It's 1 p.m. on Jan. 3, 2000, the first day back to work after the millennium holiday weekend. The weather is nasty. Four inches of snow already are on the ground and six more inches are expected by the end of the day.

Four minutes later, a District resident reports an explosion at Military Road and Nebraska Avenue in Northwest Washington. Many intersections are impassable; at others, the traffic lights are out. The District and federal governments decide to close early. Emergency shelters open to house stranded travelers, including 200 who are at Union Station because Year 2000 computer glitches have stopped Amtrak. Glitches also cause power outages and cripple the pumps that supply gasoline to snowplows.

This was the scenario confronting about 75 D.C. government officials from 42 agencies yesterday in their last all-out drill before the New Year's weekend, 23 days away. Huddled in two command centers on the eighth floor of the Reeves Municipal Center in Northwest Washington, the officials practiced how they would respond to a winter storm on the first day when the Year 2000 computer bug could disrupt government, businesses and other vital facilities that would have been closed over the weekend. (In anticipation of possible Y2K problems, D.C. public school officials have decided to delay reopening until Jan. 6.)

The District's emergency-preparedness efforts, neglected for years because of financial crisis, will be severely tested during New Year's weekend. In addition to the usual New Year's Eve partying, thousands of people will be drawn to the capital for a national celebration of the millennium on the Mall. The Year 2000 problem, in which computers have been programmed to read only the last two digits of a year, heightens concerns because the District was one of the last cities in the nation to repair its computers.

After watching the drill, Norman Dong, the deputy mayor for operations, called the city's ability to handle emergencies "pretty good," considering that the drill simulated unusually difficult conditions. "Obviously, we hope we won't be in this position on Jan. 3. But we take nothing for granted," Dong said.

The drill went something like this:

Picture a smaller version of NASA's Mission Control Center, with rows of law enforcement, health, transportation and fire and rescue officials sitting at 31 stations, each with phones and laptop computers. At the front of the room are two big-screen televisions and other monitors displaying information as it arrives.

The phone rings at the desk of D.C. police Inspector Ira Grossman. On the other end is Paul Mills, an official with the D.C. library system, who plays a police officer calling in an incident. Mills is about 100 feet away, in an office.

Reading from a script, Mills says: "This is Officer Hall of the Second District. I have a water main break at Wisconsin and Reservoir. It looks like it's gushing out the road and the street might cave in."

Grossman refers the call to the Water and Sewer Authority.

On it went for three hours--17 people from D.C. agencies reporting one distressing situation or another. Someone even conceived of a glitch in the sale of lottery tickets, with many people hitting the jackpot.

"Everybody thinks they've won? I like that," said Peter LaPorte, the District's emergency-preparedness director.