It's Mid-May But It's Going To Soon Feel Like Summer
Way Over Our Heads 5-15-2021
SPEAKERS
Jim du Bois, Kenny Blumenfeld
Jim du Bois 00:00
You asked for it. Summer’s coming. This is Way Over Our Heads. It's weather and climate podcast. I'm Jim du Bois, Kenny Blumenfeld's a climatologist. Kenny, how you doing? Especially considering that you made a bold prediction. In our last episode, you said it was going to get hot at the end of May. We're almost to the midway point of May. And it's kind of looking like your prognosis was correct.
Kenny Blumenfeld 00:28
Oh, yeah. I'm feeling smug and super smart. Oh, yeah. All of it. I'm doing all right, Jim. You know, the weather always has me on the edge of my seat. So I guess that makes today no different from any other day. But yeah, it's coming into an interesting time. For sure. How are you?
Jim du Bois 00:48
You know, Kenny, I'm doing well. I'm enjoying these last several days. We've had some sun. It's been a little bit cooler than average, but still quite pleasant. So I would have to say I'm very happy with May so far. With the one caveat: it's darn dry out there. What does our drought situation look like right now?
Kenny Blumenfeld 01:10
Yeah, it's getting uncomfortable. So, you know, we've gotten really lucky. I guess the overall story is it's for the most part been kind of normal precipitation in parts of the state, southern and central parts of the state, but dry in the far south in the northwest and parts of the far north, too. And that's kind of the overall picture. But you can't argue with it, we're just stringing together these runs of dry days upon dry days. And that is really where this year, it's kind of different from some of the other years. Now, last year, we did this too. We had very dry conditions. We had runs of over 15, and even 20 days, last spring, where we didn't have any precipitation. But we weren't concerned about drought, then, because we had this huge buffer of moist soils, wet soils that were left over from the very wet 2019. And really a kind of a multi-year period. Well, we've now kind of spent through a lot of that moisture. And so, we find ourselves about as dry as we were last spring, you know, with much of the area coming up short for precipitation. But this time, we don't have those reserves of soil moisture to draw down because we've already exhausted a lot of them. And so now we're starting to kind of see some of the consequences. We have been lucky. You mentioned it's been dry. And it has been and you know, there's been a lot of fire weather potential and some wildfires, especially out in western and northwestern Minnesota, in this kind of pre-greenup period. But we've been otherwise somewhat lucky, because although it has been dry, it's generally been cool, and not even entirely sunny. And that has kept some, not all, but some of that evaporation at bay. Obviously, you lose moisture much faster if the humidity is very low, you don't have precipitation and also the temperatures are high. And for the most part, you know, as we think of the bulk of this spring, we've kind of been avoiding that, with the exception of what was the first day or something like that of May was very warm. But you know, it's been generally cool across the state, below normal so far for May temperatures. And that has helped slow down the drying. And that's why we kind of look ahead with the warm weather coming you got to be a little bit nervous because we're about to turn it on. And if we don't get precipitation to offset the exceptional drying that is possible in the coming week or two, I think then we're gonna be looking at much more dire drought type situation.
Jim du Bois 04:03
Well, staying on the topic of dryness, I couldn't help but notice how low the relative humidities have been over the past several days. Is this unusual for this time of the year in Minnesota?
