Winter is Minnesota’s fastest warming season

NINA MOINI: At 4:01 AM, it officially became spring. We made it. We're not going to dwell so much on snow unless we get some more to come, but we did want to take a second to look at how Minnesota's winters are changing in general. According to state climate data, winter is our fastest warming season. Joining us now to explain is Kenny Blumenfeld, a Senior Climatologist with the State Climatology Office. Thanks very much for being with us, Kenny.

KENNY BLUMENFELD: Oh, good to be on. Nice to talk to you.

NINA MOINI: You too. You know, every year I find myself asking myself, is this the new normal? What's going on? Are Minnesota winters going to be like-- I used to live in Missouri, you know, Kansas City winters. But let's take a step back and just remind people what impacts our winter weather and what our winter climate is like here. Would you explain?

KENNY BLUMENFELD: Oh, yeah. Sure. So, I mean, you know, the weather that we get any given winter is going to be a combination of larger weather patterns that are occurring around the globe that are kind of driving the pattern of, say, the jet stream, which I'm sure everyone's heard of, but that's one of the steering mechanisms that kind of directs traffic for the major weather systems that we have.

So we can get into really cold or really warm periods, depending on where that jet stream is and what else is happening globally. A typical winter here is going to have, you know, in the Twin Cities area, around 50 inches of snow. We're going to have a couple dozen days at least, where the temperature at night falls below zero. And, you know, we'll actually keep the snow on the ground for several weeks during the middle of winter.

And I think what you're responding to or reacting to is that, you know, last year and this year, we really didn't have much time with snow on the ground at all. And when it came, it didn't last very long. And that definitely adds to a perception that, yeah, we're not experiencing the winters that we feel like we deserve here. Right?

NINA MOINI: But you're saying the temperatures were actually pretty average.

KENNY BLUMENFELD: Yeah. So last year was an incredibly warm winter, and so your comparison with Missouri is spot on. In fact, one of my colleagues referred to it as a Springfield, Missouri winter last year. But that was also, by a landslide, the warmest winter we'd ever recorded. It was even warmer than some of the really warm winters we had in the last 20 years.

This particular winter, the temperature ended up pretty close to normal. Just a little bit-- actually, a tiny bit below normal across most of Minnesota, depending on how you look at it and where you look at it. But we basically say, from a temperature standpoint, this winter that we're done with now in terms of the climatological season was normal for temperatures, but snowfall obviously has been very low.

NINA MOINI: And then when the snow does fall, Kenny, it feels like there are really a lot bigger weather events. Like, it's like, you could get 10 to 12 inches tonight. You know? It's not like a little sprinkle here and there. Is that a part of a trend?

KENNY BLUMENFELD: Yeah. I mean, we think it is. You know, we certainly have seen this with rainfall, where maybe it doesn't rain as frequently as it used to some summers, but when it rains, it tends to rain a bit harder. And so we've seen more days with what you might think of as heavy precipitation, and those have been then driving up the annual precipitation totals.

Now it's a little different with snow because snowfall, if you get 10 inches of snow, it might come from only 8/10 of an inch of total precipitation or maybe an inch of total precipitation. So winter is actually our dry season, and so we tend to notice big changes a little bit more. But in any case, it's been-- yeah, it's been a interesting time to kind of watch this. We've certainly had situations in recent winters where we just haven't had the combination of cold and snow and, as you're saying, we've also had these higher frequencies of heavy snowfall events.

And that has led us to kind of a weird pattern where it's really warm, but you get a heavy snowfall, and then it melts, and then it gets warm again. Or maybe it's just normal, and then you get another heavy snowfall. So even in winters where our snowfall kind of mimics what's normal in terms of the totals, it gets broken up in ways that it didn't used to. So our snowpack is less constant.

NINA MOINI: And is snow cover or snowpack, is that beneficial or more beneficial to the climate in any way or does it not really matter?

KENNY BLUMENFELD: Oh, yeah. No, snow cover is really important, actually. It does a couple things. I mean, one, I think-- let's all admit that if you enjoy winter at all, snow cover has this aesthetic effect. I mean, looking across the landscape and seeing snow on the ground. If you've been in Minnesota for a long time, that's a familiar look. I think it's sort of nostalgic.

