The current string of unseasonably warm sunny days in the Washington area probably will end late today or early tomorrow as cooler temperatures and cloudy skies move in, spoiling the rest of Thanksgiving weekend.

National Weather Service forecasters said an almost stationary high-pressure system responsible for the balmy weather of the last five days is slowly being nudged into the Atlantic by an inhospitable storm system now working its way across the center of the nation.

That system -- which has triggered unprecedented snows, high winds, tornadoes, and rainstorms from the Rockies to the Ohio Valley -- will miss the Washington area, forecasters said, but its outer fringes will bring cloudiness, possible showers and more seasonable temperatures here.

Washington's current warm spell has sent temperatures into the 70s the last four days -- a good 15 to 20 degrees above the normal daytime high for this time of year. Nights have been comfortably cool, with low temperatures in the mid-40s, about eight degrees above normal.

The high temperature yesterday at National Airport was 70 degrees, a far cry from the record of 79 degrees set for the date in 1900. But forecasters said there's a good chance the record high for today -- 75 degrees, set in 1940 -- may be matched or beaten if the cloudiness expected here holds off until late in the day.

The outlook for the rest of the Thanksgiving weekend is gloomy -- mostly cloudy, a chance of showers and slowly falling temperatures through Sunday.

The prolonged good weather of the last several days has been caused by a "whole pattern of slow air movment and light winds" throughout the mid-Atlantic region, said weather service forecaster Jeffrey Bowman. "It's been almost like suspended animation."

The storm system currently attacking the West and Midwest is also moving slowly, giving only a slight push to the pleasant high-pressure system here as it moves out into the Atlantic. The storm system which originated over the Colorado-Utah-Arizona-New Mexico "four corners" area, was reported over Missouri late yesterday and is headed northeast toward the Great Lakes.

It has brought more than two feet of snow to parts of Colorado and Wyoming, 45-mile-an-hour winds in Nebraska, tornadeos in East Texas and heavy rains from the middle Mississippi Valley to the lower Ohio Valley.