Strong-to-severe thunderstorms will be possible for a widespread area stretching from the Plains across the Ohio and Tennessee River valleys and into the Northeast.  

WEATHER RESEARCHERS UNLEASH FLEET OF DRONES THAT SAIL DIRECTLY INTO EYE OF HURRICANE

The threat of severe storms

The threat of severe storms from the Plains to the Northeast on Tuesday (Credit: Fox News)

The possibility of heavy rain with these storms could lead to flash flooding in areas that have already seen too much rain. 

The threat of flash flooding in the Northeast

The threat of flash flooding through Wednesday morning in the Northeast (Credit: Fox News)

The scorching heat continues to break records from the Southwest and the southern Plains to South Florida, with not a lot of relief in sight. 

Heat alerts through Tuesday

Heat alerts through Tuesday in the southern U.S. (Credit: Fox News)

Smoke from Canadian wildfires will cause poor air quality for sections of the Midwest, Great Lakes and Northeast. 

Tropical Storm Calvin

The forecast track for Tropical Storm Calvin (Credit: Fox News)

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Rain forecast in Hawaii

Rain forecast in Hawaii through Thursday (Credit: Fox News)

In addition, Tropical Storm Calvin in the Pacific will bring heavy rain and tropical storm winds for Hawaii.