The Synoptic and Physical Character of Oklahoma Tornadoes

Abstract

The synoptic and physical characteristics of Oklahoma tornadoes are studied for the 16-year period 1959?74. When the Oklahoma results are compared with tornadoes in Iowa (Notis and Stanford, 1973), grouping tornadoes into classes based upon direction of movement reveals a number of differences in tornado characteristics between the southern and central portions of the Midwest. In both states a strong correlation between tornado direction of movement and 500 mb flow direction is found. These results, based on 534 tornadoes in Oklahoma and Iowa, provide a statistical basis for tornado movement forecasts. Since it is widely believed by the public that tornadoes move from the southwest, such forecasts may be of greatest value in the northern portions of the Midwest, under conditions of northwesterly flow aloft. Median and expected path lengths for Oklahoma tornadoes are found to be ?1 mi and 4.2 mi, respectively. A ?2 test reveals that the tornado path length distributions are not independent of 500 mb speed in the 30?70 kt range.