Last three years prove AGW is not responsible for tornadoes

By Joseph D’Aleo, CCM

Tuesday was an active severe weather day with 29 reported tornadoes (preliminary).

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But for the season thus far, we are at the bottom end of the frequency as of the date. When it was active in 2011, the ignorant and opportunists blamed it on global warming. Last spring was very warm and activity was way down. This year, spring ranked among the coldest and activity was very low and only recently has picked up as warmth finally began pushing north to clash with the colder air to the north.

It is in the region of CONTRAST that the jet stream is energized and severe weather occurs. When it is too warm or too cold from north to south, activity is depressed. Global warming would diminish the contrast north to south and result in weaker storms, a weaker jet stream, fewer tornado outbreak and strong EF3-5 tornadoes.

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We are passing the peak of the severe weather season. The delayed shift north of the jet stream and alternating cooler and warmer weather will allow for some catch up.

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See the activity year to date this year

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See how suppressed the 300mb jet stream has been on average.

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See the activity last year (whole year).

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See how far north and weak the jet stream was. Tornadoes were above normal in southern Canada, below in the CONUS.

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In 2011, coming off the strongest La Nina since the 1950s or early 1970s, the jet stream was ideal for severe weather with a southern jet and northern jet. Tornadoes were favored to the left front of the southern jet and right rear portion of the northern one. That is where upper divergence is favored.

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See how the negative PDO which favors La Ninas by 2 or 3 to 1 and favors stronger (EF3-5) tornadoes (and more big outbreaks) correlated well with the EF3-5 counts.

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36 thoughts on “Last three years prove AGW is not responsible for tornadoes

  1. You don’t suppose that the lunar declinational angle dropping below 20.5 degrees at culmination has had some effect on the position of the jet streams, and then the production rate and location of the tornado outbreaks?

    http://research.aerology.com/lunar-declinational-affects-on-tornado-production/

    A close up of the graph for the cyclic pattern of tornado production from past cycles up to 2011 (the yellow spheres) the next year would be last year or 2012,(not yet updated with the actuals) then the next would be 2013, this years expected declinational angle driving the effective jet stream positions and interactions across the fronts. We are currently about day 2737 on the bottom scale. I would say that if the trend holds the numbers of tornadoes will continue to decrease for the next four years up to 2017 or 2018 when total tornado production will start to rise again.

    It doesn’t surprise me that models based on average stats do no better than random especially with their warming bias programing.

  2. If temperatures in the area are not rising (or the temperature differentials not increasing), it is difficult to make a case that AGW is driving the increase in adverse weather.

    I do not know how the temperatures have behaved on a regional basis say during the past 10 or so years, but if they follow the global average, then they have been in statsis and therefore what has changed between the beginning of this century to date?

  3. Thanks, Joseph.

    Now the question will be, will Chicken Little listen to the king, and believe the sky is not falling?

  4. “See how the negative PDO which favors La Ninas by 2 or 3 to 1 and favors stronger (EF3-5) tornadoes (and more big outbreaks) correlated well with the EF3-5 counts.”

    Funny, I see no correlation in that graph. It more says to me that the PDO has no relation to large-tornado frequency. Are we grasping at straws? Maybe take a look at how many south-bound then northward bend in the jet stream over mid-US occur in April-June, there you might find a close correlation. IIRC, during the 70’s, a jet stream over the Texas-Oklahoma border was very common and was always mentioned by the meteorologists in that era. Something there?

  5. I really do not understand why the scientific community associated with climate science cannot see that historically cold weather is responsible for more death and destruction than warm weather by a long shot. And that by the middle of this century we could see winter drag on a month longer spawning even more deadly frontal boundaries.

  6. LT, of COURSE they see that! But supporting the idea of ever warming weather is responsible for far more funding and career opportunities than supporting the idea of cooling, and that’s all that matters to them anymore.

    When the scare dies out, most of them will be unemployed, and they know it.

  7. … Global warming would diminish the contrast north to south and result in weaker storms, a weaker jet stream, fewer tornado outbreak and strong EF3-5 tornadoes….

    So, what you’re saying is that, if global warming were happening we would expect weaker storms, and we’re GETTING weaker storms?

    Don’t let Skeptical Science hear you saying that ….

