Recent Tornadoes are Due to Unusually Cold Weather

Reposting this 2019 blog post by Dr. Roy Spencer.

May 29th, 2019 by Roy W. Spencer, Ph. D.

I had an op-ed published at yesterday describing the reason why we have had so many tornadoes this year. The answer is the continuing cold weather stretching from Michigan through Colorado to California. A persistent cold air mass situated north and west of the usual placement of warm and humid Gulf air in the East is what is required for rotating thunderstorms to be embedded in a strong wind shear environment.

The temperature departures from normal so far this month show evidence of this cold:

In fact, in terms of departures from normal, so far this year the Northern Plains has been the “coldest place on Earth”, averaging 5-10 deg. F below normal:

The strong wind shear and warm advection provided at the “tightened” boundary between the warm and cold air masses is the usual missing ingredient in tornado formation, unlike Alexandria Ocasio-Cortez’s claim that a New Jersey tornado warning was somehow tied to global warming.

As has been pointed out elsewhere, a trend line fit to the number of strong to violent U.S. tornadoes has gone down from 60 in 1954 to 30 in 2018. In other words, the number of most damaging tornadoes has, on average, been cut in half since U.S. statistics started to be compiled:

Or, phrased another way, the last half of the 65-year U.S. tornado record had 40% fewer strong to violent tornadoes than the first half.

To claim that global warming is causing more tornadoes is worse than speculative; it is directly opposite to the clear observational evidence.

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John Tillman
December 12, 2021 2:05 pm

As an actual climatolgist, as opposed to GIGO computer gaming “cliamte scientist”, Dr. Roy is, as usual, correct.

Colder means stormier. The engine of extreme WX is the difference between warmer subtropical circulation and colder higher latitude air and sea temperatures.

Not just on Earth, but throughout the solar system.

As the lying CACA spewers are so found of falsely saying, it’s just physics.

Reply to  John Tillman
December 12, 2021 2:53 pm

I agree John – Roy Spencer is correct, as usual. Brandon is wrong, also as usual..
Best wishes to all for the Holidays.

December 13, 2021 5:56 am

December 13, 2021 Cap Allon
Dr. Vincent Gray: “The [IPCC] climate change statement is an orchestrated litany of lies.”

Reply to  John Tillman
December 12, 2021 11:54 pm

Absolutely. If you view atmospheric and oceanic circulation as a heat engine, it is driven by a difference in temperatures.

If arctic amplification is a thing, then the arctic heats up and cools off faster than the rest of the globe. You’d think that should mean that global warming should decrease the temperature difference between the north pole and the equator. That should result in decreased circulation. The opposite would prevail for global cooling.

Based on the above simplistic assumptions, global warming should result in fewer violent weather events. Global warming should be beneficial and not catastrophic and, indeed, that is what history tells us.

Reply to  John Tillman
December 13, 2021 12:55 am

I believe there is strong evidence from a number of sources that the frequency and intensity of hurricanes and typhoons were greater than today during the LIA.

John Tillman
Reply to  Graemethecat
December 15, 2021 2:26 pm

Not so. Please provide this evidence which you imagine to exist. Thanks!

Actual evidence from Earth supports my statement.

And not just hurricanes, but other intense storms:

As well as from other planets.

Joseph Zorzin
December 12, 2021 2:06 pm

“Biden Discusses Hurricanes In Kentucky”

Biden thought it was a hurricane in KY.

It doesn't add up...
Reply to  Joseph Zorzin
December 12, 2021 2:57 pm

Make it Kansas, and he’s off to see the Wizard.

Reply to  Joseph Zorzin
December 12, 2021 3:33 pm

Early yesterday there was a strong line of thunderstorms associated with a cold front that spawned a series of deadly tornadoes in western Kentucky. It looks like about 80 people were killed. So while I am as critical of his “take” on the causation of the storms as everyone else – the man is an idiot and has hired people who are worse, this time he is geographically correct if wrong on everything else about the story.

