May 1, 2018: Good News!

It seems as if our recent warm weather should be moving us towards an earlier thaw. But by how much? My gut feeling was that three very warm days should advance the ice-out date by about three days, but I’ve been holding to my estimate of May 15-18 until I could get better analysis. That arrived today, from Sean C.

His newest graph shows what rapid progress we’ve made, and that the latest weather forecast suggests a faster melt will continue. If your browser has shrunk the graph to fit your screen, you can click on the graph to see it at full size.

Here’s a summary for anyone who doesn’t remember, or didn’t see the old graph: the steep red line represents a really fast thaw (2007), while the green line shows a sluggish spring (2004).

The general idea is we need enough warm weather to melt the winter’s ice. For a cold winter like we just had, we need a thawing index of about 200, marked by the horizontal dotted red line.

The blue dots represent our actual progress towards that target, based on our recorded daily mean temperatures. You can see that we’ve been piling on the warm days, almost matching the red line.

The dotted yellow line is Sean’s old forecast from the previous version of this graph. It’s based on the long-term weather forecast we had in mid-April. He used the forecast high and low to estimate the daily mean temperature as halfway in between, and plotted a prediction based on that.

The solid yellow line is Sean’s new prediction for daily mean temperatures based on the latest forecast. You can even see how today’s cool, cloudy weather set us back a little: look how the yellow line drifts away from the red after the last blue dot.

Sean looked back at the actual highs and lows recorded each day and compared them to the mean temperatures calculated by Environment Canada after the fact, and he’s learned the mean is likely to be a degree or two warmer than the midpoint. He’s revised his new yellow line accordingly.

As we get into May, we’re not using such long-term forecasts as we were two weeks ago; Sean can now work mostly from the fourteen-day outlook. The newest forecasts are milder, so overall, the outlook is quite a bit better.

Sean’s new track shows us thawing by May 11. That sounds about right to me.* Remember, we’re talking about 100% ice-free on Lake of the Woods. Your favourite island may be reachable before that date.

*Sean’s graph is temperature oriented, but we could still have variations in humidity, wind and sunshine that could speed things up or slow them down. I like to give a range, so I’m hedging my bets and saying May 10-15.

 

April 30, 2018: The Heat Goes On.

We continue to exceed our forecast highs. We made it to twenty degrees yesterday, and it’s warmer than that today, so I was excited to get into the air for a look.

On departure from the Kenora airport, we flew west to get a look at the downtown area.

It’s hazy, but if you click on the image and zoom in, you can see that there’s been progress. Ice is vanishing from the north bays of Coney Island and the flow through Devil’s Gap is pushing further into Rat Portage Bay and closing in on Gun Club Island.

Because this was a training flight, we could fly straight west for a while, so we went to check out Clearwater Bay.

As we approached Rheault Bay, we could see most of Ptarmigan Bay and Clearwater.

We carried on for a look at the west end, where the satellite images have been showing very thin ice. It looks a bit more substantial close up, but there are lots of holes.

Next, we worked our way down to Big Narrows.

The picture above looks south east across the narrows at right angles. It’s very hazy, so the details are blurred, but if you zoom in you’ll see most of the narrows is open.

I tried to get better light by turning north east to photograph the downstream end of Big Narrows.

We worked our way up to the Barrier Islands to see how things looked there.

Still travelling north east, we’re looking over Oliver Island at the Devil’s Elbow. Lots of open water there now. That red blotch is a bug strike on the windshield. Think of it as a sign of spring.

Lastly, back towards town.

This is the view of Keewatin Channel from the south, but I took the picture from further away this time to show all the new water out by Town Island at the right side of the frame, around Thompson Island at the left, and around Anchor Island and its neighbours closer to the wingtip.

Summary: there’s still lots of ice, but holes are opening up everywhere there’s current.

What does all this warm weather do to the timeline on our thaw? Good question. As recently as last week, we were having a mix of days that were either warmer or cooler than normal, so I didn’t want to jump to the conclusion that we were thawing fast. Now we’ve had a string of three days in a row that reached well above normal temperatures. That should make a noticeable difference, but will it knock three days off the thaw? The forecast for the next while is less rosy, so I’m waiting to see what actually happens.

