Live updates: Tornado Watches issued as intense tornadoes, giant hail threaten millions

The atmosphere over the central United States is undergoing a dramatic transformation this morning, setting the stage for a dangerous bimodal severe weather outbreak. This means instead of one single storm area, we are tracking two distinct bullseyes where the ingredients for violent weather are most concentrated: the Mid-Mississippi Valley (including Chicago and St. Louis) and the Southern Plains (focusing on West Texas).

A split-flow pattern in the jet stream is the culprit, pulling one system across the northern Rockies and another through Mexico. As these two features phase together, they are opening the floodgates for a surge of high-octane moisture from the Gulf of America, creating a highly unstable environment across a massive 1,500-mile stretch of the country.

In the Midwest, the primary concern is the interaction between a sharpening stalled front and a strengthening low-level jet—a river of fast-moving air just above the surface.

This jet will act as a massive twist in the atmosphere, significantly elongating the hodograph (the tool we use to measure how winds change with height).

This setup is classic for the development of discrete supercells—individual, rotating storms that don’t have to compete for energy.

South of the front, where temperatures are soaring into the 80s, these supercells will have access to over 2,000 J/kg of CAPE (Convective Available Potential Energy). You can think of CAPE as the “explosiveness” of the air; anything over 1,000 is high, so today’s values are well into the danger zone, supporting strong to intense tornadoes (EF-2 or higher) and hail larger than 2 inches.

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Meanwhile, down in Texas, the threat is being driven by a dryline—the sharp boundary where bone-dry desert air from the west crashes into the humid air to the east.

Because the air high above Texas is exceptionally cold today, any storm that pops along this boundary will have incredible upward speed. This allows hail stones to stay suspended in the frigid upper atmosphere for a long time, growing into massive, softball-sized chunks before gravity finally pulls them down.

While the tornado risk in Texas is more isolated than in the Midwest, the sheer size of the hail and the potential for 70 mph straight-line winds as storms merge into a line this evening makes this a life-safety event for the Lone Star State.