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Climate Change

Tornados - Dr. Jeff Masters Biography

Jeff Masters, Ph.D., the Director of Meteorology for Weather Underground, speaks about what would happen if a tornado hit a large city, like Chicago or Dallas, and what the implications would be. He will also talk about the future of tornadoes and what might happen as the climate continues to get warmer.

Excerpt From

Transcript

0:00 We're going to be interviewing next, Jeff Masters, 0:04 Director of Meteorology for the Weather Underground, 0:07 and a graduate of the University of Michigan. 0:10 Jeff has written an article in the past about what would happen if 0:14 a tornado hit a very populated area in the United States. 0:18 So Jeff, in your article, 0:20 you talk about in particular, Chicago 0:23 and you're basing this on some other research that was done in the past by Josh Wurman. 0:29 So, just tell us about what the findings were about? 0:33 How bad could it be? 0:34 What happens if a F5 0:37 or F4 tornado hits a populated area like Chicago? 0:41 Yeah, the thing about tornadoes is they generally 0:43 occur over a very sparsely populated areas. 0:46 The Midwest has got a lot of wide open spaces, a lot of farmland. 0:50 But a couple of places where we do have a lot of people packed in a small area, 0:55 Chicago is about the most densely populated city in the Midwest, 0:59 a lot of people per square mile there. 1:01 So, if you get one of these high end EF4, 1:03 EF5 tornadoes blitzing through Chicago in one of these densely populated areas, 1:09 you could have about 100,000 people subjected to the winds of a EF5 tornado 1:14 and figuring a death rate of somewhere or few percent per each building, 1:18 you can get easily 10,000 people killed in a tornado 1:22 which would be an unheard of catastrophe. 1:25 Ten thousand is just unthinkable. You're right. 1:28 So, the worst weather events that have happened are less than that, as I recall. 1:36 Yeah. In the US, the great Tri-State Tornado is the world record holder 1:40 for the deadliest US tornado, 695 people killed. 1:44 That was way back in 1925. 1:46 Since 1953, we've only had one tornado in the US that has killed more than 100 people. 1:52 That was the 2011 Joplin, Missouri tornado which killed 158. 1:57 So describe, in addition to the number of people there, 2:04 are the structures capable of protecting people? 2:11 Structures are getting better. 2:13 I mean, we're always building to higher building codes in general. 2:16 So, the death toll is less than perhaps 50 years ago it would have been. 2:21 But yeah, you put a lot of people in the way of harm and they're going to get killed 2:25 because structures, especially single family homes 2:29 can't withstand the winds of an EF5 tornado. 2:31 It simply will clean them off down to the foundation. 2:34 Now in Chicago, a lot of those structures where 2:37 people live are multistory apartment buildings. 2:40 Those will not be completely leveled and the death rate in 2:43 those structures is anticipated to be perhaps a factor of five or 10, 2:47 even less than single family homes. 2:50 Just people watching who are in Chicago and maybe concerned at the moment, 2:55 we're not just talking about Chicago, 2:57 this could be any number of large cities. 2:59 We've had Joplin, we've had Tuscaloosa in the past few years, 3:03 and many cities, large cities do sit in 3:06 what we'd call Tornado Alley or places prone to tornado. 3:10 So, are there other cities you'd be concerned about? 3:14 Probably the biggest concern is Dallas because it's highly populated and it 3:19 also lies in a more tornado prone area of the country than Chicago. 3:24 Also Oklahoma City is a danger. 3:27 It's in the highest incidence for 3:29 a tornado area of the US but it's a little bit more spread out. 3:33 There aren't as many people concentrated there and 3:35 people in Oklahoma City are very tornado aware. 3:38 I mean, they get tornado warnings every year, virtually. 3:41 So, they've got a lot of experience dealing with them. 3:44 In fact, in Oklahoma City, famously, 3:46 they've had more than their fair share of F4 and F5 tornadoes. 3:51 Moore, Oklahoma, South of Oklahoma City has been hit a couple of times in 3:55 the past 10 years or so by tornadoes that were very powerful, F5 tornadoes. 4:02 So, as I understood it from the articles, 4:06 you look at the number of people who died in a tornado like 4:09 that versus the density of population, 4:13 and then extrapolate to a more densed population. 4:19 That's right. Yeah. 4:21 In Oklahoma, I don't know. 4:22 Yes, they are tornado aware 4:24 but they don't often have as many underground facilities, 4:30 don't have basements, necessarily 4:32 and perhaps, there are more mobile homes in some parts 4:37 of the country than others and that's got to come into play in these estimates as well. 4:41 Chicago wouldn't have that mobile home density that a more rural area might have. 4:47 That's true. St. Louis is another city of concern 4:50 because it's also in Tornado Alley and has a large population. 4:53 Sure. And Kansas City, 4:56 Omaha is on the way. 4:58 So, there are lots of cities out there and the Southern cities as well. 5:02 We certainly have a number of F4, 5:04 F5 tornadoes possible in the Southern states. 