Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 301505 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1105 AM EDT MON MAY 30 2016 .SYNOPSIS... Tropical Depression Bonnie remains near the South Carolina coast. This will weaken as it tracks northeast along the coastline. High pressure will build across the northeastern United States during midweek. A cold front will approach the east coast Friday. && .NEAR TERM /THROUGH TONIGHT/...
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Rain has re-entered southern Maryland as an approaching shortwave coaxes it back north. Do not expect it to reach I-95 but do think it will move a bit further northwest. Further to the west...guidance has come into better agreement on convection developing in the vicinity of the Shenandoah Valley this afternoon as the shortwave approaches and the long period of partly to mostly sunny skies into early this afternoon increases instability. Therefore, have a wedge of lower PoPs around the I-95/US 29 corridor with higher PoPs to the west and east. Tonight, the passage of the shortwave combined with diminishing instability should result in rapidly lowering PoPs across the entire area. Highs today should reach the low-mid 80s (except cooler southern MD where rain persists). Lows tonight mostly in the 60s.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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As there is no upper level steering flow to send Bonnie on its way the low will remain to our southeast through Wednesday. This means that the best chances for showers in the coming days will be in the eastern quarter of the forecast area. Believe clouds will lessen each day...especially west of the Blue Ridge as Bonnie loses its tropical characteristics. As we enter the beginning of meteorological summer temperatures will start the season in the moderate range with highs in the lower 80s. Lows will generally be in the lower 60s.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/... A backdoor cold front will weaken over the area Thursday through Thursday night...and this may lead to a few showers and thunderstorms. Another cold front will pass through from the west on Friday...and this may lead to more showers and thunderstorms. An upper-level trough will develop over the area during the weekend. There is still some uncertainty as to how much moisture will be around since guidance differs on the strength of the cold front that moves through Friday. Will leave the chance for a few showers and thunderstorms...but if the front is stronger then there should be enough dry air advection behind the boundary for dry conditions during the weekend. However...if the boundary is weak then moisture will hang around...elevating the chance for convection. A stronger cold front may impact the area early next week. && .AVIATION /15Z MONDAY THROUGH FRIDAY/...
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Guidance has been overdoing low cigs and most areas are VFR at present. THink this will continue thru day into this eve for big city terminals. However...points west particularly MRB and possibly CHO may see t-strm activity later today into early tonight. May need to amend TAFs to include this. Tonight will need to also check fog parameters given high moisture and light winds with some clearing. Guidance hints at some pretty dense fog but again... it may be overdoing things. For now have MVFR vis late tonight and early Tuesday. Sames issues with fog Wednesday morning potentially. Shower activity Tuesday and Wednesday afternoons should be less than today overall...but scattered activity still possible. A backdoor cold front will weaken over the area Thursday. A few showers and thunderstorms are possible along with low clouds. The best chance for low clouds will be during the morning hours and the best chance for convection will be in the afternoon and evening. The backdoor boundary will hang around Thursday night. More low clouds are possible. Another cold front will pass through from the west Friday...bringing a chance for more thunderstorms. Weak high pressure may build in behind the front for Saturday...but an upper- level trough will build overhead as well. Therefore...confidence in the forecast for Saturday remains low.
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&& .MARINE... Winds to remain below SCA values today thorugh Wednesday. Main threat to the waters today will be showers. A backdoor boundary will remain near the waters Thursday through Thursday night before a cold front from the west passes through Friday. Weak high pressure may build in behind the front for Saturday. The gradient should be weak enough for winds to remain below sca criteria during most of this period. However...a few showers and thunderstorms are possible...especially Thursday and Friday during the afternoon and evening hours. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ PRODUCTS...WOODY!/BJL/RCM

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