Numerical Study of Storms in the Transvaal

Abstract

An automatic procedure was developed for tracking the centroids of many weather radar. echoes simultaneously by computer. This was applied to storms recorded ID the Transvaal on 19 days of radar operation during the summers of 1976–7 and 1977–8. Of the 1861 storms tracked, only 23 percent attamed 100 km² and only 8 percent lasted more than an hour. Deviation of storm tracks to the left of the mean 500 mb winds was found to increase with increasing storm lifetimes and areas. When the 500 mb winds were strong, storm directions were usually well correlated with their areas.