According to the Storm Prediction Center, isolated severe thunderstorms are possible across much of the Midwest and eastern parts of the central and southern Plains, bringing the threat of tornadoes.

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

Although the risk is low, “potential storm hazards will include some tornadoes, heavy hail and damaging wind gusts,” the National Weather Service (NWS) said in its short-range forecast. “In addition, locally heavy rain during stronger storms may lead to isolated flash flooding in the Midwest.”

“Low risk in this context is a function of tornado probabilities, which are about 5 percent in a 25-mile area,” said Jana Houser, associate professor of meteorology at Ohio State University, Newsweek“Of course, that’s not a huge percentage, but it’s not zero either and it’s well above the everyday expectation of a tornado.”

Houser explained that a low-pressure system is currently transporting moist air northward, promoting thunderstorms. “This is also accompanied by strong winds and cold temperatures above ground. That’s the key element here – this vertical variation in temperature and wind.”

When cold air sits above warm air, it creates instability in the atmosphere, forcing warm air and moisture upward into storm clouds. “Combine that with strong winds and you get another important component, which is vertical wind shear – a change in wind speed and direction with altitude,” Houser said.

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

But even when these conditions exist, it’s difficult to predict exactly where a tornado will form. Interactions with other storms, ground topography, and other nuances affect the likelihood of a tornado forming at a particular location and time.

Houser added: “These details are very difficult to figure out in advance. So we have this broad range in which it could happen, but exactly when and where is unclear.”

“I would bet that maybe two to five tornadoes will form today.”

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 persist into the evening. For tomorrow, the risk of thunderstorms has been downgraded to low, with a less than 2 percent chance of tornadoes developing in all areas.

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