According to the Storm Prediction Center, scattered severe thunderstorms are possible across parts of the Midwest and eastern portions of the Central and Southern Plains, creating a risk of tornadoes.

The states affected by the warning are: central and eastern Minnesota, Iowa, and western Wisconsin.

While the risk is low, “potential storm hazards include a few tornadoes, large hail, and damaging winds,” the National Weather Service (NWS) said in its short-term forecast. “In addition, locally heavy rainfall in stronger storms could result in isolated cases of flash flooding in the Upper Midwest.”

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“Small in this context is a function of the probability of a tornado, which is about 5 percent in a given 25-mile area,” said Jana Houser, an associate professor of meteorology at The Ohio State University. Newsweek“That’s obviously not a huge percentage, but it’s not zero either and it’s significantly higher than your daily tornado expectation.”

Houser explained that a low pressure system is currently pushing moist air northward, which is fueling thunderstorm formation. “That’s also accompanied by strong winds and cold temperatures above ground. That’s the key element here: this vertical variation in both temperature and wind.”

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When cold air sits above warm air, it creates instability in the atmosphere, pushing warm air and moisture upward into storm clouds. “When you combine that with strong winds, you get another key ingredient, which is vertical wind shear: a change in wind speed and direction with height,” Houser said.

When thunderstorms and vertical wind shear occur in the same place, tornadoes can form.

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But even when these conditions are present, it is difficult to predict precisely where a tornado will form. Interactions with other storms, ground topography, and other nuances all affect the likelihood of a tornado forming at a particular location and time.

Houser added: “Those details are very difficult to determine in advance. So we have a broad area where it could happen, but it’s unclear exactly when and where.

“I’d put my money on maybe two to five tornadoes forming today.”

Any tornadoes that do form will likely be short-lived and on the lower end of the damage scale. “But you know, if a tornado hits your house, it doesn’t necessarily matter if it’s a weak tornado or a strong tornado. It’s still going to damage your house,” Houser said.

The risk of thunderstorms and tornadoes is expected to continue into the evening. For tomorrow, the thunderstorm risk has been lowered to marginal, with less than a 2 percent chance of tornadoes in all areas.

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