Multiple consecutive days of tornado activity spawn worst events

From Purdue University , a press release related to tornado activity without any mention of a climate change link.

WEST LAFAYETTE, Ind. – Significant tornado outbreaks and especially strong tornadoes are more likely occur within periods of activity lasting three or more days, according to a Purdue University tornado expert.

Jeff Trapp, a professor of earth, atmospheric and planetary sciences, examined 30 years of U.S. weather records and found that an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days. During those same periods, a tornado rated 3 or higher on the Enhanced Fujita scale had a 60 percent probability of hitting.

The Enhanced Fujita scale rates tornadoes from EF0 to EF5 with damage rated as “light,” including broken branches and windblown signs, to “incredible,” including leveling of strong-frame houses.

“Two extreme tornado events last year led to 32 deaths, injured more than 377 and cost $2 billion in damage and inspired this study,” Trapp said. “Unfortunately, the devastating tornadoes these past few days, tragically, seem to be bearing out the results.”

Tornadoes swept through Arkansas, Oklahoma, Kansas, Missouri, Nebraska, Iowa and Mississippi on Sunday (April 27); Mississippi, Alabama and Tennessee on Monday (April 28); and North Carolina on Tuesday (April 29). The National Weather Service received 100 preliminary tornado reports for April 27 and 28, and multiple deaths have been attributed to the violent storm system.

Trapp also found the multiple-day periods were more likely to occur during the warm months of April through July.

“The encouraging news is that the larger, more slowly evolving and moving systems that appear to contribute to multiple-day tornado periods may be more predictable,” he said. “The weather system responsible for the tornadoes this week falls in this category and was revealed in the forecast models at least five days in advance with good fidelity.”

Trapp examined tornado activity entered into the National Oceanic and Atmospheric Administration’s historical record of tornadoes in the United States from 1983-2012, which included 3,129 tornado days and 1,406 unique periods of tornado activity. Multiple-day periods made up 24 percent of the unique periods of activity.

A paper detailing his study and the results was published in the April issue of the journal Monthly Weather Review and is available online.

The idea for the research began while Trapp was participating as a lead investigator in the National Science Foundation’s Mesoscale Predictability Experiment (MPEX), a national field project to improve predictions of severe weather.

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Writer: Elizabeth K. Gardner, 765-494-2081, ekgardner@purdue.edu

Source: Jeff Trapp, 765-496-6661, jtrapp@purdue.edu

Related websites:

Purdue Severe Weather Research Group: http://web.ics.purdue.edu/~jtrapp/severe/

40 thoughts on “Multiple consecutive days of tornado activity spawn worst events

  1. Space Ref: NASA Carbon-Counting Satellite Arrives at Launch Site
    Press Release Source: Jet Propulsion Laboratory
    Posted Wednesday, April 30, 2014
    The observatory is NASA’s first satellite mission dedicated to studying carbon dioxide, a critical component of Earth’s carbon cycle that is the leading human-produced greenhouse gas driving changes in Earth’s climate. It replaces a nearly identical spacecraft lost due to a rocket launch mishap in February 2009…
    The mission’s innovative technologies will enable space-based measurements of atmospheric carbon dioxide with the sensitivity, resolution and coverage needed to characterize the sources of carbon dioxide emissions and the natural sinks that moderate their buildup, at regional scales, everywhere on Earth. The mission’s data will help scientists reduce uncertainties in forecasts of how much carbon dioxide is in the atmosphere and improve the accuracy of global climate change predictions…
    For more information about the Orbiting Carbon Observatory-2, visit:

    http://oco.jpl.nasa.gov

    and
    http://www.nasa.gov/oco-2

    http://www.spaceref.com/news/viewpr.html?pid=43138

  2. Is that coincidental with larger/longer incursions of cold air masses from the north hitting warm moist gulf air masses?

  3. Seems like a Poisson distribution. Cumulative probabilities peak after an event. The probability of a plane crash rises right after a plane crash. Probability of bus arrival rises right after a bus arrives. The reason is quite simple in that they are discrete events in time so every time you count an event, you have an increase in the numerator without an increase in denominator. That means clusters look like probability peaks.

  4. Jeff Trapp, a professor of earth, atmospheric and planetary sciences, examined 30 years of U.S. weather records and found that an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days.

    So…. when conditions are ripe for tornado formation, that’s when you get large numbers of tornadoes. The rest of the time you don’t. Duh. OK, I suppose it was worth examining the data to see if the result was unexpected because sometimes that’s what happens and you have to figure out why. But this result is pretty much like saying that it rains more when there are rain clouds in the sky. Well duh, yeah.

  5. That totally correlates with my observations in the heart of Tornado Alley – central Oklahoma. Severe weather outbreaks often occur in the context of high amplitude, slow moving trough patterns. Anyone with a basic knowledge of upper air charts can examine the computer models and see the possibility of tornado events well in advance.

