The 2010 Mississippi Valley tornado outbreak - a mesoscale and stormscale perspective

This study focuses on the 24-25 April 2010 Mississippi Valley tornado outbreak, which produced tornadoes rated up to EF-4, with damage paths stretching across nearly half of the state of Mississippi. While most of the tornadoes produced were weaker and short-lived, one particular cell spawned a rare long-track tornado with a damage path approximately 149 miles long, passing through Yazoo City, MS. Numerical simulations are being carried out to further our understanding of the environmental and storm-scale contributions that make possible the formation and maintenance of such long–track tornadoes. A two-pronged approach is being undertaken, utilizing both idealized and real-data simulations with the Weather Research and Forecasting [WRF] Model. Real-data simulations are being used to understand the role of mesoscale forcing, horizontal variability and environmental changes along the storm track, while idealized simulations are designed to isolate local environmental shear and instability influences on storm intensity and steadiness.

From the real-data runs, model soundings are being taken in the inflow environment of the Yazoo City storm in order to diagnose favorable environments in which the storm may have developed. Analysis will focus on identifying and investigating mesoscale boundaries that may have played a role in intensifying and/or sustaining the tornadic cells, as well as air mass thermal properties in the storm genesis and propagation areas. Additional parameters to be analyzed in both real-data and idealized simulations include buoyancy properties of entrained air parcels through parcel trajectory analysis and vorticity structures ingested into the modeled mesocyclone.