  8. The last plot is interesting and there does seem to be correspondence between the dips in PDO and rising tornado count. This may be clearer if the temperature was shown inverted, as here:

    http://climategrog.wordpress.com/?attachment_id=257

    HadCRUT NH may not be the most relevant dataset to choose but it illustrates the point.

    comparing the record of different force categories shows >= EF3 to be consistent, excluding often cited concerns about reliability of the data.

    http://climategrog.wordpress.com/?attachment_id=255

  9. Talking about weather events, here in Sydney, Aus, we’ve had three continuous days, yes that’s right, three days of foggy starts to the day. The sun usually burns it off by the afternoon. It’s caused traffic chaos, especially ait the airport (I am sure automatic landing technology was developed in the 1960’s to land aircraft specifically in fog at London Heathrow). There was one a week ago or so before but it’s been a while since I have seen a “pea souper”. So, if my memory serves, fog in winter in a costal area, is caused buy warm/moist air blowing over a cold body of water. The Tasman sea is cold this year?

  10. The other thing to note is that there is a very different correspondence to temperature changes during the pre-1974 cooling period than during the later warming phase.

  11. Dodgy Geezer

    You are a little behind the curve. Alarmists are claiming that bad weather is caused by increasing CO2 because they can see that a cold PDO, a cold AMO (coming), and a quiet sun are likely to produce wild weather (1950s style), which can then be claimed as proof of AGW.

  12. Ron C., I must disagree on the point where you’ve stated that Alarmists “see” anything coming at all. It is the time-honored mantra of shrieking attention seekers, from Savanarola to Jim Jones to Chicken Little (who they have the most in common with) to claim “THE END IS COMING! FAMINE, FIRE, FLOOD!!! REPENT, YE WICKED, THAT YE MAY BE SAVED!!!”

    It is an old, old act, but you know what P.T. Barnum said. It’s basically that Good Ol’ Fundamentalist Religion for people who tell themselves they’re Too Smart to fall for a hellfire and brimstone preacher. Kind of humorous, really, that one of the central doctrines of this New Faith is that everyone who holds it is, by definition, Smarter than everyone who doesn’t. (In fact, that attitude is the best way to spot the True Believers.) That’s actually an Old, Old, Religion, too, although it used to have a different name. Kind of funny how it keeps popping back up, you’d almost think it appeals to some basic dark side of human nature or something.

  13. See how the negative PDO which favors La Ninas by 2 or 3 to 1 and favors stronger (EF3-5) tornadoes (and more big outbreaks) correlated well with the EF3-5 counts.

    I’m with wayne, I don’t see a correlation either. Sometimes the dips in pdo lag the count peaks, sometimes the count peaks lag the dip in pdo. Sometimes the increase in counts continues into the spike in pdo sometimes it doesn’t.

  14. Would someone please explain how the fact that 20 years ago basically only tornados that caused destruction/damage were counted, If it was not seen by a “Certified Observer” – IT was not counted. Even if there was an obvious path of destruction and the farmer swore there was a tornado – IT DID NOT COUNT (kind of like “does a tree falling in the woods make noise if no one is around”). About 20-25 years ago they started a tornado sighting certification program. Now, in frequent tornado states, most police officers are “certified,” many Amateur Radio Operators are “certified,” the “Storm Chasers” are “Certified” (helps sell their films,) and even volunteer fireman, etc. are certified. Surely all of these “certified” sightings has to affect the increase in numbers over the last 20 years.

  15. Breaking down the regional location of tornados is key. It is local weather not global weather that causes tornados. Trenberth pushes the “warmer and wetter” world but global water vapor is on the decline and dominated by El Nino. Correct me if I am wrong, but tornados seem to happen where a strong advancing cold front triggers vertical lift and violent thunderstorms. Cold waves rapidly advance when the ground is cold and snow covered and the early May snow storms allowed a surge of cold air and provided the ground moisture to feed the storm locally.

    Its still not fully explained the precise mechanisms to cause a thunderstorm to rotate, but the jet stream and regional topography seems key to creating the rotation that turns a thunderstorm into a tornado. I thought your mention of increased tornados in Canada and fewer in CONUS was a gem. Do you have a link? During a La Nina year the Jet Stream gets pushed further north and loop back down further east. The huge tornado outbreaks in 1974 happened due to a combination of strong advancing cold front and during La NIna Year when the jet stream looped back down further east. Most of the damage in 1974 was further east around Ohio.

