Great Lakes ice cover tops 90 per cent, may cause cool, dry summer
Great Lakes under second largest amount of ice cover ever recorded
Ice cover on the Great Lakes is now the second highest on record at 91%.
That's the highest ice coverage since1979, when the ice cover peaked at 93.9 %.
And scientists are warning we can expect the the vast ice cover that now blankets the lakes to have consequences for spring flooding and summer weather.
Ice jams in the mouths of rivers flowing in the lakes could contribute to upstream floods and the cooler lake temperatures caused by the prolonged ice cover could lead to a cooler and less humid summer.
Current numbers show Lake Ontario at 45% ice-covered (which is actually pretty high for Ontario), and Lake Erie at 95% ice-covered.
“If temperatures stay low, the ice will be around into the early spring—in the teens or the lower twenties (Fahrenheit)—that could prolong the ice on the lakes,” said George Leshkevich, a scientist with the Great Lakes Environmental Research Laboratory. “The longer the ice is on the lakes it can delay the warming period.”
If this is the case, the water may stay extremely cold until later in the spring.
- Related: Lake Erie virtually locked in ice
To compare, in 2013 the average winter temperature of Lake Erie was -2.5 C, compared to this year’s average of -8 C. Environment Canada expects temperatures in Lakes Erie and Ontario to be below normal through to mid-March.
“Temperature can affect evaporation... so the water levels could go up the following year,” said Leshkevich.
Also consider that colder lakes and less evaporation could lead to a cooler, less humid summer.
The 91% ice cover for the lakes is the highest amount on record for this time of year- but the scientists believe the cover has peaked for the year.
Leshkevich says wind is a factor when predicting the breakdown of ice on the lakes because high winds over an opening in the ice can create waves that will run against the ice and break it faster.
The St. Lawrence Seaway's February prediction was for seaway traffic through Lake Ontario and the Welland Canal to begin on March 28. That is 6 days later than in 2013.
Possible flooding and ice jams
Hazel Breton, Water Resource Engineer for the Hamilton Conservation Authority says the extreme cold this year means water is not being absorbed by the snow pack but is turning into ice.
"There is a very good chance of flooding."
In particular, Breton said, "The Red Hill Creek is a flashy system and reacts very quickly."
In many locations the Grand River Conservation Authority (GRCA) is recording two or even three times as much water in snowpack as the long-term average. This could mean that come the spring melt, water levels along the river and into the tributaries could be significantly increased.
Ice jam is created when large pieces of ice get caught in shallow water and build up, cutting off the flow of water. Ice jams can build up quickly and cause major flooding making it difficult to put out timely warnings.
The GRCA is particularly concerned about build-up, which could be increased due to the amount of debris that fell from December’s ice storm. Communications Manager for the Grant River Conservation Authority David Schultz said a lot of tree branches and limbs fell into the river. If those branches get caught together, they could net the ice in some places, which can lead to flooding.
Spring-melt and April showers
The spring melt is typically mid-March into late April, but “that doesn’t get us out of the woods entirely,” said Schultz. If the melt remains high into late April, when the spring rain falls, the water levels could continue to be higher than normal.
In a lot of parts along the river dikes have been build to manage high flow in the spring, however Schultz said there are some towns such as Caledonia and Dunnville that do not have dikes built which is putting them at an increased risk of flooding.
It’s not just the river area that can be affected by high water flow and ice jams, but the tributaries that connect, running into agricultural areas south of Hamilton are also as equal risk of overflow.