5:07 So, moving forward then, 5:09 a huge concern here for a catastrophe to happen should a tornado hits a large city. 5:15 The next logical question is what is the probability or 5:19 are there reasons to believe that in the future, that these sort of F4, 5:24 F5 tornadoes are likely to become a change in 5:28 either frequency or intensity because of a warming climate? 5:34 Yeah, EF5 tornadoes are really rare. 5:37 Since 2011, the span from 2012 to 2017, 5:42 there were only one, two, three, 5:44 four, five, counting seven or so of them. 5:46 So around one or two a year and it's considered, we get a thousand tornadoes a year, 5:52 I mean there are like one in a thousand events. 5:55 But back in the year 2011, 5:57 we had nine EF5 tornadoes. 5:58 So what happens is they get concentrated in these bursts and these outbreaks. 6:03 And there's evidence over the past 20 or 30 years that when we do get tornado outbreaks, 6:09 they tend to be larger, 6:11 we're getting more tornadoes, 6:13 And there's speculation that that could be due to a changing climate. 6:18 But there is a lot of unknowns about this because 6:22 the reason that these outbreaks are getting bigger 6:25 is because of an increase in what we call wind shear. 6:28 That's the turning or the change of wind speed or wind direction with height, 6:33 which imparts a spinning motion to get the tornado going. 6:37 It's theorized that in a future climate where the atmosphere is warmer, 6:42 the jet stream move further to the North, 6:45 and the jet stream is the primary mechanism that causes 6:49 this wind shear needed to get strong tornadoes. 6:52 So the theory says that wind shear should 6:56 decrease in the future as the jet stream moves further North. 7:00 But here, we're observing that actually, 7:02 the shear in these major outbreaks over the last 20, 7:06 30 years is actually increasing. 7:08 So there's a disconnect between what we expect to happen in 7:11 a warming climate and what we're actually observing as far as tornadoes go. 7:15 So, it's uncertain why there is this increase in 7:18 the number of tornadoes and 7:20 these large outbreaks because of climate change, because it doesn't fit the theory. 7:24 So, that's a big area of research for the future. 7:29 And I might add the other main ingredient that 7:32 we're looking at for tornadoes, in order to get a good tornado, 7:35 you need a strong thunderstorm. 7:37 Which means you need lots of warm unstable air from the heating of the ground. 7:43 And of course in a warmer climate, 7:44 you're going to have warmer air temperatures which would lead to more instability, 7:49 more unstable air creating strong thunderstorm updrafts. 7:52 So that influence is expected to increase with a warming climate. 7:56 But as yet, we have not observed 7:59 that particular effect coming into play as far as tornadoes go. 8:02 So, it's still a large area of unknown. 8:06 We got to do a lot more research before 8:08 we're going to be able to conclusively say there's 8:10 a signal yet in the noise of all these observations we take about tornadoes. 8:15 It's a really tough problem. 8:17 You hit it on the head the two main things worrying about with tornadoes. 8:21 A, is the sort of convective potential of the atmosphere and how will that change and 8:28 the convective potential has to do with 8:29 how much warm moist air is packed in near the surface, 8:34 and where are the conditions above it and how that will change over time. 8:38 Then the second part is what you're calling the wind 8:41 shear or helicity in the storm and how is that going to be 8:45 changing over time. We'll be talking about that in detail about how 8:50 those two are forecast to change in the future, given the climate projections. 8:55 There is actually some evidence that it's not necessarily 8:59 the convective potential that's going to be changing all that much, 9:02 but it's perhaps the change in that rotation there, 9:06 in that wind shear that might be causing 9:09 the potential for more tornadic storms in the future. 9:13 But you're right. This is an uncharted territory 9:16 and we can say here and speculate all we want to 9:19 but we just don't know yet at the moment. 9:22 Yeah, it's also interesting that the average conditions, 9:27 what can we expect on average the wind shear will go down as the climate warms. 9:31 But it turns out that a 2013 paper showed that we shouldn't be looking at the averages, 9:37 we should be looking at the extreme events. 9:40 During the extreme events, it turns out that we're actually 9:43 seeing an increase in wind shear, 9:45 these extreme tornado causing sorts of 9:47 days when we're most prone to get these large outbreaks. 9:51 It remains to be seen why we're seeing 9:54 that extreme situation increase in recent decades. 9:58 Is it climate change? Is it natural variability? 10:00 Well, we'll probably be able to figure that out in 10:02 the next 20 or so years as the whatever natural cycle 10:06 this is will presumably go back down away from creating these larger events we're seeing. 10:12 Another factor in tornadic formation is got to be this low level jet. 10:18 There's this air that transports moisture from South and 10:21 North over the plains and elsewhere and how that changes in the future. 