May 8, 2022: Satellite Sunday?

Not really. These pictures are from Saturday the 7th, but they missed the deadline for getting posted yesterday.

The good news is, we got a solid pass from Sentinel 2 yesterday. This ESA satellite has a narrow field of view, so it doesn’t often image all of Lake of the Woods*. But when it does, the resolution is a dream.

*For broad coverage, the MODIS cameras on NASA’s Aqua and Terra satellites are better, and they pass overhead every day. But their images of Lake of the Woods are small, and cannot be enlarged.

MODIS image of Lake of the Woods from Terra satellite, May 7, 2022, in false colour.

This is a MODIS image from yesterday. The cloud cover is different from the pictures below because Terra and Sentinel 2 made their passes some hours apart.

 

Let’s start with Sentinel 2‘s view of the whole lake, in Short-wave Infrared. You can enlarge this image by clicking on it to see it full screen.

Sentinel 2 image of Lake of the Woods in Short-wave Infrared, May 7, 2022.

I don’t know if the SWIR version of a Sentinel 2 image is directly comparable to a MODIS false-colour image, but it’s very similar.

It’s very clear that ice quality is now deteriorating fast all over Lake of the Woods.

There was cloud in the northern parts of the lake yesterday, spoiling Sentinel 2’s view, so let’s take the opportunity to take a closer look at the south half of the lake, which I seldom get good images of. [It’s too much of a detour for a Kenora-based flight.] Shots of Morson and Sabaskong Bay are regrettably rare.

You can click on the following images to see them full-screen and zoomable.

Southern portion of Lake of the Woods, at higher magnification.

This is from the same image, but zoomed in even more. Click on it and enlarge it all the way to see a lot of detail. I had to cut it off just north of Big Narrows to keep the file size below the 3GB limit set by WordPress. Even then, it took me two tries to upload it to their server.

As I was preparing this post, Terry and Mary James used the comment box to ask about whether their interpretation of what the MODIS images showed at Roughrock Lake was correct.

So l’m going to show them (and you) what Sentinel 2 can really do! Note the scale at the bottom right corner. 1km is about as tight as it will go. You can try to enlarge it further, but the image gets fuzzier.

Roughrock Lake, Big Sand Lake, Little Sand Lake.

Also, this timely comment from Bargeman, via email:

I live in Minaki and have had a boat in for the last week. My wife and I broke up the last bit of ice in the middle of Little Sand Lake to Rough Rock Narrows on Thursday. So the river is open from dam to dam. This has been the quickest opening (from looking very dubious about ice being gone by May long) I can remember. The water rising creating cracks everywhere around the shorelines combined with the strong current has increased open water way quicker….thank goodness. We have Sand Lake Outpost on Big Sand Lake at it is looking like our long weekend guests will be able to stay at our place on Deadman’s Island, just north of Harbour Island.

Hope this answers your question, Terry!

So while I’m at it, let’s see if I can find something for Pete Giroux. He has a place on the Manitou Stretch, east of Lake of the Woods.

East of Sioux Narrows and Highway 71.

I think you’re in luck, Pete: this is right at the eastern edge of Sentinel 2’s latest swath.

I was also curious to see how things were looking further north, up by Red Lake and Trout Lake, but that area was covered with cloud.

Recent warm–and now moist–weather are moving things along very quickly. I tried take a look back at 2014, which was the last time we had such a late thaw. MODIS images are not available for May 6 through 9 because of cloud. The May 5 image shows only a little of the lake, and the May 10 image is blurry, but I think I can say we’re pulling ahead of spring 2014.

Aerial photos I took at around these dates in 2014 were shot in rainy weather, and are hard to make out, but I think they also show we’re doing better.

That would be good, because the lake wasn’t entirely clear until May 21 that year.

I’m confident we’re on track to keep up with Sean’s recent prediction of May 18, and since the weather has been warmer than the forecast he was working with, he may be able revise his graphs again next week.

