Centennial Honors College
Western Illinois University
Undergraduate Research Day 2012
Poster Presentation
Examining the Relationship between Surface Thermodynamic Properties
and Tornadogenesis in Supercell Thunderstorms
Richard Sample II
Faculty Mentor: Marcus Bűker
Geography/Meteorology
Observational and theoretical studies show that the rear-flank downdraft (RFD) , or
outflow, region of a supercell thunderstorm is strongly linked to surface rotation, or
tornadogenesis. The kinematic (motion) properties associated with the RFD are
believed to increase surface rotation in the vicinity of the updraft (inflow) region.
However, in order to sustain the surface rotation, air that is ingested into the storm must
still be buoyant, or the updraft (and the rotation) will dissipate. Because buoyancy is
depenedent on both temperature and humidity, both of these parameters must be taken
into account to determine the likelihood of a sustainable updraft. Equivalent potential
temperature (Өe) is a quantity dependent on both heat and water vapor content, and
thus is a good indicator of buoyant potential. The goal of this research is to determine
“threshold” Өe values of for the outflow and inflow regions for tornadogenesis to occur.
Since the dependent outcome is binary, we will use logistic regression to show the
relationship between “success” (tornadogenesis) and the independent variables (inflow
and outflow Өe ). Observational data will be obtained from previous case studies in the
literature, as well as from data that is obtained in the field.