First of the "Leading Edge" Tornado Threats

This morning, I wrote about the potential for tornadoes on the leading edge of thunderstorms. We now have a tornado warning southwest of Des Moines in just such a situation.

Unlike a supercell tornado, a tornado with a derecho has a hook or "claw" protruding from the leading side (east) side of the solid or near-solid line of thunderstorms (arrow).

You still get the rotational couplet as captured below (circle). 

Take all of your regular tornado precautions!

Addition 12:59pm: A tornado was confirmed near/at Stuart, Iowa, with this system.