Reply to  OweninGA
December 12, 2021 6:08 pm

It was a tornado, not a hurricane. There’s a big difference between the two and a president should be familiar with that difference.

Reply to  MarkW
December 13, 2021 6:57 am

I missed the hurricane bit. The transcript I read must have corrected that – I can’t stand to listen to him myself, so I thank the folks that transcribe his drivel. Of course the news can’t even be trusted as transcriptionists any more.

Reply to  OweninGA
December 13, 2021 7:44 am

Going back at least as far as Clinton, the news media has been famous for cleaning up the statements of politicians they like. For politicians they don’t like, every verbal stumble becomes front page news.

Mike McMillan
Reply to  Joseph Zorzin
December 12, 2021 6:38 pm

Biden thought it was a hurricane in KY.”

Well, why not? We get an occasional tornado in Houston, but the associated storm surge is what causes the damage.

Ron Long
December 12, 2021 2:07 pm

Let’s Go Brandon has declared the tornado outbreak to be the result of global warming. Rather, he read something that someone wrote for him to read. The two unusual forces that appear to have participated in this strong tornado outbreak is the speed of the two fronts colliding and the extreme temperature contrast between the two fronts. The cold one had raced from the NW to the E, and dumped a lot of snow enroute. Maybe global cooling will promote more tornados with more destruction?

John Tillman
Reply to  Ron Long
December 12, 2021 2:23 pm

As with all else, Bribem is a meteorlogical moron.

Curious George
Reply to  Ron Long
December 12, 2021 3:56 pm

These tornados have been caused by windmills reaching a tipping point 🙂

Rud Istvan
December 12, 2021 2:39 pm

The alarmist belief is that occasional bad weather is caused by climate change. Ignoring both meteorology basics and bad weather trends like severe tornados. Such lies are all they got left.

Arctic summer ice hasn’t disappeared.
Sea level rise is not accelerating.
Polar bears are thriving.
Children know snow…

Neither AOC nor Biden have the mental capacity to research simple basics, let alone all the failed warmunist predictions they ‘rely’ on for their alarm. They just spout nonsense, providing more targets for deserved ridicule.

Jeff Alberts
Reply to  Rud Istvan
December 12, 2021 4:57 pm

AOC has the capacity, but she doesn’t have the desire. She’s all-in on the crisis hoax, there’s no way she’d pay attention to anything that would cause her to lose face.

As for Biden, he doesn’t have any original thoughts any more, only what’s written down for him, like “end of message”.

Reply to  Jeff Alberts
December 12, 2021 6:26 pm

I have heard numerous congressional meetings where AOC spoke…occasional cortex is the perfect nickname.

December 12, 2021 2:45 pm

Notice in the graph, the high point of tornadoes was during the Ice Age scare. Somebody could write a paper about that. But then you couldn’t get it published.

December 12, 2021 2:51 pm

The Washington Post will have us believe the tornadoes are due to warm weather and is, of course, connected to climate change:
Fueled by record-setting warm temperatures, the disaster was unprecedented in many ways for the time of year and is raising questions about the possible role of human-caused climate change.”
How Friday night’s rare and deadly December tornado outbreak unfolded (

Dave Fair
Reply to  Alba
December 12, 2021 3:27 pm

Supposedly, there are meteorologists on TV, posting to the internet and writing for newspapers. Why aren’t just a few of the more prominent of them pointing out the CliSciFi lies and the complicity of their political enablers? Name for me one meteorologist that is unaware of the atmospheric conditions which spawn tornados. Are they all so afraid of losing their jobs such that not one of the more prominent of them will simply state the facts and let people draw their own conclusions?

Jeff Alberts
Reply to  Dave Fair
December 12, 2021 4:59 pm

Are they all so afraid of losing their jobs such that not one of the more prominent of them will simply state the facts and let people draw their own conclusions?”


