Thursday, 17 January 2002: 1:45 PM
Topographic and synoptic influences on cold season severe weather events in California
This preliminary study looks at identifying the role played by terrain features under favorable synoptic conditions in creating severe weather events in California. Using a 25-year dataset from Storm Data, the authors found that the distribution of tornadoes, hailstorms, waterspouts and funnel clouds, shows definite topographic influences. The complex terrain of California has been shown to contribute to the frequency and severity of convective severe weather events, especially in areas of significant low-level convergence. By studying the locations of these severe weather events on a local scale, we have identified several pockets of greater storm frequencies. Composite synoptic features were then identified up to 24-h periods prior to times of greatest storm severity. While the majority of these cases were associated with post-frontal convection, we found marked differences in synoptic patterns between events in northern, central and southern California and between types of severe weather events. In identifying the contributing synoptic patterns and the subsequent terrain influences, a useful guide for severe weather prediction can be created. Although simplistic in design, the proposed guide is meant as a tool to be used to complement other forecasting tools currently being used.