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Meteo-tsunami vs. seiche

With more people heading out to the beaches, we need to be aware of two rare but dangerous waves that can happen as storms move over the lake.

Meteo-tsunamis and seiches are two types of rare waves that do not happen often on the great lakes, but when they do they can either wow us, or pose as a deadly threat.

A meteo-tsunami most recently occurred in Ludington, Michigan on April 13. Maybe you saw these photos of the Ludington pier, captured by Todd and Brad Reed. The first photo looks like the lake is empty, and the second shows water submerging the pier. Within 42 minutes, the water in Lake Michigan is said to have potentially risen around 10 feet.

When the water came in to submerge the pier, models have shown that a meteo-tsunami occurred. The red colors show abnormally large waves that moved towards shore.

A meteo-tsunami is a large wave that forms due to the weather overhead. Strong thunderstorms can create big changes in air pressure and strong winds. If the thunderstorm is moving fast enough, over 60 miles per hour, a meteo-tsunami can form.  These waves come in quick. On July 4 of 2003 a meteo –tsunami moved into the Warren Dunes, and due to subsequent rip currents, seven people drowned.

A seiche forms due to the same variables, thunderstorms in the vicinity that cause changes in air pressure and strong wind, but it’s not as fast moving or large as a meteo-tsunami. During a seiche, the water within the lake sloshes around from one side of the lake to the other over a long period of time. It is commonly mistaken for high and low tide.

The water may take a couple hours to return to the shore, and when it comes back it can cause flooding or unexpected changes in water depth.

Both of these waves are dangerous and have had a history of causing damage and death not only at the Warren Dunes, but also Grand Haven, Holland and Chicago. Researchers are still working to find a way to forecast for meteo-tsunamis and seiches, but in the meantime, make sure you know if there is a threat for severe storms before you head to the beach.

 

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