A study of flash flood potential in Western Nevada and Eastern California to enhance flash flood forecasting and awareness

This study identifies the critical synoptic scale patterns associated with flash floods in Eastern California and Western Nevada. Synoptic data from the 500 mb level was collected for the identified flash flood days and classified into three unique patterns. Sounding data from Reno and Winnemucca were used to identify critical thresholds for parameters for each unique pattern used in heavy rainfall forecasting. The critical thresholds were then used to develop a new Flash Flood Potential Index (FFPI) for each of the three patterns. The new indices were compared to the current FFPI method using flash floods data in 2004 and 2005. The new indices were found to produce more a representative FFPI value for flash floods days over the current FFPI method. However Flash Flood events are rare in Eastern California and Western Nevada, these new methods require additional cases and testing by operational forecasters for a complete validation. (Abstract shortened by UMI.)...