Peculiar 'ice pancakes' line Lake Michigan shoreline

Chicagoans were treated to an unusual icy spectacle this month as frigid waves of cold air moved across the region. Sightings of ice pancakes could be seen covering much of the Chicago shoreline on Lake Michigan.

This time of year, which is notoriously known for bitterly cold air across the northern United States, these ice pancakes, or other peculiarities like ice bites or ice balls, can appear on bodies of water such as rivers, lakes or oceans. As the UK Met Office explained, "they require specific conditions in order to form and can form in one of two distinct ways."

Ice pancakes are commonly seen in the Baltic Sea and around Antarctica, but they also form frequently on the Great Lakes and in Canada when temperatures drop well below freezing for several days.

"Ice pancakes form on seas or lakes with enough wave action to prevent a solid sheet of ice from forming," AccuWeather Meteorologist Jake Sojda added. "Or, there could already be a thin covering of ice, but then waves cause the ice to break up."

As the broken pieces of ice move to and fro in the waves, they bump into each other, chipping off many of the pointed edges and causing the floating ice chunks to become more rounded in appearance, Sojda explained. When the pieces collide together and water splashes up around the edges and refreezes, it creates thicker ice around the periphery of the ‘pancake,' which often makes the edges look raised.

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In freshwater, the water temperature has to be below 32 degrees Fahrenheit to form ice and to create an ice pancake potentially. In saltwater, the temperatures have to be a bit lower, as saltwater freezes at a lower temperature.

"Ocean water typically has to cool to 28 F before ice starts to form," Sojda says.

While ice pancakes look like solid discs, they are actually quite slushy and break apart easily when lifted.

Other icy occurrences, such as ice jams, ice balls and even ice bits, can also be seen in and along the Great Lakes during the winter months.

Great Lake water temperatures as of Jan. 21, 2022.

The Great Lakes, on average, are usually 25 percent covered by ice by late January, but this year they are only 20.2 percent ice-covered, according to the latest ice analysis from the Great Lake Environmental Research Laboratory. However, this is the highest percentage of ice coverage since 2018 and 2019. In 2020 and 2021, the average ice cover on the Great Lakes was less than 10%.

This year's slightly below-average ice coverage is likely due to the slightly higher-than-average water temperatures across all of the Great Lakes.

Waves of cold air will continue to cause water temperatures to drop and ice cover to increase on the Great Lakes throughout the end of January, but a more active storm track is likely throughout the first half of February that will likely bring the potential for rain and snow.

"We'll probably see the ice cover increase steadily through the end of January," Sojda explains. "Then, overall, [the ice cover will] probably level off during the first part of February."

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