Hi. I don’t usually do anything with Ice Patrol until around the ides of March, but this winter seems to be extraordinary, so I want to get some remarks down before I forget the details.
First off, Kenora had the mildest December on record, including a rare Green Christmas. The hourly mean temperature for the month was just -3ºC*. That means we didn’t make much ice, and ice roads that usually become useable at the end of the year were unsafe until late January.
*What is the hourly mean temperature for the month? There are 24 official hourly temperature measurements taken every day, and 31 days in December. Add them all up and divide by 744 to get a number that tells you something about the overall conditions for the month.
Sometimes weather observers take extra observations if the weather changes suddenly, but those are not used in the hourly mean, as they would distort the average.
A more normal mean temperature for Kenora in December is in the -12ºC range, and a cold winter (like 2013) might have an hourly mean for December lower than -20ºC.
We had some colder weather in January, but although it felt bitter, most of that ‘cold snap’ was actually pretty normal. There were a couple of days where the wind chill prompted Severe Cold warnings, but it never quite reached -40º, so I did not unpack my parka. The ice roads on Lake of the Woods did open, but it wasn’t long before things got milder again, and then the ice roads were closed again for a while.
Elsewhere, the winter roads vital for travel to northern communities have been unsafe, paralyzing vital freight movement. Several bands in Manitoba and Northwestern Ontario have declared emergencies. At best, there will be a very short window when the roads can hold up to heavy trucks.
February was another exceptional month. About a week after Groundhog Day, we had several mild days with rain. Significant rain in February: we’ve seldom seen more than a trace before. The snow vanished. I checked with Stu Everett, who monitors the thaw in relation to the loss of snow cover, and he says there has never before been a day in February where the recorded depth of accumulated snow was zero. He did a little poking through the records, and last century it used to be common to have more than 70cm of snow on the ground by the end of the month. That’s thigh deep. Lately, that much snow has not happened nearly as often.
What does the lake look like? Regular contributor Jared Cantor snapped a picture on February the 17th.
As usual, you can click on this photo to see the full-resolution version.
North portion of Lake of the Woods, looking north.
As you can see, the lake is almost entirely frozen and snow covered. It certainly should be, in the middle of February. But I’ve noticed some poor-looking ice on Safety Bay, so I also hunted up some satellite images to see what the near infrared pictures would look like.
Lake of the Woods imaged by Sentinel 2 in short-wave infrared on February 16, 2024.
Sentinel 2 got a good look at Lake of the Woods on February 16th. If you zoom in on this picture, you can see some open water in Keewatin Channel, and perhaps a few air holes around Big Narrows. More conspicuous in this image is some bare ice down by Big Island. It might be thin there, too.
So, where is all this taking us? It’s safe to say that the ice is thin, perhaps only half as thick as a typical winter. That suggests that it won’t take long to thaw once we pass the inflection point, where the mean daily temperature is consistently above freezing.
For that kind of stuff, I go to Sean Cockrem, the guy who does the fancy graphs.
Sure enough, he’s been plotting. To get an idea of how things go in unusually mild winters, he ran through all the data since 1990, and compiled a graph that shows it all as percentile ranges.
You’ll definitely want to zoom in on this graph to see it full screen, but here’s how it works. Each of the smoothly curved lines represents the coldness of past winters, based on Sean’s Cumulative Freezing Index and shown not as years, but as percentiles: 50th percentile, in green above the middle of the pack, depicts a median kind of winter. The dark blue line at the bottom is a 99th percentile track, like an extremely severe winter.
The bumpier red line is a plot of this winter, much milder than normal. You can see that January dip, but mostly it’s sticking pretty close to the 25th percentile. Another way to say that is that despite that run of frigid days in January, three out of four winters are colder than this one. So far. And the forecast leans towards more mild temperatures in February. Above freezing temperatures are predicted for later part of the month, which would push our red line closer to the 10th percentile track.
For perspective, historical February temperatures usually run to a high of about -9ºC with lows of close to -20ºC. Last year was more like that, and had an hourly mean of -12.8ºC. This year our February hourly mean is just 5.8ºC so far, and with warmer weather coming, that’s likely to rise.
It gets even more interesting when you look at how the lines end. As you’d expect, in colder winters, we keep making ice later into the year, while mild winters tend towards an earlier thaw.
Sean has some thoughts on what that might mean come spring: “Following the 25th percentile curve, usually the inflection date happens around March 20th, and following the average thaw duration for that warm of a winter, the lake would ice free by mid April.”
He also points out that he is neither a statistician nor a climatologist, so feel free to take your own experiences into account.
In summary, we’re having a mild winter, with very little snow cover. That means the ice is already thin, and not well insulated. All the signs point to an early thaw.
But as the experts like to say: “Climate is what you expect. Weather is what you get.”
On that note, Ice Patrol and I are going back into hibernation. Regular posts will resume as we approach the inflection point.
February 19, 2024: Special Winter Report | Lake of the Woods Ice Patrol (wordpress.com)