These entities often form along with rear flank downdrafts from supercells and usually spawn from mesocyclones.
The progenitors of these phenomena appear as velocity couplets. These entities are generally located at the center of a hook-shaped echo on the southwest of their progenitors. These entities often form along with rear flank downdrafts from supercells and usually spawn from mesocyclones. A few waterspouts may be sea versions of this phenomenon, and their strength can be measured using the Fujita scale. For 10 points, name these tightly rotating columns of air that frequently hit the Midwest.
The progenitors of these phenomena appear as velocity couplets.
Tornadoes [or twisters; prompt on "mesocyclone" before mentioned]