The Storm Prediction Center in Norman, OK has issued a Tornado Watch for much of central and eastern Iowa until 10:00pm. Most parts of the state along and south of Highway 20 are in the watch.
Development is expected to begin at any time in central Iowa as boundaries interact with the warm front. That warm front is between Ames and Des Moines and is slowly moving to the southeast.
Early storms should develop into isolated supercells. Any supercells that develop carry the threat of strong winds, large hail, and strong or long-track tornadoes. This is a very unstable situation and there is plenty of ingredients to support violent storms over the next 6 hours.