Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 170259 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 959 PM EST Fri Feb 16 2018 .SYNOPSIS...
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An area of high pressure will briefly build north of the region overnight. A wave of low pressure will pass to the southeast Saturday. A second area of high pressure will return briefly again on Sunday before another storm system approaches from the west early next week.
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&& .NEAR TERM /THROUGH SATURDAY/...
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Gusty northwest winds behind a passing cold front will diminish overnight as colder air moves in as well. Temperatures as of 930 pm range from 52 in St. Marys County in southeast Maryland to 36 in Allegany County in western Maryland. Expect temperatures to continue to fall throughout the rest of the night. High clouds will build into the region Saturday ahead of a developing coastal low pressure system. Cold air in place with dewpoint temperatures in the teens will evolve ahead of the next wave of precipitation. This wave consists of a mix of snow and sleet for the most part from southwest to northeast. There is a hint of some light freezing rain, mainly across parts of the Central Shenandoah Valley late Saturday morning into Saturday afternoon. Snow and sleet could accumulate between 1 and 3 inches with a glaze to less than one tenth of an inch of ice due to some freezing rain. The farther northern and northeastern zones and near the Mason-Dixon line will encounter more snow than sleet due to colder surface temperatures. Winter Weather Advisories are in effect across the northwestern two-thirds of our region with a Winter Storm Watch in effect over the western ridges of western Maryland, western West Virginia and western Virginia. There will be a light accumulation of snow and sleet to the southeast of our Advisories in the Metropolitan areas and into southern Maryland with a higher emphasis on a mix of snow and rain or sleet and rain becoming all rain later Saturday. The precipitation will end from southwest to northeast across the region later Saturday evening, most likely ending and moving out of the region around midnight. High pressure will build in behind the departing precipitation and its affiliated low pressure system overnight Saturday night. Temperatures will be chilly Saturday night.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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The precipitation will end from southwest to northeast across the region later Saturday evening, most likely ending and moving out of the region around midnight. High pressure will build in behind the departing precipitation and its affiliated low pressure system overnight Saturday night. Temperatures will be chilly Saturday night. High pressure will influence a lot of sunshine and quickly modifying temperatures Sunday with highs reaching about 10 degrees milder than Saturday`s highs. A return flow will develop Sunday night as high pressure moves east. Moisture and temperatures will be on the increase throughout Sunday night.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/... High pressure will be moving away from the coast as return flow settles in. Isentropic lift will allow showers over our area through the day and possibly into the night. Temperatures will remain well above freezing, with highs reaching the 50s. A cold front will stall to our west Tuesday into Wednesday. We will remain in the warm sector and high temperatures both days will reach the 70s. Showers associated to this front are more likely towards the western counties of our CWA Tuesday and part of the day Wednesday. The front will then moves across slowly Wednesday night or Thursday. The front will then stall to our south as waves of low pressure tracks along it and maintain the unsettled weather over our area Thursday and into Friday. Temperatures will decrease behind the front, but not enough to bring p-type concerns. High temperatures will be in the 50s. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
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Winds are diminishing across the terminals this evening as high pressure becomes more aligned overhead and just to our northeast. VFR conditions through Saturday morning, before quickly becoming IFR with visibilities and cigs being reduced with snow and sleet moving in from the southwest. The precipitation will end by midnight Sat night but low cigs could persist until daybreak Sun. Periods of sub-VFR conditions possible Monday into Monday night as a front moves through our area. VFR conditions expected Tuesday and Wednesday. Some sub-VFR periods possible late on Wednesday as showers move through.
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&& .MARINE...
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SCA conditions expected through the overnight with gusts of 20 to 25 knots over the main stem Chesapeake and Tidal Potomac. Winds 10kt or less Sat through Mon. Winds are expected to remain below SCA criteria on Monday, then they will increase on Tuesday but are not expected to reach SCA criteria. Similar conditions expected on Wednesday, therefore no small craft advisory expected these days.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Winter Storm Watch from Saturday afternoon through late Saturday night for MDZ501. Winter Weather Advisory from 2 PM Saturday to midnight EST Saturday night for MDZ003>006-502-503-505-507. VA...Winter Weather Advisory from noon Saturday to midnight EST Saturday night for VAZ025>027-029-030-040-501-504-507-508. Winter Weather Advisory from 2 PM Saturday to midnight EST Saturday night for VAZ028-031-505. Winter Storm Watch from Saturday afternoon through late Saturday night for VAZ503. WV...Winter Weather Advisory from noon Saturday to midnight EST Saturday night for WVZ055-502-506. Winter Storm Watch from Saturday afternoon through late Saturday night for WVZ503. Winter Weather Advisory from 2 PM Saturday to midnight EST Saturday night for WVZ050>053-504. Winter Storm Watch from Saturday afternoon through late Saturday night for WVZ501-505. MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ530- 531-535-536-538>540. Small Craft Advisory until 3 AM EST Saturday for ANZ532-533- 537-541-542. Small Craft Advisory until 6 AM EST Saturday for ANZ534-543.
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&& $$ SYNOPSIS...KLW NEAR TERM...KLW SHORT TERM...KLW LONG TERM...BJL AVIATION...BJL/KLW MARINE...BJL/KLW

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