Traverse City Record-Eagle

December 13, 2013

Chill may stabilize levels in big lake

By MICHELLE MERLIN mmerlin@record-eagle.com
Traverse City Record-Eagle

---- — TRAVERSE CITY — Arctic winds swept across the country this week, and numbed the Grand Traverse region with near-zero degree wind chill as a steady stream of snow flurries whipped off the bays and Lake Michigan.

Lake-effect snow has been northern Michigan’s frequent companion for a month, and cold air chilled Lake Michigan waters to between 41 and 42 degrees Fahrenheit, two degrees below this time last year.

The temperature marks a return to long-term averages, and most closely matches those of 2008, said National Oceanic and Atmospheric Administration experts.

It’s too early to predict with certainty, but bay watchers are hopeful the early cold winter will allow Grand Traverse Bay to freeze over, an event that hasn’t occurred since March 2009.

“You can’t forecast ice coverage; it’s more of an observed thing,” said Keith Berger, a meteorologist at the National Weather Service in Gaylord. “This wind knocks the freezing back down again. You might get (ice) on the top, but then along goes a wave and it brings up 40 degree water and ice is gone.”

A frozen lake can mean less evaporation, higher lake levels and less lake-effect snow later in the winter, although experts say the Grand Traverse Bay is considered frozen when ice reaches to Power Island, an event that usually doesn’t occur until late February or early March.

“I think it’s a good indication that our ecosystem, our lake ecosystem, is nice and healthy and working the way it should,” Christine Crissman, executive director for the Watershed Center Grand Traverse Bay. “It’s going to be a positive thing for our water levels.”

Last year, lake levels hit record lows in December and January. Scientists predict lake levels will be around a foot higher than last year for the next six months, but still about 16 inches below long-term averages.

Researchers at the Great Lakes Environmental Research Laboratory at the National Oceanic and Atmospheric Administration predict around 55 percent of the Great Lakes to have ice cover this year, slightly above a 39-year average of 53 percent, and well above the averages of recent years.

“We’re seeing large variability in not only the extent of ice, but the thickness of the ice in more recent years,” said George Leshkevich, a physical scientist at the research lab.

Cold temperatures indeed make lake water more susceptible to freezing, but experts said that even with cooler temperatures, ice won’t be able t form if gale-force winds continue throughout the winter.

But the threat of winds can’t dampen the hope among some that ice could cover the lakes this year.

“We need precipitation coming down that’s not from the lakes, and we need a barrier to prevent evaporation in order for those lake levels to rebound,” Emily Shaw, the education coordinator at the Inland Seas Education Association, said.

A frozen lake potentially could trim lake-effect snow, which forms whenever temperatures are low and there’s a 13-degree Celsius difference between surface temperatures and deeper lake levels, Berger said.