  6. NOAA cumulative tornado count as of April 29, is at 235, just 2 more than the 233 at this time in 2013, the quietest year in a decade.

    RE: Jeff Trapp, …. found that an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days.

    Where is the news value in this?

    What is an outbreak? Does it include 20 tornados over 5 days? Does 10 tornados in 3 days count as an outbreak? Does an outbreak have to be part of one weather system? Can you have a “period of tornado activity” that is not an outbreak?

    That tornados come in temporal clusters isn’t news. If he had said, “74% of the time we get 20 or more tornados in three or LESS days”….. that would be news. But the “three days or more” make this pretty ho-hum.

  7. It’s so good to see intelligent scientific effort. Sadly other green looters are hunting through the tragic tornado sites looking for global warming lies.

  8. “a press release related to tornado activity without any mention of a climate change link” That’s because eveybody already knows that the non-increase-in-temperature over recent decades is the sole cause of all recent extreme weather events. Duh! [sarc]

  9. hopefully by now, both sides of the debate understands weather =/ (dne) climate. and thus will not make assinine statements about one (or several) system tornados wrt climate variations.

  10. Jeff Trapp, a professor of earth, atmospheric and planetary sciences, examined 30 years of U.S. weather records……

    This is one of the reasons the debate HAS to take so long. The minimum, WMO period for climate is 30 years, there is also a Santer stated minimum of 17 years (model projections) for the ‘human signal’ to become apparent.

  11. Number 1 rule of weather forecasting: The weather for today will be the same as yesterday’s.

  12. Most severe tornado episodes lasting several days are a direct result of lunar declinational tides in the atmosphere, the most intense and long lasting out breaks occur when the Earth is having a heliocentric conjunction with one or more of the outer planets. The combination increases the total ionic and tidal energy used to create the rapid condensation in a narrow front, and the cyclonic wind speeds generated, it is not just the dramatic dew point and thermal gradient across the front.

    I am currently starting the uploading of weather forecast maps for the next five years to my web site. At this time it is up to June 15th 2014, I hope to have maps up loaded from hard drive to server through the end of 2019 with in the next week. The developer had to load the CSV data onto a windows 7 machine due to problems with windows 8 non compatibility problems, who would have thought?

  13. The recent tornado outbreak has sadly killed around 40 people according to news reports.

    New York Times – 25 March, 1913
    DEADLY TORNADOES OF RECENT DECADES –
    South and Middle West Visited by Numerous Violent Storms in Last 25 Years
    ….loss of life was estimated at more than 450. The injured numbered twice that many….

    http://query.nytimes.com/mem/archive-free/pdf?res=F10C15FC345E13738DDDAC0A94DB405B838DF1D3

    ——————————–

    Newsweek 28 April, 1975
    The Cooling World
    There are ominous signs that the Earth’s weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production…….

    The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it…..

    …..Last April, in the most devastating outbreak of tornadoes ever recorded, 148 twisters killed more than 300 people and caused half a billion dollars’ worth of damage in 13 U.S. states….

    To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world’s weather. The central fact is that after three quarters of a century of extraordinarily mild conditions, the earth’s climate seems to be cooling down……

    http://www.washingtontimes.com/news/2006/apr/2/20060402-112828-5298r/

    In recent years we have been told about the hottest decade on the record and that the USA is getting hotter with hottest years somewhere in there.

    “U.S. Annual Count of Strong to Violent Tornadoes (F3+), 1954 through 2012″

  14. Stephen Rasey: I had the same frustration with the press release’s ambiguity. If it had said that 74% of reported tornadoes occur within x days of 20 other reported tornadoes, that y% of tornadoes occur with the tornado season of __, and the mean and variance of the total reported tornadoes within that season are u and v, then we could have started to make something of it.

    As it is, it’s like most newspaper stories: it lacks the information the reader would really want to know about the topic.

  15. In other news…cold air outbreaks and heat waves are found to occur on sequential days.
    Geez, talk about obvious.

  16. davidmhoffer says

    “So…. when conditions are ripe for tornado formation, that’s when you get large numbers of tornadoes. The rest of the time you don’t. Duh. OK, I suppose it was worth examining the data to see if the result was unexpected because sometimes that’s what happens and you have to figure out why. But this result is pretty much like saying that it rains more when there are rain clouds in the sky.”

    My take on it in some that when it is raining continuously for x-days or hours it is more likely to rain hard. This is a reasonable and not necessarily obvious conclusion. It might be, like the plains of Africa late in the rainy season, that nearly all heavy rains come during short, sharp thunderstorms. This doesn’t happen early in the season.

    Their observation is that as the “continuous” conditions extend their “hour count” the likelihood of a powerful tornado rises significantly (detectable with high confidence). It might have been that it was more like a wound spring releasing a lot of energy at once instead of the same energy over three days. The paper useful.

  17. Have I understood this correctly? If conditions suitable for tornado formation last for 3 days (instead of, say, 1 day), there are likely to be more tornados. Well, well. Who’d have thought it?

