The first significant snowflakes of the season blew into the region on swirls of arctic air yesterday, setting a wintry tone for a week that will end with Christmas.
Accumulation was modest. After light snow had been falling for four or five hours, the largest amount reported in the area was about an inch.
Although falling flakes added effect, it was plummeting temperatures and rising winds that truly spelled the coming of winter.
In several areas, automobiles skidded off slick roads. Minor accidents littered Route 32 between Crofton and Columbia, one witness said. The Chesapeake Bay Bridge was reported closed in both directions for a time.
Slickness, ice and a lack of traction got the better of motorists in a number of spots despite numerous warnings and the efforts of hundreds of highway workers deployed throughout Maryland, Virginia and the District.
Using trucks loaded with chemicals, the workers tried to keep wet roads from becoming icy in the face of a cold front that sent frigid blasts from the far north.
At Reagan National Airport, the temperature fell almost 20 degrees in six hours, from 41 degrees at 4 p.m. to 22 degrees at 10 p.m.
By 7 p.m., winds were gusting as high as 36 mph. The wind chill at National was computed at 5 degrees at 10 p.m.
Transportation officials cautioned drivers this morning to be alert for black ice, a thin layer of ice that forms over asphalt and is hard to distinguish from wet pavement.
"People just need to slow down and be careful," said Ryan Hall, a spokesman for the Virginia Department of Transportation, which is responsible for most roads in Northern Virginia. The agency dispatched 400 trucks to spread chemical de-icer on interstates and primary routes yesterday.
At 7 p.m., he said that most of the snow had melted on impact and that keeping the moisture from freezing was the principal concern.
"No matter how long we're out there, there can always be spots that freeze up," Hall said. "In this area, it only takes one accident to make rush hour terrible. People need to be careful, give yourself plenty of room, take it down below the speed limit. Don't be in a rush. . . . If you see wet pavement, it's probably ice."
Lora Rakowski, spokeswoman for the Maryland State Highway Administration, urged motorists with computer access to check www.marylandroads.com and click on "Chart" for weather information, road conditions and live cameras that show traffic flow on major roads. "It's a treasure-trove of information," she said. "It's about hitting the cyber highway before the actual highway."
Maryland called in about 170 workers and prepared 166 pieces of equipment to fight snow and ice in the Washington suburbs, Rakowski said. By 3:15 p.m., the first crews were spraying de-icer along roads in Gaithersburg, she said, and by 7 p.m., the other crews followed. In the District, 85 workers operating 80 trucks began work at 4 p.m.