Kenny Blumenfeld 04:15
It's not. I mean, I'd say the frequency of very low relative humidity is a little bit unusual in the context of the last several years. But this is the thing: our climate is really keyed to sunlight. And another thing that sunlight keys is the landscape. And you know, I know we talk about these terms, photosynthesis, evapotranspiration, evaporation, and I'm not sure if people are really thinking about what it all means but there's this beautiful relationship with the kind of normal cycle of the sun and how spring progresses and it goes like this. As you get into say, April and especially early May, the sun is quite strong. And as a result, temperatures generally, you know, can warm up a bit. But you have a problem in that usually, unless spring came very early, you don't have everything fully green yet. And so when all the plants aren't green, and the grasses aren't green, and the trees aren't all leafed out, and even when they are, it still takes some time for all of the systems to really get moving. But that means that there's not moisture being conducted through those, through those plants. And if it's not being conducted through those plants, and it's not entering the atmosphere. And so usually in the spring, you get much drier conditions, until that sort of green up really kicks in and starts contributing additional moisture to the atmosphere. So if you're going to have fire weather, it's usually before you're fully green. It's usually kind of typically, not always, but typically the first half of May and into April. That's kind of your main fire weather season. And then after that, you've got enough moisture in the air, because of all the plants that the humidities are higher, and it's harder for, you know, things to burn, they don't burn quite as readily. So it's all keyed to the Sun, the Sun kind of triggers the photosynthesis which then leads to all that plant growth which then leads to the plants conducting moisture and use it and going through that evapotransportive process whereby they pull moisture out of the ground, conducted through their various root stem and leaf systems and then transmitted back to the atmosphere. So that's all synchronized by the Sun. And it keys to our rainy season, once that moisture really kicks in, you start seeing our monthly precipitation starts to go up. And it stays up until, you know, mid-September, when the Sun starts getting weak enough that the evapotranspiration and photosynthesis shut down, and everything kind of goes back to sleep and things start drying out. So then you get another dry weather and fire weather season typically, in September, late September and October. You ever notice, Jim, that, you know, unless you're in a really extraordinary circumstance with extreme drought, you don't usually get big wildfires during the hottest time of year? Have you ever noticed that? They're not usually in July and August when you might expect them to be?
Jim du Bois 07:32
You know, Kenny, I never considered that before. But you're right. My recollection now, you don't see major fires during those months.
Kenny Blumenfeld 07:41
Well, I think of all of our really big fires, too. What was that? What was it the Pagami, the Pagami Creek fire, or Pagami Lake fire, the Boundary Waters fires of 2007 and nine and 11? Those were in May. And then you have the famous, the kind of historical Cloquet and Hinckley fires that were in the past, and those were in the fall. Those were in September and October. Even though July is far and away our hottest month, and we can be scorching hot, and we can be in extreme drought in July, there's still usually enough moisture in the air to prevent, you know, the fire weather people call them fuels, that prevent those fuels from building up and drying out a lot. And so instead we see our main fire weather window, basically going from whenever the snow leaves the ground, up until you know, maybe mid to late May. And then the next piece of it would be September and October.
Jim du Bois 08:49
Well, Kenny, we just entered a new decade and at the end of every decade, the NOAA climate normals change. So now we're looking at a period that would entail the years 1991 to 2020, where previously we were looking at stats from 1981 to 2010. What has the shift in normals indicated so far? You know, honestly there weren't any big surprises for Minnesota because, you know, we track all of this. And Minnesota's population is pretty aware of the changes that have been ongoing. In the Twin Cities, there was a very subtle increase in the temperatures. The average temperature in the Twin Cities went up annually by about six tenths of a degree over the previous normal period. So, there was a generalized increase in temperatures. It was strongest in January and December. And it was pretty robust in, you know, May through September growing season also, but we did lose a little bit of ground in February and in April, meaning that the period 1991 through 2020 in February and April was actually a little bit cooler than the period from 1981 through 2010. And if you can really think about it, you're kind of subbing in the 2010s and taking out the 1980s. And what that means is that February and April were actually a little bit cooler for those two months in the 2000 10s than they were in the 1980s in the Twin Cities, and this is also true across much of Minnesota. But all the other months, by and large, were either the same or warmer. And we sort of see this across the state too. Also, the state got wetter, we got more precipitation. The 2010s, that period from 2000, really 11 through 2020 was very wet in Minnesota, the wettest on record. And so no surprise that that ended up driving up our already fairly high, historically kind of elevated annual precipitation, but that too was not across the board increases and month to month. We really saw it concentrated here in the Twin Cities. May got a lot wetter, June got a lot wetter, and a couple of the kind of mid and late fall months. Whereas we lost precipitation pretty helpfully in March. And you can think of that, as you know, whatever happened to the high school tournament blizzards? Those don't seem to happen. We didn't have, we hardly had any of those in the 2010s, and so our snowfall and precipitation stats really drove down during March across basically all of Minnesota. But by and large, the 2010s were kind of snowy. And so even though the snowfall came down from the 1981 through 2010 normal period, we did see most stations in Minnesota continuing to be at or above historical high marks for snowfall in the 2010s. It just wasn't quite as snowy as the the 1980s that they replaced, but it was one of the snowiest decades on record. You know, no really big surprises in Minnesota. I would say the one thing that's different from this time, of course, we were just getting to know each other when the last normals were released. But in 2011, when those were released, the period 1981 through 2010 really jumped in terms of temperature over what had been the previous normals period. So that was almost like this head turning kind of shock where, you know, we saw some of the winter months in particular had warmed by, you know, more than three degrees at many stations. So, these very large changes in temperature that we saw the last time those weren't really replicated this time. The warming was much more subtle, kind of giving the impression that the sharp upwards trajectory that we had been on maybe leveled off a little bit in the last decade.
