Area Forecast Discussion
Issued by NWS Sterling, VA

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996 FXUS61 KLWX 060210 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 910 PM EST Mon Dec 5 2016 .SYNOPSIS... High pressure will briefly build over the region tonight. Coastal low pressure will impact the area Tuesday into Tuesday night before high pressure briefly returns again for Wednesday. A potent cold front will pass through Thursday and arctic high pressure will build overhead during the weekend. && .NEAR TERM /TONIGHT THROUGH TUESDAY NIGHT/... Clouds have thickened across most of the area early this evening. Light rain is falling over far southern VA and North Carolina. Precip will begin to overspread the far southwest corner after 06Z, but most probably after 09Z. Current temps and dewpoints suggest precip will fall initially as light rain. After a few hrs of saturation, temps may drop below freezing at the higher elevs for rain to freeze on contact. There is good model support for fzra in Highland, Pendleton and the western portions of Grant, Mineral, Alleghany counties. There are also two RAWS stations, Nathaniel Mtn (3004 ft) in Hampshire county WV and North Zone Portable RAWS in western Rockingham (3830 ft) where current dewpoints are low enough to support wet-bulb temps below freezing. Have thought about expanding the current winter wx advzy east to include Hampshire, Hardy, Augusta and Rockingham counties, but the areal coverage of fzra seems too small to warrant an advzy for the entire counties. There is also weak support for fzra over the Blue Ridge mtns, however, dewpoint has been rising at Wintergreen and is currently at 37F. So, fzra appears highly unlikely at this time. Sub-freezing air could linger over the highlands through most of the day according to the 12Z ECMWF ensembles, so current advzy looks good in areal coverage and expiration time. Rain moderate to heavy at times will fall over the rest of the area and should begin to taper off between 00Z-03Z Wed. Total precip amounts of 0.5 to 1.0 inches are expected with up to 0.20 inches of frza possible over the highlands. .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... The shortwave trough will move across the region Tuesday night. Temperatures will likely max out in the 30s and around the low 40s across the I-95 corridor Tuesday afternoon/evening. Temps will slowly rise into the evening however winds will become NW by Wed morning and cool dry air will move into the region. Sunny conditions expected Wednesday with temperatures reaching the 40s and 50s along I-95. A cold front will approach the region && .LONG TERM /THURSDAY THROUGH MONDAY/... A storm system will approach from the west Thursday and Thursday night. A chance of rain or snow showers exist across the region each period. Precipitation should be light in intensity with chilly temperatures. High pressure is expected to build in from the west Friday through Saturday night. This high could bring the chilliest air so far this season. Some upslope snow showers could also occur in the Potomac Highlands. The high will move offshore of the East Coast Sunday ahead of the next approaching trough of low pressure Sunday night into Monday. This next storm system could bring a chance of wintry precipitation at the onset Sunday night, change over to rain, before ending as a little snow sometime on Monday. The confidence in the timing and precipitation type is low. The 12z GFS model is moving this storm system eastward much faster than the 00z European model. We will have to see how the 12z European model handles the storm. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... LIFR/VLIFR conditions expected 12Z Tue-06Z Wed across all terminals in moderate to heavy rain. Cigs and vsbys begin to improve after 06Z Wed. VFR conditions expected Wednesday. Mvfr to ifr conditions possible in any rain or snow showers Thursday and Thursday night. Winds variable 5 to 10 knots Thursday becoming northwest and increasing 10 to 15 knots gusts 20 knots Thursday night. && .MARINE... High pressure will build overhead tonight before coastal low pressure impacts the waters Tuesday. A Small Craft Advisory is in effect for portions of the waters Tuesday afternoon. No marine hazards expected Thursday. Small craft advisories possible Thursday night. Winds becoming northwest 15 to 20 knots gusts 20 to 25 knots Thursday night.&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for MDZ501. VA...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for VAZ503-504. WV...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for WVZ501-503-505-506. MARINE...Small Craft Advisory until 5 PM EST this afternoon for ANZ530>543. Small Craft Advisory from noon to 6 PM EST Tuesday for ANZ532>534-537-540>543. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for MDZ501. VA...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for VAZ503-504. WV...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for WVZ501-503-505-506. MARINE...Small Craft Advisory from noon to 6 PM EST Tuesday for ANZ532>534-537-540>543. && $$ SYNOPSIS...HSK NEAR TERM...LFR SHORT TERM...HSK/LFR LONG TERM...KLW AVIATION...LFR/KLW MARINE...LFR/KLW

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