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Posted at 11:20 PM ET, 01/17/2011

Icy conditions likely last into morning commute for D.C. and points north and west

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Tonight & Tomorrow: A dusting (south & east) to 1" (north & west) of snow/sleet this evening, then becoming mainly sleet and/or freezing rain overnight into early morning, except turning to plain rain south & east of D.C. Icy road conditions in the District and to the north & west probably don't improve until 8-9 a.m., when temps warm slightly and precip goes to all rain before ending by afternoon. The exception is Frederick, central Loudoun, northern Fauquier counties and points north & west, where ice lingers even later into the morning.

If ice builds up enough, some power outages are possible by early morning, mainly in the northern/western suburbs.

Detailed forecast & SchoolCast by zone (***updated!***) | Forecast through the weekend

Stay tuned for live updates to appear below...

11:20 p.m. Update: This will be the last update for the night. Radar shows a solid area of moderate (a few pockets of heavy) wintry precipitation across the entire area. It's going to be a long, icy night in most places. And as our latest forecast suggests above, a likely difficult morning commute with significant icing and school delays/closings possible, especially from D.C. to the north and west. (Note, SchoolCast for immediate north/west suburbs updated to 2 apples.) Sleep well and check back with us in the morning.

10:50 p.m. Update: The National Weather Service has now upgraded Montgomery, Frederick, Howard & Carroll counties, as well as Baltimore City and County, to a Winter Storm Warning in effect until noon Tuesday due to the substantial icing expected (around .25").

10:20 p.m. Update: The latest model data is in, and confirms what we've suspected and is mostly implied in the forecast above. Which is that as the precipitation turns to mainly sleet and/or freezing rain tonight, temps are going to have a lot of trouble rising to and above freezing in the immediate north and west suburbs (e.g., Montgomery and Fairfax counties) until at least an hour or two after sunrise (so, maybe not until 9 a.m. or so) and even later further north and west (e.g., Loudoun and Frederick counties). That means the possibility of significant icing well into the morning commute for those areas. Even in D.C. proper, icing could be an issue into the first part of the commute before daylight has a melting impact by, say, 8 a.m. or so.

9:30 p.m. Update: A wintry mix continues throughout D.C. and vicinitiy - with precipitation liable to change from snow, to sleet, to freezing rain, from one minute or one mile to the next - and many roads have a light but slippery coating of snow and ice. Parts of western Fairfax County and into Loudoun County have actually seen a bit of a gap in the precip. That should fill in shortly, though may reappear from time to time through the night with those areas being toward the western edge of the main slug of precip. Temperatures everywhere in the area are in the upper 20s to near 30, and it seems unlikely they'll reach the freezing mark north and west of the District until after sunrise.

8:15 p.m. Update: Radar has blossomed nicely with a mix of precipitation types - snow, sleet and freezing rain - being reported across the area. A light coating of snow or snow/sleet has formed in some places, especially north and west of town. A Freezing Rain Advisory has been issued through midnight for St. Mary's and Calvert counties in Southern Md. and just to the west in King George County, Va., where NWS expects a few hours of freezing rain before changing to plain rain.

7:15 p.m. Update: Reports of flurries, light snow and/or light sleet starting to come in around the area. A more organized area of precipitation, probably in the form of snow and/or sleet, likely arrives in the metro area from south to north between about 7:45 and 9 p.m. Icy patches may develop quickly once precipitation arrives, with most everyone right now at or a little below freezing.

What's happening where you are? Leave a comment below...

By  |  11:20 PM ET, 01/17/2011

Categories:  Forecasts, Forecasts, Forecasts

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