Keep in mind that when we talk about ice-out on Lake of the Woods Ice Patrol, we mean the whole lake, entirely free of ice. Significant areas are opening to boat traffic every day, and things will be improving daily. One of the bottlenecks we face right now is a lack of  Marina access. Northern Harbour is situated on deep water, and is still iced in. Two Bears Marina, in Keewatin, has soft ice all around their docks and were not operating yet when I stopped by yesterday. Devil’s Gap Marina might have enough water to launch boats, but their open water doesn’t reach very far yet.

I haven’t surveyed a full list of marinas, but if you’re a marina operator, and you have news, feel free to use the comments form on the ABOUT page to let us know how things are shaping up for you. Are you launching yet, or opening soon?

Do you have friends who would want to follow Ice Patrol? I often get emails from people asking to get on the list. THERE IS NO LIST! To follow Ice Patrol and get the emails, visit the Ice Patrol home page and look for the FOLLOW button at the right side. Click it, and you’ll get an email every time I post a new article. If you change your mind, visit again and simply UNFOLLOW.

However, those emails do not tell the whole story. For one thing, if I update a post, a new email does not go out. If you want more, including updates, comments, links, access to archives and satellite images, and an FAQ page that is helpful to new users, visit the actual website.

To ensure that you see updates, use the refresh button on your browser to reload the page.

The emails are timely and keep you updated, but the website is the real thing.

 

April 30, 2022: Satellite Saturday

Well, it’s raining again. We’re setting records for April precipitation as I write this.

That means the last couple of days haven’t been good for satellite photos, but we got an exceptionally good look at the lake on Wednesday. Sentinel 2 is a European Space Agency satellite that takes high resolution pictures. It doesn’t come our way every day, and when it does, it often images only part of the lake because of it’s narrow field of view.

But on Wednesday, everything aligned.

You can click on these pictures to see them at higher resolution!

Sentinel 2 image of Lake of the Woods, in true colour.

Yes, that’s a colour photo. There’s just not a lot of green in our landscape yet.

But if you’d like something a bit more vibrant, Sentinel 2 also offers a short-wave infrared option.

Sentinel 2 image of Lake of the Woods, in short-wave infrared.

Note the scale (5km) in the bottom right corner. But wait, there’s more good news. This satellite can show more detail than this. I can’t upload a picture of the whole lake at the highest resolution; the file is too big. But I can zoom in for a better look at the north part of the lake, and upload that.

Don’t forget to click on these images to see the full-screen version. Click on that to see the picture’s full resolution.

Sentinel 2 image of the northern part of Lake of the Woods in short-wave infrared.

So on this image, I thought I noticed something. In a recent aerial photo from Tom Hutton, taken the same day, you could see rotten ice south of the Keewatin Channel, extending past Town Island towards Scotty.

Let’s zoom in even tighter on that area, to a 1km scale.

Sentinel 2 image of the Wendigo and Bigstone Bay in short-wave infrared.

Now we can clearly see the dark blotches of softening ice, extending from the open water in Keewatin Channel and Second Channel at the upper left, towards Scotty Island near the middle of the frame.

This is the ice that I expect to yield next.

It’s also worth noting that there are multiple tiny patches of water visible in the vicinity of Middle Island, at Eagle Pass at the east end of Hay Island, and near Railroad Island, south of Hay.

Rapidly rising lake levels, and more importantly, the increasing outflows through the Norman Dam* that the rising water necessitates, should help to erode more ice, starting in these areas with significant currents.

*The Lake of the Woods Control Board strives to keep the lake levels within specified limits. A month ago, the lake was pretty low. Multiple Colorado lows have dumped a lot of first snow, and then rain in the lake’s drainage basin. The board reports that the average lake level has been rising by over an inch a day, (25cm in a week) and will continue at close to that rate for several more days. In the meantime, outflow through the dam has gone from 450 cubic metres per second three weeks ago to more than double that, at 925. Fun fact: a cubic metre of fresh water masses one tonne.

So enjoy the rain!