Determining the Relative Frequency of Occurrence of Local Cumulonimbus Activity through Discriminant Analysis

Abstract

Discriminant analysis is used to develop a cumulonimbus prediction equation (Z index) for a single station during the period June through September. Based on dependent data, the Z index explains 43% of the variance, while the more commonly used K index explains only 34% of the variance in the same data set. Verifications with 4 years of independent data demonstrate that the Z index yields a lower seasonal Brier Score than the K index, precipitable water content, persistence and the climatological average of cumulonimbus activity for June?September. It is concluded that the Z index provides a meaningful first approximation to the probable development of local cumulonimbus activity during the period June?September.