Wintry conditions forced postponement of last night's Washington Bullets-Philadelphia 76ers basketball game at Capital Centre and cancellation of horse racing at the area's three operating tracks. In addition, Laurel Race Course officials called off today's program.

Garnett Slatton, executive vice president of the Bullets, said last night's game was postponed by the National Basketball Association even though both teams were in Washington.

"It's really a matter of safety. We got word from local authorities that driving conditions were extremely hazardous {by midday}," Slatton said.

Slatton said he had measured nine inches of snow in Capital Centre's parking lot, with drifts of up to two feet.

The game has not yet been rescheduled, Slatton said. The last time a Bullets game was canceled at Capital Centre was Feb. 20, 1979, also because of snow.

In horse racing, Rosecroft and Charles Town were not scheduled to operate today.

The decision to cancel yesterday cost Laurel owners money.

Laurel called off yesterday's program at 11 a.m. -- about 1 1/2 hours before post time -- after revised forecasts called for a heavier snowfall than originally anticipated. Because Laurel had committed to race at 10:30 a.m. -- the official start of its work day -- the decision meant track owners had to pay employes for a half-day of work.

"As of 10:30, we were informed that the snows were going to taper off," said Laurel president Frank De Francis. "Our track maintenance man said the track condition was fine, the jockeys said they would ride, and our admissions people were ready to go. About three minutes later, the skies opened, and then we received the updated forecast."

The cancellation put adrift yesterday's feature race, the $40,000-added Sports Palace Handicap, which De Francis said likely would not be rescheduled.

Racing is scheduled to resume Friday at the three tracks: Laurel begins at 12:30 p.m., Rosecroft at 7:30 p.m. and Charles Town at 7:15 p.m.