By CBS 2 Chicago Staff

CHICAGO (CBS) — When Thursday morning’s severe storms crossed over Lake Michigan the wind gusts and pressure change created a rare 1.5′-2.5′ Seiche along the Chicago shoreline.

Seiches are a rapid rise in water levels that often resemble a miniature tsunami.

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In the Great Lakes, storms will push water ahead of them — causing it to pile up along the shoreline before oscillating back toward the
shoreline on the opposite side of the lake. This can continue for more than three hours before the water finally levels off.

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Think of a bathtub filled with water. If you push that water toward the end of the tub, it rises to the edge before sloshing back toward the other side of the tub.

Seiche

(Credit: US National Parks Service)

Sometimes a Seiche can be deadly. On June 26, 1954, a 10-foot Seiche along Chicago’s Montrose Beach and North Avenue Beach swept eight fishermen off the piers and break walls to their deaths.

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Another wave phenomenon seen on Lake Michigan is a Meteotsunami. These are also caused by strong storms, but they are a series of waves that only last minutes to a few hours.

CBS 2 Chicago Staff