Chicago beaches under swim ban for possible seiche

Officials caution that waders, swimmers or fishermen along Chicago's lake front should stay away because of a possible seiche, or large wave.

Seiches occur when strong, sustained winds cause large amounts of water to move from one part of a lake to another. Meteorologists liken it to water sloshing around in a bathtub.

The National Weather Service says a storm front crossed over the lake Wednesday afternoon, causing a 2-foot drop of water levels on the east side of the lake.

It warned that as a result, a 2-foot rise or better was possible on the west side. But it appeared by Wednesday night water levels swelled about a foot before receding.

The weather service says water fluctuations and dangerous rip currents are still possible.