Donald S. Foster, 65, a meteorologist with the U.S. Weather Service who specialized in forecasting and analyzing tornadoes and other severe storms, died of cancer Aug. 30 at the Washington Hospital Center.

Mr. Foster, who was born in Middletown, Ohio, graduated from Miami University in Oxford, Ohio. During World War II, he was a meteorologist in the Army Air Forces. He later held a commission in the Air Force Reserves and retired in 1976 with the rank of colonel.

After World War II, Mr. Foster joined the old U.S. Weather Bureau. He was assigned to France and Germany and then moved to Kansas City, Mo., where he helped establish the National Severe Storms Forecast Center. He also did graduate work at the universities of Chicago and Kansas.

In 1967, he was transferred to the National Oceanic and Atmospheric Administration, which includes the present Weather Service, in Suitland. There he was chief of the analysis and programming branch of the computer division.

Immediately after retiring in 1972 he went back to the Weather Service as a research meteorologist in the Technique Development Laboratory, specializing in the statistical analysis and forecasting of severe storms. He remained there until his death.

Mr. Foster, who lived at Rossmoor Leisure World in Silver Spring, received the Bronze Medal of the Commerce Department for his work in forecasting tornadoes with computer techniques during his years in Kansas City and also was a member of a group there that received the Silver Medal for saving lives and property by forecasting severe weather. He received a number of Meritorious Service awards.

Survivors include his wife, Gretchen, to whom he was married for 39 years, of Rossmoor; two sons, Richard and Robert, both of Pacific Palisades, Calif., and his mother, Ruth Clouse of Xenia, Ohio.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society, or to the Inter-Faith Chapel, Rossmoor Leisure World, Silver Spring, Md.