Tornadoes in perspective

With all the interest in tornadoes, I thought it would be helpful to provide some contextual data (focusing on US tornadoes).

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Damaged houses along Grace St. in St. Peter. (Photo courtesy of St. Peter Kiwanis)
One thing that has to be said is that tornadoes are very powerful, but very small and short lived meteorological phenomena. They are like bullets being fired from cheap handguns by incompetent shooters. There are many stories of two gang bangers aiming their rods at each other at short distance, emptying them out, and failing to harm each other. In the mean time, a stray bullet from a drive by shooting can enter a home and kill an innocent young girl sitting at the table doing her homework.


Tornadoes are similar. The famous St. Peters tornado outbreak of Minnesota involved two major tornadoes from the same cell (I like to think of them as one phenomenon), which covered a great deal of ground over a very long time period, but only two people died. In 1925 a single tornado covered about 65 miles of land (same as the St. Peter tornado, roughly) in Missouri, Illinois and Indiana. It was probably an F5 (same as St. Peter). a total of about 695 people were killed, including 234 individuals in the town of Murphysboro, Illinois.

Here’s a description of the Minnesota event:

At 3:50 pm a tornado touched down 7 miles … east of Avoca, Minnesota…. As the tornado moved through Murray and Cottonwood counties, it damaged or destroyed 150 farmsteads, killed 500 dairy cattle…

At approximately 4:30 pm the twister… entered Comfrey, a town of 550 people located in both Cottonwood and Brown counties. … It moved through the center of town, destroying a grain elevator, the town hall and most of the main street businesses downtown. The town’s firehouse collapsed, and the school was heavily damaged. Fifty homes were destroyed and 100 people were left homeless. … Approximately 75% of the buildings in Comfrey were damaged or destroyed.

As the tornado moved through Brown County it achieved F4 strength where it damaged or destroyed 130 more farmsteads and killed 500 cattle. Approximately 15% of the 1000 farms in Brown County sustained damage … Northwest of Hanska a man was killed as a result his house collapsing. …. At one point the tornado had a width of 1.25 miles (2 km). After traveling across six counties for 1 hour and 25 minutes, the twister lifted back into the clouds at 5:15 pm …. With a path of 67 miles (108 km), this tornado is the fifth longest track tornado on record in Minnesota.

A few minutes later at 5:18 pm, the same supercell produced another large tornado two miles to the east of Nicollet. One mile to west of St. Peter, a 6 year old boy was killed when he was thrown from the vehicle he was riding in. At 5:30 pm the twister hit St. Peter, a town of about 10,000 people, at F3 strength. It inflicted severe damage on much of the town. … Gustavus Adolphus College sustained heavy damage after taking a direct hit from the twister, …. Officials estimated 500 homes in St. Peter were damaged or destroyed, and over 1000 trees were uprooted. Debris from St. Peter fell as far as Rice Lake, Wisconsin, 136 miles away….
[source]

A few years later, my wife showed me her dorm room, destroyed by this tornado. An iron radiator had broken loose and plowed into the very bed she may very well have been asleep in.

Except that it was spring break, the town was empty, the early warning system worked pretty well, Minnesotans tend to be cautious about tornadoes, and the rest of the tornado’s track was across sparsely inhabited farmland. So only two people (and a LOT of cattle) died in that disaster, even though there was an enormous amount of property damage.

All of the 25 deadliest US tornadoes seem to predate radar and early warning systems. Science can save your life.

So, how many tornadoes are there a year, and how deadly are they? Since tornadoes are small and short lived, counting them has been difficult and reliable data are only available for recent years. Even recent data are far from perfect. The death rates may be more accurate, but it is also possible that some earlier deaths attributed to tornadoes were actually due to other sorts of storms, given changes in the ability to verify tornadoes as opposed to, say, straight line wind storms.

Having said all that, the following chart (based on data from disastercenter.com is very interesting:

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(In case you can’t make it out, the maximum on the Y-axis is 1,400.)

