April 12, 2018: Predictions

The recent correspondence with Sean, who used mean temperatures to extrapolate an ice-out date, got me thinking about all the different ways people try to predict the thaw.

My friend Linda reckons on about four weeks from the time the ice roads close until she can get to her camp on Treaty Island. That’s not a bad method; when the ice roads close, it’s because the ice is weakening.

My co-worker Cam is an ice fisher, so he pays a lot of attention to the thickness and quality of the lake ice. Way back in early March, he was talking about how it could take a long time to melt this year, and he even said the May long weekend could be jeopardized.

By mid-March, I was seeing nearly normal amounts of open water, so I felt more optimistic than Cam. I made allowances for the snow cover and thicker ice, but still felt we’d be clear in slightly more than six weeks, or around May 6-10. But then our little cold snap at the end of March turned into a prolonged stretch of very low temperatures, and my six-week timeline started to slip away.

Long-term forecasts showed temperatures persistently below normal, which made it even harder for me to figure out what might happen.

Then Sean wrote to say how he’d used temperature records to compare this winter to other recent ones. In his analysis, this winter resembles the winter of 2014/2015. In the spring of 2015, it took about four weeks (27 days) for the lake to melt after the mean daily temperature rose above freezing.

The Weather Network has a fourteen day forecast, and it looks as if that shift may happen on April 17 or thereabouts. If that holds up, Sean’s model would suggest an ice-out date of May 14 or 15.

I’m going to hedge a little, because of the snow cover, which is heavier this year than it was in the spring of 2015, and also because temperatures are still forecast to remain cooler than normal.

As of today, I feel Lake of the Woods could be ice-free around May 15-18, just days before the May long weekend.

On the other hand, you could argue that because this year is thawing later than 2015, things could happen faster. May is typically warmer than April, after all. Certainly the right combination of rain, sunshine and warm breezes could speed things up.

Remember: most lake dwellers don’t need the lake to be entirely ice-free to get to camp.

In the end, we’ll have to wait and see. Which brings us back to aerial photographs, my preferred way to show what’s actually happening. Stay tuned.

3 thoughts on “April 12, 2018: Predictions

  1. IMHO, you’re right to focus on snow cover as the main factor at this stage. Noon solar insolation might be around 1000w/sq.m., but the alabedo of snow means maybe 75% of that goes back to space. Ice is maybe 1/2 that, and water 1/2 again.

  2. I gage break up based on the ice leaving the small lakes in Winnipeg. It is around two weeks after the ice is gone on the small lakes. The lakes we see are in Southdale and or Lindenwoods.

  3. Thanks for your reports and predictions. I’m a long time seasonal resident on Thompson Island . Our earliest arrival by boat was April 14, 1998 and the latest was May 18 , 1996 and there was still ice on the lake that weekend. I think you mid -May prediction is reasonable, but would not be surprised if our late arrival record is broken .

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