Master of Science
Dorian J Burnette
Arleen A Hill
Recent research has shown tornado activity over portions of the U.S. is impacted by internal ocean-atmospheric forcing. Impacts of seasonal and annual precipitation on tornado activity have also been assessed in previous studies, but no published research has included a full assessment of the soil moisture balance despite the known influences of soil moisture on thunderstorm activity. Therefore, this research explores the influence of soil moisture balance on tornado activity over Arkansas, Louisiana, Mississippi, and the western portion of Tennessee. Two measures of the soil moisture balance were used, the Palmer Drought Severity Index (PDSI) and the Palmer Z-Index. Tornado day counts were computed from tornado path data and transformed into percent of normal values for comparison with the two drought variables and various ocean-atmospheric teleconnections (e.g., El Niño-Southern Oscillation). Results suggest the impact of soil moisture balance on tornado counts over the Southern Mississippi River Valley is mostly during the warmer months from late winter into the spring. Forward and backward stepwise regression modeling identified the Z-Index and the winter (December-January-February) Oceanic Niño Index as the most important variables influencing tornado day variability over the Southern Mississippi River Valley during the spring season (March-April-May).
Dissertation or thesis originally submitted to ProQuest
Rodriguez, Delmer, "Winter-Spring Tornadoes and Drought over the Southern Mississippi River Valley" (2023). Electronic Theses and Dissertations. 3051.