Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 261857 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 257 PM EDT Wed Oct 26 2016 .SYNOPSIS... High pressure will continue to drift east from the area through tonight. A cold front will cross the area Thursday evening. High pressure then builds over the area through Friday night. A secondary cold front crosses the area this weekend with high pressure then into at least the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... As of 2pm, a surface ridge axis extends from high pressure near the ontario/quebec border to the MD part of the Chesapeake Bay. Weak low pressure is over eastern IA. A light east or south wind is over the area on the west side of the ridge. Winds will shift south across the area through the night, though this progress will depend on the movement of the ridge axis which may stall until Thursday morning. The progress is complicated by a warm front shifting east from the eastern Great Lakes. Associated lift should cause some sprinkles to push east along the Mason-Dixon line rest of this afternoon into the evening. Should appreciable rain develop, then an in-situ cold air damming wedge would develop. This would not be overcome by south winds overnight and would be delayed well into Thursday. High clouds thicken and lower through tonight with temperatures more mild than last. Expect inland locations to drop around 40F and near shore areas to the mid 40s. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Low pressure develops as it moves east across the Upper Midwest tonight and the eastern Great Lakes Thursday. The associated cold front crosses the area Thursday evening with prefrontal rain showers crossing the area from the west from the late morning to the late afternoon. Likely PoPs were reserved for roughly north of the Potomac River where greater convergence occurs into the afternoon. Guidance consensus has activity developing/enhancing east of I-95 in the late afternoon/early evening. This could develop into a line with gusty showers for southern Maryland into the evening hours. Expect generally a quarter inch QPF north of the Potomac (maybe a tenth south) with perhaps half an inch for southern MD. Upslope rain showers look limited with likely PoPs decreasing to chance from afternoon to evening. Gusty winds accompany the cold front with an abrupt shift from south to west. Magnitude is generally 20 mph with gusts to 30 mph. Higher gusts possible in convective showers, particularly in southern MD. Max temps Thursday mid 50s along the Mason-Dixon, then low to mid 60s across the rest of the CWA. However, development of an in-situ cold air damming tonight would result in lower temperatures, particularly north. Gusty NW winds diminish into Friday morning as 1025mb surface high pressure builds directly overhead Friday evening. Temperatures near normal with maxima around 60F and minima around 40F (inland). && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Falling heights attempting to descend out of eastern Canada will be competing with a building ridge over the southeastern United States over the weekend and into much of next week. At the moment, it appears the ridge to the south will win out. This will result in a warmer and drier than normal pattern over the Mid-Atlantic. Over time, the ridging to the south begins to slowly retreat westward which may allow for falling heights and increasing precipitation chances by the second half of next week. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... VFR generally conditions prevail through the TAF period. However, a warm front developing over PA tonight and a cold front crossing Thursday evening brings a risk for showers and low ceilings. A light onshore flow develops across the area tonight, turning south and increasing with gusts around 20 knots Thursday morning. West, then northwest winds are expected behind the cold front. Showers may be gusty, around 30 knots particularly east from I-95. NW winds with gusts 20 knots into Friday morning before easing. High pressure overhead Friday evening. Mainly VFR expected over the weekend with southwesterly flow around 10 knots Saturday becoming westerly behind a frontal passage Saturday night into Sunday. && .MARINE... High pressure is just east of the area with a light east winds developing. Wind shifts south overnight and increases ahead of a cold front that crosses Thursday evening. SCA begins at 7am for southern MD waters then expands at 10am for all waters with southerly channeling of 20 to 25 knots. The northward progression of winds may be slowed depending on the pressure pattern. Likely showers late Thursday afternoon/evening associated with the cold front. Strong gusts and special marine warnings possible with the showers. Wind shifts W then NW behind the cold front Thursday night with gusts around 25 kt into Friday morning. Tranquil Friday evening under high pressure. Southwesterly winds ahead of an approaching cold front Saturday will likely result in Small Craft Advisory level wind gusts over the waters. Winds should diminish by Sunday as the front stalls over or just south of the waters. && .CLIMATE... Baltimore-Washington International Thurgood Marshall Airport (BWI) near Baltimore MD dropped to 32 degrees this morning, marking the first time since April 10th that the temperature has dropped to freezing (low on April 10 was 26 degrees). Washington Dulles International Airport (IAD) in northern Virginia dropped to 30 degrees, which is the first time the temperature has fallen below freezing there since April 14th (when the low was 31 degrees). Ronald Reagan National Airport near Washington DC (DCA) was 41 degrees this morning. Its last day at or below freezing was 31 degrees on April 10. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 10 AM Thursday to 6 AM EDT Friday for ANZ530>532-535-536-538>542. Small Craft Advisory from 7 AM Thursday to 6 AM EDT Friday for ANZ533-534-537-543. && $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...BAJ LONG TERM...DFH AVIATION...BAJ/DFH MARINE...BAJ/DFH CLIMATE...DFH is the U.S. government's official web portal to all federal, state and local government web resources and services.