ESTIMATING PRECIPITATION AT SAN FRANCISCO FROM CONCURRENT METEOROLOGICAL VARIABLES

Abstract

Variables obtained from synoptic sea level and upper air charts are investigated to determine their significance in the estimation of concurrent rainfall. Eight variables consisting of sea level pressures and pressure gradients, pressure heights and height differences, and the temperature-dew point differences at two upper levels are combined into a graphical procedure to estimate the probability of occurrence of rainfall. With the probability of occurrence rising to above 50 percent, supplementary charts are used to estimate the amount of rainfall to be expected.