Number of tornadoes in outbreaks is increasing

Discussion in 'Weather In The News' started by NancyM, Dec 2, 2016.

  1. NancyM

    NancyM EF0

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    Headline doesn't quite fit with the content of the article but the content is interesting:

    Tornado Outbreaks Are On The Rise, And Scientists Don't Know Why

    "Mathematician Michael Tippett at Columbia University, who tracks these outbreaks, says that while the number of tornadoes nationwide varies a lot year to year, the overall average is pretty steady...
    "But the number of tornadoes in outbreaks is increasing," he says. And the number of tornadoes in the most extreme outbreaks — those where at least a dozen tornadoes hit a region within one to three days — is increasing the fastest."

    http://www.npr.org/sections/thetwo-...-are-on-the-rise-and-scientists-dont-know-why
     
  2. Bill Hark

    Bill Hark EF5

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  3. Steve Miller

    Steve Miller Owner
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    Science Magazine says:

    The number of tornadoes pounding the United States during the most extreme outbreaks has roughly doubled over the past 50 years, a new analysis shows. But the study also yields a big surprise: The increased severity of such tornado outbreaks, at least at first glance, doesn’t seem to be related to climate change.
    ‘Outbreak tornadoes are on the rise’ articles are on the rise. Why? Because of a Mathematician named Michael Tippett at Columbia University who recently made some bold statements:

    The number of tornadoes in outbreaks is increasing. And the number of tornadoes in the most extreme outbreaks — those where at least a dozen tornadoes hit a region within one to three days — is increasing the fastest.
    Trippet further states:

    It’s not the expected signature of climate change. It could be either something else, or we really don’t understand what climate change is doing. The increase doesn’t seem to be related to better reporting in recent years so the trends seem to be genuine. The team then looked to weather data for a scientific explanation.
    His comments resulted in the following top-ranking articles on Google:

    NPR: Tornado Outbreaks Are On The Rise, And Scientists Don’t Know Why
    CSM: Is climate change causing more extreme tornado outbreaks?
    CBS: Biggest tornado outbreaks are spawning more twisters
    Climate Central: Extreme Tornado Outbreaks Are Becoming More Extreme
    In-Depth: Tornado swarms are on the rise — but don’t blame climate change

    While each author offers an opinion of his/her own, many seem far from valid. In fact, a tiny amount of common sense goes a long way when considering reasons why all of a sudden it’s news that more tornadoes occur during outbreaks then did 50 years ago. Trippet’s lack of expansion on reporting trends is where I take my opportunity to interject a theory — and it has absolutely nothing to do with the weather itself.

    Timing is everything
    Let’s start with the fact that comparison stats begin at 50 years ago. Take a look at the map and consider population increases and the space this population increase now occupies. If you need a visual aid to fully comprehend population growth and shifts, check out the new Google Timelapse. It seems most plausible that more people in more places equals more eyes on the sky resulting in more reports.


    6774e8f08e1d5fb2e385fb5cfed97301.png
    Courtesy: NOAA Storm Prediction Center
    Advances in technology
    Reporting tornadoes has never been easier than it is today. It will become even easier with crowdsourced weather becoming mainstream. 50 years ago? Not so much. In fact, even 10 years ago, reporting a tornado was not anywhere near as easy as it is today. Let’s consider reporting avenues over the last three decades:

    • 2000’s: 10 years ago we weren’t all carrying smart phones with the ability to open an app and instantly report, call a NWS WFO, contact local authorities, etc.
    • 1990’s: The internet was in it’s infancy. Public reporting prior to, and during much of this period, was by called or radioed in only.
    • 1980’s: Home telephones, amateur radio and citizens band radio were primary means for reporting. HAM radio and CB were the only mobile means by which one could report or relay a report of a tornado sighting.

    863c5ed867b4f07bd6f71b7662584a92.png
    Awareness is key
    Between broadcast media, social media and efforts by the NWS and private weather industry, the general public is more weather-aware than ever. Those who are aware of the potential are more likely to ‘spot’ a tornado because they’re looking for one.

    Storm Chasing
    Over the last 30 years storm chasing has become popular. Over the past 10 years the number of storm chasers has grown exponentially. Hundreds of people driving to the vicinity of threatening radar signatures will no doubt net a higher number of tornado reports. Some of these needles-in-the-haystack might not otherwise have been reported.

    What do YOU think?

    Original article: https://medium.com/@SteveMillerOK/o...-rise-heres-my-theory-772225a8eb9f#.kkvblnjj0
     
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  4. Jeff Duda

    Jeff Duda Resident meteorological expert
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    That's some pretty good discussion, Steve. I think you made some very valid points and I think there's something behind those points.

    I have some additional resources and thoughts I can offer on the subject:

    Check out this recent BAMS article on how expanding cities and residential areas leads to increased risk of tornado disasters: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00150.1

    Also, as is briefly suggested in the article, since the dawn of the WSR-88D (i.e., the Doppler radar era) the yearly counts of (E)F0 tornadoes has been increasing regularly. So I think detection of weaker tornadoes that might have otherwise gone undetected and better discrimination between weak tornado damage and that caused by non-tornadic straight-line wind when two events occurred at the same location might also be leading to overall increased tornado counts. I'm not fully aware of the statistical method Tippet et al. used to define and analyze "outbreaks" but an increased overall count seems consistent with increases in tornadoes per outbreak as well.
     
  5. rdale

    rdale EF5

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    Steve - your data appears to be using all tornadoes. It's expected that far more EF0s are in the books now than in the past due to better observing and communications. But that's why this study (it came out in March so not sure why it hit the news cycle again?) and papers from Brooks and Elsner have been singing the same song for years. If it was just a factor of the spotting side of tornadoes - I would surmise that more days with tornadoes would be in the logbooks. But we have fewer days with tornadoes...

    http://stormtrack.org/community/thr...rend-implications-plausibility-longterm.27735
     
  6. Todd Lemery

    Supporter

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    Or, there have been fewer tornados lately, but a higher percentage of those are being reported...
     
  7. Warren Faidley

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    It's rather telling that the upwards trend initiated around 2004, right when social media and mobile electronics began to explode or improve to the point were we had almost constant communications and radar while chasing -- in addition to increasing numbers of experienced chasers. I think this factor alone has contributed to increasing number of tornadoes reported. It's also interesting to see how the numbers have plunged over the last 5 years because of the drought.

    Edit: I'd like to see a study / graph showing the "age" of dwellings involved in tornado strikes, fatal and otherwise to see how much population expansion factors into the equation.
     
    #7 Warren Faidley, Dec 8, 2016
    Last edited: Dec 8, 2016
  8. rdale

    rdale EF5

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    But there isn't an increasing number overall, as shown above. There's an increasing number during big events. There is a decreasing number of tornadoes being reported on non-outbreak days when compared to the past.
     
  9. brody_clifton

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    Speaking of tornado outbreak, has anyone peeked at the current GFS output for Christmas Eve? Strong negative tilt shortwave (with ample moisture?) vicinity eastern southern plains/Arklatex. Something to watch. 9af333eb695352a0e9d4733f6f085fd2.gif
     

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