Characteristics of supercells simulated with tornadic and non-tornadic RUC-2 proximity soundings. Part II: Sounding variables as predictors of simulated low-level rotation

Soundings that were extracted from the RUC-2 within the near-storm environment of radar-observed mature (≥ 2 h after development) supercell storms by Thompson et al. (2003; 2007) have been simulated in a numerical cloud model at 1 km horizontal resolution (250 m vertical). The soundings were originally obtained near supercells that were non-tornadic (454 cases), weakly tornadic (F0-F1; 309 cases), and significantly tornadic (F2-F5; 134 cases). In Part I, the sensitivity to the method of storm initiation was demonstrated and shown to be important for determining storm type and longevity.

In Part 2, we explore whether the model can statistically reproduce these low-level rotation differences within the sounding groups: that is, is the rotation strength of the significantly tornadic RUC-2 supercell soundings, in the group mean, significantly greater than the rotation strength of the weakly tornadic and non-tornadic RUC-2 supercell soundings? Such a relationship would increase confidence that the sounding parameters believed to be important in strong low-level rotation in supercells (such as 0-1 km AGL SREH, lowest 100-mb mean parcel LCL height, and lowest 100-mb mean parcel CAPE) can be reproduced in storm-scale models, for the purposes of storm-scale forecasts. Furthermore, using a multiple regression model, this study provides a unique opportunity to improve our understanding of how these sounding parameters individually and jointly influence low-level rotation strength and longevity.

This study is funded in part by the National Science Foundation (AGS-0843269). Simulations were conducted on NCSA's Dell PowerEdge Linux Clusters.