Rain And Severe Weather Possible This Weekend

SPEAKERS

Jim du Bois, Kenny Blumenfeld

Jim du Bois  00:00

The hunt for meaningful rain continues. This is Way Over Our Heads. It's a weather and climate podcast. I'm Jim du Bois. Kenny Blumenfeld's climatologist. Kenny, you're back in town after a little vacation in the northwestern part of the state. How does it feel to be back here in the Twin Cities and kind of anticipating the possibility that we're going to get some rain?

Kenny Blumenfeld  00:23

It feels familiar. By now, Jim, I'm, you know, I think I've learned how to temper my expectations. I actually think some of the areas, I was West Central Minnesota, Northwest Minnesota, kind of Otter Tail County area, I think some of those areas are going to do pretty well, this weekend. Twin Cities it's iffy. So I'm excited at the prospect of rain and, you know, always sort of eager and cautiously anticipate potential for severe weather, which we have today. Also, and I'm also thinking about our friends up in northeast Minnesota with the Greenwood fire, which of course is not the only fire but it's the kind of biggest one in the state right now and thinking about their prospects for precipitation, which are not stellar. So, yeah. And how are you?

Jim du Bois  01:11

Kenny, I'm doing well. Interesting that you bring up the Greenwood fire because in an email you sent out today, you talked about a couple of scenarios with the Greenwood fire, one that would be good, and one that would be bad. And there was a person...I can't remember his exact title, but he's involved in the firefighting activities with the Greenwood fire. He was on Minnesota Public Radio this morning, and he had pretty much the same analysis that if they get some good rain up there, that will be wonderful. But if there is little to no rain, and there is a wind shift, and the winds increase, obviously from a fire control standpoint, that would be a bad case scenario. So, that seems to be what we're confronting. Either, we can get some great rains that can help extinguish the fire or get some winds that will increase the area the fire is covering.

Kenny Blumenfeld  02:03

Yeah, that's exactly right. I mean, so, I guess one of the interesting things about this setup is that for the first time in months, we're actually talking about a real weather system, a low pressure system, you know, counterclockwise rotation with a strong cold front. And in a tight pressure gradient, and I think the savvy listeners probably remember that it's that pressure gradient, that change in pressure over a relatively short distance that actually drives the winds. So, you name two scenarios, one where you get wet, and one where you get the winds. Well, the second of those two is guaranteed. It's going to be windy on Saturday, especially in northern and northeastern Minnesota, you know, not not a howling, you know, driving gale or anything like that, but you know, 20, 25 mile an hour winds with some gusts up around 30, 35 miles an hour. So, that wind is all but guaranteed tomorrow, and the real wildcard is does it rain? And you know, I'm not sure exactly how much rain is required to extinguish a fire or even just to kind of slow it down. But I have poured water on bonfires before and know that, and anyone who's done that knows that, you know, the first part you pour just goes right back into the air. You hear sizzle and, you know, maybe the fire slows down a bit, but it takes quite a lot to put it out. So, I'm not sure if it's a quarter of an inch or a half an inch of rain or how much rain it would take to really notably affect this fire. But I don't think it's likely to happen. I think it's possible that they get enough rain up there, but it's just as likely that they, you know, end up with a 10th of an inch or less, and it's it's remotely possible that they get virtually nothing. And that all they really get out of this is a cooler air mass and that wind shift with stronger winds on Saturday.

Jim du Bois  03:59

So, Kenny, what you're saying is this could be another hit or miss scenario for large portions of Minnesota.

Kenny Blumenfeld  04:07

Yeah, so the system is like I said, it's strong. It has a nice arcing cold front. So, what it has going for it, which I really like, it's actually really good ingredients, is it has this increasingly powerful cold front slamming into a warm and humid airmass. I mean we've had temperatures in the 80s and 90s across the entire state for the last few days. And that airmass is still in place today on Friday. And this cold front is going to plow into it, so that's good. Along that cold front thunderstorms will develop, and the low pressure system, the anchor of it, the middle of it, is kind of going to be pushing northeast word across North Dakota into far northwest Minnesota and in Manitoba. The problem is is when these systems start to really wind up after the cold front ignites the main round of thunderstorms, give it three to six hours or so, the storms start to migrate towards the low pressure area though, so they kind of, you'll see them sort of moving leftward towards that low pressure area. And so, initially, you might see a really impressive band or arc of intense thunderstorms but as it moves east across Minnesota, I would expect it to start to become more fragmented and fractured. And so, the eastern parts of Minnesota including Rochester, the Twin Cities and the Arrowhead region are definitely in a more of a hit or miss type of situation where they could get clocked with a good thunderstorm and maybe an inch of rain, or they could get shut out of this thing entirely. And in general, I'd say the best chances of heavy precipitation are in northwest Minnesota, which is good, because that's where the drought is most extreme, or it's actually in the exceptional category right now. But even in northwest Minnesota, the rainfall is not going to be complete, it's not going to cover everyone.

Jim du Bois  06:04

So, we are recording this on Friday morning, August 20. And we may have over the weekend here two rounds of potentially severe weather, the first of which happens late this afternoon, starting in western Minnesota, and then moves eastward. And then another round potentially on Sunday. So, which one do you think has the potential to pack the most punch?

