Many of the most damaging types of weather begin quickly, strike suddenly, and disappear rapidly, destroying small areas while leaving neighboring areas untouched. Such event as a tornado(龙卷风) struck the northeastern part of Edmonton, Alberta, in July 1987. Total damages from the tornado went beyond $250 million, the highest ever for any Canadian storm. Traditional computer models of the atmosphere have limited value in predicting short-lived local storms like the Edmonton tornado, because the available weather data are generally not detailed enough to allow computers to study carefully