On the left side of each image, the direction and the speed of the environmental wind is shown by arrows. Horizontal vorticity produced by the shear in the lowest levels is tilted into updraft creating cyclonic (+) and anticyclonic (-) vertical vorticity on south and north side of storm. Dynamic low pressure in response to rotation enhances updraft. Rain causes downdraft in middle which splits storm in 2. For a right (left) moving storm, cyclonic rotation is in updraft (downdraft) and anticyclonic rotation is in downdraft (updraft) with tight reflectivity gradient (inflow flank) on south/east (north) side of storm.