More than 900 flight delays and about 200 cancellations have been reported at O'Hare and Midway airports Wednesday as thunderstorms persist through the Chicago area. A ground delay went into effect around 5 a.m. at O'Hare and was expected to last most of the day due to the storms, the Federal Aviati on Administration said. The average delay at O'Hare was slightly over two hours. Ground delays are issued to control air traffic volume to airports where the projected traffic demand is expected to exceed the airport's acceptance rate for a lengthy period of time, according to the FAA. The situation is normally a result of weather-related issues. As of noon, 856 flights were delayed at O'Hare, and 179 were canceled, according to FlightAware. At Midway, 112 flights were delayed, and 29 more were canceled. Pedestrians walk in the rain in Auburn Gresham Wednesday. Pat Nabong/Sun-Times Over 1,500 ComEd customers in the Chicago area were without power Wednesday morning, according to a ComEd outage map. Roughly 200 Chicago customers were affected by the outages, while nearly 1,000 customers were affected in the southern suburbs, including South Holland, Calumet City, Tinley Park and Chicago Ridge. Between 5 a.m. and 9:30 a.m. Wednesday morning, state troopers responded to 22 property crashes, 10 injury crashes and 10 motor assists on various expressways, Illinois state police said. A flood advisory was in effect until 4:45 p.m., according to the weather service and Office of Emergency Management and Communications. Flooding was reported in the westbound lanes of Interstate 80 west of the Stevenson Expressway, where the right lane was completely covered in water, state police said. A pedestrian crosses a partially flooded South Peoria Street in Auburn Gresham Wednesday.Pat Nabong/Sun-Times A stronger wave of storms was expected through the afternoon that may bring damaging winds over 60 mph and hail. Earlier, tornadoes were possible, the National Weather Service said. But the odds of a tornado threat "decreased significantly" Wednesday afternoon, according to Gino Izzi, a meteorologist with the weather service. "Mother Nature is starting to tip her hand, and it's looking increasingly likely that we're not going to get the fuel needed for the tornado-potential type thunderstorms," Izzi said. The storms are expected to end and give way to cloudy and windy conditions around 6 p.m. or 7 p.m., and temperatures were expected to be in the mid-60s near Lake Michigan and closer to 70 degrees near O'Hare, according to the weather service. Areas near and south of the Stevenson may experience the worst of the storms, which are expected to move in from Iowa as the day progresses, according to Jake Petr, another meteorologist with the weather service.For those needing to commute during the severe weather, Petr recommends having wireless emergency alerts turned on in case any severe weather warnings are issued. He urged commuters to stay off expressways and be aware of a place to seek shelter.State police advised commuters not to try driving through flooded roads, taking short cuts or driving around barricades. Check back for details on this developing story. ...read more read less