Abstract
A synoptic precipitation climatology was derived for central Texas centering on Austin. Characteristics of the 500 mb wind field were combined with a surface wind parameter to “type” the 1200 GMT circulation pattern for 2327 days of study. The relative frequency of precipitation was computed for three consecutive 12 h periods following 1200 GMT for each circulation type. Use of the derived precipitation frequencies as a first estimate of the probability of precipitation, given a predicted circulation pattern, was evaluated for its effectiveness as a forecast tool. Results indicated that for the first 12 h period, use of the synoptic climatology provided guidance inferior to that currently available to forecasters in the field. However, for the second and the third 12 h periods, the synoptic climatology provided guidance better than that available to meteorologists over teletype and the weather facsimile network.
