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Claims Of Increasing Tornado Outbreaks Don’t Hold Water

December 3, 2016

By Paul Homewood




Who will rid me of this junk science?


The latest attempt to prove that tornadoes are becoming more extreme:



Tornadoes and severe thunderstorms kill people and damage property every year. Estimated U.S. insured losses due to severe thunderstorms in the first half of 2016 were 8.5 billion USD. The largest U.S. impacts of tornadoes result from tornado outbreaks, which are sequences of tornadoes that occur in close succession. Here, using extreme value analysis, we find that the frequency of U.S. outbreaks with many tornadoes is increasing and is increasing faster for more extreme outbreaks. We model this behavior by extreme value distributions with parameters that are linear functions of time or of some indicators of multidecadal climatic variability. Extreme meteorological environments associated with severe thunderstorms show consistent upward trends, but the trends do not resemble those currently expected to result from global warming.


As any proper expert on tornadoes knows, many more tornadoes get to be reported nowadays, simply because of changes in reporting procedures.

McCarthy & Schaefer explained this fully in their paper, TORNADO TRENDS OVER THE PAST THIRTY YEARS, which they wrote in 2003:


This paper looks at the reported frequencies of tornadoes and their characteristics over the contiguous United States since 1970. There was a significant increase in tornado occurrence during two periods in the last 33 years – in the early 1980s when National Weather Service (NWS) warning verification began, and in 1990 when the WSR-88D [Dopppler] became operational…..


The years 1950-1969 were a growth period because it was the start of the public awareness and communication revolution that gave tornadoes increased publicity due to television news coverage and graphic depictions of tornadoes and tornado damage….


The increase in reported tornado frequency during the early 1990s corresponds to the operational implementation of Doppler weather radars. Other non-meteorological factors that must be considered when looking at the increase in reported tornado frequency over the past 33 years are the advent of cellular telephones; the development of spotter networks by NWS offices, local emergency management officials, and local media; and population shifts…..


The growing “hobby” of tornado chasing has also contributed to the increasing number of reported tornadoes. The capability to easily photograph tornadoes with digital photography, camcorders, and even cell phone cameras not only provides documentation of many weak tornadoes, but also, on occasion, shows the presence of multiple tornadoes immediately adjacent to each other.


When these weaker tornadoes are stripped out, it is clear that there is a declining trend of stronger tornadoes.




This Tippett paper defines a tornado outbreak as one containing at least six tornadoes. But given that more tornadoes are now reported than in earlier decades, it is inevitable that more such outbreaks are now being recorded, and that they will tend to have a higher number on average.

Indeed, McCarthy’s comment “ shows the presence of multiple tornadoes immediately adjacent to each other”, is particularly relevant. Prior to the use of mobile phones and Doppler, many of these would have simply been lumped together as just one big tornado.


This paper seems to be a classic case of a team of scientists, who appear to have little knowledge of the subject, using computer models to arrive at a preordained conclusion. 

  1. A C Osborn permalink
    December 3, 2016 9:31 pm

    Paul, off topic.
    Have you seen Booker’s latest piece on Renewables?

  2. RAH permalink
    December 3, 2016 9:57 pm

    They have not a leg to stand on and the very fact that someone would try to make such a claim just shows how far down the propaganda hole they’ve fallen. NOAA Storm Prediction Center shows that in 2015 there were:
    0 – EF 5
    3 – EF 4
    18- EF 3
    64- EF 2
    396 – EF1

    And 2016 had fewer tornadoes though I guess the accounting of strengths will have to await their 2016 end of year report. Anyway one cuts it the outbreaks aren’t getting more severe and in fact have to be getting less.
    Since 2005 only the years of 2008, 2010, and 2011 have ended with tornado counts above the mean with 2008 being a record year. The lowest count was 2013 which was a record.

  3. tom0mason permalink
    December 3, 2016 11:18 pm

    The whole ideology is plain wrong!

    CO2 does not ‘hold heat’. There is not any more energy in the ‘weather system’ than the sun supplies.
    How and why tornadoes form is dependent on so many variables. Tornadoes is nature at work dealing with with local surface temperature, upper atmospheric conditions — including but not limited to changes in air temperature, local winds, air pressure, the amount and type of dust in the air, all have impacts. As does the local geography and topology govern how and when tornadoes form. This far more complex than these numbskulls understand.
    There certainly is not any historic data (from the last 1000 years) that would indicate the number or strength of tornadoes are linked to just the local or global atmospheric temperatures changes.

    It’s just the same old idiotic meme of ‘more CO2 causes more XXXX’. Always the meme never has any direct factual evidence to justify the assertion, at best there are only modeled compliance to the hypothesis.
    Extreme junk!

  4. Broadlands permalink
    December 3, 2016 11:25 pm

    “Extreme meteorological environments associated with severe thunderstorms show consistent upward trends, but the trends do not resemble those currently expected to result from global warming.”

    “As a final caveat, inferring tornadic actively solely from the environment has considerable uncertainty even in the current climate and at least as much in projected climates.”

    Yawn? Now that we have all of these facts, what’s next?

  5. December 3, 2016 11:35 pm

    Reblogged this on Climatism and commented:
    How is it that Paul Homewood, armed with an internet connection, a cup of coffee and a few hours can destroy a “scientific” study funded with other people’s money, over hundreds of hours, published by a “scientific” article for hundreds of thousands of dollars?

