Think twice before venturing out on any frozen lakes or ponds in the area. They likely aren’t solid quite yet.
A west suburban boy discovered that Tuesday after falling into an icy pond in Downers Grove. He tried to take a shortcut home from school and plunged through the pond’s dangerously thin ice. Firefighters and paramedics rescued him after a chilly 20 minutes.
Water typically freezes around 32 degrees Fahrenheit, but the science of how fast that happens depends on multiple variables, including air temperature, water temperature, wind, currents and water size.
“There isn’t a set formula for calculating ice formation,” climatologist James Angel said. “I wouldn’t go out on any ice unless someone who knows what they are doing has checked it out.”
Consistently cold temperatures, like those experienced this week, help ice form, said Lt. Commander Jillian Lamb, Detroit spokeswoman for the Coast Guard. But it’s nearly impossible to give an accurate prediction of how quickly bodies of water in the area will freeze solid.
Lake Michigan and moving rivers, like the Chicago River, are not completely hardened yet, said Ricky Castro, a meteorologist with the National Weather Service. Smaller lakes and ponds may be further along.
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“It depends on the width and depth,” Castro said. “Lake Michigan is pretty deep in the middle but more shallow on the shores. That’s why there is some light ice forming. On rivers, you’ll see ice forming near the banks. The wider it is, the harder it is to cover.”
The thicker ice gets, the more cloudy or milky colored it appears, Castro said. Think of hockey or ice skating rinks. Recent snowfall has hindered this visual, though.
“Snow paradoxically acts as an insulator,” Castro said. “If you have snow on top of a body of water that’s ice covered, the ice is not going to get as thick. Even if the water is rapidly freezing, it is best to err on the side of caution unless it has been tested and cleared.”
It’s best to play it safe and stay off ice, unless otherwise marked. For winter ice activities, Lamb notes that people should dress for the temperature of the water, not the air, choose brightly colored clothing, and carry a life jacket, ice pick or screwdriver.
“People need to remain vigilant and cautious when going out on the ice,” Lamb said. “Always, always, always exercise caution. Check your weather and ice conditions before going out. It is rarely consistent day to day.”