Ben's Weather Blog

After a pretty average weekend, temperatures are expected to get back up to above normal, but not by much.

It will start around midnight tonight, when a warm front will come through:

This will raise temperatures by a few degrees, and bring in a warmer airmass. There might be precipitation along the front, but most likely we won’t get anything.

For the next few days, expect highs around 13-15 and lows around 3-5, with the exception of tomorrow night, when we may actually reach the negatives.

On Wednesday night, a low will pass over southern Alberta, and some precipitation may reach here. Here’s another map:

After that, expect a quite warm Friday, with a high getting into the high teens. After Friday, it seems we may end up diving into a cold wave.

But what is the reason for all this? Well, it’s going to involve many more maps:

First of all, let’s start with right now; the first image. The upper-level flow has been very active lately, with rounds of lows circumnavigating the globe. As you can see, we can find 5 on the scope of the map. On the second map, now for tomorrow’s forecasted conditions, we can find low #2 has dissipated, while #1 has strengthened. As this low continues to strengthen, ridging begins on the west coast and quickly balloons to what we can see on the third map, for Wednesday. This is the usual pattern for North America; if there is a low in the Gulf of Alaska and nothing is blocking ridging on the west coast, it will happen.

This ridge isn’t strong though, so the heat won’t be as well. In the fourth picture, now for Thursday, we also find a weak subtropical jet is trying to form. We can also see the main jet stream seems to be breaking up a lot at the top of the ridge, which is normal for weak, tall ridges that are starting to decay.

As we get to image 5, for Saturday, we see the very small hint of a subtropical jet stream is gone, but another weak bit of flow connecting the bottom points of the ridge are connecting a bit. The jet extension (strong, zonal flow) from Siberia is pushing the stuck low over to here, and temperatures will drop quickly after the end of the work week.

Some of you may be wondering what all the red and blue dashed lines on the maps are, so here’s an explanation. They are contour lines for the distance between the surface and the altitude at which the pressure reaches about half of that. It is generally warmer when that value is higher, and vice versa. If you look very closely, you may be able to see some numbers on the lines, which is a value at the contour in decametres. The thick blue line at 540 is approximately where rain will change over to snow.

Well, that’s it for today! No posts tomorrow, but I’ll be back Wednesday.

Here it is! Last year’s winter was quite a rollercoaster, with long periods of alternating warm and cold, as well as a lot of snow. So, what will it be this year? Currently, we’re far enough away that we can’t really be certain on anything. However, there seems to be an increasing amount of evidence of near to below normal temperatures, and near to above normal snowfall. Here, I’ll list out all of those signs.

Before we start, I would like to clarify what time range I mean by “winter.” Technically, it’s December 21 to March 19. That, however, does not really show the actual length of an Edmonton winter. Our typical first snow that doesn’t entirely melt until spring is in the first half of November. So we’ll put the start there, but for convenience round it to the beginning of November. For the end, we’ll say it occurs when the snow may still be on the ground, but the warming is noticeable and it’s starting to actually feel like spring. This would usually happen in the first half of March, and I’ll round it again to the start. So, our adjusted winter is November 1 to February 28.

So, let’s start with an easy one. La Niña. We are currently about 1 degree below average, with that value expected to drop even more. This isn’t a particularly strong La Niña, but not a very weak one. So, just with this, we can still expect a lot of both warm and cold, though cold will probably occur more often. Every La Niña is different, so we will have to look for other signs.

Next, the Pacific Ocean. Since spring, the sea surface temperatures in the northern Pacific, from the Gulf of Alaska to Japan, have been very very hot. This means the jet stream likes to be farther north, and that carries over to here. It’s partially the reason we were in one heat wave for most of September. During the last third of the month though, things started to finally cool down in the Gulf of Alaska. In the last week, very rapid cooling has begun in the entire area that was hot. This means the jet stream will want to stay lower, and heat waves will become much less likely, if this trend continues.

Another reason is what’s going on in Siberia. Lately there, it’s been cold, but more importantly snowy. Very snowy. A big mass of snow there is creating a mass of cold air, also pushing the jet stream south. This manufactures many a trough, meaning for the next month or two, big ridges will be very hard for the atmosphere to make.

