A Central Texas Synoptic Climatology and its Use as a Precipitation Forecast Tool

Herschel T. Knowles Atmospheric Science Group, The University of Texas at Austin, Austin 78712

Search for other papers by Herschel T. Knowles in
Current site
Google Scholar
PubMed
Close
and
Kenneth H. Jehn Atmospheric Science Group, The University of Texas at Austin, Austin 78712

Search for other papers by Kenneth H. Jehn in
Current site
Google Scholar
PubMed
Close
Full access

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.

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.

Save