    Surely there must be more cerebral articles for us to digest?

  18. Whenever there are a lot of tornadoes, they occur over several days.

    I better write that down.

    Meanwhile, how does this help me or anyone else? As Rasey said, “Where is the news value in this?”

  19. Meanwhile they were reporting on the news this morning that Congress is looking into why NOAA hasn’t spent the money allocated to upgrade their weather forecasting computer system. Supposedly the US weather model ranks only fourth in the world for accuracy, behind European, UK and Canadian models.

    The WSB Radio report is here.

    The specific rankings appear to come from Cliff Mass, whose blog is here.

    Cliff’s most recent blog above appears to be an update of a more detailed posting from 2012 .

  20. Grrr, that should read “The most recent Cliff Moss Mass post ..”

    (this was all done pre-coffee).

    Breaking news: Global Warming degrades cognitive performance — it’s worse than we thought.

  21. Trapp also found the multiple-day periods were more likely to occur during the warm months of April through July.
    I think periods of extra cold spring temperatures are behind the extra tornado activity. Canada is again experiencing a cold spring and spring weather has been getting colder since 1998 for United States especially April and May. When this extra cold sprig air meets the warm moist air from the Gulf the result is usually periods of major tornado activity.I think the authors missed looking at the cold spring air component more closely.. As we enter this 30 year cold cycle, the tornado activity may pick up .

  22. RE: Rasey 4/30 10:36 pm, Joe Born 5/1 2:22 am
    If there is any validity to statistical conclusion attributed to Trapp, i.e. “that an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days. “
    Then it follows that an outbreak of 20 or more reported tornadoes has a 26 percent probability of occurring in a period of only one or two days. This is mildly more interesting to contemplate. Large (20 or more) clusters of tornados are three times more likely to need three or more days to play out than those that need two or fewer. But that statement implies we are talking about equal sized clusters —- and there is no such guarantee. The observation is an artifact of the classification. Bigger clusters need more days. More days allow for bigger clusters.

    As for outbreaks of 2 to 19 tornados, we can draw no information.
    And is 1 tornado an “outbreak?”

  23. There appears to be a definite correlation between below normal Spring weather in Canada , more specifically the Canadian Prairies region Spring and the number of Spring tornadoes in the United States. The best example is the April 1974 super out break when the spring weather over the Praireies was 3 degrees C below normal. But here are some other years -1982, 1995, 2002, 2008, 2009 ,2011, 2013. These years account for some of the largest spring tornado out breaks . It seems that this cold air continues to sweep south in the Spring where it meets the warm moist air from the Gulf. Lets hope this year does not repeat.

  24. … damage rated as “light,” … to “incredible,”

    Really? “Incredible”? Like wow, man, that’s a gnarly adjective, dude. And I thought those scientists were, like, real drips, man.

  25. Intersting….

    From the study “weather records and found that an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days”.

    So let me get this straight: The more days a storm lasts, the more increased chance of more tornadoes. WOW, thats amazing.
    I wonder how much money was spent to fund that study?

    ;>P

  26. Last year saw the fewest US annual tornado count in decades.
    Interestingly, this was a non-event for the liberal press, and tornadoes went unreported by the MSM until we had a spat of tornadoes in November – and then this was a sure indicator of “global warming!” Never mind the real story was the record low levels.

    Barf.

    This was the second-to-last nail in the coffin for ABF news, for me.

    The last nail was the typhoon Haiyan MSM news feeding frenzy.

    While this tropical cyclone was about as strong as 30 others in the last hundred years, it was a sure sign of “Global Warming” for the profiteers of doom. The liberal press ate it up.

    The REAL news – the fact that there were NO Atlantic Hurricanes last year, NONE, went unreported.

    This liberal press bias is intolerable.

    I have sworn off of Dianne Sawyer and the ABC “World” News, and I now get my news by other less biased means.

  27. ghads. spell checker changed the first ABC to ABF. Why, oh, why, oh why…

  28. …an outbreak of 20 or more reported tornadoes had a 74 percent probability of occurring during a period of tornado activity lasting three or more days.

    Yeah! That is sort of like; there is a 74 percent probability of my thirst occurring after a period of three or more hours spent in the hot sun.

    It boggles my mind, that grant money is cheerfully given out for foolish stuff like this.

  29. A study a few years ago “discovered” that people living in urban ghettos are exposed more pollution than people in suburbs. Huh.

  30. I’ll refrain from breaking into “Hail Purdue”, but only long enough to point out that it would be nice if all major institutions of higher learning followed the model that John Purdue wrote into the university charter. It’s no coincidence that the output from that institution tends to be ones as straight-forward as this. Isn’t science without a hidden agenda rather refreshing?

  31. I’ll refrain from breaking into “Hail Purdue”, but only long enough that it is quite refreshing to see the straight-forward science that tends to come from this institution. John Purdue was wise to put into the university charter some of unusual mandates that he did, and this is the result.

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