Date of Award

December 2022

Document Type


Degree Name

Master of Science (MS)


Atmospheric Sciences

First Advisor

Catherine Finley


Streamwise vorticity developing within the forward flank (FF) of supercell thunderstorms has been found to modulate the intensity of the low-level mesocyclone. However, few studies have quantitatively investigated FF vorticity contributions to low-level mesocyclone intensity. This study investigates the relative contribution of streamwise vorticity within the FF to the low-level mesocyclone strength using two Cloud Model 1 simulations with 75 m horizontal grid spacing initialized with the 18Z Jackson, MS, special sounding from the environment that produced the 27 April 2011 Tuscaloosa tornado. Vorticity budgets were calculated along forward trajectories that enter the low-level mesocyclone. Trajectories traversing through the FF contribute 10-25 percent of the vertical vorticity in the mesocyclone. The increases in horizontal vorticity and the proportional contribution of vertical vorticity from the FF is highest at tornadogenesis and peak tornado intensity, suggesting that the FF contribution aids in tornado intensification.