U.S. residents from the Great Lakes to the Mid-Atlantic who since late this week have struggled through intense heat and potentially hazardous smoke from Canada's wildfires now face challenges from weather that should bring relief – thunderstorms Saturday that will also bring the potential for flash floods and tornados. 

A severe weather threat is in effect from the Ohio Valley through the Mid-Atlantic and Northeast, according to CBS News. As many as 50 million people in towns and cities including Cleveland, New York, Philadelphia, Pittsburgh and Washington, D.C., could be impacted by damaging winds, large hail, isolated tornadoes and flash flooding, the news outlet also reports. 

Hazy skies and air quality indexes in the code Orange and Red ranges were prevalent throughout much of the Mid-Atlantic region until the thunderstorms arrived in mid-afternoon. 

There was no reports as of early Saturday night of major storm damage, but rain is forecast throughout the region into the night and is expected to clean skies Sunday and bring temperatures down into the high- or mid-80s.