Besides my friend Kurtis, Ken is my local weather Guru. Here is a exerpt from his last communication. Thought you might find it interesting if you are an amature weather geek like me. Read on Garth!


And speaking of seasons, now we have something to watch. One of my very favorite agencies to deride, the Climate Prediction Center (CPC), has issued its bombshell of a seasonal outlook. Whereas a couple months ago, it looked like we were heading into an El NiƱo winter, and all the forecasts called for another warm one, the CPC now, for no reason other than that’s how the darts hit the board, thinks it’s more likely we’ll have both a cold December, and a cold winter.

Here’s how this works; we’ll do it for winter only, which is defined as December through February: Take the 30-year period from 1981 through 2010, and compute the average temperature for each December through February period. Rank them according to temperature, and then just cut that 30-year record into thirds, so you have a “warmest” third, a middle third, and a “coolest” third. If you were to pick a season from the whole group at random, you would have a ~33% chance of picking a season from each or category. Thus, in any given year, unless you have a reason not to, you would expect a ~33 chance of being cool, a ~33% chance of being “normal,” and a 33.33% chance of being warm.

Well, the CPC sees some reason not to do that, so for us, we have a slightly better than usual chance of being cool. It’s not real dramatic: for Minneapolis, it’s about a 38% chance, instead of 33% That means we have about a 28% chance of being warm.

Don’t worry about the statistics of it. The point is they are saying that this winter is more likely to end up in the coldest third of the spectrum than in the middle or warm end. Have a little perspective, complements of me.

The ten coldest December through February period from that 30-year record include some doozies, most of which will have been forgotten or just not-known-about by the readership. But most of you remember the winter of 2010-2011, because *that* was a winter, and it was recent. Remember? Remember the gigantic December snowstorm, and the Metrodome roof collapsing? Remember The Enormous Snowpack That Would Not Go Away? Remember the floods on every major river and tributary in the Upper Midwest? Remember those dark, horrible thoughts you were having? That was the winter of 2010-2011. That winter, by the way, would come in at #10–tenth coldest for that 30-year period. It was #10 and it brought us to our knees. It was snowier than it was cold, but my experience tells me people remember it as being miserably cold.

So the CPC is saying we’re leaning that way, or perhaps colder.

Well, a cold winter requires a good strong snowpack that starts relatively early. Without the snow, the ground can absorb sunlight; with it, the sunlight gets reflected away almost entirely. The difference can be massive–easily 15-25 degrees. All but one of the 10 coldest seasons had significant snowcover by the first week in December. That timing is no coincidence: the sunlight is entering its period of minimal potency, and so the snowcover makes it seem that much less efficient, which nearly guarantees that the snow will stick around long enough to keep reflecting the weak sunlight away, and suppressing temperatures further. This is the sort of feedback on which cold winters rely. Although it is possible to have a warm, snow-free December and still wind up with a statistically cold December-through-February (it requires a brutal January and/or February), the easiest way to do it is with deep snow by early December. If the snow doesn’t really start sticking until after the solstice, well, then it’s against a backdrop of gradually intensifying sunlight.

So, what we are looking for is a rather substantial snowstorm in the next 2-4 weeks. It doesn’t need to be a blizzard, but it does need to establish a blanket of six inches or so, and no fewer than four inches. Even if that does happen, we could still get into a warm pattern that eventually melts the snow, but a warm pattern with snow on the ground and a warm pattern without it are two very different things–easily by 15-25 degrees. Without that snowpack though, the odds of a cold winter come way down. So now you know what to root for; it depends on which way you want it to go.

And how does it look for big snow?

Well, we certainly won’t be getting any for the next 5-7 days. Temperatures on Wednesday could approach 70 again in some locations, and mild air will linger flirtatiously through the remainder of the weekend, even if it never really gets back to Wednesday-ish levels. After that, indications are that will we be cooler than we have been, but still not cold. With one exception from yesterday’s 6AM run, the models have been keeping our region dry and major snowstorm-free through the remainder of November. Beyond that point, there are hints that much colder air will at least be closer to us, but the details will depend, to an extent, on where it snows, when, and how much.

So for now we wait. Might as well enjoy too!


Kenneth A. Blumenfeld, Ph.D.
Research Director, ORC International
Adjunct faculty, Dept of Geography, U of MN