    The 2012 La Nina kept the jet stream further north and blocked moisture from reaching the southern Great Plains, so there was little moisture and a high pressure that caused a dearth of tornados in the southern great plains. I suspect that despite an increase in Canadian tornados, they are much less common due to their distance from the source of warm Gulf air

    With ENSO neutral this year, but a cold PDO and strong Pacific HIgh, the jet stream at 300mB was pushed northward and California was dry. But as spring approached the ocean land contrast faded more readily relative to a PDO-/LA Nina year in 2012, Around May 18th that breakdown in the thremal contrast allowed the jet stream to dip and split and curled right over Oklahoma. San Francisco State has a great website with a do it yourself animation to recreate the jet stream. Go to http://squall.sfsu.edu/scripts/jet_big_archloop.html

  16. Last three years prove AGW is not responsible for tornadoes.

    feynman: there is no proof in science.

    weird that D’Aleo would suggest that the science on this was settled. Somebody revoke Joe’s skeptic card.

  17. Chris4692 says:
    May 30, 2013 at 7:07 am

    See how the negative PDO which favors La Ninas by 2 or 3 to 1 and favors stronger (EF3-5) tornadoes (and more big outbreaks) correlated well with the EF3-5 counts.

    I’m with wayne, I don’t see a correlation either. Sometimes the dips in pdo lag the count peaks, sometimes the count peaks lag the dip in pdo. Sometimes the increase in counts continues into the spike in pdo sometimes it doesn’t.

    I agree “correlate” is a strong word for a few dips lining up. “correlated well” I would suggest is overstating the evidence, a wee little bit.

    http://climategrog.wordpress.com/?attachment_id=257

    There is a relationship to be had there . The main one I see being warming periods have less activity than cooling periods.

    I think that is main point Joe is trying to make. He probably ought to be careful about claiming short term correlations.

  18. Growing up in the south, in Alabama in the middle of tornado alley we always knew that the worst times were not when it was warm and not when it was cold, but in those times when the two clashed. What part of this do these climate scientists not get?

  19. “See how the negative PDO which favors La Ninas . . .

    I don’t follow this bit about the PDO and it seems to be a distraction. The graph below the note (blue bars with heavy red line for the PDO) offers nothing about La Niñas and otherwise seems to be an overlay of unrelated data.

    Paul Homewood [not a lot of people know that ] recently posted about tornado history. Here is one:

    http://notalotofpeopleknowthat.wordpress.com/2013/05/08/long-term-tornado-trends/

    There are a couple of others – just search the site –
    His posts are clearly stated.

  20. The PDO is a definite player in tornado formation but the correlations get murky by “global averaging” or in this case regional averaging. All tornados evolve from supercell thunderstorms. The triggering mechanism is usually a cold front that lifts the moist air. The more violent storms develop when there is a vigorous updraft, which requires dry cold air above and warm moist air below. Moist air has cools twice as slowly as dry air. When a cold front lifts moist air into an upper level of dry cold air it allows “free convection” creating violent updrafts. The PDO and La Ninas controls the location of that dry cold upper level air.

    During a -PDO/La Nina the stronger Pacific High forces the jet stream northward over the Canadian Rockies and then it turns southward further east. A jet stream descending from Canada delivers cold dry upper level that contrasts with lower level moist air that is ideal for tornados. Typically those conditions will develop more often in eastern Great Plains during a -PDO/La Nina and the western Great PLains experience a more uniform air mass vertically. However during a -PDO/neutral El Nino, the blocking Pacific High is weaker and allows westerly winds to flow straight across the Rockies espicially in the spring when the ocean land temperature contrast weakens. This delivers cold dry upper level winds to Oklahoma and produces the contrasting vertical structure needed for violent tornados. Climate is regional not global!

  21. I find myself in reluctant agreement with Mosher. Along the lines of Feynman, I would instead say that that theory is wrong.

  22. Anyone interested in following the activity in Oklahoma this afternoon, at present they are following several storms that fired up along the dryline within the last hour and are now displaying typical rainfree, cloudbase ‘lowerings’ (i.e. “wall clouds”) from which tornadoes can develop:

    http://kfor.com/on-air/live-streaming/

    .

  23. Richard Holle says May 30, 2013 at 1:26 am

    You don’t suppose that the lunar declinational angle dropping below 20.5 degrees at culmination has had some effect on the position of the jet streams, …

    How?

    Through what factors or mechanism?

