Deep freeze causes 'slightly above' average ice coverage on Great Lakes

Ice coverage on the Great Lakes is "slightly above" average for this time of year according to the Canadian Ice Service. Lake St. Clair and the western basin of Lake Erie are almost completely covered.

Canadian Ice Service says Lakes are 5% covered, but U.S. counterpart estimates 12.6% coverage

Patches of ice float down the Detroit River, which connects Lake St. Clair with Lake Erie, on Dec. 29, 2017. The Canadian Ice Service said ice coverage on the Great Lakes is slightly higher than normal for this time of year. (Chris Ensing/CBC)

Ice coverage on the Great Lakes is "slightly above" average for this time of year, according to the Canadian Ice Service.

The Lakes are currently five per cent covered, which is about two per cent higher than the normal average, said Doug Leonard, senior ice forecaster with the Canadian Ice Service.

"Right now in the Great Lakes we're slightly above normal ice conditions," said Leonard. "Lake Erie is mostly covered now and we've seen a lot of new ice growth in the last couple of days with cold temperature."

Last year at this time, about four per cent of the Lakes were covered. And in 2015 the numbers were even lower. 

"It's all very thin ice and it's all very recently formed," said Leonard.

Map: Ice coverage on the Great Lakes

This map combines the latest ice information available from Canadian Ice Service charts for Dec. 29, 2017. This ice information is updated on the organisation's website daily in areas of known marine activity. (Canadian Ice Service)
  • Colours represent the concentrations of ice.
  • Red represents areas which are completely covered by ice.
  • Green and blue represents areas with the lowest coverage.

American numbers

South of the border, the U.S.'s National Oceanic and Atmospheric Administration (NOAA) charts the ice coverage numbers much higher. 

According to NOAA, the Lakes are 12.6 per cent covered by ice, compared to 2.9 per cent at this time last year. It's not clear why there is a discrepancy. 

The U.S. National Oceanic and Atmospheric Administration pegs the Great lakes ice coverage at 12.6 per cent, which is higher than the Canadian estimates. (NOAA - Great Lakes Environmental Research Laboratory)

Safety first

Leonard said the Canadian Ice Service uses satellite imaging and observations from ships, planes, and helicopters to chart the ice coverage of the Lakes.

"The main reason is for the safety of anyone who is out in marine navigation," he said.

The thin ice could easily be melted away, Leonard adds, by strong winds or slightly warmer temperatures.

"I would be very surprised to see the entire surface of Lake Erie frozen over in the next few days,: said Leonard, explaining it takes multiple days of very cold temperatures for even a thin layer of ice to form.