Jim du Bois 13:10
Are severe weather statistics part of this period that defines what a normal is?
Kenny Blumenfeld 13:17
Ah, that's a really good question. You think they would be, wouldn't you?
Jim du Bois 13:21
Yeah, yeah.
Kenny Blumenfeld 13:21
I mean, wouldn't you like that? It would be nice to have normals. You could kind of, and by the way, if anyone's wondering what is a normal, it's really, just think of it as an adjusted 30-year average. The reason I say adjusted is because if a station has every single day available, and for every single month and every single weather variable, then it’s essentially just a 30-year average. But these are usually volunteer observers who make these observations, and they're often on vacation for a couple days out of the year. And you have to have a method for sort of estimating what those values would be if they had made every observation or if nothing had changed. And so, there's minor, very, very minor adjustments that can be made. But a normal is a 30-year adjusted average. And no, they're not, there aren't really good severe weather metrics because of some of the...you know, if you think of temperature, precipitation, Jim, those are kind of objective measurements. I mean, sure, there's a little bit of human error that goes into reading a rain gauge, but if you read 1.37 inches of precipitation out of your clear bucket or out of your manual rain gauge, you might be off by a 100th of an inch and it's a valid measurement, and with temperature, most of the volunteer observers actually have a sort of semi-automated system that logs the values for them, the high and the low temperature. So, it's pretty objective, but think about hail now or strong winds or you know, damaging winds or tornadoes, there's no real objective way of measuring, you know, there's no tornadoometer that you could use to measure the various aspects of a tornado. And we also know that you're a Skywarn weather spotter. You've been trained on the severe weather training, and so you know how to spot storms, and you think of our ability to see these over time has also improved. So, it's kind of hard to standardize that data set. But it would be great if we could come up with, you know, some kind of functional 30-year average. So, we knew, you know, here's the number of hailstorms that we should expect in Minnesota or in this area in a given year. Here's how many times we expect it to hail at your location in a typical year, yeah, all that stuff would be great. But no, we don't we don't have much for that at all.
Jim du Bois 15:59
Well, speaking of severe weather, last week, we observed the 56th anniversary of the May 6, 1965 tornado outbreak that hit parts of the southwestern western and northern metro areas, and I believe Kenny 13, 14 fatalities? 13?
Kenny Blumenfeld 16:20
Yeah.
Jim du Bois 16:20
Somewhere around there.
Kenny Blumenfeld 16:21
I mean 13 at least.
Jim du Bois 16:21
Yeah, yeah.
Kenny Blumenfeld 16:22
And a lot of, you know, hundreds of injuries and a lot of damage and a lot of stories. You know, everyone who is there, not me, I was not around yet, but everyone who is there had a story from that day. You remember anything about it? Are you too young?
Jim du Bois 16:39
Well, no, Kenny, I do remember it because it was my birthday. And I remember distinctly having a kind of mini-birthday celebration, we were going to have a bigger one with friends over the weekend. That was a Thursday night. So, I had a little piece of cake. There's actually a photo of me I dug up with the cake and little did I know the rest of the evening would be spent in the basement listening to some pretty compelling live reports called in by listeners on WCCO radio. But that's my biggest memory. Now, we were in a part of the Twin Cities that was not impacted by the storms. There was no damage in our neighborhood.
