More than 60 million people are at the risk for severe storms on Tuesday across a 1,800-mile stretch from central Montana to the Mid-Atlantic.
Storms, expected to get going during the afternoon hours, will be capable of all hazards, especially damaging winds and very large hail for cities like Omaha, Nebraska, Chicago, Indianapolis and Washington.
On Wednesday, severe storms will once again be possible for 35 million people across two separate areas, Montana and the Mid-Atlantic.
Once again all storm hazards will be possible for cities like Baltimore, Maryland, Washington, Charlotte and Raleigh, North Carolina, and Columbia, South Carolina.
In addition to severe storms, flash flooding will also be a concern especially Tuesday afternoon and evening for areas where multiple rounds of rain and storms train over the same areas. A flood watch is up for 10 million people across northeastern Illinois, including Chicago, where rainfall rates with afternoon storms could be 2 to 3 inches per hour.
The high heat and humidity will provide fuel for the severe thunderstorms.
As of Tuesday morning, nearly 60 million people remained under heat alerts across parts of the Central Plains, Midwest and South.
High temperatures in the 90s combined with high humidity will lead to dangerous heat index values of 105-115.
Across Texas, several cities were looking at more days ahead of triple-digit temperatures where it has already been an excessively hot start to the summer for cities like Austin and San Antonio.
San Antonio saw 17 days of 100 degrees or hotter in June, when the average is just two.
Austin is already at 24 days this year with highs above 100, which is more than any other year up to this point on record.