(CNN) Towering waves were forming Thursday on the Great Lakes, with swells that could reach 20 feet, CNN meteorologists said.

Huge waves have been spotted over southern Lake Michigan, following a mass of cold air that pushed a north wind over the region, CNN meteorologist Michael Guy said.

Lake Ontario could get waves of up to 20 feet near its center, Guy said. Waves as tall as 10 feet could form on Lakes Huron and Erie, peaking on their southern shores.

Photos of lakeshore flooding & large waves at Whiting Lakefront Park this morning, shared by Jerry Smith. A Lakeshore Flood Warning remains in effect until 9AM Thu for Lake & Porter Co IN (3pm today for Lake IL & 7pm for Cook). Avoid flood prone areas near the lake. #ilwx #inwx pic.twitter.com/6G2dz4nH3T — NWS Chicago (@NWSChicago) February 26, 2020

About 1.5 million people south of Lakes Michigan, Erie and Ontario are under lakeshore flood warnings, CNN meteorologist Dave Hennen said.

Strong winds fueling the waves are associated with a winter storm that's due to dump heavy snow and rain over the Great Lakes, New England and into Canada, he said.

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