It's 3:30 a.m., 10 degrees below freezing, one inch of snow is on the ground and more is falling, fast. Glenn Johnson has 90 minutes to decide the fate of 48,000 Howard County students.

By 3:45 a.m. he's driving in a whiteout.

"These aren't good conditions," he remarks as visibility drops to about 20 feet.

Whenever the weather turns foul, Johnson -- the Howard County school system's director of transportation for 18 years -- wakes up around 3 a.m. and hits the roads.

The forecast on Thursday was grim: snow, sleet and freezing rain overnight and into Friday morning. But the skies stayed clear until after midnight, forcing school officials around the Washington region to delay decisions about closings until the morning.

A little after 4 a.m., John Matthews, the director of transportation for Montgomery County schools, calls and asks what Johnson is thinking.

"I don't see how we can do anything at all," he replies. Johnson and Matthews both plan to recommend a closing.

Buses actually can handle a lot of snow, Johnson explains. But his responsibility is not just the buses. In Howard County, 9,000 students are designated walkers, and 2,500 teenagers drive to school, as do all the teachers. At 4:15 a.m., Johnson passes Glenelg High School. Plowing in the parking lot has not yet begun.

Howard County road crews have been salting the roads since 2 a.m. The crews can salt the whole county by 8 a.m., but that would be too late: Buses start their routes at 7.

Plows in Howard County are equipped with Global Positioning System devices that indicate nearly two-thirds of the roads have been salted by 4:30. Hardly anything is plowed.

Johnson confers one last time with the rest of his team via radio.

"I've talked to Montgomery, P.G., Carroll, Anne Arundel. Anybody thinking anything other than a close for this morning?" he asks.

"Definitely closure," one voice says.

"I just slid into a ditch and had to pay a guy $10 to pull me out," another driver offers.

AccuWeather Inc., the forecasting service used by the school system, is predicting an end to the snowfall by 7 or 8 a.m., but wind gusts could cause drifting. Freezing could be a problem.

Johnson calls Superintendent Sydney L. Cousin just after 5 a.m.

"There was one time, probably 10 years ago now, I recommended we close, and the superintendent at the time indicated we could go two hours late," Johnson recalls, saying it was the only time in 18 years his recommendation was ignored. "We went, but it wasn't pretty."

In the next 10 minutes, a flurry of phone calls notifies school officials, police, the county highway department, bus drivers and local radio stations that Howard County schools will be closed. To thwart ambitious pranksters, a series of secret code words are used to authenticate the calls.

By 5:15 a.m. it's official: School's out.

At 8 a.m. the snow and rain have turned to drizzle. The clouds are thinning. The major thoroughfares are plowed.

"It's only raining. Who was the idiot who closed school today?" Johnson asks, mimicking the question he says people probably are asking right now.

"If we're going to make a mistake, we're going to make a mistake on the side of safety," Johnson says. "But today the call was good."

For Tyler Conway, 7, of Ashburn, no school means more time for the snow.