Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261842 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 242 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 /THROUGH TONIGHT/... Breezy conditions will continue this afternoon with frequent gusts around 25 to 35 mph. A sct to bkn cu deck will dissipate toward evening as well. A stray shower cannot be ruled out across northern portions of the CWA this afternoon but most places will be dry. Weak high pressure will build overhead this evening...allowing for dry and seasonable conditions. However...the high will move offshore tonight and low pressure will approach from the west. Also...an MCS may develop and quickly move through the Ohio Valley tonight and into our area toward morning. Showers and perhaps a thunderstorm are possible toward morning. Severe weather is not expected during this time since any instability will be elevated. The best chance for showers will be across the Allegheny and Potomac Highlands into eastern West Virginia and northern Maryland. Min temps will be in the 50s across most areas to around 60 in Washington and Baltimore. Low pressure will pass through the area on a 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. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Low pressure will pass through the area on a 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 /18Z FRIDAY THROUGH WEDNESDAY/... VFR conditions are expected through tonight. A few showers are possible Saturday as low pressure passes through. Marine air behind a boundary that will stall out overhead will likely cause subVFR cigs Saturday night...and possibly as early as Saturday afternoon. Did not introduce in TAFS yet because confidence in where the boundary sets up Saturday is still low. 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 early this evening. Winds will quickly diminish around sunset. A Small Craft Advisory remains in effect through early this evening. Gusts around 30 knots are possible...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... A west to northwest flow will continue to cause anomalies to fall through this evening. However...minor flooding is still likely with the high tide late this afternoon for Straits Point. Water levels will also be close to minor flooding thresholds with the high tide cycle late tonight...but confidence is too low for an advisory at this point given the fact that anomalies are falling. Elsewhere...water levels will remain below minor flooding thresholds. 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 begin as early as the tide cycle Saturday morning...but confidence is low. Confidence in minor tidal flooding is higher for Saturday night into Monday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Coastal Flood Advisory until 5 PM EDT this afternoon for MDZ017. VA...None. WV...None. MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ530>543. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...IMR AVIATION...BJL/IMR MARINE...BJL/IMR TIDES/COASTAL FLOODING...BJL

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