Jeff Masters on May’s Tornado Drought: More Evidence of Extremes

May 20, 2013

Despite last week’s lethal tornado in Texas, and the continued rash of storms today – the first part of May saw an unusually low number of tornadoes, – striking in contrast to 2 years ago, when in 2011 we saw an awesome eruption of tornado fury across the US. Jeff Masters of Weather Underground addresses the issue in the video above – both kinds of extremes are very low probability events.  Coming in such close succession, they tend to reinforce the “weather whiplash” story that has characterized our “new normal”.

Jeff Masters at Weather Underground:

With just three tornadoes during the period May 1 – 7, 2013 has had the third-fewest U.S. tornadoes during the first week of May since record keeping began in 1950. The only year with fewer tornadoes during the first week of May were 1970 (zero) and 1952 (two.) During the ten year period 2003 – 2012, the U.S. averaged 73 tornadoes during the first week of May, with a high of 239 during May 1 – 7, 2003.

UPDATE: Then again, the tornado drought may be ending.
Breaking – CNN:

(CNN) — At least one person was killed and around a dozen injured Sunday when a string of tornadoes tore through four states, ripping roofs off homes, downing power lines and tossing trees like matchsticks

One tornado touched down near Wellston, Oklahoma, taking out power lines and damaging several homes, according to video from CNN affiliate KFOR. The affiliate’s helicopter pilot estimated the funnel cloud to be about a half-mile wide.

“It’s tearing up everything,” the pilot said. “Just ripping everything up in its sight.”


24 Responses to “Jeff Masters on May’s Tornado Drought: More Evidence of Extremes”

  1. omnologos Says:

    This is particularly awful. There is no accepted definition of “extreme weather”, and if word spread out that CO2 emissions cause a tornado drought, people would leave their car engines running all night.

    • Either you are demonstrating total ignorance or intentionally misleading or a mixture of that and denial
      Did you just read the headline and make comments out of your head or did you actually watch the video?

      Where could we find the definition for extreme weather event? It would have been nice if the IPCC had one considering they review all the peer review information.

      From the IPCC (AR4); The accepted definition .

      Extreme weather event An extreme weather event is an event that is rare at a particular place and time of year. Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of the observed probability density function. By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense. Single extreme events cannot be simply and directly attributed to anthropogenic climate change, as there is always a finite chance the event in question might have occurred naturally. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g., drought or heavy rainfall over a season).

      Click to access ar4-wg1-annexes.pdf

  2. dillweed7 Says:

    Let me preface my comment, I believe in climate change and I love renewable energy (Go Germany!).

    He clearly states, repeatedly, that we do not know, we don’t know, we don’t know.

    He is not advancing the notion this is current low tornado count is evidence for ‘extremes’.

    He is honestly stating we don’t know. Even offering argument for fewer tornadoes.

    He said he didn’t know.

    Again, I believe in climate change and, additionally, I love renewable energy.

    Trying to attribute blame of so many things to climate change damages credibility. His comments show an understanding of that. The headline doesn’t.

  3. dillweed7 Says:

    From looking at climate statistics from 60 years, he concludes (by one calculation) that 2012 was a one in 60 some thousand year event and that 2013 some 3 thousand year event.

    How reliable can such a conclusion actually be?

  4. junkdrawer88 Says:

    In the mid 70s my late brother worked for NOAA in Rockville, MD.

    Seems an early computer model for what was then called The Greenhouse Effect found that, with enough energy added to the system, the jet stream would meander wildly and the model soon showed a week of summer, followed by a week of winter pretty much year round.

    The model was discarded because, obviously, that couldn’t happen.

    That’s how he told the story to me in the mid 80s. And my late brother was a staunch Reagan Republican.

    For what it’s worth.

  5. ahaveland Says:

    As climate changes the conditions that can create tornadoes will also change – that could create more or less of them.
    Tornado formation requires a sweetspot of factors converging at the right time – but I can bet when tornadoes form, they will be stronger than average.

    Perhaps a naive analogy would be like trying to whistle or play a flute which set up resonant vortices – if you blow too hard or at the wrong angles, then no whistle is produced.

  6. omnologos Says:

    Let’s see who would have the courage to write in these comments that, if the tornado count were on the way up, Masters would NOT claim that as more evidence of extremes.

    Come to think, even if the number of tornadoes were magically to remain the same year-on-year, Master would still claim that as more evidence of extremes.

    When wildly different phenomena can be easily attributed to the same cause, that’s a way to show the cause is not a cause, but an excuse.

    • How about amusement not courage.

      First off you claim that ‘There is no accepted definition of “extreme weather”’, and then you claim that there is. So we can conclude that you were wrong!

      By the definition above if the numbers of tornados were going up, it would be an example of extreme weather event. The reason would be that it would be above 90% percentile. Did you not comprehend my first post?