The steady increase in tornadoes is almost certainly due mainly to ability to spot them. This does not rule out the possibility that changes in climate (global warming) could related to tornado frequency, but this is not the first data set one might want to use to explore this issue. As I have suggested before, there is likely to be a link. What seems to be a qualitative shift in deaths is probably the implementation of warning systems and better science and safety education.

Comments

  1. #1 Lorax
    May 12, 2008

    What seems to be a qualitative shift in deaths is probably the implementation of warning systems and better science and safety education.

    WRONG WRONG WRONG!!! Science kills people, it doesn’t save or even help people. Ben Stein said so and he was in a mediocre comedy movie (actually two now, although the latter is a tragedy more than a comedy).

  2. #2 freelunch
    May 12, 2008

    Mediocre? I demand satisfaction. Pasta at dawn. Bueller was a classic of the genre. Sure, Stein’s shtick was pretty lame, but it worked in that movie because the rest of the movie hit all the notes right.

    Oh, back to the tornadoes. One thing that is likely to help keep deaths down is that the tornado warnings are becoming more well-targeted, so people do not get sick of false positive warnings and start to ignore them.

  3. #3 chezjake
    May 12, 2008

    This is a side issue, but I think it’s relevant. Weather radios have been available for home use for over 20 years, and the National Weather Service has been improving signal and reach of weather radio transmitters. Yet, I don’t think there’s a single car that comes standard with weather radio reception, and just a few where it’s an option. This would be very easy and quite cheap to implement as an addition to standard AM-FM radios. You’d think that people in the tornado belt would be demanding it.

  4. #4 Greg Laden
    May 12, 2008

    Yet, I don’t think there’s a single car that comes standard with weather radio reception, and just a few where it’s an option.

    The weather band is standard in the Subaru. This is not a radio that turns off the CD player or FM/AM if an alarm comes across the wires, but it is easy to switch to the local weather band and get the weather.

    I may be wrong about this, but when we got our Subaru last year it seems to me that it was not an option (in the Forrester)

    Of course, the emergency broadcasting system would work on the FM, but not on the CD!

  5. #5 mark
    May 12, 2008

    We’ve had some watches, warnings, and tornadoes in the VA-DC-MD-PA area lately. I noticed something not too swell–many Pennsylvanians live near the Mason and Dixon Line, and watch Baltimore-based tv. Those stations did not continue the storm coverage after the warning was lifted for the Maryland side of the line, but the Pennsylvania stations did. Yet for those in Pennsylvania watching Baltimore tv (especially those tuning in late), there was no indication that they were still in peril, that the warning remained in effect in Pennsylvania.

  6. #6 Stephanie Z
    May 12, 2008

    We got the weather band with our Outback (2002?), but it was used, so I can’t say whether it was standard then. Our much beloved and lamented 2001 Forrester did not have it.

  7. #7 Greg Laden
    May 12, 2008

    Mark:

    Another Yankee Trick!

  8. #8 Mojave66
    May 12, 2008

    I’m curious– is there any explanation for the large spike of deaths in the early 1970′s? I do note there was a spike in tornados at the same time, but the scale of the two are pretty stark in contrast.

  9. #9 Greg Laden
    May 12, 2008

    Moja:

    One spike is 1974 when two especially bad tornadoes happened in the same year. In both cases, the tornadoes moved very quickly, one happen to hit a building/house with a lot of people in it, the fatally hit several targets within a matter of seconds.

    I think it really is a matter of chance, except with better warning systems, these cases may have been less severe. Still, keep in mind that this really could happen any time. We had a tornado come out of nowhere here last year, killing one person. No warning. But if that very tornado happen to hit a building with a lot of people in it, it would have been a spike in the data.

    (I quickly add… there was a warning in the sense that severe storms were bearing down on the village. Everyone really should have been in the basement for that reason alone. But the tornado warning had not gone off, the tornado formed instantly, wiped out a house, and moved on)

    On top of this, though, I also wonder about construction practices as well.

