Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 132000 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 300 PM EST Sat Jan 13 2018 .SYNOPSIS...
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Canadian high pressure will approach from the northwest through Sunday...causing blustery conditions. High pressure will build overhead Sunday night and Monday. A low pressure along with its associated cold front will pass through from the Midwest Tuesday. Low pressure will continue to develop offshore Wednesday before high pressure returns for late next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Blustery northwest winds will continue through this afternoon ahead of building Canadian high pressure. Temperatures this afternoon will be about 30 to 40 degrees colder compared to yesterday afternoon. Temps will be in the mid to upper 20s across northern Maryland/eastern West Virginia and in the lower to middle 30s for most other locations. The gusty northwest winds and cold air will cause wind chills to remain in the teens and 20s for most locations...but near zero along the ridge tops this afternoon. Blustery northwest winds will continue through tonight as high pressure slowly approaches from the Midwest. More cold advection will cause min temps to drop into the single digits and teens tonight with wind chills ranging from 10 to 15 blow zero along the ridge tops to the single digits for most other locations. A Wind Chill Advisory is in effect for the ridge tops.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Canadian high pressure will slowly build overhead Sunday through Sunday night...bringing dry and cold conditions. Highs Sunday will remain in the 20s for most locations despite sunshine. Lows Sunday night will be in the single digits and teens. Did lean toward the colder guidance Sunday night for rural areas and sheltered Valleys due to radiational cooling. There will be some high clouds that could prevent radiational cooling to some degree...but current feeling is that the deck will be thin so it shouldn`t have too much of an impact. High pressure will remain overhead Monday before weakening and gradually shifting toward the east coast Monday night. More dry and cold conditions are expected during this time. Max temps Monday will range from the mid and upper 20s in northern Maryland to the middle 30s in central Virginia. A northern stream closed upper-level low and surface low will drop south into the Great Lakes Monday night. This system will begin to carve out a longwave upper-level trough over the central CONUS. High and mid-level clouds will increase during this time...but it should remain dry with the system still well to our west.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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The middle of next week will feature cold weather with some snow chances, followed by a moderating trend during the late week and into next weekend. A clipper system will be moving through the Great Lakes on Tuesday with its trailing cold front crossing the area Tuesday and Tuesday night. As an upper level trough/energy and jet max move atop the boundary Tuesday night, cyclogenesis will likely occur off the eastern US coastline, with the low then moving northeastward towards the Canadian Maritimes Wednesday/Wednesday night. Uncertainty is still high with regards to the evolution, but there will be chances for some accumulating snow in the Tuesday-Wednesday time-frame, first with the frontal passage and the intensifying upper jet, with potential for additional snow if the low can develop and intensify at a further west longitude and further south latitude. Climatology and pattern at this point would favor points further north/east towards New England for the more significant snowfall. Cold and blustery conditions will follow behind the front for later Wednesday and into Thursday with high pressure and moderating conditions expected for Friday and into the weekend. Highs ahead of the front Tuesday will be in the 30s/40s, falling into the 20s for Wednesday, and slowly moderating through the 40s by Friday and perhaps back near 50F for next Saturday. The coldest night will be Wednesday night with widespread teens in the forecast.
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&& .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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VFR conditions are expected through Monday night. Northwest winds gusting around 25 to 30 knots this afternoon will gradually diminish tonight through Sunday. Light winds are expected Sunday night through Monday night. There is potential for sub-VFR conditions in some snow in the Tuesday-Wednesday time-frame, although uncertainty is high at this point. Widespread VFR will return for Thursday. Gusty northwest winds are also expected to develop Wednesday into Thursday.
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&& .MARINE...
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Canadian high pressure will approach the waters through Sunday before building overhead Sunday night into Monday. The high will gradually weaken and slide east Monday night. A Small Craft Advisory remains in effect for the waters for gusty northwest winds through Sunday. The strongest winds are expected through this evening with peak gusts around 25 to 30 knots. Sub-SCA conditions likely to begin Tuesday, although potential for SCA conditions will be increasing later Tuesday and Tuesday night, and especially Wednesday into Thursday as a cold front crosses the region and northwest winds increase behind the front.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Wind Chill Advisory from 8 PM this evening to 10 AM EST Sunday for MDZ501. VA...Wind Chill Advisory from 8 PM this evening to 10 AM EST Sunday for VAZ503-504-507-508. WV...Wind Chill Advisory from 8 PM this evening to 10 AM EST Sunday for WVZ501-503-505-506. MARINE...Small Craft Advisory until 5 PM EST Sunday for ANZ530>543.
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&& $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...MM AVIATION...BJL/MM MARINE...BJL/MM

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