Winter launched a sneak attack early yesterday, zeroing in on the Washington area with from four to 11 inches of snow driven by winds up to 25 miles an hour in the most severe storm to buffet the area this early in December since 1957.

The snowfall surprised forecasters, who had expected it to pass south of the District. "We got caught with our pants down," said one National Weather Service official.

Light snow began falling shortly after midnight and grew heavier through the night, the weather service said. The storm finally let up an hour after dawn, leaving behind hazardous driving conditions but relatively light weekend traffic and public transportation disruptions.

An Alexandria woman, Elizabeth Bernard, 20, of 4609 Ferry Landing Rd., was killed yesterday afternoon when the car she was driving hit a slick spot and skidded into another car and then off an embankment on Backlick Road near Richmond Highway in Fairfax. Two passengers in the second car, Mary Flaherty, 43, and her daughter, Maureen, 15, both of 8817 Gateshead Rd., Alexandria, were admitted to DeWitt Army Hospital at Fort Belvoir.

Area police reported dozens of other accidents, including a tractor-trailer that skidded off the Beltway near Kenilworth Avenue in suburban Maryland.

By last night, main roads and bridges in the area mostly had been cleared, and officials predicted the biggest problems commuters would face this morning would be on residential and other secondary streets, many of which have not been cleared.

Streets that yesterday were filled with slush became icy last night as temperatures plunged into the teens. Area road crews worked throughout the night to sand or salt slick spots before this morning's rush hour.

Temperatures are expected to hover around freezing today, but officials expect to complete their snow removal operations before this afternoon's rush hour.

Al Long, a Metro spokesman, said icy roads may delay some buses this morning, but the rail system is expected to operate on schedule. Yesterday, Metrorail experienced sporadic delays until about noon, Long said. "We had trouble all morning. We had trains die on us on the Orange and Blue lines," Long said. "After that, we had trains die on the Red line." Service on the Red line past Woodley Park was shut down for about two hours yesterday afternoon because of water accumulation in the tunnel.

Some Metro buses were delayed as long as two hours yesterday.

Most school districts in the area said they would decide this morning whether to open at regular times or delay the start of clases, depending on the weather and road conditions. In Maryland, Charles, St. Mary's, Calvert and Prince George's counties' schools will open an hour later than usual. In Virginia, Prince William and Fairfax counties' and Fairfax City schools will open two hours late, and in Fairfax there will be no preschool or kindergarten today and elementary schools will operate on their regular (non-Monday) schedules. District of Columbia schools will open on time.

The storm developed Saturday over the Gulf of Mexico and moved northeast, passing near Cape Hatteras, according to forecaster Gary Ellrod. He said forecasters had expected the capital region to be "right on the boundary line between heavy snow and no snow. . . .but it came further north than we thought. We were 80 to 100 miles off."

The storm blanketed large portions of western and central Virginia and northern Maryland, reaching into the northern Atlantic states. Philadelphia received seven inches of snow, but Harrisburg, to the west, got very little, Ellrod said.

Locally, National Airport reported a seven-inch snowfall and airport officials suspended flight operations from 6:40 a.m. until about 9 a.m. because of the weather. Dulles Airport in western Fairfax County received 11 inches, but officials there said operations were not affected. Crews at Baltimore-Washington International, where six inches of snow fell, managed to clear runways without delaying flights, the airport management said.

Some area police and highway officials expressed relief that the storm, with its unexpected intensity, occurred on a weekend. "What a gift on a Sunday," said D.C. Traffic Engineer Seward Cross. "This is the best time of the entire week it could have happened for the least impact."

Others, dealing with multiple fender-bender accidents and snagged road and street-clearing operations, were less sanguine. "They're driving us up the wall -- cars left on the Beltway," sighed Maryland State Police Lt. Morris Krome in Montgomery County. "The idiots are still spinning out."

D.C.'s Cross said the city's snow control center opened at midnight to monitor road conditions and that half of the District's snow crews were mobilized at about 3 a.m. Within 45 minutes, with the temperature dropping and the storm's intensity gathering, a full mobilization was declared.

Portions of the Beltway early yesterday were littered with ditched or abandoned vehicles. In Virginia, a six-mile stretch between Shirley Highway and the Woodrow Wilson Bridge over the Potomac still was rocky with ice and hard-packed snow at about noon.

Merchants open yesterday reported varying signs of the storm's impact.

"We're definitely doing less than we should be," said Steve Kovin, assistant manager of Cedar Posts, a store selling Western-style apparel at White Flint Mall in Montgomery County. "People tend to go bonkers when they see a snowflake. The Redskins game against St. Louis probably didn't help either."

Dave McIntosh, manager of Waxie Maxie's, a record store at Congressional Plaza in Rockville, agreed. "I would say that we're not doing what we would have hoped for."

Others said they had no choice about shopping, snow or no snow. "Nothing would have prevented me buying my kids toys today," said a woman at Bloomingdale's in White Flint. "They would have killed me if I hadn't gone shopping today like I promised."

At a Hechinger's store on Georgia Avenue in the District, sales clerk Peter Jones said one customer yesterday morning asked for 11 snow shovels. "We only had eight . . . he got eight different types at eight different prices. The only one he didn't get was the one we're using ourselves out front."