Reply to  Dave Fair
December 12, 2021 5:14 pm

I’m a meteorologist and do just that, however I am not a TV Met, but I’ll tell it like it is to anyone that will listen!

Reply to  Dave Fair
December 12, 2021 5:20 pm

Why, during one period, did seemingly reasonable people accuse their neighbors of witchcraft, based on no evidence, sentencing them to death?

Reply to  AndyHce
December 12, 2021 6:13 pm

Panic can be epidemic. Add to that the usual ambitious politicians wanting more power. Witchcraft was, to some degree, well know then. It made a good power lever.

At least until some honest, intelligent people interfered.

Tom Abbott
Reply to  Dave Fair
December 12, 2021 5:29 pm

Happily, the meterologists in my area never refer to Human-caused Climate change when talking about the weather.

They just stick to the facts. And it is very much appreciated.

The tornado pattern is following the familiar pattern: In the early spring and summer, the focus of energy for tornadoes is in the central and south-central U.S., and as the season turns into fall, the focus of the energy moves east and northeast, like it did here.

This particular storm front formed up basically east of Oklahoma, and then moved east, so we got very little of the heavy weather.

If a storm system like that had moved through Oklahoma, everyone would have been aware of it, and storm chasers would be dogging the storms every step of the way, telling us where they were and what they were doing.

I don’t know if tornadoes get extensive coverage in other States the way they do in Oklahoma. Oklahoma stays right on top of the tornadoes.

Reply to  Dave Fair
December 12, 2021 6:11 pm

Because they have families to feed.

Tom Abbott
Reply to  Alba
December 12, 2021 5:24 pm

““Fueled by record-setting warm temperatures,”

Those “record-setting” temperatues were only about one degree warmer than the record. Most of the records were set in the 1930’s.

Reply to  Tom Abbott
December 12, 2021 6:18 pm

The record highs were also being caused by a storm system that was pulling warm and humid Gulf air northward. That Gulf air is still warm and humid this time of year is also nothing unusual.

Anthony Banton
Reply to  Tom Abbott
December 13, 2021 8:46 am

The high temperatures/humidity resident over the area affected did, of course, fuel the storms that spawned the tornadoes.
That they (max temps) were not an absolute record for the time of year is irrelevant as there is another side to the equation needed to make them.
That of cold air advancing across those high temps.
In the form of a cold front with marked wind shear.

Reply to  Anthony Banton
December 13, 2021 9:25 am

All of the models agree that the polar regions should warm the most.
All of the models agree, that the more water vapor there is in the air, the less impact CO2 is going to have.

As a result, if CO2 was causing global warming, intense storms should be decreasing.

The warm air in this case came from the Gulf of Mexico and was brought north by a weather system. Nothing unusual about that, even this time of year.

To bed B
Reply to  Alba
December 12, 2021 11:29 pm

19 EF4 tornadoes in December since 1950, or about one every 4 years. The last one in 2015 or 6 years ago.

2 EF5 since 1950, in December. The last one in 1957.

This might be unprecedented for length of the path and deaths, but only for December. The latter just an unfortunate passing through a highly populated area. The former just weather.

December 12, 2021 2:52 pm

Temperature differences not absolute temperature are what cause storms of all types.
The LIA was stormier than most of the 20th Century.
AGW was supposed to involve a polar thermal enhancement meaning smaller differentials between equator and poles.
As usual with AGW theory the reality is the opposite.

December 12, 2021 2:59 pm

Spencer says it’s getting colder. NOAA’s USHCN data says is getting warmer … . I’ll place my bets on Spencer as he uses observed versus altered data.

December 12, 2021 2:59 pm

Rolling Stone’s headline says

Extreme Storms Will Be ‘New Normal,’ FEMA Head Warns After Deadly Tornadoes”

This has become the standard response of those who receive a paycheck all year long to have a plan and supplies in place at the time of need…
Is it a fear of personal failure thing? Or a hidden request for a bigger budget ? Do they believe what they are saying? Or are they really saying “Our response to this event will be the new normal”?

