Inconvenient: NOAA data shows U.S. Tornadoes on the decline since 1970

We’ve been told time and again by climate alarmists that global warming would make more severe weather. In fact, the opposite is true according to recently released tornado data from NOAA’s Storm Prediction Center.

By Paul Homewood

https://www.spc.noaa.gov/wcm/2017/torngraph-big.png

https://www.spc.noaa.gov/wcm/2017/torngraph-big.png

2017 was a relatively busy year for tornadoes in the US, ranking third since 2005 on preliminary data.

This was mainly due to a spurt in numbers in January to March, most of which were weak EF-0 and EF-1 tornadoes. There were though three EF-3s in an outbreak in January, which sadly led to 20 fatalities.

 

https://www.spc.noaa.gov/wcm/2017/ptorngraph-big.png

https://www.spc.noaa.gov/wcm/2017/ptorngraph-big.png

As for longer term trends, regular readers will recall that we need to discount weaker tornadoes, as NOAA explain:

One of the main difficulties with tornado records is that a tornado, or evidence of a tornado must have been observed. Unlike rainfall or temperature, which may be measured by a fixed instrument, tornadoes are short-lived and very unpredictable. If a tornado occurs in a place with few or no people, it is not likely to be documented. Many significant tornadoes may not make it into the historical record since Tornado Alley was very sparsely populated during the 20th century.

Much early work on tornado climatology in the United States was done by John Park Finley in his book Tornadoes, published in 1887. While some of Finley’s safety guidelines have since been refuted as dangerous practices, the book remains a seminal work in tornado research. The University of Oklahoma created a PDF copy of the book and made it accessible at John Finley’s Tornadoes (link is external).

Today, nearly all of the United States is reasonably well populated, or at least covered by NOAA’s Doppler weather radars. Even if a tornado is not actually observed, modern damage assessments by National Weather Service personnel can discern if a tornado caused the damage, and if so, how strong the tornado may have been. This disparity between tornado records of the past and current records contributes a great deal of uncertainty regarding questions about the long-term behavior or patterns of tornado occurrence. Improved tornado observation practices have led to an increase in the number of reported weaker tornadoes, and in recent years EF-0 tornadoes have become more prevelant in the total number of reported tornadoes. In addition, even today many smaller tornadoes still may go undocumented in places with low populations or inconsistent communication facilities.

With increased National Doppler radar coverage, increasing population, and greater attention to tornado reporting, there has been an increase in the number of tornado reports over the past several decades. This can create a misleading appearance of an increasing trend in tornado frequency. To better understand the variability and trend in tornado frequency in the United States, the total number of EF-1 and stronger, as well as strong to violent tornadoes (EF-3 to EF-5 category on the Enhanced Fujita scale) can be analyzed. These tornadoes would have likely been reported even during the decades before Doppler radar use became widespread and practices resulted in increasing tornado reports. The bar charts below indicate there has been little trend in the frequency of the stronger tornadoes over the past 55 years.

EF1-EF5 Tornado Counts

EF3-EF5 Tornado Counts

https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology/trends

 

Not that this stops NOAA continuing to publish grossly misleading graphs, such as the one below:

https://www.ncdc.noaa.gov/sotc/tornadoes/201713

 

Since NOAA also appear reluctant to update their graph for strong tornadoes beyond 2014, I will help them out:

 

image

https://www.spc.noaa.gov/wcm/#data

Despite those three EF-3s in January, the year ended with a record low 15 EF-3s and stronger, equalling the records set in 1987 and 2016.

There were also only two EF-4s, well below the mean of 7.4, and no EF-5s at all, the strongest tornadoes of all. Indeed, we have now gone five years without an EF-5.

It is evident that strong tornadoes have been in a steady decline since 1970.

As for this year, we are now through the season when we can expect to see most tornadoes, and the strongest ones. So far the year is running at the lowest number since 2005.

 

U.S. Annual Tornado Trends

 

Provisionally there have only been four EF-3s, and nothing stronger, which is extremely low.

We keep being told that weather is becoming more extreme, but as far as tornadoes go it is the opposite which is true.


Even better, overall deaths from tornadoes are decreasing as well, due to better warning systems. The exception is one recent event in 2013, the year of the F5 Moore, OK  tornado.

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31 thoughts on “Inconvenient: NOAA data shows U.S. Tornadoes on the decline since 1970

  1. With a large number of Doppler radars, detection of weak tornados should be increasing. Every time we have strong thunderstorms here in Texas, the local TV stations tend to do to continuous coverage, and often report the signature for a tornado that pretty much only appears on radar.

    • Today any tornado, even weak tornadoes far from populated areas,
      can be used as climate change propaganda by the media.

      In the 1970’s (assuming people even knew about tornadoes
      in the middle of nowhere), almost no one cared about global warming,
      or falsely linking a tornado to global warming.

