Higher Great Lakes, more powerful meteotsunamis possible

Rising Waters

(WOOD) — With water levels near an all-time high on the Great Lakes this season, scientists are warning that meteotsunamis will be more noticeable and could produce more damage than during low-water years.

Meteotsunamis are still a relatively unfamiliar phenomenon to most in the Great Lakes, even though they’ve been happening for years.

A meteotsunami is a large mass of water that slams into shore, hitting a very localized area. Ludington experienced one last year. Its pier went from bare to submerged in minutes.

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A meteotsunami occurs when a strong line of storms races over a long span of water towards land at speeds of 55 mph to 70 mph. As the storm rushes across the water, it begins to build up water ahead of it. When that wall of water falls into sync with the small waves it’s colliding with, it can amplify. This wall of water looks like a giant mound until it rolls ashore.

A meteotsunami is different from a seiche, which is a standing wave that sloshes back and forth over the entire lake. A meteotsunami travels more like a real tsunami and only hits a relatively small localized area. An animation tweeted by the National Oceanic and Atmospheric Administration shows the difference between the two.

It’s believed a meteotsunami swept almost 20 people off the beach during the Fourth of July in Grand Haven in 1929. Ten people drowned. There was no warning as the water rapidly rose, overtaking the shore.

A meteostunami happens fast, lasting from minutes to a maximum of two hours. Because of that, meteotsunamis were thought for a long time to be freak waves.

As our technology has advanced, scientists can now see why they happen. Unfortunately, the best way to detect a meteotsunami is by rapidly updating surface pressure sensors around and in the middle of the Great Lakes. Right now, almost none installed will do that.

A sensor in Ludington captured the pressure and wind jump during last year’s meteotsunami.

Ludington barometric pressure graph spikes during meteotsunami
A graph by NOAA shows the barometric pressure during the meteotsunami that hit Ludington April 13, 2018.
Ludington wind speed graph spikes during meteotsunami
A graph by NOAA shows the wind speed during the meteotsunami that hit Ludington April 13, 2018.

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With the lack of a sensor network, meteotsunamis are very hard to forecast, especially considering they can bounce around the lake, hitting a location that wasn’t even in the line of sight for a strong storm. The deadly meteotsunami that hit Chicago in 1954 happened seemingly out of the blue. The large wave bounced around the bottom of Lake Michigan until it slammed into the Windy City.

NOAA, in conjunction with the University of Wisconsin, University of Illinois at Urbana-Champaign and University of Michigan, is working to create a forecast and warning system.

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