10:26 You mentioned the fact that the jet stream may be shifting in its location 10:30 as the Polar regions melt and then where that jet stream winds up meandering, 10:36 all bets are off and how that's going to change 10:38 but if you decrease the temperature gradient presumably, 10:42 you're going to change or maybe decrease the strength 10:45 of the jet stream has that affect all the other parts is- 10:50 That's why we're going to have graduate students for a long time, 10:53 I guess, who's trying to work these things out. 10:56 Tornado outbreaks happen worldwide. 10:58 Famously, they happen in the United States and 11:02 the United States is probably the place with greatest frequency of tornadoes. 11:05 But when we look at the top 10 most deadly tornadoes in history, 11:10 USA is not in the top three and surprisingly, 11:16 the greatest number of tornado deaths happens in Bangladesh. 11:20 Can you speak to why Bangladesh? 11:23 Bangladesh has a large area of very warm moist air 11:29 that invades it in the tornado season they have there 11:32 because they're close to the Bay of Bengal which has got very warm waters. 11:36 And when that warm moist air collides with some of 11:38 the cold dry air coming down from the Himalayas, 11:41 then you get a situation where you can get some strong tornadoes. 11:45 And they don't get very many, 11:47 they only get five or 10 tornadoes a year in Bangladesh, 11:50 but they're very vulnerable to tornadoes 11:52 just because there's so many people in Bangladesh and the construction is not as 11:57 strong as say, you'd get in the US. Also they 12:00 don't tend to have basements because Bangladesh is very low lying. 12:03 So, you combine the five or 10 tornadoes with a lot of people that are vulnerable, 12:08 then you're going to get a large death toll. 12:09 What is it you imagine we could do in 12:12 research realm that is going to give us more information and 12:15 help us be able to forecast these storms earlier so that people in Chicago would have, 12:21 for example, a longer time to prepare tornadoes bearing down on them? 12:27 We really need to invest in more field research. 12:30 Tornadoes are hard to observe. 12:32 They tend to blow away whatever measurement estimates we put in 12:35 their way and they're very rare, especially strong tornadoes. 12:40 So, we need to get a lot more data out in the field on just how they form, 12:45 how they move, how they intensify. 12:47 And to do that, we need to spend a lot of dollars, 12:50 we need to put millions of dollars worth of equipment out there, 12:53 we need to put a lot of people out there. 12:54 There have been a number of field studies in recent years looking at tornadoes. 12:58 In fact, there was one in the Southeast US called SE Vortex 13:01 recently and they plan to continue that study in the future. 13:05 Unfortunately, that study has had its funding 13:08 projected to be cut by the latest budget proposal 13:11 and I think that would be a big mistake because the 13:14 Southeast US is uniquely vulnerable to tornadoes. 13:17 We don't understand them as well there and 13:20 some of the highest death tolls we've seen in recent years have been in Alabama, 13:25 Mississippi and particularly, in the year 2011 when we had 13:28 some really hellacious tornado outbreaks in that area. 13:31 It's been somewhat easier for us to study tornadoes out in 13:35 the Great Plains in part because they are plentiful, 13:39 in part because the air is drier there 13:42 so we have this clouds at a higher base and we have 13:44 more opportunity to see them from a distance. 13:47 And also must be blunt, 13:49 there are fewer trees out there. 13:51 So, it's a greater visual range. 13:53 It's harder, of course, in the Southeast where they have lots of trees 13:58 to go chasing these storms, 14:00 makes it much, much more dangerous. 14:02 But you're exactly right because we can use radar technology to a point 14:07 but that curvature of the earth doesn't allow you to use the radar to get 14:11 down to the surface to see where the surface winds are in the vicinity of a tornado. 14:16 So you really have to have ground troops, if you 14:18 will, to get right in there and make those measurements. 14:21 So, moving forward, we need more of this kind of research to happen 14:25 but you don't see that being high on the list of our current priorities? 14:30 No. I mean, the current administration is very anti-science, they've proven that. 14:34 They're not very keen on providing funds for research. 14:39 Either tornadoes, hurricanes, weather in general, 14:42 they're all subject to cuts, it looks like. 14:46 I want to thank you, Jeff for spending some time with us and to talk about tornadoes. 14:50 This concept that if a tornado hits a major metropolitan area, 14:54 the potential for death and destruction is tremendous 14:59 and I don't think we really spend much time thinking about that as a possibility. 15:04 So, how we prepare for that in the future is a challenge for urban areas 15:09 but that is a real issue for almost every city in the Eastern United States, I'd say. 15:14 Absolutely. 15:16 Thank you. 15:17 All right. Thanks.