Back to more global anomalies now. There is a condition that is stacked called Atmospheric Angular Momentum, or AAM. This has models that forecast it. For a while now, this has been far in the negatives, meaning the amount of west-to-east flow in the atmosphere has been very low. Models though, have been recently forecasting this to return to near normal, meaning fewer blocks will develop, and ones that do will be more easily broken up. For our geography, if there’s a block in the area, we’re very likely hot. If the AAM is positive, then few big heat or cold waves can occur, resulting in average temperatures. Out of all values, near neutral is the most likely one to have us end up will cold temperatures.

Finally, some more long-range models. Recently, we’ve gotten close enough that different ones are starting to agree a lot, and they’ve been saying what I said at the start of this post. Near to below normal temperatures, and near to above normal snowfall. This hasn’t just been for part of the winter time frame, but the whole thing.

One more thing to mention; conditions right now are actually surprisingly similar to last year, so last winter might not be too bad of an analog of this one.

So there you go, the preliminary 2025-26 winter forecast. It’s more like the winter forecast, because the non-preliminary forecast will probably just end up being the monthly outlooks.

A lot is coming in the next week, in weather, but also this blog. Get ready for an August and September recap, preliminary 2025-26 winter forecast, and 2025 wildfire season recap, as well as the normal one medium-range forecast (this one) and 2 short range. This one is about a very strong cold wave on the way this weekend, which may or may not end up continuing for a while.

Let’s start with right now. Here is a surface analysis map.

That blue line is a cold front, actually the same one that came through over 50 hours ago on Saturday morning. You can see on the map it is connected to a low around the northern tip of Labrador, and there is also another low a little to the west of it. That is a trough.

Now, let’s go to the forecasted current conditions from the GFS model run this morning.

You can see the same two lows, and the big trough in the jet stream. I also marked a high and two lows that make up on omega block we have right now. This isn’t a strong one, and it’s also moving. As you can see, we’re exiting a trough, (which was the one that brought -3 on Saturday night) and we’re entering a weak ridge.

Now, I’ll jump ahead all the way to Wednesday night.

I marked the same highs and lows as before, so you can what’s changed. As you can see, the omega block moved east, but the west low is breaking off. This is not a rare occurrence, but actually the normal. When an omega block travels from west to east over North America, the westerly low will almost always break off. For us this week, it means we’ll get a short shot of slightly below average temperatures on Wednesday, before we warm back up again as the low completely cuts off.

It is not until Friday night, when something very interesting happens. Here’s the map:

As we can see, a new trough has come over from Asia, and is starting to interact with the cut-off low. Once they get close enough, the low reconnects, and a very deep trough is created, which will drop temperature from near 20 to negatives in only 36 hours.

So here we go, the forecast for the cold wave. Let’s start with Environment Canada. Currently it’s saying a high of 16 on Friday, low of 3 Friday night, 7 Saturday, -2 Saturday night, and 4 Sunday. Accuweather, starting on Friday’s high is 21, 4, 10, -2, 2, -5, 6, -3, 9. Finally, The Weather Network says 17, 8, 10, 1, 3, -2, 6, -1, 7. So overall, the website forecasts are agreeing the coldest day will be Sunday, with a high of 2-4. Now for the models.

Still waiting on the update so this can be in Celsius. Overall here, we’re agreeing on more near 0 highs for both Sunday and Monday.

Now what about precipitation? There might be some, but probably not a lot. It seems a front will probably give up a bit, but the main low will pass south of here. The timing currently is “probably just Saturday.” If we get any precipitation in the night, then we might just get our first snow!

The title did say “MAYBE extended,” so what’s that about? Most forecasts are thinking after Monday, we’re going to return to near-to-above normal temperatures. However, there is one interesting outlier: GFS. If you look back up to the graph above, You’ll see it. The average high for that time is around the red line, but you can see GFS in blue is well below that. So what is going on? Well, I dug into it, and it’s really complicated.

It seems the thing this model is forecasting is really big blocking high appearing over Europe. If the model is right, this will block the trough we’re just exiting now from moving east after it travels in the Atlantic. That is the low you can see in the picture. Because of this immense block, the jet stream erupts into chaos in eastern Canada, and our trough coming this weekend doesn’t really have anywhere to go, so it kind of just stays here.

This is only one model, and no other have caught onto it yet. Maybe it’ll disappear in a day or two, or maybe an extended cold wave will manifest. We’ll just have to see.