SPECIAL REPORT: Weather-driven tsunamis are real on the Great Lakes

Photo provided by Debbie Maglothin

Lake Michigan is a great spectacle year-round, even when it gets rough. There’s a unique phenomenon that happens on the lake that scientists have recently begun to discover.

This phenomenon is rare and only has only happened a handful of times over the past 100 years that scientists know of. While this spectacle is a sight to see, it’s also a Great Lake danger.

July 4, 2003 was a day filled with fun and family memories at the beach quickly changed.

Seven people lost their lives in Lake Michigan, all in an eight-mile stretch of beach from Warren Dunes State Park south to Harbert. It was an entire year's worth of drownings in one day.

Originally thought to be rip currents, now experts are leaning toward something far more powerful, something similar to a tsunami.

Tsunamis are often driven by earthquakes, which causes enormous energy to spread out in the form of waves. These waves travel quickly and are incredibly large.

But what occurred at Warren Dunes in 2003 didn’t come from an earthquake.

“In the Great Lakes, we have a similar effect only instead of being driven by earthquakes, it’s driven by meteorology -- hence the word meteotsunami,” said Eric Anderson, oceanographer at the Great Lakes Environmental Research Laboratory.

Anderson is one of the lead scientists studying the meteotsunami phenomena at the Great Lakes Environmental Research Laboratory in Ann Arbor.

“It’s driven by something like a thunderstorm,” said Anderson. “If that thunderstorm has just the right conditions it can create one of these waves.”

One of the most recent meteotsunami events happened on April 13 in Ludington.

“All of a sudden my daughter calls and says ‘Get down here. The breakwall’s under water,’” said Debbie Maglothin, eyewitness to Ludington meteotsunami. “I said, ‘Yeah right.’ I pull in and the breakwater’s under water and I said ‘Oh my gosh.’”

You can see the Ludington pier submerged as the meteotsunami roared ashore in the video above.

Shortly beforehand, almost the entire pier was exposed! Within minutes, the water level rose 10 feet.

“When it washed up the beach and broke the doors open on that one building, it sucked a chair and there was a love seat, too,” said Maglothin. “To witness it was off-the-charts awesome!”

The photo above, taken by Ami's mother Debbie, shows one the chairs from that building floating like a toothpick.

Debbie says the wave came and receded at least seven times.

It caused damage along the beach and destroyed many docks in marinas further north in Manistee.

Most of what we see on Lake Michigan are called wind waves. They’re generated by wind and have a relatively small wavelength up to 100 feet or more. Wavelength is the distance from one wave to the next.

When you’re in the water, the wave hits you and then passes.

Here’s what makes a meteotsunami so dangerous: they can have wavelengths up to several miles or more and travel very quickly.

When the wave arrives, it just keeps coming and coming, inundating the coastline and obliterating property.

“You do have a sudden change in water level,” said Anderson. “Oftentimes these look like a very quick flood and then retreat of water. That’s a lot of water coming in and out that can cause things like strong currents, that can put lives in danger.”

Meteotsunamis are rare.

Records show the most recent example in Ludington last April, the Warren Dunes incident 15 years ago that killed seven, an occurrence in Chicago back in 1954 that killed eight, and another July 4 incident in Grand Haven in 1929 that killed 10.

The water in the Grand Haven rose suddenly 15 to 20 feet!

There are two elements in meteotsunami formation. The first, a rapid pressure rise and that pressure pushes down on the lake creating waves much like dropping a penny into water and what do you get? Rings spreading out from the center. Same concept here. The second ingredient are thunderstorms moving across the lake at 65 plus miles an hour and the speed of the thunderstorms has to match the speed of the water wave created by the pressure rise.

Those ingredients synced up perfectly in Ludington.

The image in the video above is a radar image of the line of storms that caused that event.

Fortunately, it was a cold day so when the wave arrived, the beach was largely empty.

“I can’t even tell you, to see that much water move at the same time and do what it did,” said Maglothin. “We were really lucky that day that nobody’s on that breakwall because there’s people out there all the time. If this happened in the summer, people would have died that day.”

That's in part why scientists from NOAA and its partners are implementing a meteotsunami warning system.

Sensors are currently being installed all around the Great Lakes and will detect rapid changes in atmospheric pressure, one key ingredient in the formation of meteotsunamis.

These meteotsunamis are rare and the reason why is because a very unique set of weather conditions must be present and come together at exactly the right time. Usually there’s always a fly in the ointment which prevents them from happening.

Events like the Blizzard of ’78 are rare because, like these wave events, all ingredients must be on the table and come together at precisely the right time.

When conditions do support events like this, scientists want to be able to warn people, hence the meteotsunami warning system.

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