Lightning erupts over downtown Chicago on Wednesday, June 12, 2013, as a line of powerful storms cross over the Midwest. A massive line of storms packing hail, lightning and tree-toppling winds began rolling through the Midwest Wednesday evening and could affect more than one in five Americans from Iowa to Maryland before subsiding. AP Photo/Dr. Scott M. Lieberman A wall cloud, containing a reported funnel cloud, passes over the Wanatah, Ind. area as a line of severe storm moves through the area Wednesday June 12, 2013. AP Photo/The LaPorte Herald-Argus, Bob Wellinski Lightning emerges from a storm cloud over Clear Lake illuminating a lone cypress tree Wednesday June 12, 2013 in LaPorte, Ind. A massive line of storms packing hail, lightning and tree-toppling winds rolled through the Midwest Wednesday evening driving people into basements for shelter, tearing down power lines and causing flooding in low-lying areas. Lighting flashes over the Chicago skyline, Wednesday, June 12, 2013. An unusually massive line of storms packing hail, lightning and tree-toppling winds was rolling through the Midwest on Wednesday and could affect more than one in five Americans from Iowa to Maryland. Duane Barkema's truck sits on its side in Alexander, Iowa, after a tornado was reported in the area on Wednesday, June 12, 2013, in Alexander and Belmond. AP Photo/The Des Moines Register, Bryon Houlgrave CHICAGO (AP) - A massive storm system originally forecast to affect one in five Americans from Iowa to Maryland surged Thursday toward the Mid-Atlantic after largely failing to live up to its billing in ferocity through the Upper Midwest. Authorities in Ohio reported early Thursday morning that high winds from possible tornadoes had damaged barns in the northwest and knocked out power in some areas in the center of the Buckeye State. Meteorologists warned about the possibility of a weather event called a derecho (deh-RAY'-choh), which is a storm of strong straight-line winds spanning at least 240 miles. By early Thursday, a derecho hadn't developed. And Greg Carbin of the National Weather Service's Storm Prediction Center in Norman, Okla., said, "With each hour that goes by, it's less likely." While the Midwest dodged a derecho, several tornadoes, large hail and flooding did some damage. In the small town of Belmond, Iowa, about 90 miles north of Des Moines, Duwayne Abel, owner of Cattleman's Steaks & Provisions restaurant, said a tornado demolished part of the building. No one was in the restaurant at the time. "I was, oh, 8 miles west of town and I looked toward town and I could see a funnel cloud, having no idea it was exactly where our restaurant was," Abel said. His wife and an employee were able to get out of the restaurant and sought shelter in a basement. In Iowa, at least two businesses and a home were "completely damaged," authorities said. A storm ripped through a farm in rural Alexander, destroying a motor home. Tens of thousands of people across the Upper Midwest lost power. In Wisconsin, authorities said thunderstorms packing heavy rain and high winds caused a Wal-Mart roof to partially collapse. Lake Delton Fire Chief Darren Jorgenson says two employees had minor injuries, but no customers were hurt. "We're just happy that we don't have reports of injuries or fatalities," said Stephanie Bond with Iowa Homeland Security and Emergency Management. We just hope the extent of the damage is minimal. Even before the storms moved through, officials postponed Wednesday night's Chicago White Sox game against the Toronto Blue Jays and canceled a symphony concert at the city's downtown Millennium Park. The Metra commuter rail system temporarily halted service, and Northwestern University canceled classes and finals at its campuses in Chicago and suburban Evanston. Airlines canceled more than 120 flights at O'Hare International Airport. Pennsylvania Emergency Management Agency spokesman Cory Angell said a standby worker was added at the emergency operations center in Harrisburg and officials had ensured two National Guard helicopters were ready if needed for water rescues. Winds reached nearly 100 mph in some places. In addition to the people who killed in the storm, 34 more people died from the heat wave that followed in areas without power. Associated Press writers Charles Wilson in Indianapolis, Barbara Rodriguez in Des Moines, Iowa, and Seth Borenstein in Washington, D.C., contributed to this report.