Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 160228 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 928 PM EST Thu Feb 15 2018 .SYNOPSIS...
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A cold front will cross the area Friday morning. High pressure will build north of the area Friday night. Low pressure will then pass to the southeast Saturday night. A second area of high pressure will return early next week before the next cold front affects the area during the middle of next week.
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&& .NEAR TERM /THROUGH FRIDAY/...
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Radar imagery as of 9 pm Thursday shows a band of light to moderate rain showers moving east across southern Pennsylvania. Some of these rain showers have reached into northern Maryland and the eastern West Virginia Panhandle. Rain amounts across southern Pennsylvania appear to be averaging one half to one inch in the moderate rain, but lesser amounts in the light rain. Surface observations out of Cumberland, Thurmont, and Westminster in western and central Maryland indicate a northerly wind around 10 knots with gusts between 20 to 25 knots as these rain showers sagged across these areas during the last hour or two. Rain amounts have been averaging a couple of hundredths of an inch to up to one quarter of an inch. Temperatures have also dropped between 3 and 7 degrees in the past hour or two due to the cooling of the rain falling in these areas. Just to the south of these pressing rain showers, temperatures remain in the upper 60s to near 70 with a persistent southwest wind. As these showers move south and east during the next couple of hours, so will the sharp cold front that is currently across northern Ohio and central Indiana. Through the remainder of the night, additional rain showers will develop along and ahead of the cold front and move east into our region. Rain amounts will average between one quarter of an inch in southeastern zones to as much as an inch in the northwestern zones. No flooding is anticipated as the southwest winds at the surface, westerly winds aloft, and a cold frontal passage timing should offset this factor. The cold front should cross our area around 09z and move to our south by 15z Friday morning. As for the remainder of the day Friday, cold high pressure will build in from the west. Temperatures, dewpoint temperatures, and available moisture will be on the decrease as a breezy northwest wind ushers in drier air throughout the day. Friday`s high temperatures may actually occur around midnight tonight or shortly thereafter as we look at the cold front to pass through the area in the middle of the night Thursday night/early Friday morning.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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Friday night into Saturday morning will be influenced by cold high pressure. Clearing skies Friday night and dry air in place will transition to mostly sunny skies Saturday morning. Temperatures Friday night will fall from near 50 around sunset to the upper 20s by sunrise Saturday morning. Also, expect a 10 to 15 degree drop in our dewpoint temperatures. We should encounter increasing clouds late Saturday morning through Saturday night as high pressure moves to the northeast and brings the wind direction out of the northeast then the southeast rather quickly. At the same time, an area of low pressure is expected to form along the mid-Atlantic Coast before pushing out to sea. The coastal low is expected to spread snow and sleet from southwest to northeast Saturday through Saturday evening. The low will be moving rather quickly, despite it being a coastal low. Therefore, wintry precipitation may only persist for a couple of hours. Snow to liquid ratios will be generally around 5 to 1, or less where sleet mixes and between 7 to 10 along the Mason Dixon line where precip remains as snow through the event. Snow amounts of an inch or less are expected south of I-66 with 1-3 inches north of there. Precip ends by midnight Sat night.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... High pressure builds overhead on Sunday bringing dry conditions over our region into Sunday night as southerly flow settles in. A low pressure system moving towards the Great Lakes will push a warm front over or nearby on Monday that could bring unsettled weather over our area. A cold front will then stall to our northwest Tuesday into Wednesday and keeping southerly flow over us. Depending on how close it stalls, we could experience some precipitation. The front will then slowly move across on Thursday keeping the chance of precip over our CWA. A warming trend will be in place in the long term period as high temperatures will be gradually increasing from the 40s and 50s on Sunday into near the 70s Tuesday and Wednesday. High temperatures will drop around 10 degrees on Thursday due to the front. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/...
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Rain showers expected overnight as a cold front crosses the area with brief cigs restrictions into MVFR category. Despite some of these rain showers briefly shifting winds to the north and gusting to around 25 knots this evening near MRB and MTN, the primary wind shift is expected around 09Z with gusts around 20 to 25 kts expected. Snow expected late Sat at onset with a quick transition to snow/sleet mix Sat evening with precip ending by midnight Sat night. Flight restrictions are likely late Sat and Sat evening. VFR conditions are expected during on Sunday as high pressure builds overhead. Periods of sub-VFR conditions possible Monday into Tuesday as frontal boundaries affect our area, but it will depend on how close they move.
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&& .MARINE...
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A cold front will approach the waters overnight before passing through Friday morning. Instability is limited...but strong winds remain aloft. A line of showers will be capable of mixing some of those winds down early Friday morning. Special Marine Warnings may be needed...but confidence is low at this time due to the limited instability. Southerly winds tonight into Friday morning will turn to the northwest behind the front later Friday. A Small Craft Advisory remains in effect for the waters during this time. Winds may continue to gust past SCA criteria Friday night...but winds should diminish Saturday and remain below SCA criteria through early next week. Winds are expected to remain below SCA criteria from Sunday into Monday night, therefore no small craft advisory expected these days. Winds will increase later on Tuesday, which will be monitored in case a SCA is required.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 7 PM EST Friday for ANZ530>543. && $$ SYNOPSIS...KLW NEAR TERM...KLW SHORT TERM...KLW LONG TERM...BJL AVIATION...BJL/KLW MARINE...BJL/KLW

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