As Des Moines was hit with strong thunderstorms Tuesday, pictures of a "shelf cloud" start ... tornadoes, according to the National Severe Storm Laboratory. Shelf clouds are usually confused with ...

LP supercells often produce tornadoes and large hail. The classic, textbook supercell looks much like the figure above. The storm will have a flat updraft base and potentially a wall cloud ...

Most alarming was a funnel-shaped cloud reported by eyewitnesses, and captured in photographs. Say "funnel" and lots of us think: "tornado." But not all funnel clouds are tornadoes, even when they ...