Ice cover on Lake Michigan has reached a record extent for March. Monday’s analysis by the Great Lakes Environmental Research Laboratory shows total ice concentration on Lake Michigan at 90.1% — the most ever recorded in March.
This is officially the most ice we’ve had at any time of the year since 1979 when Lake Michigan ice cover stood at 93% on Feb. 26, according to records from Environment Canada, the weather agency that publishes the most detailed ice records from the Great Lakes dating back to 1973.
In this unusually cold winter, we’ve seen several spikes in ice coverage on the Great Lakes. This most recent spike has been the greatest.
Normal maximum ice concentration on Lake Michigan is about 31%, averaged out since records began in 1973. The lowest maximum ice concentration was reported in 2002 at 11.83%.
Across the Great Lakes, total ice concentration stands at 90.5%. While that’s not a record, it is the most in 2013, and the most since 1979 and the most on record in March. According to records by Environment Canada, that was the five-lake network’s iciest season with 93.90% total ice concentration. The record is in reach because more cold weather is expected with moderately light winds for the next few days.
Will the buildup of lake ice cause a cold spring? Yes, but that won’t likely be the main factor in this spring’s weather. This ice will keep the lake cool in two main ways:
1) Ice is cold, duh. If you have two glasses of water, one with ice cubes and one without, the one with ice will take longer to warm to room temperature. This is an imperfect analogy, however. The volume of ice in Lake Michigan relative to its overall volume is much, much smaller than the cube of ice to glass example I just gave.
2) Ice reflects the sun’s energy. As meteorologists, when we consider the energy budget (how the sun’s incoming energy is absorbed or reflected), if some of that energy is being reflected back to the sky from bright white snow and ice on the lake, that is energy that otherwise would have been absorbed into the dark waters of the lake. That reflection of energy further slows warming.
Even though 90.1% is a lot of surface coverage for ice on Lake Michigan, it still isn’t a lot of volume. The vast majority of the lake’s volume is still above 32 degrees. That means one good wind storm will slosh that ice around and wear it down and slowly melt it.
Significant snow pack and cold weather patterns will be the primary drivers of a cold spring across the Great Lakes.