Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 210120 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 920 PM EDT Fri Apr 20 2018 .SYNOPSIS... Strong high pressure will slowly migrate eastward into the northeastern states by Sunday, and off the coast on Monday. Unsettled weather is expected to return by the middle of next week as low pressure approaches the area from the southeast U.S. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
Strong high pressure is centered over the Great Lakes and upper Midwest this evening. Satellite shows clear skies extending to the Ohio Valley, with only a few thin cirrus propagating eastward later tonight at worst. Below normal temperatures are expected tonight with lows in the 30s. Went with cooler guidance as light winds are expected for most areas (except a persistent light breeze over central MD/DC metro). A Freeze Warning has been issued for much of the same area as last night. Overall, temperature forecast seems to be on track. Low levels remain dry, so any frost should be patchy.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Benign weather conditions are expected this weekend as high pressure slowly shifts eastward from the Great Lakes into the northeastern U.S. Light winds and below normal temperatures are expected as a result. Mid to high level clouds will move overhead Saturday afternoon and may persist into Sunday as a jet max and mid level energy moves across our area. High temperatures will be in the 60s with lows in the 30s and 40s, though it should be warm enough to preclude frost/freeze issues in areas where the growing season has started. && .LONG TERM /MONDAY THROUGH FRIDAY/... High pressure will shift offshore on Monday as a mid-level cutoff trough and associated surface low move across portions of the Southeast. Conditions should remain mainly dry, with slightly below normal temperatures. On Tuesday, the aforementioned area of low pressure will slowly track north toward our CWA. The latest deterministic guidance has trended slightly slower with the northward progression of this area of low pressure, suggesting it`s possible that we remain dry much of the day Tuesday as well. On the other hand, both the GEFS and EPS have many ensemble members that move the system along faster, bringing precipitation in during the day Tuesday. It appears as though the most likely time period for steadier rainfall across the area will be Tuesday Night, when both deterministic and ensemble model guidance point toward a cool, soaking rainfall across the region. Forecast confidence decreases considerably for Wednesday and Thursday, but the potential for active weather remains. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... VFR expected through the weekend with light winds as high pressure passes to the north of the terminals. VFR conditions are expected during the day on Monday. MVFR conditions likely begin to develop Mon night as easterly flow ensues. Flight restrictions are likely Tuesday and Wednesday as an area of low pressure approaches from the south bringing rain. Winds will increase out of the east during this time as well. && .MARINE...
-- Changed Discussion --
Winds subsided quickly early this evening, but a subtle pressure surge on the east side of ridging building to the north will likely result in marginal SCA conditions in northerly channeling over the Maryland portion of the Chesapeake Bay. Given trends in hi-res guidance, reconfigured the Small Craft Advisory, as the surge may enter northern portions of the Bay by 10 PM and exit by 1-3 AM. As high pressure builds further to our north, light winds are expected over the weekend. Sub SCA conditions are forecast Monday as a departing ridge of high pressure will keep winds light over the waters. SCA headlines may be needed Monday night through Tuesday as easterly flow strengthens thanks to low pressure developing/approaching from the southeast U.S.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING... Persistent onshore flow is expected to result in increased tidal anomalies and possible coastal flooding during the middle part of next week. && .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...None. MD...Freeze Warning from 2 AM to 9 AM EDT Saturday for MDZ003>006- 503-505-507-508. VA...Freeze Warning from 2 AM to 9 AM EDT Saturday for VAZ025>031- 038>040-051-501-502-505>508. WV...Freeze Warning from 2 AM to 9 AM EDT Saturday for WVZ051>053. MARINE...Small Craft Advisory until 3 AM EDT Saturday for ANZ531>533- 539>541. Small Craft Advisory until 6 AM EDT Saturday for ANZ534-537- 543.
-- End Changed Discussion --
&& $$ SYNOPSIS...IMR/DHOF NEAR TERM...ADS/IMR/DHOF SHORT TERM...IMR/DHOF LONG TERM...KJP AVIATION...IMR/DHOF/KJP MARINE...ADS/IMR/DHOF/KJP TIDES/COASTAL FLOODING...DHOF

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.