      Extreme 90% percentile

      “Come to think, even if the number of tornadoes were magically to remain the same year-on-year, Master would still claim that as more evidence of extremes.”

      No he would not unless it was the same as 2011 every year then that would be an extreme climate event (The shifting from one state to another).

      Jeff Master and Peter are invoking logic you are just ranting…

      • omnologos Says:

        I must be the quietest ranter in the history of the ‘net.

        Anyway. Definition of “rare” still vary. Read SREX. FAQ 3.1, and try to discuss with them

        Click to access SREX-All_FINAL.pdf

        FAQ 3.1 | Is the Climate Becoming More Extreme?…One approach for evaluating whether the climate is becoming more extreme would be to determine whether there have been changes in the typical range of variation of specific climate variables…Another approach would be to ask whether there have been significant changes in the frequency with which climate variables cross fixed thresholds that have been associated with human or other impacts…to make such a metric useful to more than a specific location, one would have to combine the results at many locations, each with a different perspective on what is ‘extreme.’

        Three types of metrics have been considered to avoid these problems, and thereby allow an answer to this question. One approach is to count the number of record-breaking events in a variable and to examine such a count for any trend…Another approach is to combine indicators of a selection of important extremes into a single index, such as the Climate Extremes Index (CEI)…A third approach to solving this dilemma arises from the fact that extremes often have deleterious economic consequences. …

        None of the above instruments has yet been developed sufficiently as to allow us to confidently answer the question posed here…

        • By this are you saying you agree with the 2012 “Changes in Climate Extremes and their Impacts on the Natural Physical Environment” report? Because you are making Jeff &Peter point, more Evidence of Extremes. Why did you not finish the last part?

          “None of the above instruments has yet been developed sufficiently as to allow us to confidently answer the question posed here. Thus we are restricted to questions about whether specific extremes are becoming more or less common, and our confidence in the answers to such questions, including the direction and magnitude of changes in specific extremes, depends on the type of extreme, as well as on the region and season, linked with the level of understanding of the underlying processes and the reliability of their simulation in models.”

          • omnologos Says:

            Your rhetoric is infantile. I have quoted a specific FAQ from that report which contains a text I find frank, intelligent and useful. Why would that mean I would have to agree with everything else, only you and your kindergarten teacher will ever understand.

  7. g2-b31f1590b0e74a6d1af4639162aa7f3f Says:

    The notion that AGW could very well be impacting the year to year variation in tornado activity in the Midwest shouldn’t be all that surprising.

    After all, tornadoes basically “follow the jet stream”. Jet-stream wind-shear is effectively a “pull starter” that spins up tornadoes. No jet stream, no “pull starter” to spin up tornadoes.

    Thanks to AGW, the temperature gradient between the mid-latitudes and the Arctic has been decreasing. It is this gradient that gives rise to the jet stream. Weaken the gradient, and you weaken the jet stream. Weaken the jet-stream, and it begins to “wander” more — so in one year, the jet-stream may tend to remain far north of the US Midwest, while the next year the jet-stream may get tend to get “stuck” over the same region.

    So it should not be surprising to see an increased year-to-year variation in the number of tornadoes in a specific region. It’s too early to make a definitive call on this based on data — but atmospheric physics tells us that this is entirely plausible.

    In the long-term, we may see fewer tornadoes on average (a weaker jet stream means less wind-shear “pull-starter” action), but when tornadoes do form, they might be stronger and longer-lasting (due to more water-vapor fuel in the atmosphere).

    Again, we don’t have the data to make this call yet — but this is just the sort of prediction that one might expect from basic physical science principles.

  8. g2-b31f1590b0e74a6d1af4639162aa7f3f Says:

    Just following up on the tornado vs. jet stream thing…

    IIRC, during last year’s “tornado drought” in the US, Canada got more than its share of tornado activity (due to the jet stream spending more time over Canada than usual for much of that year).

  9. dillweed7 Says:

    I was hasty in my original comment. After I posted and read my comment and re-listened to the vid I thought I had made a mistake and looked for a way to remove my comment, but found none.

    I have since listened several more times. Again, I believe in Climate Change.

    I find myself wondering how one can look at climate statistics for the last 60 years and then conclude that the out break of 2011 was a one in 63,000 year event and that 2013 current dearth of tornadic activity is a one in 3000 year chance. Based upon that and all of the don’t knows that we didn’t know – makes me believe just what he said. We don’t know.

    I find this concerning because when you look around one finds so many instances of people trying to connect things to Climate Change – often I assert in a tenuous matter especially where the evidence supporting the claim is referred to obliquely and is very difficult for a reader to evaluate the basis for the claim.

  10. […] declaring the tornado drought officially […]

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