  10. #10 carlsonjok
    May 13, 2008

    In 1925 a single tornado covered about 65 miles of land (same as the St. Peter tornado, roughly) in Missouri, Illinois and Indiana.

    Two minor points to be made here: First, a quibble to be sure, the path of the 1925 Tri-State Tornado was well over 200 miles long. Second, it had been a matter of some debate whether it was one, continuous tornado or not. There is a current research project, by current and former members of the National Severe Storms Lab and the Univerity of Oklahoma, that is looking into the question. Preliminary results indicate that it was, indeed, one tornado, but the work is ongoing.

  11. #11 Greg Laden
    May 13, 2008

    Carl: Not a quibble at all, but a common problem and a very good point. Even the St. Peter tornado (the F4/5) was either one or two. If a tornado lifts off and the same cell drops again, that is counted as two, not one.

    Which is really the point of the beginning of my post … about how tornadoes are like testosterone poisoned gang bangers semi-randomly firing off Saturday night specials in urban neighborhoods. The consequences in terms of human life are at the end of a highly uncertain probability chain.

  12. #12 carlsonjok
    May 13, 2008

    Indeed. Having moved to Oklahoma as an adult, I am often asked by friends and acquaintances from back east whether or not I am afraid of tornados. The statistic I heard (although I am not sure how accurate it is) was that a tornado will only hit a particular location in the state only once every 1700 years. Although, a map I saw of recent tornado paths showed a couple places in Moore that got hit twice within a few years.

  13. #13 Greg Laden
    May 13, 2008

    The property that I mentioned that had the tree ripped apart had been hit earlier, with several trees topped (but the house never damaged badly).

    Considering that tornadoes are often embedded in very nasty storms that have wider effects, I think they should be taken seriously.

  14. #14 laurisa
    May 13, 2008

    On top of this, though, I also wonder about construction practices as well.

    Posted by: Greg Laden

    Yeah, I heard something about a bridge…??? (not related to tornado topic) Although it did fall as designed, yes?

  15. #15 Greg Laden
    May 13, 2008

    I think the bridge was built cheaply. That’s a Minnesota thing, though, isn’t it? With all due respect, Minnesotans don’t get that the lowest priced item (including bids for building a bridge) are not real options. Minnesota is the only state where Sears actually ships the 100 garage door opener loss-leader because people here actually buy it when it is advertized.

    But the real reason the bridge fell down is because of the way inspections were carried out. The MnDOT lead by a political appointee of our moronic governor …

    Tim Pawlenty, future Vice Presidential Candidate, is The Governor Who Let The Bridge Fall Down.

  16. #16 The Nerd
    May 13, 2008

    Lorax: Are you joking? Trying for sarcasm? I can only hope so (as I see in your blog you’re not completely insane).

  17. #17 Greg Laden
    May 13, 2008

    Lorax is pillar of strength in the Minnesota community of rational pro-science pro-science education pro-other-good-stuff activists. He is pseudonymous but he has killer kreds.

  18. #18 Deepsix
    May 13, 2008

    “There are many stories of two gang bangers aiming their rods at each other at short distance, emptying them out..”

    I’m never going to get that image out of my head.

  19. #19 Hank Roberts
    May 13, 2008

    Google:
    “… 2007 Subaru Outback Consumer Review on Edmunds.com. … They eliminated the weather radio band which I think was a mistake, I used it a lot.”
    http://www.edmunds.com/subaru/outback/2007/consumerreview.html

  20. #20 greg laden
    May 13, 2008

    I’m never going to get that image out of my head.

    I was told this by an experienced cop years ago, and the image remains in my head as well.

  21. #21 Julie Stahlhut
    July 1, 2008

    “There are many stories of two gang bangers aiming their rods at each other at short distance, emptying them out..”

    The animated version of The Boondocks once used exactly this image to open one first-season episode (which was, in many ways, not for the squeamish.) That’s the scene that remains in my own head, and this blog post turned it loose again.

  22. #22 Greg Laden
    July 1, 2008

    Then there is this: