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Back-to-back days of severe weather brought widespread flooding across the Midwest — and even a tsunami on Lake Michigan. It wasn't the typical kind of tsunami caused by seismic activity, but footage of the weather event showed how dangerous rising tides can be.

The event that transpired on the shores of Lake Michigan is known as a "meteotsunami," which according to the National Oceanic and Atmospheric Administration are large waves driven by air-pressure disturbances that often come with severe thunderstorms and squalls. When the storm hits, it creates a large wave that moves toward the shore. 

The Great Lakes are no stranger to these events. The Weather Channel said about 100 occur in the region every year, and this one appeared to be relatively small.

Bob Dukesherer, a senior forecaster at the National Weather Service office in Grand Rapids, Michigan, told CBS News that Tuesday's meteotsunami "was on the small side," measuring 1 to 2 feet on the south end of Lake Michigan and a foot or less in western Lower Michigan.

"We are not aware of any major damage," Dukesherer said. "We did receive one report of some larger plastic walkway sections on a beach being strewn about by the water rise, otherwise, no major damage that we are aware of." 

A video posted by the city of Holland shows the water of Lake Michigan taking over a beach shore during heavy rain. 

While these types of events "happen fairly often in the Great Lakes," Dukesherer said that they are usually "very small, less than a foot." This week's, however, was driven by a strong line of thunderstorms that had winds measuring "at times to near-hurricane force" at about 75 mph, he said.

Unlike meteotsunamis, which are triggered by atmospheric conditions, regular tsunamis are triggered by seismic activity and can get far larger and leave significantly more damage in their wake. Tsunami waves are known to exceed 100 feet, but meteotsunamis typically pack waves of roughly 6 feet or less. Some events, however, have reached larger heights.

In April 2018, a meteotsunami in Lake Michigan caused a water level change of 8 feet, which Dukesherer described as "very significant," adding that it produced damage in the Michigan cities of Ludington and Manistee.

"The biggest events that we are aware of have produced double-digit water-level changes on the order of 10-20 feet. An event in 1954 swept people off a breakwater in Chicago, resulting in multiple fatalities," he said. "So in the realm of meteotsunamis, this was on the smaller side but still notable."

Spotting one of these events can be difficult. 

"Identifying a meteotsunami is a challenge because its characteristics are almost indistinguishable from a seismic tsunami," NOAA says. "It can also be confused with wind-driven storm surge or a seiche. These uncertainties make it difficult to predict a meteotsunami and warn the public of a potential event."

The National Weather Service's Grand Rapids station said on Tuesday that passing storms had brought "damaging winds and hail to the region" as well as strong wind gusts. The Midwest faced back-to-back weather extremes this month, with dangerously hot temperatures followed by days of rain and storms that left some emergency declarations and evacuations in nearby states. 

In:
• Science of Weather
• Severe Weather
• Lake Michigan
• Tsunami
• Michigan

Li Cohen

Li Cohen is a senior social media producer at CBS News. She previously wrote for amNewYork and The Seminole Tribune. She mainly covers climate, environmental and weather news.

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