Which is what I told myself last week, when this current warm spell was forecast to be less dramatic and shorter lived. I hope to hear from Sean tomorrow, and I’ll be interested to see how this looks on his graph, because that will give perspective on how much difference these recent warm days should make.

A late addition to this post: Tim Seitler took some pictures of the south end of Lake of the Woods from an airliner descending into Winnipeg from 40,000 feet. These show the Buffalo Bay and Buffalo Point areas.

I like how the top picture shows the clear sky above the haze layer.

Still lots of ice down there. Tim sent high-res photo files, so you can click on them to zoom in, just like mine. Thanks, Tim.

 

April 29, 2018: Direct Comparison

Today the satellites captured the sharp images we need to make a direct comparison between 2014 and 2018.

2014 is relevant because it also had thick ice and a late thaw, whereas this time last year, the lake was already ice-free.

All of these images came from NASA’s Terra satellite, and are used with permission of Liam Gumley of the Space Science and Engineering Center at the University of Wisconsin-Madison.

First, the natural-colour images, in which ice is white when it’s strong, and darkens to grey as it thins and weakens, with open water showing as black.

April 29, 2014. Natural Colour.

April 29, 2018. Natural Colour.

The thaw is more advanced now than on this date four years ago. The biggest differences are seen at the north end and east side of the lake. The southwest area of the lake looks more similar, and even seems to have more ice this year.

The drawback to the natural-colour pictures is that while the white ice stands out well, the dark water and dark land are hard to distinguish.

The false-colour versions of the same images  offer better contrast between land (green) and water (black), but less contrast between land and ice (turqoise).

April 29, 2014. False Colour.

April 29, 2018. False Colour.

Now it’s easy to see that while the American part of the lake has stronger ice, everything on the Canadian side is melting much faster than 2014. Four years ago, it looked the other way around.

To summarize: in 2014, Lake of the Woods was not completely free of ice until May 21. This year has mostly been looking a little better, as if it should clear by May 18, and that picture is now improving.

Our mean temperatures only rose above freezing two weeks ago, but things have warmed up fast since then. Today is warm (17°C) and breezy, tomorrow should be even warmer (19°C) and downright windy.

If we could keep that up, we’d stay on track for a very fast thaw, but temperatures Tuesday and Wednesday will colder than normal. After that we should return to roughly normal temperatures, which means daytime highs of about 14°C and overnight lows of about 2°C, so I expect the ice to go at a more normal rate next week.

I’m confident that we’re doing better than 2014. I believe the ice will be gone before the Victoria Day weekend, but I’m not sure how many days before.

I’ll have a better idea after I get a fresh look at the lake from the air. I’m looking forward to flying tomorrow, but I’m supposed to be training someone, so we might not go if it’s too windy.

There are growing numbers of boats in the water, but remember that most docks are still iced in. If you call your marina, be prepared to hear that they’re not launching yet.

April 28, 2018: Flashback

The late spring we’re having this year invites comparison to 2014, a notorious year that saw lake ice hanging around until May 21.

So let’s take a look back.

2014

This is a picture I took of Keewatin Channel on April 29 of 2014.

2018

And here’s one of the same area from from April 26, 2018. The extent of the ice is roughly comparable, but the colour of the ice is completely different.

That matters. Here’s a comment from Stu Everett, who looked into how snow cover and sunshine affect break-up.

I came across a research paper from the 1960’s on freeze up and thaw of lakes that had an interesting observation. The study concluded that freeze up has a lot to do with processes such as sensible and latent heat transfer. On the other hand, break up was impacted more by radiation and wind. The study observed that once the ice was snow free, a sort of green house effect occurred, and the ice began to melt not only from the top but also from the bottom. In short, the ice becoming snow free has a major impact on melting.

So I went to the Environment Canada historical weather site and took a look at the last day there was snow on the ground at the airport by year, as a proxy for when LOW was snow free. I then calculated the average length of time from last snow on the ground to ice out on LOW. The average length of time was 27 days. To cut to the chase, last snow on the ground at the airport was April 17th this year. If it works out to be an average year then, the ice should be out on May 13th.