Kenny Blumenfeld 17:20
Where were you, Jim?
Jim du Bois 17:21
Living by Bde Maka Ska at the time.
Kenny Blumenfeld 17:24
Okay, yeah.
Jim du Bois 17:25
So there, now there were reports supposedly there were funnel clouds spotted over Lake Nokomis heading toward Harriet, Bde Maka Ska, Lake of the Isles. We were hunkered in the basement so we couldn't confirm or deny those reports. But there was a lot going on that night. And Kenny it begs the question, we haven't seen an outbreak like that for the Twin Cities since 1965. Statistically, are we overdue?
Kenny Blumenfeld 17:56
Yeah, I mean, on one hand, something like that we really only have one instance of it on record, so we have no idea what the return period is. We could look at other kind of similarly major events that were in the region that maybe didn't do exactly what that one did and assume that the recurrence interval has averaged about 20 to 25 years between major tornado outbreaks in what we now think of as the Twin Cities area. So, from that perspective, yeah, I mean, you know, you could, I suppose count July 3 1983, and maybe start the clock ticking there, because that was brutal. But we haven't in the Twin Cities area had anything like that in, you know, somewhere between, what 38 and 56 years. And so, it's, um, it has, you know, we should remember that this kind of thing happens. It's so hard for people to picture something that they've never experienced. And this is one of the, you know, we talk about this, you and I talked about this at bars all the time.
Jim du Bois 19:11
Oh yes, we do, Kenny.
Kenny Blumenfeld 19:12
How, how can, how do you warn people about the likelihood of something that they can't really comprehend? There's no real analogy, and you can only point at other towns in the United States where something like that has happened that maybe made the news during their lifetime. And you kind of say, we'll see that can happen here too, because we've had this kind of thing. I worry about that. Because we never know, we don't get a, we don't get a memo saying it's gonna be this year, or it's gonna be today, even. We don't know, I mean, obviously, we know it's not going to be today. There's no chance for the kind of outbreak
Jim du Bois 19:47
Right.
Kenny Blumenfeld 19:48
We, you know, we'll get a little heads up in that we'll know when the conditions are right for you know, unusually potent severe weather outbreak, but we're not going to know from the, you know, 15 times we have that kind of advanced warning in a given year somewhere in Minnesota. We're not really going to know which one to four of those is actually going to produce memorable weather in that part of the state. And of that one to four experiences, we won't know, is this, the one? Is this the one that's going to, you know, wreak havoc on the Twin Cities? So, it would be great if people, you know, kind of maintain situational awareness, knew where they were at any given time, the name of the county that they're in and what the nearby communities are so that when the next one comes, they kind of recognize their situation, and where they are, and you know what they might need to do. Yeah, it does concern me. Another thing, though, Jim, from Bde Maka Ska I believe, if you, and this is one of those things, you know, merely rewind the clock 56 years, I'm pretty sure that from the south shore of that lake, in 1965, you would have been able to see from the southeast, you would have been able to see the tornadoes to the west. And from the southwest, you would have been able to see the tornadoes up in Fridley. So, you know, no big deal. You kind of blew it, should have gone outside and looked.
Jim du Bois 21:26
Right. I don't think my parents would have been too happy about that. So...
Kenny Blumenfeld 21:30
Oh, I think everyone belonged in the basement.
Jim du Bois 21:32
Right.
Kenny Blumenfeld 21:35
But I think, yeah, you know, I, I, when I was a kid, the infamous Lake, Harriet-Har Mar tornado that went from Edina into southwest Minneapolis and then kind of jumped over towards Roseville. Well, also passed through Lake Street, Chicago Lake area, that tornado, a bunch of my friends saw it. And I was only about a mile at most from the path that its nearest point. And there were some signs. I was already an avid weather observer, but I was like eight, or not even eight, I was seven. So ,I always wonder what did I really see? And what could I have seen if I had just, you know, stayed outside a little longer or, you know, looked down the block. Because it was, it was, but you know, what do you do? You got to, I guess, if you're like me, then you spend the next 30 years trying to find tornadoes.