Dave Fair
Reply to  DMacKenzie
December 12, 2021 3:34 pm

It is scary that the head of the Federal agency responsible for responding to weather disasters either doesn’t know about the atmospheric conditions causing tornados or is lying to the public for political reasons. About the only way his statement could be remotely correct is if he believes that the northern CONUS will cool in the future.

Reply to  Dave Fair
December 12, 2021 6:21 pm

The man who runs FEMA, believes whatever the man who appointed him, tells him to believe

Gunga Din
December 12, 2021 3:23 pm

Mr. Layman here.
Even I know that a storm develops when a cold front meets a warm front. The stronger the fronts, the stronger the storms.
In the age of “record highs” due to CAGW, how could a really strong AND persistent cold front even exist?

Only a “Political Climate Scientist” would claim only “Man’s-Fossil-Fueled CO2 Emissions” caused the warm front and ignore what caused the persistent cold front.
(The answer is Nature caused both.)

I’m not implying that Brandon is aware enough to understand he what read off his teleprompter.
(Maybe they let AOC have the keyboard at time to promote the GND?)

Jules Guidry
December 12, 2021 4:46 pm

The climate clowns are getting buried in their own bs, as mom nature proves them wrong. And they try to make it fit their computer models for CGW. This latest round of tornadoes should be just another nail in the climate change coffin. But, it won’t. The politicos will continue to babble on and try to dance around the data. Sheesh.

David S
December 12, 2021 5:15 pm

Why does this graph show the opposite; an increasing trend?

It doesn't add up...
Reply to  David S
December 12, 2021 5:33 pm
Reply to  David S
December 12, 2021 5:41 pm

It is showing all tornadoes. In the years before storm chasers and mobile dopplar there were many unreported tornadoes. That is why the only reliable long-term record is of EF3 and stronger. Better reporting doesn’t mean more tornadoes, just more known tornadoes.

To bed B
Reply to  Wade
December 12, 2021 11:37 pm

They used to have a caveat that the trend was due to better observation of EF0 tornadoes detected on radar. These barely leave damage worth reporting.

Tom Abbott
Reply to  David S
December 12, 2021 5:53 pm

I would say the larger numbers of detected tornadoes in later years are due to a better ability to find even very small tornadoes because of increased technology.

A better measure is the strength of tornadoes. There are a lot fewer EF4 and EF5 tornadoes now than in the past. There are a lot more EF0 tornadoes detected nowadays because of technology. The technology is so good now that they can spot areas of rotation before they become tornadoes.

Another thing is weak tornadoes, EF0 and EF1, have a habit of spinning up and putting down a tornado, and then spinning down and the tornado goes back into the clouds, and then a few miles later, the same thing happens and it happens over and over again, so here you have a case where one circulaton area can generate numerous weak tornadoes that jack up the total numbers, but do little or no damage.

Strong tornadoes tend to stay on the ground for long periods of time and can do great damage as a result.

Reply to  David S
December 12, 2021 5:54 pm

It’s a classic look-elsewhere effect unless your data covers everything. You will find the same problem with damages and fatalities you need to be careful because population and building numbers have increased and the baseline probability has changed.

Steve Reddish
Reply to  David S
December 12, 2021 6:01 pm

Dopplar radar

December 12, 2021 5:24 pm

I still remember the outbreak of 1974. It was caused by the approaching ice age.

Reply to  Alan
December 12, 2021 5:29 pm
Tom Abbott
Reply to  Alan
December 13, 2021 8:27 am

If you look at the chart at the top of the page you will see that the number of strong tornadoes was largest during the 1960’s and 1970’s, which was the coldest period since the 1910’s, and temperatures were something like 2.0C cooler in the 1970’s than today.

Colder weather, and the larger contrast between cold and warm fronts, spawns stronger tornadoes.

