Tornado frequency in the Southern Plains as related to Sea Surface Temperatures in the Pacific Ocean

Variations in Sea Surface Temperature Anomalies (SSTAs) from El Nino/Southern Oscillation, Pacific Decadal Oscillation, and other tropical and extra tropical phenomena have a profound effect on planetary and synoptic scale weather patterns over the Southern Plains of the United States. Such impacts are associated with changes in the number of tornadoes in the region when viewed on a monthly time scale. Therefore, one can identify areas in the Pacific exhibiting significant relations with above and below average tornado months in the Southern Plains

This is addressed by regressing a tornado time series against SSTA time series. A data set of tornadoes, spanning the years 1950 to 1997, is used to identify the time of day, day, month, year, intensity, length, and width of each tornado record. The Southern Plains has been objectively regionalized into eight coherent areas. This process is essential to ensure tornado characteristics are coherent within a geographic location. If this step is ignored, much of the signal could be lost in using broader areas. Contrary to previous work, this study has identified sensitivity in the central North Pacific Ocean, as opposed to the tropical Pacific, as the major source of signal. However, various coherent tornado regions relate somewhat differently to the Pacific Ocean SSTA signal, thereby suggesting that the subdividing the Southern Plains may enhance potential predictability. Results of this work can be used to form a linkage suggesting physical hypotheses for above and below average tornado months based on current SSTA observations.