Jim du Bois 22:36
Right.
Kenny Blumenfeld 22:36
Which I did.
Jim du Bois 22:37
What's interesting too, Kenny, looking back to the 1965 outbreak is there are very few photos in existence of those tornadoes. And they were numerous and large, and in one case long lived, at least one case. And yet, we have very few photos. Now one variable, though, was the fact I believe it was dark during a lot of those tornadoes. So, there wasn't the opportunity to get good photographs. Also, of course, we didn't have a camera, a digital camera in our pocket at the ready so it was more difficult for someone to actually take a picture. But if you look at the outbreak in Fargo, North Dakota in June of 1957, that was very well documented. There were a lot of photographs, including some film that was taken, I believe, by a TV cameraman. And it's interesting why there are so few photos from that outbreak. Is that unusual, Kenny? Or is that an outlier? Or, you know, how do the various outbreaks over time rank I guess in terms of how well photographed or documented they are?
Kenny Blumenfeld 23:48
You know, a lot of the big ones from the mid-century and before just didn't have much photo documentation. I mean, you know, the tornados from 1965 in the Twin Cities were, they were moving at a pretty good pace. I mean, I think they were, as far as I could tell, they seemed to be highly visible. A lot of people witnessed them. But you had, it wasn't like now where you got a phone in your pocket with a camera on it. You had to think camera and have it with you. And I think when people were gawking at the tornado, those who weren't being hit by it, they were kind of making a decision of well, I can stay here and watch this once in a lifetime thing. Or I can go try and get my camera and possibly lose this opportunity. And so, I think that's one piece of it. The other was, you know, for as much as we say WCCO was giving people heads up, I mean, everything I've heard from those radio broadcasts, and I believe I've heard everything, every second of it. It was much less forecasting of, you know, here's what's on the ground right now so much as like relaying and urging people to stay in their basements and relaying information that in some cases may have been minutes, dozens of minutes old. And I don't think there was a great opportunity for people to know exactly which storm at what time was producing a tornado right then. There was, you know, I think one or two instances during their radio broadcast where callers were mentioning seeing the tornado right then and there. But a lot of them were calling into report something they had seen a while ago. And so, it would have been hard, and there were a lot of thunderstorms that night. So, knowing which one was the one producing the tornado out of the, you know, 50 or so that went across the Twin Cities that evening, that would have been challenging. I, I...and the other thing I would point out is, you know, Todd Krause from the weather service did go around to various historical societies, and it seems like from that evening, there are between four and six kind of credible tornado photographs that have...I think four is probably a good number, but maybe five or six credible photographs of the tornadoes at various parts of the area from that evening. And that's actually a pretty good number. How many tornado photos do you know of from the May 22, 2011 Minneapolis to Fridley tornado, Jim?
Jim du Bois 26:34
Interesting, yeah. Good.
Kenny Blumenfeld 26:36
Believe the number's at zero.
Jim du Bois 26:38
Yes. Boy, that's, I hadn't thought of that, Kenny. That's, because that was in that was during the day there was plenty of daylight. And yeah, that's surprising.
Kenny Blumenfeld 26:49
There's, there's actually some video that a gentleman took from kind of Central Avenue area. And that's actually amazing video with power flashes. And so you could presumably with permission, freeze that video and make a screenshot, but I know of no pictures of the tornado. And also, the June 14 (1981), Twin Cities tornado not well photographed, there were two pictures that I know of. And then a little bit of video from Roseville area. And St. Anthony tornado from 1984, zero photographs. The Hugo killer tornado on Memorial Day weekend of 2008. escaped not just photography, but also videography, nothing, not a shred of documentary evidence that it actually existed in the form that we know from surveys and radar that it did. And that was also a daylight tornado in a supercell thunderstorm, meaning all you had to do was be in the right location and you could have seen it wide open. But nobody was there
Jim du Bois 27:59
Interesting.
