A band of severe thunderstorms swept across Chicago and its suburbs from late Saturday into early Sunday, bringing torrential rain, high winds and frequent lightning. The National Weather Service issued flood warnings for parts of Cook, Will and Lake counties through midday as water pooled on roads and in low-lying areas. Utility operator Commonwealth Edison reported about 61,000 customers without electricity as of 9 a.m. Sunday. The company said it expected to restore service to 80 percent of affected customers by 9 p.m., with full restoration projected by 2 p.m. Monday. In Aurora, the outages disabled water-pumping facilities and two fire stations, prompting contingency measures. Storm damage was scattered but significant. A four-story apartment building in Mount Prospect was evacuated after high winds stripped off its roof, while flash flooding swamped streets and basements in Cicero and other western suburbs. Downers Grove fire crews extinguished a house fire believed to have been ignited by lightning, and several trees toppled onto homes in Romeoville and Joliet. Aviation and recreation were also disrupted. O’Hare International Airport recorded 264 flight cancellations in the 24 hours to 8:30 a.m. Sunday, and dangerous waves kept a beach-hazard statement in effect along southern Lake Michigan until Monday morning. The weather eased by midday Sunday, and the National Weather Service allowed remaining advisories to expire later in the afternoon. Forecasters said temperatures would reach about 81 °F with only isolated pop-up showers before a cooler, less humid air mass settles over the region by mid-week.