  24. usurbrain says May 30, 2013 at 7:21 am

    Would someone please explain how the fact that 20 years ago basically only tornados that caused destruction/damage were counted, If it was not seen by a “Certified Observer” – IT was not counted. Even if there was an obvious path of destruction and the farmer swore there was a tornado – IT DID NOT COUNT

    It ‘counted’ in the Ft. Worth CWA (forecast and warning area) IF there was damage (or video). The public is notorious for citing something as benign as roll clouds and mammatus as ‘nados … there is also straight-line (outflow and downburst winds) wind damage, which is not the product of ‘nadoes either …

  25. jim Steele says May 30, 2013 at 7:59 am
    ..
    Its still not fully explained the precise mechanisms to cause a thunderstorm to rotate, but the jet stream and regional topography …

    What kind of topology? Very curious about that factor … don’t recall seeing any papers on that subject (unless you’re alluding to ‘geography’ instead e.g. central and midwest CONUS areas) …

    .

  26. Here’s the set up for bad storms on the Southern Plains. Anytime it is late in the season (April 1 onward) and a “Siberian Express” or “Yukon Express” is sending cold core systems straight south along the Pacific Coast and those systems are taking a hard left turn down by Baja, that is the set up. Full stop. I’d say there is a degree of correlation between this set up and La Nina and to an extent with Negative PDO. But as we can see that cannot be the sole factor. Although 1974 was definitely Negative PDO and heading toward the bad La Nina of 1975 – 1977

  27. “What kind of topology? Very curious about that factor …”

    I used “topography” to refer to both broad geographic as well as local effects. Broadly speaking the alignment of the Rockies and Appalachians provides an unobstructed corridor for cold air to move south and warm Gulf air to move north. That’s primarily why 73% of all tornados happen in the USA, and more specifically in tornado alley. The colliding air mass provide the trigger to lift the air. The Rocky Mountains from a barrier that dries and cools the air as it flows from the west . This provides the upper level dry air that promotes free convection. Still in order to progress from a super cell thunderstorm into a tornado, rotation is needed. That rotation is likely due to “jet streaks” embedded in the the more general jet stream flow. Jet streaks are commonly caused by contrasting surface temperatures created by differential cooling and heat of those surfaces. Dry uplands and wet lowlands can initiate jet streaks. As an aside, I am curious if tornado’s “fondness” for trailer parks is a function of local heating that facilitates jet streaks.

  28. jim Steele says May 30, 2013 at 1:11 pm

    “What kind of topology? Very curious about that factor …”

    I used “topography” to refer to both broad geographic as well as local effects. Broadly speaking the alignment of the Rockies and Appalachians provides …

    Well, that’s what I thought … don’t know about trailer parks, but, trailers themselves are boxes basically set on ‘skimpy’ pads with little to no anchoring and are subject to straightline wind damage (that kind of blamed was often blamed on ‘nadoes).

    You process of tornado genesis could use a little refinement too, such as including the ‘local’ conditions created by the tornadoes themselves (e.g. rear flank downdraft winds) which hasten/aid/assist their going ‘viral’ in a big way:

    http://en.wikipedia.org/wiki/Rear_flank_downdraft

    The rear flank downdraft or RFD is a region of dry air wrapping around the back of a mesocyclone in a supercell thunderstorm. These areas of descending air are thought to be essential in the production of many supercellular tornadoes.

    It isn’t solely a matter of a cold front, warm air, and the jet stream; all those are necessary … but ignore some of the smaller, less outstanding factors (such as veering winds vs ‘backing’ winds) and all you’d ever have are gustnadoes and (more or less benign) waterspouts!

    Gustnado – http://en.wikipedia.org/wiki/Gustnado

    VEERING AND BACKING WIND

    http://www.theweatherprediction.com/habyhints/48/

    .

  29. “You process of tornado genesis could use a little refinement too, such as including the ‘local’ conditions created by the tornadoes themselves”

    Of course, but I wasn’t trying to write a text book on tornado formation, just outlining the broad regional factors that increase the probability of tornado formation. But you make my point. Its local climate not global climate that drives extreme weather.