One other observation I would make is that the length of time from last snow to ice out varied from 19 days (2013) to 36 days (2012). This is a tighter spread than the analysis using inflection date, but there is not a huge difference. And the averages work out to 27 versus 32 days. So the May 15th date +/- a few days is probably a good guess, as you previously indicated. Finally, as the study I cited earlier noted, a major wind storm once the ice is weakened could “blow out” the lake somewhat earlier

I added the emphasis to the radiation and wind part, because I think that’s key. Sunshine makes a difference. Judging from my pictures, late April of 2014 was cloudy with snow flurries.

If you’re curious about how ice melts from the bottom, here’s a comment on that topic from a day or so earlier. Brian wrote:

Fun fact – the maximum density of fresh water is about 4°C.

In winter the ice is (obviously) at or below zero, and floats. There’s also a relatively thin layer of water between zero and 4°C under the ice which, being a bit less dense than the 4°C water below, also floats.

I suspect in spring, sun and meltwater above 4°C can displace/warm the cold layer so instead of a cold boundary layer, a less dense warm boundary layer can replace it (as now warmed to 4°C, the old cold boundary water falls to join the denser bottom water), which hastens ice bottom candling.

I was hoping to find a pair of clear satellite shots from the same late April date of 2014 and 2018, but clouds spoiled things. The best I could do was a sharp image from April 29, 2018  and a blurry one from April 26 this year. (Coincidentally, the same dates as my pictures above.)

A quick refresher: thick ice is turquoise, weak ice is darker, open water is black.

2014

2018

I thought this year would look better than 2014. It doesn’t look it, at least not on the blurry side. But on the sharp side of the picture, pay close attention to the Whitefish Bay/Sioux Narrows area at the right edge of this image. I think we’re doing better there, and I trust that sharp imagery more. Also, keep that three-day difference in the dates in mind: by the 29th, we may see a much darker lake.

On the whole, I think we’re starting to pull ahead of 2014, and we’ve got a couple of really warm days coming to give us a further boost. Sunday and Monday are forecast to hit 18°C. After that we’ll see a brief dip to below-normal temperatures to ring in May before things bounce back to near-normal for a while.

Signs of spring: Most of our marinas are still iced in, but Caroline texted me Friday morning to say there was a boat at the Clarion’s docks. Later that afternoon I saw a pair of jet-skis frolicking in Kenora Bay, and another boat on a trailer heading for somewhere to launch.  Oh, and I spotted a pelican the other day.

April 26, 2018: A Pretty Picture

I went flying before sunrise this morning, and came home to land at eight o’clock in the morning, just as a layer of cloud was breaking up. The lake looked beautiful.

To help you get oriented, Scotty Island is above the center of this picture that looks south west. Zoom in and you can see the beach. Burley Island and Queen Bee Island are in the left foreground.

This second shot is centered on Channel Island, with Leisure Island just in front of the aircraft’s nose. That patchy lighting from morning sun shining through a scattered cloud layer is pretty, but it makes it hard to tell water from ice. Clicking on the picture to see  it in higher resolution will help. Keewatin Channel is almost wide open to a point south of Shragge’s Island, and that patch of open water at the bottom right corner extends nearly to Billygoat Island.

One last photograph as we turned to line up with the airport.

Looking north toward Coney Island, with Devil’s Gap Marina near the middle of the picture, and Golf Course Bay at the right. Off the wingtip, water is pushing from Devil’s Gap out past Johnson Island and Goat Island.

Despite an overnight low slightly below freezing, the ice continues to deteriorate rapidly. Most of the ice is very dark now, which means not only is the snow cover gone, but also that water is seeping into the ice through fine cracks.

I wrote to Sean, the guy that makes graphs based on the mean temperature and thawing index, to ask if the visible changes are apparent in the data. He sent this.

This is an updated version of a graph he created last weekend. The steep red line represents a very fast thaw from 2007. If we could match it, we’d have an ice out around May 8, but that’s kind of a best case scenario. The green line uses data from a much colder, slower spring in 2004. (It would have taken a long time to melt thick ice that year.) More realistically, the yellow line is our forecast weather. Sean reckons we’ll need a thawing index of about 200 to melt the thick ice that formed over our cold winter, and the forecast takes us to that point around May 18th. The blue dots represent our actual progress this year. For now, we’re managing to stay close to the fast track.

As we head into the weekend, I’m looking forward to photographs from guest contributor and pilot Andrew Kozlowski tomorrow. Weather permitting—it might be blustery and showery—he’ll try to take pictures of Clearwater Bay and a few other areas.

