Forecast radar from NAM model on Saturday.

It’s not a major storm, but a mix of frozen precipitation and rain in some areas will make for a messy Saturday. Slick travel is possible in parts of the D.C. region, especially between the morning and midafternoon.

The precipitation is likely to move through the region fairly quickly, and large amounts are not expected. But enough may fall that untreated road surfaces may be covered by a thin coating of snow and ice, especially in the colder parts of the region north and west of downtown Washington. Another possible scenario places much of the accumulating frozen precipitation north of the immediate metro area, leaving behind just a patchy wintry mix with limited impact.

Total accumulations of snow and ice are expected to range from none in areas well south and southeast of Washington, to a coating inside the Beltway, to up to an inch or two in our far northern areas.

Timing

Light snow could break out in the region between around 5 and 9 a.m. Saturday, before changing to sleet and freezing rain between midmorning and midday from south to north. There could be a pause in the precipitation after an initial morning burst between mid-morning and early afternoon. And there’s also some chance the initial morning burst passes just north of Washington.

During the afternoon, mostly light amounts of sleet and then freezing rain are expected, changing to plain rain along and especially east of Interstate 95. Precipitation should taper off from west to east between the late afternoon and early evening hours.


American model shows sleet as the primary precipitation type around midday in the Washington region.

The time period of most concern for traveling is between the morning and midafternoon, when we expect most accumulation of snow and ice.

Impacts

Because of the cold air streaming into the area Friday and Friday night, air and ground temperatures will be cold enough for snow and mixed precipitation to accumulate. Most locations should fall into the 20s overnight Friday before the precipitation begins. This means snow should stick to untreated paved surfaces when it begins Saturday morning, including neighborhood roads, driveways and parking lots.

Both motorists and pedestrians should be on alert for slick conditions.

As the precipitation transitions from snow to sleet and freezing rain, a light glaze of ice may top the coating of snow, but visibility should improve in most areas during the afternoon. Also, as temperatures rise above 30 degrees during the afternoon, freezing rain that falls will have difficulty adhering to paved surfaces (untreated bridges and overpasses being an exception), so we do expect travel conditions to slowly improve, especially near Interstate 95 and east.


NAM model temperature forecast on Saturday.

In colder areas west and north of the Beltway, temperatures may remain near or below freezing for the duration of the event, so untreated surfaces could remain slick into the evening, and a glaze of ice could build up on trees and power lines. However, at this time, we do not expect enough ice accretion for widespread power outages.

A hard refreeze is not expected Saturday night, and temperatures may even rise to just above freezing in many areas, but untreated spots may remain slick in our colder areas.

Snow/sleet amounts


Snow forecast from the National Weather Service.

Sleet and snow accumulations could reach an inch or two well north of the city, with an inch or less inside the Beltway and in the nearby suburbs.

Little or no snow accumulation is expected in far southern and eastern areas, south of Prince William County in Virginia and through Southern Maryland.

Here are model snowfall amounts for Washington:

  • American (GFS): 0.7 inches
  • European: 0.7 inches
  • NAM and high-resolution NAM: Dusting
  • Canadian: None

Ice (freezing rain) amounts


Ice accumulation from the National Weather Service.

West of Interstate 95, a glaze of up to a 10th of inch is possible, on top of the snow and sleet, with amounts tending to increase as you head west toward the Interstate 81 corridor and north toward the Mason Dixon line. A few spots could receive up to 0.2 inches of ice accumulation.

Right along Interstate 95, we can’t rule out a very thin glaze of ice, mainly on trees and elevated surfaces before temperatures rise above freezing.

(The above forecast maps were created by the National Weather Service. We generally agree with their projections. On Friday, we do plan to make our own accumulation prediction maps for this event.)

Uncertainties

Some models continue to forecast the heavier and steadier precipitation ending up mostly north of the city, which could cut down on impacts from snow and ice in areas around the Beltway and especially to the south.

Exactly where a possible front-end burst of snow travels through will have important implications for where roads quickly turn slick Saturday morning. Some models have it missing areas from around the District south entirely and only forecast very light, patchy precipitation, which could cause a few localized slick spots but probably wouldn’t amount to much.

Temperatures are also a bit of a wild card. Warmer models predict temperatures to rise above freezing in most of the area between midafternoon and early evening, which would allow conditions to more rapidly improve. The colder models keep it below freezing west of Interstate 95 for most of the event. We lean toward these colder model forecasts, as cold air wedged into the region is difficult to dislodge.