We certainly see a lot of Minnesotans expecting that as you get into December and you're approaching the big holiday seasons. But it has other benefits beyond-- you know, beyond its looks. Obviously, it's a recreational resource. People like to ski or snowmobile. But even beyond that, it insulates the ground, meaning it keeps the ground from getting much colder.

So even when you have a deep snow pack and the temperatures are really low in the middle of winter, that snow is actually acting like a blanket on the ground, and that stops the frost from accelerating deeper into the ground, which can cause damage to things. So when you don't have snow on the ground, but you have a decent amount of cold air around, like we had this winter, you get pretty deep frost, which can start to interfere with septic lines. It can mess with the foundations of smaller structures.

And then lastly, the snowpack. Because winter is our dry season, the snowpack actually plays a really critical role hydrologically because it stores all that water that falls as snow over the winter time, and then it releases it during the spring melt. And so when you have a year without a lot of snow or where you're melting the snow shortly after it falls, then you don't have that big release during the springtime, and that can have a suppressive effect on lake levels, stream levels, how much water actually goes into the soil.

And so that can alter some of our kind of normal hydrology cycles. And all that means is typically in the spring, when you melt all that snow, our streams and rivers and even some of our lakes will kind of reach their peak levels or their peak flow as a result of receiving all of that water in one big push across the landscape. And if you don't have that snow melt, then that normal peak in hydrology doesn't occur.

And just imagine there's all kinds of plants and animals that are dependent on those cycles of hydrology. And then, of course, when you combine these years where you don't have maybe the large snow melt that you're accustomed to with something like what we had last year, which was a huge influx of water into these systems from heavy rainfall where we had massive flooding last June, that really further alters the timing.

So now, instead of having your peak water levels and your peak flows in March and April, you're getting them in June, and there aren't a lot of things adapted to that kind of peak hydrologic cycle. So yeah, it does have important relationship with many components of life here in Minnesota.

NINA MOINI: Absolutely. So Kenny, before I let you go, what do you think Minnesotans should take away with the types of winters we've been having the last couple? You know, is it that we have to see with time? We have to start making some changes now and preparing now. I'm assuming your office is preparing for whatever might be coming down the pipeline. But what do you think the main takeaway should be for Minnesotans?

KENNY BLUMENFELD: Yeah. I mean, if you're really thinking about the weather and the climate, I mean, honestly, the first thing to remember is that we have very short memories. Nina, if we had talked three, just-- actually two full years ago, we would have been at the end of one of the snowiest winters on record in Minnesota. And we were having the opposite problem. There were actually snowmobile trails that were closed because of too much snow.

NINA MOINI: You're right.

KENNY BLUMENFELD: So I think the first takeaway is that the extreme variability that's always been part of our climate, the ups and downs that one year is going to be really warm and another year's going to be maybe cooler, or one year is going to be really wet or snowy, and the next year might be dry or lacking snow, that variability that's been inherent to our climate is still going to be there, even as we go through changes, as we move into the future. I mean, we've continued to see extreme variability even as our winters have gotten warmer and even as our snowpack has become more erratic.

NINA MOINI: OK.

KENNY BLUMENFELD: So I guess the other take homes would be, winter is our fastest warming season. The warming is already underway. A lot of people have been in Minnesota for 30 years or more already can't really recognize the winter now compared to the winter of their childhoods, so it's a fast warming season. But you have to remember, there's that variability that's imposed over that. It's just a fact of our climate because we're here in the middle of the continent, we have access to all these air masses.

So we're going to continue seeing warming conditions. We're probably going to continue seeing heavy snow and heavy precipitation and years with wonderful snow opportunities. But we're also going to have more of these years where we can't really find winter. That seems to be a fact we can't escape.

NINA MOINI: Thank you so much for breaking that down for us, Kenny. It can be a lot for people to know what's going on, so I really appreciate your perspective.

KENNY BLUMENFELD: Well, great talking with you. And if this helps at all, I'm very happy. Thank you very much, Nina.

NINA MOINI: Thank you. That's Kenny Blumenfeld, senior climatologist with the State Climatology Office.