      In fact, global cooling was a hot topic for a while in the mid-1970s.

      People who do the writing and reporting in the mainstream media today
      tell us what THEY THINK we should know, and that has changed a lot
      since the 1970s.

      … not to mention much greater capability today
      for spotting weak tornadoes far from populated areas.

    • So your right about more weaker storms being detected than ever before. According to NOAA in 2015 there was a total of 1177 tornadoes detected in the US. Here is the breakdown:

      696 EF 0/U
      396 EF 1
      64 EF 2
      18 EF 3
      3 EF 4
      0 EF 5

      The ability to detect tornadoes of any strength has over time increased significantly. More people and doppler radars spread out over more of the country. Plus an ever increasing number of trained spotters among them. Thus the NOAA has created an “Inflation Adjusted Annual Tornado Trend” graph. https://www.spc.noaa.gov/wcm/adj.html

  2. “contributes a great deal of uncertainty”…….

    It doesn’t contribute uncertainty……it makes it EF’in impossible

  3. I have a very big quibble with a severity rating factor that uses damage estimates of structures (measured in $$) as a metric. It is completely subjective as the structures are neither uniform in construction nor cost.
    Wind speed, humidity, temperature, air pressures….all the physical parameters that account for the energy of the phenomena are all that should be accounted. How expensive somebodies prized green-house orchids are, is of no concern to the tornado.

    Would the same tornado get down-rated on the EF scale when it passes over the tracks and into the poorer side of town?

    • The type of damage done is an indicator of wind speed. Wind speed produces the severity rating on the ER scale. Dollar value of the damage has nothing to do with it.

    • As one who performed storm surveys for NWS/NOAA for a few decades, I feel somewhat qualified to respond here. A tornado would not be downgraded or upgraded if it did damage in more or less affluent areas, simply because the EF process supposedly takes that into account now, by allowing for the type of construction. A tornado is going to be looked at over it’s path length, and given an overall classification at its worst state. However, there is always going to be some subjectivity in classifying whether storm damage is tornadic, or what strength is decided upon. It’s much easier to classify larger tornadoes; there’s just a clear difference at the upper end. Of course, was it an EF-3 or an EF-4 (moderate versus strong)? Well, when you speak about moderate and strong tornadoes as a group, it doesn’t really matter. For weak tornadoes, which most are obviously, it can be tough to reach a confident conclusion. Also, a problem I see is the honesty of the surveyor. I have seen big-time weather nerds (some of them Senior Forecasters and supervisors) classify damage as a tornado when signs really didn’t point that way. And, if there was a rotational signature present on the 88D, then that’s all the additional confirmation that was needed for them. Also, there are problems when the actual issuer of the warning, if one was sent, is the same person to actually assess the damage and make the classification. Can you say conflict of interest? There are lots of problems with the Storm Data statistics, and these problems have changed over the years, but I guess they’re all we have. Lastly, trying to decide whether or not to issue a tornado warning is very hard; one can see a lot of rotation out there, but, what’s a warner to do? Not issue a warning and take the chance that a weak tornado touches down and kills someone? Try sitting in the MIC’s office and explaining that one. So, society is going to see a lot more false alarms. I (and many meteorologists in the field) believe the number of weak tornadoes over the past 6 decades has increased not only due to increased population and public reporting, but also because of the fielding of Doppler radars, which can be a double-edged sword.

      • Never underestimate the political-budget climate at the local level.
        You can much more easily get state or federal emergency money if “a tornado” strikes for employee overtime (fire, police, EMT, ambulance, county workers), tree removal, emergency funds, and general publicity, but no one at the state or federal level will work very hard if all you bother claiming is “wind” or “hail” damage to a county vehicle or county building.

  4. it’s pretty simple, tornadoes have been on the decline because of the increase water vapor from the +AMO phase. More moist air = less tornadoes. When the +AMO phase reverses and becomes negative tornadoes will increase again in time. My feeling

    • Tornadoes don’t just form anywhere.

      The land in the central United States is the best breeding ground for the storms which produce tornadoes. The land in the Great Plains is relatively flat, which allows cold dry polar air from Canada to meet warm moist tropical air from the Gulf of Mexico. It’s along the front between the two airmasses that most tornadoes form. link

      Moisture seems to be a requirement for tornadoes.

      It also seems that less moisture can equal fewer tornadoes.

      Drought can help create warmer and drier than normal conditions, which brings about greater dew point depressions at the surface, and thus higher cloud bases. The higher the cloud base, the harder it is for a circulation to reach the ground to become a tornado. While not as extreme as the drought in 2014, the current drought does cover much of the same region. The drought helped contribute to 2014’s below normal spring tornado count. link

      AMO probably has a part in tornado frequency. The above link refers to ENSO, PDO, and AMO.

