Evolution of Southern Plains Supercells and Tornadoes through the Early Evening Transition

Long-lived supercells and tornadoes often persist into the night and present a significant risk to society. While there is some understanding of the initiation and maintenance of these storms during the day, less is known about how they evolve through the environmental changes of the early evening transition (EET). This study compares near-storm environments of different supercell evolution types and tornadic vs non-tornadic supercells in the Southern Plains using parameters derived from Rapid Refresh (RAP) model analysis gridpoint soundings. Results indicate that environmental characteristics that modulate supercell maintenance may be different than those previously shown to modulate supercell intensity. Most notably, long-lived nocturnal supercells occur in environments with significantly less convective inhibition (CIN) than other evolution types. It is also shown that the differences between tornadic and non tornadic supercell environments differ before and after sunset. Finally, there are relatively few differences in the environments of tornadic supercells when they are producing a tornado compared to when they are not.