wpostServer: http://css.washingtonpost.com/wpost2

Most Read: Local

Posted at 09:19 PM ET, 01/20/2012

Sleet and snow overspread region, turning to ice late tonight ; roads treacherous

Links for detailed forecast information:
* Snow accumulation map, storm timeline, and forecast by zone
* Frequently asked questions
* PM Forecast Update*
Follow our updates on Twitter & Facebook

1:00 a.m. update (last one until 5 a.m.): Reports from blog commenters and Twitter followers indicate roads are snow covered and treacherous throughout the region. Although snow will decrease and gradually change to sleet and freezing rain from south to north for the rest of the night, temperatures will remain below freezing, mainly in the mid-to-upper 20s. Until roads are treated or temperatures rise above freezing (probably late Saturday morning), they will remain slick.

Snowfall amounts so far? Generally 0.5-1.25”. (A lot of the accumulating snow we’ll see from this system has fallen, especially south of D.C.)

This is our last update until 5 a.m. We welcome you to comment and discuss conditions with any other night owls below. Thanks for following our updates, and we’ll be back soon.

12:30 a.m update: In our frequently asked questions blog post, we talked about an initial “thump of snow” before precipitation lessened in intensity and that the next period of steady precipitation would probably wait until after sunrise Saturday. It looks like that idea is working out.

Precipitation is decreasing in coverage and intensity to our southwest and mixing more frequently with sleet. So from D.C. and points south , after around 1 a.m., expect lighter precipitation and a gradual transition to mostly sleet and then freezing rain/drizzle over the next few hours. North of D.C., snow will hang around longer. Temperatures should more or less hold steady.

Link: Share you snow photos

12:10 a.m. update: Snow continues, mixed with sleet at times around the region and becoming all sleet towards Fredericksburg. Between 1 and 3 a.m., the precipitation will likely transition to more sleet in the immediate metro region from south to north. So far, amounts in northern Virginia have generally been 0.25-1”, with the greatest amounts west of the beltway. Around the District and into Maryland, 0.25-0.5” of snow seems most common. Temperatures are now into the mid-to-upper 20s in most locations making for slick snow-covered roads.

11:45 p.m. update: With steady snow overtaking much of the region and temperatures falling to 30 or even lower, snow is sticking to roads in most places, even downtown. Everyone needs to exercise caution traveling. Some locations northeast of D.C. may not have accumulation and sticking yet, but that will change rapidly in the next hour

. Link: Closings and delays Saturday

Keep reading for photos, reports, and earlier updates...

Here is a collection of reports and photos we’ve received so far via Facebook and Twitter. Allow a few seconds to load...

Earlier updates:

11:30 p.m. update: A moderate to even heavy snow band in Fairfax county is heading into D.C. Locations inside the beltway where roads are just wet are likely to become snow covered with heavier snow rates, and temperatures falling to near 30.

11:10 p.m. update: Snow continues to be the dominant precipitation type, but many spots are also reporting sleet mixing in. They include: Alexandria, Falls Church, Silver Spring, Southeast D.C., and parts of Charles county. West and northwest of the beltway, snow continues to prevail it seems.

10:45 p.m. update: From the District and points east, mainly light snow and flurries are falling. To the west and southwest, steadier snow is falling with some pockets of moderate to heavy snow. In many of these areas west of the beltway the snow is sticking on roads, so use caution traveling. Snow will begin to stick inside the beltway and to the east as snow increases in intensity over the next hour or two.

South and southeast of the District, we have seen some reports of sleet. Let us know if you have sleet or freezing rain mixing in where you are.

10:15 p.m. update:Maryland and D.C. are now into the light snow and flurries. Moderate snow is within about 30 minutes of moving into Fairfax county. Already Facebook fan Jill Satterfield reports: “We’re in western Fairfax, and street and sidewalk are coated and totally white.”

10:00 p.m. update: Light snow has more or less overspread all of northern Virginia and is knocking on D.C.’s and Maryland’s door. There are some moderate areas in the band that extends southwest to Charlottesville, which will come northeastward and help get the accumulation going between now and midnight

9:45 p.m. update: Facebook, blog, and Twitter reports indicate snow into Dumfries, Burke, Annandale, Springfield and Alexandria.

9:30 p.m. update: Reports of snow rapidly spreading east. Twitter followers and blog commenters say snow now falling in Centreville and Fairfax

9:15 p.m. update: Snow and/or sleet are moving into D.C.’s far west and southwest suburbs. Snow is falling in Winchester and Front Royal. We’ve also seen reports of light snow and/or sleet in Charlottesville and Stafford and Spotsylvania counties. A Twitter follower indicates flurries are as close by as Prince William county. The precipitation seems to be arriving on the early side of our forecast window and should move into the immediate metro region around 10 p.m.

Sticking? Temperatures are just above freezing around the District and to the south and east, but will fall below freezing once snow/sleet begins. Snow/sleet may take an hour or so to begin accumulating in these areas. North and west of the District, temperatures are below freezing and have been for hours, which will allow frozen precipitation to quickly accumulate on most surfaces.

By  |  09:19 PM ET, 01/20/2012

 
Read what others are saying
     

    © 2011 The Washington Post Company