    Another classic example of the “climate change” scam in action.

  6. December 4, 2016 1:01 am

    Killer tornados increase when La Niña comes. Watch out.

    • Les Johnson permalink
      December 4, 2016 9:23 am

      I used to think so too. But I looked at ENSO vs outbreaks, and while it appeared early in my research, that la nina was associated with the outbreaks, I found a “break point” around mid century, where outbreaks became associated with el nino.

      I will see if I can find that again.

    • Les Johnson permalink
      December 4, 2016 9:47 am

      Here is NOAA data on ENSO/outbreaks. They found the same thing I did.

      I suspect that the real relationship is either chance, or that a regime change encourages outbreaks. If it changes from warming to cooling, or vice versa, then outbreaks more likely. If its warming, then el nino. If its cooling, then la nina is linked. But just a supposition, and it really does not fit the later data. Also, a plurality of outbreaks occurs in neutral conditions. So probably chance.

      • December 4, 2016 12:36 pm

        Les, the Allen paper refers to an analysis looking beyond tornado stats to the causal conditions. I would like to know more.

        “Past studies that have relied on eyewitness records alone have had limited success, said Allen. “For example, previous work has shown a clear linkage between ENSO and winter activity, but spring–the season when most of tornadoes occur in the southern U.S.–remained an enigma until now,” Allen said.

        To get around these challenges, the Columbia University team created indices derived from environmental conditions such as wind shear, temperature and moisture. Each is a key ingredient in severe storm formation, and each is influenced by ENSO. The scientists then verified the indices using available observational records.”

      • December 4, 2016 2:18 pm

        The Allen paper is behind a paywall, but I have added a link to an article by Michon Scott that clarifies the findings. ENSO sets environmental conditions that favor or disfavor tornado formation, and the influence is particularly strong in springtime in SE USA (“tornado alley”).

  7. December 4, 2016 3:54 am

    “Extreme meteorological environments associated with severe thunderstorms show consistent upward trends, but the trends do not resemble those currently expected to result from global warming.”

    So it’s not AGW that’s doing this?

  8. Athelstan permalink
    December 4, 2016 9:58 am


    It put me in mind of this lot.

    The above article is and purely speculative crap, ie propaganda from advocates – sock puppets who press the US governments buzzers ‘more money please’ and nothing else.

    Have a look:

    Hourihan is the director of the R&D Budget and Policy Program for the American Association for the Advancement of Science (AAAS), where he is a regular source of information and analyses on past, present, and future science budgets for policymakers and the science community. He has served in this position since 2011.

    Prior to joining AAAS, he served as a clean energy policy analyst at the Information Technology & Innovation Foundation (ITIF). While at ITIF, he tracked federal energy R&D investments and innovation activities, and authored several white papers and policy briefs exploring the role of innovation in solving the nation’s energy and climate challenges. He also regularly coordinated Congressional briefings, conferences, and events bringing together leading experts in government, industry, and academia. Previously, he served as Jan Schori Fellow at the Business Council for Sustainable Energy, a coalition of energy firms and utilities working to engage policymakers for market-based solutions to sustainable energy development and climate change.

    “market-based solutions to sustainable energy development and climate change.”

    yeah right – nuff said.

    • December 4, 2016 1:14 pm

      My late father, PhD Chemistry from MIT, referred to AAAS as the American Association for the “Assassination” of Science. Seems it still holds.

      • Athelstan permalink
        December 4, 2016 6:47 pm

        Ms Joan Gibson,

        Your father was evidently a perceptive man, that sort of insightful comment ” American Association for the “Assassination of Science.” and If it were my kin, would make me very proud to be lucky enough to call him, ‘my dad’.

  9. December 4, 2016 10:21 am

    Prof. Roger Pielke Jr. wrote in the Wall Street Journal:
    ‘…my research led me to a conclusion that many climate campaigners find unacceptable: There is scant evidence to indicate that hurricanes, floods, tornadoes or drought have become more frequent or intense in the U.S. or globally.

    In fact we are in an era of good fortune when it comes to extreme weather.’

  10. January 8, 2017 11:32 pm

    Where I live, we have two tornado seasons. The big season is the winter to spring transition and the smaller second one is the fall to winter transition. 

    Ingredients needed: enough moisture, enough convection, wind sheer and a rotating cell. Even with those, I suspect the conditions are damped-driven with a threshold. [Of note is that summer is the time of the year with the least variation in temperature and humidity. Our rainy season starts in November (coincidentally, that’s when our secondary tornado season begins) and runs through May (coincidentally, that’s when our primary tornado season ends). Fall to winter transition sees an increase in day-to-day variability (including high variability of the diurnal range) but as it gets colder, the amount of moisture and convection decrease (never goes away, we have warm (relatively) water over roughly half of the compass to draw from). [It is more likely to snow here in March than December, for instance.]

    As the sun starts to get higher and gets at or above 45 degrees elevation in February, we start getting more convection and higher absolute humidity. With the rapid rise of solar elevation during the 4 weeks before the Equinox and the 4 weeks afterwards, the clash of the older colder air contrasts with the increasingly warmer land and water bringing in a greater temperature and humidity contrast (warm side versus cold side) until the whole jet stream tracks move far enough north to allow the usual summer (June typically) onset of HHH (hot, hazy and humid) yet lower precipitation amounts. These go down from June to October (the driest month).

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