While 2010-2013 was below the average of 52.4% ice coverage on the Great Lakes, last winter was one for the record books. Ice coverage on the Great Lakes was 92.5%, peaking on March 6th. Although the 2013-14 winter came in second place to 1979's all-time record extent of 94.7%, last winter's ice broke the record for its longevity. Incredibly, ice lasted until June 5th on Lake Superior! So how does this year's ice coverage compare?
Large ice cover extent on the Great Lakes requires ample arctic air and light winds over a long period of time. Having chilly water temperatures the year before helps too (which we had, thanks to last year's ice coverage). Ice started to form early, with Lakes Superior, Huron and Michigan seeing ice on November 20th. In fact, it was the first time in the reliable data set (since 1973) that ice formed on those three lakes that early. Although the lake ice had an early start, it was slow to expand when compared to last year. On January 5th, the lakes were observed with 10% ice coverage. Meanwhile, last winter's ice extent reached 10% almost a month earlier, on December 14th. Ice coverage continued to expand during January and into February of this year, however, starting on February 7th, a stretch of well below freezing temperatures and light winds began, which brought a rapid accumulation of ice. From the 7th through the 18th, ice coverage extent rose dramatically, from 49% on the 7th to 85% on the 18th. Like last winter, ice covered caverns were popular with tourists once again. 120,000 people visited the Apostle Island National Lakeshore on Lake Superior to explore them, setting an all-time record (see more on ice caves here: http://www.cnn.com/2014/03/13/travel/wisconsin-ice-caves-lake-superior).
.gif)
Like last winter, ice coverage peaked this March at 88.32% ice extent on the 1st. Since then, milder air has worked in, with spring-like temperatures recently. Additionally, a few windy days helped to break up the ice on the lakes. While frigid air can still work in, the increasing March sun angle melts ice more effectively, even with colder temperatures. While we will likely not reach the levels of last year, this year's ice coverage is still very impressive. The long melting season will also keep lake temperatures cool, which may aid in cooler air temperatures in areas surrounding the lakes this spring.