Kenny Blumenfeld 27:59
So, I think it has something to do with the nature of the beast. I mean, this is why storm chasers do what they do. Because if you know where to go, and you know how to position yourself, and then you have an understanding of the environmental conditions and all of that, then it's just kind of a matter of going to the right place, adjusting a little bit and then waiting. But if you're not in that position, then it can be very difficult to get a photograph or video of one of these things even on days where the ingredients are right there. And you know, the landscape of the Twin Cities doesn't necessarily make it any easier. With buildings, trees, bridges, all kinds of obstructions, and plus, you know, roads that if you are a chaser, you have to contend with traffic, detours, construction season, and all of that. So there's actually a decent amount of forces working against good photographic or video documentation of these things.
Jim du Bois 29:02
Well, Kenny, we had teased it at the beginning of the program today, that summer is coming. So, what can we look forward to Kenny?
Kenny Blumenfeld 29:11
Across the state, we're moving into a warm weekend and next week is starting to look hot. I mean, you know, so it's gonna be a beautiful weekend pretty much statewide. I can't think of a part of the state even, you know, Grand Marais I suppose if the water or if the wind is blowing off of the lake might be a little bit cooler, but I do expect warm conditions pretty much statewide Saturday and then ramping up a bit even more on Sunday with temperatures, I expect them 60s and 70s on Saturday depending on which part of the state you're in. 70s and 80s on Sunday, and then just you know, keep dialing it up as we get into Monday and Tuesday. Some of the official forecasts now have temperatures in the 80s for most of next week. And if you read the forecast discussions, the weather service forecasters in the Twin Cities anyway have been noting that the main guidance that they use to populate their temperature forecasts has had what's called a cool bias, meaning that it's been tending to make temperature forecasts that are a little lower than what gets realized. So in any case, we have the potential, later next week especially, for some widespread 70s and 80s, across Minnesota. And some of the output I saw from the European model recently has temperatures getting close to 90. So that's really kind of the dominant pattern for the next week to 10 days it's just going to be warm, increasingly humid. And although that humidity will be good in terms of preventing some of the fire, we really are going to need precipitation, because that evapotranspiration, the loss of water right out of the soil and out of the plants is going to really accelerate with those higher, higher temperatures. So it is going to feel like summer. Jim, I think we have, we have a decent shot now if the current forecast pattern holds, then I wouldn't be surprised if you do see people swimming in Minnesota lakes, at least in southern Minnesota on Memorial Day weekend. It's a possibility. I'm not promising it, but there's enough warm weather in the models now and in the forecast that we could see that. But we also really like some precipitation, because the water levels are pretty low.
Jim du Bois 31:45
Well, Kenny, the last episode, you said it would be hot at the end of May. That was your gut feeling. And it looks like things may be lining up to make that happen. But we shall see. There's always that variability.
Kenny Blumenfeld 31:58
Yeah, it certainly looks possible. I think that we're going to certainly, the second half of the month will be warmer than the first half. That's a no brainer. And it will pull our average up to kind of normal to above normal for the month. I think that's a no brainer. But are we really going to stand out? And is it going to be a kind of a hot end of the month? Well, that that part remains to be seen. But yeah, right now I'm feeling okay about that statement and about the side bet that I made with one of my colleagues about may finishing kind of warm.
Jim du Bois 32:33
Well, Kenny, enjoy the beautiful weekend ahead and we'll enjoy the taste of summer that's coming. Fingers crossed for some much-needed precipitation as those moisture levels start to increase.
Kenny Blumenfeld 32:46
Yeah, that's the big one for sure.
Jim du Bois 32:48
Yeah.
Kenny Blumenfeld 32:48
Need that precipitation.
Jim du Bois 32:50
But Kenny, enjoy, and we'll talk to you in about a week.
Kenny Blumenfeld 32:54
Yeah, you too. Good to talk to you, Jim. Thanks a lot.
Jim du Bois 32:57
This is Way Over Our Heads. It's a weather and climate podcast. I'm Jim du Bois. Kenny Blumenfeld's a climatologist. We'll catch you next time.