Severe Storms Threaten 90 Million in US Midwest

The volatile pattern is being driven by a deep dip in the jet stream and a surface low pushing northward, which together feed instability into the central states. High dew points and strong daytime heating supply the moisture and energy that fuel powerful thunderstorms. Severe weather has already drenched parts of the South and Northeast: areas of Tennessee received up to 9 inches of rain, and a flash flood emergency was declared near Huntsville, Alabama. The National Oceanic and Atmospheric Administration (NOAA) warns of a "potentially significant severe weather event" for the Upper Midwest mid-week.

The storms have already turned deadly. In Queens, New York, an 85-year-old man was killed by a falling tree during weekend wind gusts that reached 64 miles per hour in Brooklyn and downed more than 250 trees across the city. In Pittsburgh, a resident said his home was knocked off its supports by violent gusts. Flood watches affecting about 6 million people remain in place. By Thursday, more than 26 million Americans in Chicago, St. Louis, and Milwaukee will face renewed risk as the cold front moves east.