Midwest prepares for intense severe storms, threat of derecho

A derecho moving through Iowa last year killed four people.

There is the potential for widespread severe weather Wednesday evening in parts of the Midwest, including Chicago, Milwaukee and Minneapolis. Widespread power outages and extensive tree damage is possible, especially in Wisconsin, where the severe risk level is at four out of five. The threat for a derecho -- long-lived, straight-line and damaging winds associated with rapidly moving thunderstorms -- is part of a larger severe weather outbreak that is expected to affect over 85 million Americans from the upper Midwest to the Northeast over the next two days. While tornadoes garner a lot of attention because of their destructive ability, derechos can rival tornadoes in terms of destruction an impact. Derecho damage is typically "in one direction along a relatively straight swath," according to the National Weather Service. Last year, a derecho caused major destruction in parts of Iowa and Illinois. The derecho had gusts up to 140 mph, spawned two tornadoes, killed four people and caused widespread damage and power outages. A "derecho of this intensity is a roughly once-in-a-decade occurrence" for the area, the NWS said.