Plan views of 0–1 km AGL vertically integrated streamwise vorticity (m s −1, blue to red shaded), lowest-model-level (12.5 m AGL) pressure perturbation (hPa, blue to green contours, positives not plotted), simulated reflectivity contoured at 40 dB Z (black contour), and relevant surface boundaries subjectively identified every 600 s from (a) 3600 to (l) 10 200 s. Plan views of lowest-model-level (12.5 m AGL) θ e ′ (K, green shaded), lowest-model-level (12.5 m AGL) vertical vorticity (s −1, blue to yellow contours), simulated reflectivity contoured at 40 dB Z (black contours), and relevant surface boundaries subjectively identified every 600 s (a) from 3600 to (l) 10 200 s. Plan views of lowest-model-level (12.5 m AGL) θ ρ ′ (K, green shaded), 0–1 km AGL mean horizontal vorticity (s −1, red vectors), 0–1 km AGL mean storm-relative winds (kt, black barbs), simulated reflectivity contoured at 40 dB Z (black contours), and relevant surface boundaries subjectively identified every 600 s from (a) 3600 to (l) 10 200 s. The black dots on the hodograph as well as dashed horizontal gray lines on the skew T–log p diagram represent 1-km height increments up to 10 km. (2000), and the green dot indicates the CM1 grid motion to keep the storm centered. The red dot on the hodograph indicates storm motion calculated by the method of Bunkers et al. The virtual temperature profile is in purple. The modified sounding that was used as the CM1 base-state is depicted in solid lines on the skew T–log p (red and green) and hodograph (black). The observed temperature and dewpoint traces are dashed red and green lines, respectively, and the observed wind profile is a dashed blue line on the hodograph. Skew T–log p diagram of NSSL’s Probe 1 observed sounding east of Cheyenne, WY, in the preconvective environment at 1930 UTC.