Area Forecast Discussion
Issued by NWS Sterling, VA

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521 FXUS61 KLWX 241833 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 233 PM EDT TUE MAY 24 2016 .SYNOPSIS... A ridge of high pressure will build south of the region through the remainder of the week and into the weekend. A low pressure system may affect the region late in the weekend and into early next week. && .NEAR TERM /THROUGH TONIGHT/... Upper low continuing to slowly pull away from the region with drier northwest flow working into the area. Mostly sunny skies will continue for the rest of the day along with a few cirrus as well as some instability cumulus. Can`t rule out an isolated sprinkle or light shower either but the vast majority of the region should remain dry. Sky will also appear slightly hazy in some locations with wildfire smoke lofted high in the atmosphere. Mostly clear skies and light winds for the overnight hours as ridge of high pressure noses in. Some patchy fog likely in a few areas, especially north and west, but low levels are drying considerably, and crossover temperatures will struggle to be met, so widespread fog not expected. Lows generally 50-60F. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Mostly sunny, warm, and dry weather will be the theme on Wednesday as ridge of high pressure dominates. Will be a weakening remnant vort/shortwave approaching from the west during the day, but instability will be lacking as moisture return is slow to occur, so only have a slight chance in the higher elevations of the far western counties. Highs will be in the mid 80s pretty much area- wide, with relatively low humidity as dew points hold in the 50s. Wednesday night will also be dry, lows upper 50s to mid 60s. Thursday will see more in the way of moisture return with dew points rising back into the low/mid 60s. This will lead to the development of some isolated to scattered showers/thunderstorms, especially in the higher terrain. Very weak wind field aloft though, so organized severe not expected. Temperatures warm a few more degrees with highs in the mid/upper 80s. A few showers/storms may linger into Thursday night. Mild night in store with lows in the 60s for all. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Remaining hot (U80s) and humid (U60s Tds) Friday with chances for isolated afternoon thunderstorms in the moderate instability, very low CAPE environment. Thunderstorm coverage will be greatest where orographic forcing helps with convective initiation. With weak steering flow, activity will have a difficult time moving off the higher terrain, though there could be a storm or two east of the Blue Ridge that develops due to localized influences. Saturday looks dry across most of the area, as poor mid-level lapse rates develop, with mid/upper ridge extending further north into the area. This keeps any shower and storm activity confined to the west over the higher terrain. Temperatures/dewpoints cool a few degrees from Friday. Changes begin to develop late Saturday into Sunday as low over the Atlantic approaches the eastern seaboard from the SE. While ultimate track of the system is uncertain at this time, precipitation shield ahead of system could begin to impact the area as early as Sunday and continue into early next week. Onshore flow and cloud cover ahead of system will also help to cool temperatures back below normal. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... Predominantly VFR through at least Thursday night. Some fog may bring some reductions late tonight, early Wednesday morning, but have left VFR for now as coverage will be patchy. Will also be some isolated-scattered showers and thunderstorms around on Thursday which may bring some brief reductions...but coverage will be scattered at best. Winds out of the northwest this afternoon with gusts up to about 17 knots become light and locally variable tonight, before turning light south/southwest Wednesday through Thursday night (less than 10 knots). While most of Friday will end up VFR, could be a few isolated storms with sub-VFR possible in and around any activity. Uncertainty increases Sunday as coastal low approaches the eastern seaboard, though rain chances (and associated sub-VFR) possible as early as Sunday. && .MARINE... Marginal SCA in effect for gusts up to 20 knots through this afternoon. Lighter winds return tonight and through Thursday night. May be a few isolated-scattered thunderstorms on Thursday. Flow remains sub-SCA Friday and Saturday, though there is a low- end chance for a thunderstorm over the waters Friday. && .CLIMATE... We put together some records (preliminary) of how this month compares to rainy Mays on record for our area. Washington, DC (records since 1871) Most days in May with at least a trace: 25 (in 1952 and 1943) So far in 2016 (through 2PM EST on the 24th): 20 Most days in May with at least 0.01": 20 (in 2003) So far in 2016 (through 2PM EST on the 24th): 18 Highest May monthly rainfall: 10.69" (in 1953 and 1889) So far in 2016 (through 2PM EST on the 24th): 5.22" Baltimore, MD (records since 1870) Most days in May with at least a trace: 25 (in 2003) So far in 2016 (through 2PM EST on the 24th): 20 Most days in May with at least 0.01": 21 (in 1882) So far in 2016 (through 2AM EST on the 24th): 17 Highest May monthly rainfall: 8.71" (in 1989) So far in 2016 (through 2PM EST on the 24th): 4.92" Dulles, VA Most days in May with at least a trace: 23 (in 2003) So far in 2016 (through 2PM EST on the 24th): 21 Most days in May with at least 0.01": 21 (in 2003) So far in 2016 (through 2PM EST on the 24th): 17 Highest May monthly rainfall: 10.26" (in 2009 and 1988) So far in 2016 (through 2PM EST on the 24th): 6.07" && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ530>543. && $$ SYNOPSIS...MM NEAR TERM...MM SHORT TERM...MM LONG TERM...MSE AVIATION...MM/MSE MARINE...MM/MSE CLIMATE...DFH is the U.S. government's official web portal to all federal, state and local government web resources and services.