  5. As has been repeatedly pointed out by Lindzen and others, a back-of-the-envelope calculation would suggest that in a warming world as the poles warm more than the tropics, the equatorial to polar temperature gradient (which drives weather on a large scale) should decrease. So we expect extreme weather events such as hurricanes and tornadoes might decrease as a consequence. There is also evidence of increased storminess during he LIA.

    The silly CAGW crowd don’t seem to realise that the data on tornadoes presented here might actually support (or “be consistent with”) global warming. But that it leads to a safer world.

  6. They don’t count the tornado called Donald Trump, ok I know he is abrasive, but by God it was time we put a screwdriver into the light socket and said enough was enough, proud that I voted for him, like anyone that follows this blog voted for the criminal Hillary? I know people come here for climate news but none such unless you listen to Elizabeth Warner, she will have you all arrested for being deniers.

    Sorry for the political rant, not the place, but you just get pissed off.

    • I’m also proud I voted for Trump. OT — your comment about putting screwdriver into a light socket brought to mind “How I Learned About Electricity”. I was 4 years old and I had little tiny fingers. I went to plug something into the wall socket, with my little fingers holding the plug by the metal prongs that go into the socket. I shocked the ******* out of my self, and went crying to my mom, who thought it was amusing. 😢

    • well here is something crazy…
      I am an anarchist and I oppose voting as it is violence, pure and simple, and I’m not going to get into it here. You can research why if you don’t agree with the statement.
      However, I’m likely to come out of moral retirement to vote for Trump next election. If we stay out of another major entanglement and some other items I’m following… I’m moving in that direction

      • “However, I’m likely to come out of moral retirement to vote for Trump next election.”

        I think you will have a lot of company in doing that, too.

        • Tom, I butchered that sentence. I’m temporarily abandoning my moral position on voting to cast my vote for Trump, potentially, this next election. Pardon if I was confusing, I re-read it and it is very poor grammar.

          • I meant Trump will probably pick up some new first time Trump voters the next time around if he continues his winning ways. And one of them might be you. 🙂

    • “but you just get pissed off.”

      There is a lot of that going around these days. But most of us unwashed, “dog trained”, bible clinging, gun toting, racist, undereducated, deplorables, just sit and grit our few remaining teeth and wait for the next election day.

      A little poem this deplorable composed recently concerning the latest craziness about Trumps most recent SCOTUS AJ appointment.

      “As always the loons are loudly playing their same old worn out tunes
      But Kavanaugh will be confirmed and adjudicate for many moons.

      We’ve seen it before and know how it goes and how it will end.
      Despite the annoying insulting din the real people will not bend
      And so red state democrats will end up betraying their “friends”
      because for themselves they must fend.

      And so another win for Trump and the Constitution it will be
      But what I can’t wait to see
      Is the day Ruth “Buzzy” Ginsburg is gone
      Because that is truly going to be the bomb!”

  7. In the past there was still a chance that even the larger tornadoes might not have been reported if they occurred well away from population centers and caused little to no damage.

  8. The tornado statistics may show a ‘jump’, from recent activity.
    Commander In Chief Donald Trump just ‘tore-NATO’ a new orifice for not meeting their annual spending commitments. To say the least, Macron and Merkel are not ‘happy’…

    • I think the press interpretation of what Macron said, and what he really said are quite different.

      One interpretation gives the impression Macron is criticizing Trump, but Macron’s own words don’t sound that way to me. I don’t think Macron is unhappy with Trump. Merkel may be, though.

      If she is mad, it’s because Trump spoke the truth and she can’t stand to hear it.

      The delusional socialists don’t want their pipe dreams of socialist nirvana disturbed and Trump comes along and shakes them and wakes them up out of their dreamworld, and yells, “Snap out of it!” And they don’t like that. It makes them cranky. They want to go back to sleep but Trump won’t let them.

  9. I don’t understand the conflicting graphs from NOAA. Why does one show increase, while others show decrease? How can the same organization publish conflicting graphics? Am I missing something?

    I’ll look at them again, and see if I can answer my own question.

    • Um, that’s kinda the point of this whole article. One of the graphs is for ALL reported tornadoes, and the other is for only the LARGEST (F3+) reported tornadoes. The key word here is “reported”. 100 years ago, the smaller tornadoes (F0-F2) were less likely to be reported (or even noticed) because 1) the area where most tornadoes occurred was sparsely populated, so the chance of a person being around to see a small tornado was smaller, and 2) we did not have advanced technology to detect the formation of tornadoes via satellites. The difference in “noticeability” was not so large for the largest tornadoes, because 1) they are big, and can therefore be seen from further away, increasing the chance that someone will see them, 2) they tend to last longer, and are therefore less likely to be missed by people who just don’t happen to be looking at that particular part of the sky during the brief time a smaller tornado exists, and 3) They tend to travel farther, thus becoming visible to people over a much larger area. Still, even the largest tornadoes COULD have gone unnoticed 100 years ago, if they hit a particularly sparsely-populated area, but we believe the vast majority of them were reported; unlike the smaller tornadoes, a sizable portion of which were NOT reported.

