Chicago weather: Iced over Lake Michigan could mean cooler spring

CHICAGO (WLS) -- More than half of Lake Michigan is iced over, and that percentage could grow if the bitter cold sticks around this Chicago winter. What does that mean for spring?

"There are numerous factors which determine our temperature trends for subsequent seasons, but ice cover on Lake Michigan is certainly one thing that can contribute to a cooler than average spring ," ABC7 Meteorologist Tracy Butler said. "In addition, we should now be seeing fewer lake-effect snowstorms and lake-effect clouds than we have experienced this winter."

As of Monday, 56-percent of Lake Michigan is iced over, according to the Great Lake Surface Environmental Analysis [GLSEA]. That's compared to 36.9-percent of the same date last year.

Overall, more than 84-percent of the Great Lakes are covered in ice as of Monday, compared to 67-percent on the same date last year, according to the GLSEA. By March 2014, 92.5-percent of the Great Lakes were frozen over. The highest amount of iced-over lake is 94.4-percent in 1979.

PREDICTING SPRING

The National Weather Service also looks at the history of cold winters to help predict spring. Chicago's 20 coldest winters (December-February) led to some of the coolest springs (March-May) and summers.

"A lot of atmospheric factors work together to influence seasonal temperatures from year to year, but with historical records we can at least see what has happened in the past after a really cold winter," according to NOAA.gov.

Last year's winter, which was the coldest December-March in history, has not yet been factored into the list. But by looking at those that are, statistics show that only one of the coldest winters was followed by an average spring. Twelve of the 20 were cooler than average, but the remaining seven were warmer.

"Summer numbers seem even more prone to a fallout," Butler said.

When it comes to summer predictions, five of the 20 coldest weathers also produced the coldest summers on record. Just like spring, more than half of the summers were cooler than average, while 7 of the summers were around average, and only two saw an above average high.

"Last summer, we only had three days where the temperature reached 90 and usually we hit 90 at least 17 times," Butler said.