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Light to moderate snow likely for Thursday morning commute, with slick roads

A winter storm is streaking toward the Washington, D.C., area. Snow is likely to coincide with the morning commute, producing slick roads and hazardous travel conditions. Capital Weather Gang's Jason Samenow has your forecast. (Video: The Washington Post)

5:10 p.m. update: We have now published our latest forecast update. Follow this link: PM Update: Snow pushes in tonight, lasts into early Thursday; Morning commute may be ugly

3:10 p.m. update: The latest run of the NAM model generally supports our forecast of 1-3 inches for the immediate area, with a little more south and a little less north. The SREF model suite increased its average snowfall forecast a hair up to 4 inches from 3 inches in its previous run for the District. It leaves open the possibility snow totals could be on the high side of forecasts, but has a wide range of solutions – from a dusting to 8 inches. At this point, we’re leaning towards holding firm with our forecast displayed on the map deeper down in this post.

2:10 p.m. update: The National Weather Service has issued a winter weather advisory – for generally 1 to 2 inches of snow – for the entire metro area from midnight to noon Thursday.  It expects the heaviest snow during the morning commute.  The advisory does not include our far west and northwest areas, including the I-81 corridor.  Southeast of Fredericksburg, Va., a winter storm warning is in effect for 3-6 inches of snow.

12:55 p.m. update: The European model has come in pretty snowy with Thursday’s forecast, suggesting more like two to four inches for the immediate metro area and one to three inches for our northern suburbs. For now, we’ll stick with the snowfall forecast we describe below, but the European may portend a shift toward increasing or higher end amounts.

Original post, from noon

A major southern winter storm streaks toward the region overnight, spreading light to moderate snow into the region. The snow is likely to coincide with the morning commute, producing slick roads and hazardous travel conditions. The cold ground means the snow will stick immediately.

While we expect accumulating snow in the D.C. area, the heaviest snow — by far — will occur southeast of the D.C. metro region. Richmond could get five to 10 inches of snow and the Norfolk area around a foot.

D.C. is on the northern edge of this storm system, which is the trickiest place to forecast. “Identifying exactly where the heavier snow will stop and start is always the most difficult along the edge of the storm,” says Wes Junker, Capital Weather Gang’s winter weather expert. “For this reason, snow totals may need to be adjusted upward or downward if the storm track shifts north or south. We urge you to closely monitor forecasts.”

Key points:

  • Snow likely begins between midnight and 4 a.m., from south to north.
  • The steadiest and heaviest snow probably occurs between about 4 a.m. and 8 a.m.
  • Snow tapers off from west to east between about 8 a.m. and noon.
  • We expect roughly one to three inches of snow in the immediate D.C. area, two to five inches in D.C.’s far southern areas, including Fredericksburg, and less than an inch in D.C.’s far northern suburbs, including Columbia and Frederick.
  • The snow will be heavier and start earlier (and potentially last longer) south and southeast of the District
  • If the storm tracks a bit farther north than currently forecast, more substantial snow amounts could impact the immediate D.C. area, and the snow would last longer (BOOM scenario, 25 percent chance)
  • If the storm tracks a bit farther south than forecast, very little snow may fall, and it will not last very long, likely ending by around sunrise, with minimal effects on the morning commute (BUST scenario, 15 percent chance)
  • Temperatures will mostly be in the mid-20s to around 30 while the snow falls, though it may be right around freezing in the city when the snow begins before falling to around 30.
  • Some school delays and cancellations are likely.  We’ll issue a SchoolCast and FedCast this afternoon

Related: Winter storm forecasts are about more than a number on a map | Boston just inches away from snowiest season, with more in the forecast | Extreme February cold ices over most of Chesapeake Bay in rare event

Model forecasts:

Here’s a look at the forecasts from various computer models…

High resolution NAM model: One to three inches for immediate D.C. area, less north (one inch or less), and more southeast (three to eight inches)

GFS model: Generally one to two inches for immediate D.C. area, with two to four inches to the southeast and less than one inch to the north

Canadian model: One to two inches for the District and immediate southern suburbs, two to four inches for the District’s far southern suburbs, and less than one inch north of the District

The SREF model simulations, not shown, forecast an average of three inches for D.C., with a range of zero to eight inches

Forecasts from  the media and the National Weather Service

National Weather Service





Programming note: We’ll have  a SchoolCast by mid-afternoon, and another forecast update by 5 p.m.

Link: Our full forecast through the weekend