      Now, we know that, over any reasonable time period, the vast majority of tornadoes (ones that actually occur, not just those that are reported) are of the smaller type. But we also know that, 100 years ago, the smaller types of tornadoes were less likely to be noticed or reported. Fact is, nobody but God knows how many tornadoes touched down in the US in 1918. So we are pretty sure that the REPORTED count of tornadoes (total, all sizes) in 1918 understates the ACTUAL count by quite a bit. Yet this REPORTED number is exactly what is present in the first graph. So the increase in REPORTED tornadoes (total, all sizes) over the last 100 years does not really mean there was an increase in ACTUAL tornadoes; it just means we’ve gotten better at detecting the smaller tornadoes, which make up the vast majority of all tornadoes. In statistics, we call that an “artifact”

      One statistical solution to this artifact is to only count the largest tornadoes, i.e. F3 and higher. We assume that, even 100 years ago, all of them were observed (that assumption may not be completely accurate, but we can say with some certainty that nearly 100% of F3+ tornadoes WERE observed, even 100 years ago). And when you only look at the largest (and therefore most likely to be noticed and reported in the past) tornadoes, surprise, surprise, we DON’T see an increase in numbers of tornadoes over the course of the last 40 years, when global warming was supposedly occurring. In fact, we see a DECREASE in tornadoes (F3+) over that period. And while that may not be enough to “prove” that global warming causes fewer tornadoes, it almost certainly DISproves the global-warming-alarmist argument that global warming causes MORE tornadoes.

      Consider this analogy. The number of tooth cavities discovered by dentists is several times as large as it was 100 years ago. From that statistic, someone might surmise that public oral hygiene has taken a turn for the worse over the last century. And some dishonest lobbyist for the ADA might use that statistic to lobby Congress for efforts to combat tooth decay: free (i.e., taxpayer-funded) dentistry for poor people; more fluoride in the water supply; bans or extreme taxes on candy, sweet baked goods, and sugary drinks; and of course, tons of publicly-funded research. And, based on the statistics, those would all be reasonable. But the statistics have a couple of rather glaring artifacts. First of all, the population today is about double what it was 100 years ago, so even if there was no change in the number of cavities per person, the total number of cavities, for the entire population, would be expected to double. So you have to adjust for population. But if the number of cavities is 5 times as high as a hundred years ago, and the population is only twice as high, you still have 2.5 times as many cavities per person. But you don’t, because of the second, and biggest, artifact. You see, 100 years ago, the vast majority of people never saw a dentist. And, in general, those least likely to see a dentist were also least likely to have good oral hygiene, and therefore most likely to have cavities. So the number of cavities discovered by dentists is a very poor indicator of the ACTUAL number of cavities in the population as a whole.

      Note, it’s not just that 100 years ago, a small percentage of people saw a dentist; it’s that that percentage has CHANGED (for the better) over the last century. If it was still true, today, that a small percentage of people saw a dentist, and if that percentage remained constant over time, we could at least say the number of dentist-discovered cavities was a pretty good “proxy” for the actual number of cavities, and could reasonably extrapolate that the increase in “observed” cavities was a smaller-scale, but proportionate, reflection of a similar increase in the “actual” number of cavities. But today, almost everyone sees a dentist at some point in their lives, and most of us do so on an annual or semi-annual basis. So it is far more reasonable to postulate that the increase in the number of people seeing a dentist has much more to do with the increase in the number of dentist-observed cavities, than does some hypothetical degradation in oral hygiene.

      But, if we just divided the number of dentist-observed cavities by the number of dentist visits by patients, for each of the last 100 years, that “cavities per visit” data set WOULD be a pretty good indicator of the incidence of cavities over time. And who knows, that might even indicate that yes, we really do have more cavities, per person, than we did 100 years ago. If so, it’s more likely caused by the increase in sweets and sugary beverages in our diets than by a degradation of oral hygiene. But at least the lobbyist could say that the increase in cavities was REAL, and not an artifact of poor statistical methods.

  10. I’m a resident of “Tornado Alley” and tornado frequency and strength are definitely down over the last few years.

    It used to be that just about any stormfront coming through was going to generate big tornadoes. That’s not the case now. If this is CAGW then we want more of it. We like mild weather and fewer, weaker tornadoes.

  11. These days we are told many things and expected to believe them, which later on prove to be the opposite of the Truth. The whole Global Warming-Climate Change affairs were built on this idea.

  12. The history deniers will soldier on ignoring the inconvenient truths like all good cultists. Time to stop the climate lies!

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