV...None. MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ530>543. && $$ SYNOPSIS...BJL NEAR TERM...BJL/MM SHORT TERM...BJL LONG TERM...IMR AVIATION...BJL/MM/IMR MARINE...BJL/MM/IMR TIDES/COASTAL FLOODING...BJL/MM is the U.S. government's official web portal to all federal, state and local government web resources and services.