Kenny Blumenfeld  06:31

Honestly, to me, the one today it just has more going for it on a wider over a wider area. To me it looks like the Friday night, Friday afternoon, evening and early overnight storms will just be stronger and have more energy, in general. Mostly, it's because the airmass out ahead of it is stronger, the winds aloft are kind of the same today and Sunday. Sunday's system, I would imagine it's going to focus more to the southwest, maybe South Dakota, Nebraska and Iowa. And I don't think there'll be much in the way of truly severe weather covering large areas of Minnesota. Whereas tonight, honestly, on Friday evening, I could see some wind damage and maybe even some tornadoes in parts of western Minnesota, especially in the first few hours as these thunderstorms really get going. There's a couple missing ingredients here. Usually with a good severe weather outbreak, you'd like to see the air mass kind of dry off quickly as you ascend through the atmosphere. And you also like to see it cool off kind of quickly. And in this particular case, there's a little too much summer left in this airmass. So, it stays a little warmer with height than it would be ideal. And it stays a little too moist with height compared to what would be ideal. And so, that leaves us just a little bit short. But if those ingredients were not missing, we would be actually looking at tonight a very high-end potential for a really powerhouse severe weather event. Instead, I think because we're short those two ingredients. It's more like a good old fashioned severe weather risk with, you know, some storms that are going to approach kind of almost get unhinged, but not quite make it all the way there, you know. Maybe they get uncorked for a half an hour or an hour. So, we're just sitting short of what would be required for a major, major outbreak. And I think on Sunday, we're even farther away from that because we lose not just those two ingredients, but we lose other ones too. So, I would say today's the more potent of the two days. There's also scattered precipitation chances across much of Minnesota on Sunday. But I wouldn't be surprised if by the time we get to Monday morning, more than half of the state did not receive a quarter of an inch total. I wouldn't be surprised of that at all. So, it's still...so it's still the precipitation lottery.

Jim du Bois  09:03

Well, as we look ahead to next week, any change in the pattern that becomes apparent?

Kenny Blumenfeld  09:09

Yeah, that's a good question. Everything that I can see and what the forecasters have been talking about suggests that we at least have more and perhaps better opportunities for precipitation next week. We don't know how long that kind of pattern shift will last. And we don't know if it's a seasonally permanent one, or if it's a temporary one. But what it looks like is going to happen is the whole kind of summertime pattern that we've been in for not all of but most of the summer with a big ridge of high pressure out to the west and a big trough of low pressure to our east that that whole pattern is going to flatten and shift to the south a little bit and it's going to put Minnesota much closer to the transition zone where you've got cooler, more mild air to the north and then warm, humid summer like here to the south. And that transition zone looks like it'll be pretty active with disturbances kind of moving along it. So, we don't know exactly where the kind of a front separating the two air masses will be, but it looks like it'll be somewhere in the region. And so, it's possible that we'll see chances of precipitation Tuesday, Wednesday, Thursday and Friday of next week. And again, we don't know exactly how long this will last. I just like the idea that we have, you know, potentially several days in a row with precipitation chances, and these could be healthy thunderstorms, too. So, although there's no smoking gun signal that the state's gonna get, you know, widespread one-to-three-inch rainfall or anything like that, certainly, the chances are as good next week as they have been at any point since the beginning of May. So, I'm happy to be able to say that. What it means for the drought is that some areas might be able to at least stall the drought's progress. You might be able to slow down the development or the accel, you know, at least stop it from accelerating a bit. Halt its expansion, maybe even make up a little bit of lost ground. That would be good. And if we're lucky, then we could maybe even stay in that pattern for more than a week. And, you know, have say, a whole period of above normal precipitation. Oh, wow, that would, that would be nice if we had kind of two or three weeks of above normal precipitation. I think people would be really happy with that. But all of this is just speculation at this point. For all we know, this whole transition zone ends up in Iowa, and we end up high and dry here in Minnesota. Or on the other hand, maybe we do get lucky. Something we'll have to revisit as we, as we turn the corner into the beginning of next week.

Jim du Bois  11:45

Well, fingers crossed on the rain, and be sure and monitor your favorite media source to stay on top of any potential severe weather, especially this afternoon into this evening, this is Friday, the 20th of August. But also on Sunday, keep an eye out for any severe weather activity. And Kenny, we'll check in with you next week, and maybe there'll be some, some good news.

Kenny Blumenfeld  12:09

Oh, we can hope so, Jim. I mean, at a minimum, you know, we're going to cool down this weekend, and that's going to be nice. I think people will welcome something that doesn't feel like the middle of summer. I think that'll be that'll be welcomed. We just hope that it's not fanning the flames too much in the, in the northeast parts of the state. And yeah, hopefully if you get rain, enjoy it, because it's been hard to find this summer.

Jim du Bois  12:33

Well, Kenny, enjoy the weekend. We'll keep our fingers crossed on the rain and stay safe.

Kenny Blumenfeld  12:40

Yeah, thanks. You too, Jim.

Jim du Bois  12:41

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.