April 25, 2018: Rapid Progress

The weather has stayed warm and windy, and it’s making a big difference to the ice. The long-term forecast still anticipates a cool start to May, but for now we’re melting ice while the sun shines.

I’ll start with two pictures taken as we climbed out of Kenora this morning.

That’s Rabbit Lake beside the nose of the aircraft. If you’ve ever wondered why it has that name, compare the shape to a chocolate Easter bunny. It’s distorted by the low angle, and the ears don’t show well, but you can get the idea. Click on this picture to see a larger version that will let you admire the open water stretching all the way from Keewatin Channel at the left to well down the Winnipeg River at the right.

Our second shot looks west down Treaty Island. This picture was hastily taken as we started to turn on course, so naturally I cut off Safety Bay on the right edge and buried Devil’s Gap under the nose. That’s Rogers Island right on our nose, and beyond that you can see water opening up in the Tangle. Still plenty of ice in the Manitou, of course.

Fast forward to our return this afternoon.

This is Whitefish Bay, down by Sioux Narrows, looking west. It’s hazy, and the lighting is flat, so at first I thought all those ripples by the windshield wipers might be open water… but no. Click to zoom in, and you can see cracks in the underlying ice; that’s surface water. Further to the right, there is real open water at Whitefish Narrows, and it has expanded in the last few days.

 

This is Witch Bay in the foreground. Above and to the right are Andrew Bay, Pipestone Bay, Hay Island,  and Bigstone Bay. The ice is much darker, and it looks weak.

Let’s go to the satellite imagery, Bob.

The image above is from yesterday. The image below is from today.

There’s a thin veil of cloud, but that ice looks a whole lot darker. Also, the Rainy River is eating ice at the south end. Falcon Lake and West Hawk look transformed.

To see a comparable natural-colour satellite image with some features labelled, click here or visit the FAQ page.

We’re doing much better than I expected a week ago. Instead of a mild weekend followed by below-normal temperatures, we’ve had several days of average or better warmth, with steady wind and strong sunshine. That could shorten our thaw by a few days.

The long-term outlook is improving, too. While the fourteen day forecast is still calling for a cool start to May, it now talks about returning to normal conditions by the second week, so  although we may still get some cooler weather, it looks as if it could be short-lived.

Will we get set back by a spell of cooler, cloudier weather, or do we dare hope?

 

 

April 24, 2018: Bad Ice

Let’s start with a little drama. I mentioned yesterday that a couple of trucks went through the ice this past weekend. There’s video footage of one sinking at Kenora Online.

A second truck went down in the Clearwater Bay area. Kenora Online has a story and a picture of that, too.

No one was injured in either incident.

We now return to our usual programming. I said yesterday that open water might extend from Safety Bay, on the Kenora waterfront, to Keewatin Channel by today.

So close! Late this afternoon, a few meters of this water passage were still blocked by rotten ice. Click on this picture to zoom in.

I pay careful attention to this area because it goes early and the thaw spreads outward from Keewatin Channel to reach Town Island, Scotty Island and, eventually, the rest of the lake.

Devil’s Gap is making advances in  both directions, and the open water by the Clarion Inn now stretches as far as Bush Island and connects to Safety Bay by the Lake of the Woods District Hospital campus.

A quick technical note. I received a comment from John, drawing my attention to another satellite website, so I’ve added a new link for fans of satellite imagery. The Zoom Earth Link is an interesting alternative to the University of Wisconsin-Madison’s MODIS image site. Zoom Earth is easier to use: there’s just one zoomable image that updates every day. The coolest thing is how easy it is to flip from day to day. (Note: if you zoom in too far, the date option will disappear as change from the satellite picture to an aerial photo from last year!) Another plus is that you can turn on labels for geographic features, and that helps you to get oriented. Downside? No false-colour imagery, and it takes about a day to update, so it lags behind the MODIS images.

If you follow Ice Patrol only by email, you won’t see the sidebar with those links, the comments, or the archives. To use these features, type icepatrol.ca into your browser, or click the link.

Cottage Life interviewed me and  you can click the link to see their article on our late thaw. Maybe this has added to traffic on Ice Patrol, because I notice I’m getting over 2000 hits a day now. It’s been a record year for media coverage.