  30. _Jim says:
    May 30, 2013 at 12:36 pm

    Richard Holle says May 30, 2013 at 1:26 am

    You don’t suppose that the lunar declinational angle dropping below 20.5 degrees at culmination has had some effect on the position of the jet streams, …

    How? Through what factors or mechanism?
    Reply; The lunar declinational angle relative to the equator at culmination varies from a Maximum of ~28.8 degrees either side to a minimum of about 18.3 degrees, as the 5.25 degrees it runs North and South of the ecliptic plane, goes in and out of phase with the 23.5 degrees of the axial tilt of the earth, on an 18.6 year period cycle.
    At the times when the lunar nodes ( the declination at spring and fall equinox is crossing the ecliptic plane and the equator at the same time) the culmination of the apparent solar declination and the lunar declination at culmination is the same ~23.5 degrees, and the tidal bulges of both combine to produce king tides in the oceans and atmosphere.

    These repeating tidal effects in the atmosphere set up synchronized waves in the atmosphere commonly called El Nino maximums that occur around the synergism of the solar and lunar declinational culminations. As the declinational angle of the moon increase up toward the maximum it causes a gap in peak effect right at culmination then returns as it passes back through synergy, these dual pulses of shear generation in the primary and secondary tidal bulges created in the atmosphere, cause a split peak in tornado generation, with a surge of hail production in the middle when the two components of the forming tidal bulge, warm high dew point air masses from the South East quadrant and the cooler dry air masses from the North West sliding toward the South East then carolis effects wrap them together just past the peak occurrence of the synergistic culmination angles.
    Now that the lunar declinational angle at culmination is less than 20.5 degrees there is just a single peak at each primary and secondary tidal bulge effect in the atmosphere when the apparent solar and lunar culmination angles are the closest to the same, so it shifts the standing waves found in the jet streams (that help to produce conditions for tornado production) temporally forward into the summer more than in the spring peak production that is seen, when the declination at culmination is above 24 degrees.
    This effect can be clearly seen in the past distribution of tornado production from the past cycles shown in the initial links I posted;

    this set of plottings uses the 6558 day long period of filtering past tornado data for repeating patterns, as it has higher synchronization than the 18.6 year Mn period or the 19 year Metonic cycle.
    Part of the process of tornado production is based on the amount of available ions in the atmosphere and the charge gradient across the frontal boundary, more negative from the polar regions and more positive ions coming from the equatorial regions. It is this charge increase and decrease concurrent with lunar declinational tidal bulges that drive almost all intense or extreme weather.

    Now that the solar magnetic activity and the earth residual magnetic fields are decreasing together there will be less drive to produce ion charge gradient as strong as they were with a more active sun. So there will be more loopiness to the jet streams wanderings as well as lower ionic potentials, so the frontal boundaries will be more position varied than in the past more active sun periods as well as lower levels of extreme weather outbreaks.

  31. Just because the actual conditions that allow for tornado formation didn’t get started until the peak of the season was almost past doesn’t mean they won’t linger into the season we usually don’t associate with tornado season. Everything else having to do with seasonal conditions seems to be running late this year although it wouldn’t break my heart to see the tornado season wind down in June like it normally does.

  32. Steven Mosher [May 30, 2013 at 7:59 am] says:

    Last three years prove AGW is not responsible for tornadoes.

    feynman: there is no proof in science.

    weird that D’Aleo would suggest that the science on this was settled. Somebody revoke Joe’s skeptic card.

    Wait, what? Is this really coming from the guy who insists BEST and other fraudsters *proved* warming with no significant UHI!

    Steven, for an English or philosophy major or whatever you are you sure go out of your way to torture logic and language.

    Ripping that quasi-quote out of context is a dis-service to Feynman who was likely referring to the scientific discovery *process*. He would not say there are no knowns and everything is an unknown. If you asked him whether the Earth orbits the sun he would agree Copernicus has been proved correct.

    P.S. You want an absolute truth? Here’s one. Most people would revoke *your* skeptic card before that of anyone else.

  33. Steven Mosher says:
    May 30, 2013 at 7:59 am

    Last three years prove AGW is not responsible for tornadoes.

    feynman: there is no proof in science.

    weird that D’Aleo would suggest that the science on this was settled. Somebody revoke Joe’s skeptic card.

    Looks like Joe has tamed his Icecap story (which is where this came from) and has added a couple images from the Moore tornado, see http://icecap.us/index.php/go/joes-blog – it now says:

    Last three years provides evidence AGW not responsible for tornadoes

    By Joseph D’Aleo, CCM

    Tuesday was an active severe weather day with 29 reported tornados (preliminary). More outbreaks have occurred this week with a slow moving front. It followed the big EF5 tornado last week at Moore, Oklahoma. It was the first EF5 since 2011. An image and a volumetric radar cross section are shown.

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