Extreme Tornado Outbreaks Have Become More Common

[KendraReed]

Thoughts?

"Now, a new study shows that the average number of tornadoes in these outbreaks has risen since 1954, and that the chance of extreme outbreaks —tornado factories like the one in 2011—has also increased."

http://iri.columbia.edu/news/tornado-outbreaks/

 

[Matt Ashworth]

Interesting read for sure, and definitely food for thought. I would be interested in knowing if these outbreaks are also beginning to occur in areas where they historically have not happened before as well (didn't see that mentioned later in the article but I may have missed it while skimming through the later sections).

 

[Will Campbell]

I wonder how much of the increase can be attributed to 6 bazillion social media warriors surrounding every storm these days, compared to a few spotters/farmers back in mid-century.

 

[rdale]

I wonder how much of the increase can be attributed to 6 bazillion social media warriors surrounding every storm these days, compared to a few spotters/farmers back in mid-century.

Minimal. If you look back in time, the dataset they use (F2+) has stayed constant over the ages. The recent jump in tornado counts are on the F0/1 side.

 

[Andy Wehrle]

I wonder what their definition of an "extreme" outbreak is? Obviously there are two in modern history that stand in a class by themselves, those of 3 April 1974 and 27 April 2011. The data really isn't good enough to guess how often such outbreaks might occur, but recent research suggests the outbreaks of 21 March 1932 and the Enigma Outbreak of 1884 might have been on that scale, given the paucity of detection and surveying resources in those days.

Close behind the "super outbreak" group is the Palm Sunday outbreak of 1965. Only nine years between outbreaks with a double-digit violent tornado count is quite extraordinary based on what we know.

Then you have your more "typical" (but still rare) high risk outbreak that might max out at 3-5 violent tornadoes if populated areas get unlucky. Your Super Tuesday 2008, 3 May 1999, 26 April 1991, etc. Would these be considered "extreme" by the definition of the article?

 

[rdale]

I wonder what their definition of an "extreme" outbreak is?

From the report:

Outbreaks are sequences of 6 or more F1+ tornadoes (regardless of location in the contiguous United States) whose successive start times are separated by no more than 6h (ref. 2)

 

[Andy Wehrle]

But...there are outbreaks, and then there are "extreme" outbreaks.

 

[Drew Terril]

They are really vague about defining terms. They use "extreme outbreaks" in the headline and yet do not define what that means. But, from sifting through the text to the data line, it seems that what tornadoes do occur seem to be clustered into a smaller amount of setups according to the article.

I haven't broken down data for the rest of tornado alley, let alone outside of the alley, but it seems to me that the 1950-1970 was more active in terms of violent tornadoes in Oklahoma than the past 30 years. Granted, the ones the last 30 years have gotten a great deal more attention because they hit populated areas, but it's something I found rather interesting myself.

 

[Jeff Duda]

Pretty loose definition of a tornado outbreak if you ask me. Otherwise, I think a different article came out last year basically saying the same thing. Could be consistent with some other research I've read that suggests the environments supportive of tornadoes may become less common with climate changing the way it is.

 

[rdale]

But...there are outbreaks, and then there are "extreme" outbreaks.

What is the difference? I don't see that differentiated in the study.

 

[Randall Bragg]

Just reviewed tornado outbreak stats since 1950 and found 3 "super" outbreaks of 200 or more tornadoes, 2 of 300 or more tornadoes, and just one extreme outbreak of 401 tornadoes (May 2003) with 42 fatalities. Do we rate the difference between an outbreak, a super outbreak, and an extreme outbreak by number of tornadoes, number of fatalities/injuries, or billions of $ in damage as insurance companies do as mentioned in the article. I guess the definition is subjective to where you live, life experience, and storm chasing events. Pardon the pun, but I guess the definition is "Up in the Air".
There are several days with 100 or more tornadoes during an outbreak, are they simply called outbreak events?

 

[TJKLECKNER]

I assume that the number of tornadoes is relatively the same as 100 years ago, just that now we have more people spread out and every tornado is counted. In the past if a tornado hit a field in unpopulated Kansas, nobody would see or care about it. With more population comes more billions of $ in damage.

 

[rdale]

I assume that the number of tornadoes is relatively the same as 100 years ago, just that now we have more people spread out and every tornado is counted.

Not necessarily. That's why these studies use major tornadoes and drop the EF0/1s when doing them.