Powerful storms spawned by intense heat and humidity produced flooding and tornadoes in the Midwestern United States on Saturday, disrupting travel and cutting power to thousands of homes. The National Weather Service said more than 7.5 inches of rain — the amount the city would see over two months during a normal summer — fell at Midway Airport in Chicago in the past day. “A large area is being impacted by this system,” said Jack Hales, a weather service forecaster based in Norman, Oklahoma. “But some of the heavier rain totals … have been in Chicago. The water content in the atmosphere is very high.” The National Weather Service issued severe weather alerts for many areas in Illinois, Indiana, Wisconsin, Iowa and Minnesota, and flood watches for dozens of counties.