Ice in, ice out? DNR notes winter’s ‘unusual’ cycle

By Nicole Brodzik
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A reader sent this photo of Lake Waconia taken on March 8 – just one day after the official 2017 ice-out date. (Submitted photo)

High winds and warmer weather led to historically early ice-outs for a number of west metro lakes.
But more recent cold temperatures and snow fall have reversed the ice-out call on some shorelines. The situation has left Minnesota Department of Natural Resources officials perplexed.

As of March 13, a number of smaller lakes in Minnesota which had previously been called for ice out have been called back. The colder weather and snowfall over the weekend of March 11 largely contributed to the phenomenon, according state DNR climatologist Pete Boulay.

“I’ve never run into a year where lakes have refroze over,” Boulay said. “This winter is shaping up to be very unusual.”

Noted naturalist Jim Gilbert has been studying and recording lake conditions for nearly 50 years. This refreeze cycle is something he hasn’t seen either.

“Never,” he said. “I’ve been doing this since 1970 and this has never happened. I don’t know what to do with it honestly. The records from this year are going to look crazy.”

Gilbert said he’s worried about this year’s ice cycles will be recorded, as they’ve never encountered anything like this before.

Boulay said he’s not sure how the DNR will record the official ice-outs either, but said he assumes they’ll adopt the later date, when the ice is gone for good.

“One way to evaluate an ice-out is asking if you can drive a boat and go around the entire lake.” Boulay said. “If the lake has refrozen, you can’t. I have to imagine we’ll be using the next ice out-date, whenever that is.”

Lake Waconia is one of the lakes that did not have a refreeze after its March 7 ice-out date, which was over a month ahead of the median ice-out date of April 14. High winds on areas with even small pockets of open water can start to break down ice earlier than usual, and is likely a factor in this year’s early ice out date.

Before this year, the earliest ice-out announced was on March 15, 2000. Lake Waconia was called for its 2016 ice-in on Dec. 9, meaning the lake saw just 88 days of ice this winter.

“That’s huge,” Gilbert said. “It means a lot for the animal and plant life on the lake.”

Gilbert said he’s been using lakes to study global warming and noted that recent trends show clear indications that global warmings effects are becoming more pronounced.

“Last year, we had the longest growing season in Minnesota history,” he said. “Yeah, sure, it’s fun to have early spring and have it be warm – I like it, too – but it’s very concerning.”

Swede Lake in Watertown was originally called on Monday, March 6, the earliest since 2000, when it was called on March 8. As of March 13, the lake has frozen over again.

A number of other local lakes – including Whaletail, Independence, Long Lake and Lake Langdon – were also called for ice-out on March 7. All of those dates were records, as well, but those lakes may see ice cover coming back, which would mean those records would not stand.

Lake Minnetonka is expected to be called in the coming week, but Boulay said it’s difficult to make the call on that particular body of water.

“Lake Minnetonka is very complicated,” he said. “It’s bigger lake. It has a lot of shoreline and bays, so overall it’s just more complicated. I don’t like forecasting ice outs on lakes like that, because there are so many factors.”

Some of the other factors he mentioned that affect ice out dates are the temperature, the size of the lake, the orientation of the lake and its exposure to weather and wind. For example, a lake that is sheltered from the wind, but sees a lot of snow fall is likely to have a later ice out date than one that is open to the elements.

Boulay added that if anyone who lives on a lake wants to help the DNR with their records, they can contact the climatology office at [email protected]