Area Forecast Discussion
Issued by NWS Sterling, VA

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650 FXUS61 KLWX 181525 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1025 AM EST Wed Jan 18 2017 .SYNOPSIS... High pressure will build toward the region today before settling overhead Thursday. A warm front will move into the area Friday and it will stall out nearby through Saturday. Low pressure will affect the area to start the new week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Cold front has mostly cleared the area, though parts of southern Maryland are still ahead of it with a bit of patchy lingering fog. With the front, winds are shifting to the northwest and a general drying trend is getting underway. This should cause the remaining fog to erode and dissipate. Small/compact upper level low crossing the area midday combined with some lingering moisture and developing northwesterly flow has lead to a strato-cu deck of clouds, especially northeastern areas, along with spotty showers. As the low passes, expect clearing developing by the afternoon for central VA. The northwest flow will also help to touch off upslope rain/snow showers, although with warm boundary layer conditions, any snow accumulations will be negligible. Peak wind gusts to the 20-30 mph range, though some mountain ridges may approach 40 mph. Highs today quite mild, from 50-60F. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... High pressure then builds in for tonight and Thursday with dry and mild conditions expected. Lows tonight in the 30s, with highs Thursday into the 50s again. Low pressure system will then push northeastward out of the Mississippi Valley and into the Lower Great Lakes Thursday into Thursday night before weakening on Friday. This will send an area of rain towards the Mid Atlantic states for Friday along the weakening warm frontal boundary. Current indications are that the highest chances of rain will fall in the 15z-21z (10am-4pm) time period for the DC Metro area. Rain will then taper off by the evening with clouds and possible areas of fog persisting Friday night. High temperatures Friday will range from the mid 40s north/east to low 50s south/west. Lows Friday night around 40F. && .LONG TERM /SATURDAY THROUGH TUESDAY/... A weak boundary will remain overhead for Saturday...but ridging overhead behind a departing disturbance should allow for dry conditions across most areas. Temperatures will continue to be above normal for this time of year. A potent jetmax in the southern stream of the jet will track into the Gulf Coast States Saturday night...forming a cutoff low. The low will track northeast into the Tennessee Valley and Mid- Atlantic Sunday before passing through our area Monday. Details with timing are uncertain this far out...but it does look like a soaking rain is likely Sunday into Monday. The low will slowly pull away from the area during the middle portion of next week. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... Fog has lifted at the TAF sites, but we will see a strato-cumulus deck of clouds with bases from about 3000-5000 feet agl persist through the day, and this may cause occasional periods of MVFR, mainly at MRB. A sprinkle is also possible but should not affect operations. Otherwise, gusty northwest winds with gusts of 15-25 knots today. VFR will continue with winds slackening tonight and Thursday. Sub-VFR conditions then expected to develop again on Friday with period of rain and lowering ceilings as a warm front crosses the region. Low clouds and areas of fog may persist Friday night. Low clouds are likely for Saturday through Sunday. Areas of fog are possible Saturday morning. Rain chances will increase Saturday night into Sunday as low pressure approaches from the south. IFR/SubIFR conditions are most likely during this time. && .MARINE... Southerly winds will turn northwesterly as cold front crosses the region this morning with gusts 20-25 knots expected today. Therefore, SCA is in effect through 8 PM. Winds will slacken tonight. Sub-SCA winds then expected Thursday through at least Friday night. A weak boundary will remain near the water Saturday. Low pressure will approach the waters Saturday night through Sunday before passing through Monday. A Small Craft Advisory will likely be needed for the waters during this time. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 8 PM EST this evening for ANZ530>543. && $$ SYNOPSIS...BJL/RCM NEAR TERM...MM/RCM SHORT TERM...MM LONG TERM...BJL AVIATION...BJL/MM/RCM MARINE...BJL/MM/RCM is the U.S. government's official web portal to all federal, state and local government web resources and services.