Inclement weather and thunderstorms, expected on and off all day long, caused delays and cancellations at O'Hare, where temperatures may reach about 70 degrees, officials said.

The morning round of storms was expected to 'pack a punch,' with the possibility of severe weather later in the afternoon.

The National Weather Service Chicago warned that periods of storms are expected through Saturday morning.

Supercell thunderstorms are dangerous storms that unleash large hail, roaring winds and powerful tornadoes.

Close to 200 flights at Tampa International Airport were delayed Friday as a round of thunderstorms moved across the area.