To bed B
December 12, 2021 11:20 pm

The NBC wrote
“Since 1950, there have only been 19 F/EF4 tornadoes in the U.S. during the last month of the year and only 2 F/EF5 tornadoes.
The last EF4 tornado to strike the U.S. during the month of December was during the Christmas Outbreak of December 2015…
An EF5 tornado is the strongest designation a tornado can receive. Exceptionally rare, these tornadoes can produce wind speeds higher than 200 mph. The last EF5 tornado to strike the U.S. was Moore, Oklahoma, in May of 2013. That was 3,125 days ago and the longest streak on record.”

So EF4 hit a little more often than once every 4 years in December, on average, and the last one was six years ago. Only two EF5 in December since 1950, and both in the 50s. The longest streak in days between EF5 in any month was just broken. This was only the second EF4 for the year when the average is 7 per year.

And these clowns still come up with

“Victor Gensini, a professor of meteorology at the Northern Illinois University who has published studies on links between climate change and severe storms, said in an email that events like this may become more common in a warming world.”

December 13, 2021 12:26 am

There has been unusually warm weather over much of the USA this December.

and clearly the recent tornadoes, in cold weather, not the usual season, and of that scale and impact were an extreme weather event and climate change is undoubtedly involved.

This is the 4th extreme weather event in the USA/Canada in 6 months: record heatwave, record rainstorms near Vancouver, NY flooded and now this…

And if you look at the rest of the world, more truly extreme weather.

The chances of all this ‘just happening’ in one 6 months is off the scale. Isn’t it?

charles nelson
Reply to  griff
December 13, 2021 12:33 am

You sound mentally ill.

Reply to  charles nelson
December 13, 2021 12:46 am

griff is never right, about anything.

Reply to  charles nelson
December 13, 2021 10:29 am

He sounds well compensated to me with the consistency of a troll script.

Reply to  griff
December 13, 2021 1:51 am

The chances of all this ‘just happening’ in one 6 months is off the scale. Isn’t it?”


Reply to  TimTheToolMan
December 13, 2021 7:52 am

griff, like most global warming enthusiasts, doesn’t understand, and doesn’t want to understand, statistics.

Reply to  griff
December 13, 2021 1:55 am

and clearly the recent tornadoes, in cold weather, not the usual season, and of that scale and impact were an extreme weather event and climate change is undoubtedly involved.”

In fact I’ll go one further. Climate change is causing fewer tornadoes as measured over the last 70 years. So, in a sense, yes these tornadoes are indeed influenced by climate change and were less likely to have occurred as a result.

Reply to  TimTheToolMan
December 14, 2021 7:20 pm

The number of strong and violent tornadoes in the US is decreasing, and they’re also being shifted away from eary summer and towards cooler times of the year.

Reply to  griff
December 13, 2021 2:26 am

About a decade ago in the UK the Met Office stated (a) that UK cold snowy winters had about a 1/20 chance of occurring and (b) that the events are independent from year to year.

We had three back to back in the UK a decade ago, according to the Met Office that must be a one in 8,000 year chance. So likely its only happened once before in the entire Holocene?

Or alternatively they don’t know what they are talking about. Like Griff.

Climate believer
Reply to  griff
December 13, 2021 2:43 am

 “is off the scale”

Lol…. bonus key phrase!! +10 fear points.

Reply to  griff
December 13, 2021 3:12 am

You should be declared officially insane.You have no sense of reality and discredit yourself all the time with your comments.Please check yourself into a mental asylum.This is no sarcasm and i’m not trying to be mean.You really need to be kept in check and hopefully you can heal.

Reply to  Tony
December 13, 2021 11:11 am

“You have no sense of reality…”

A trait that has become all too common lately.

Clyde Spencer
Reply to  TonyG
December 13, 2021 11:49 am

A detachment from reality is one of my defining characteristics of a Liberal, particularly the Progressive branch.

Reply to  griff
December 13, 2021 6:15 am

Griff, you just showed you are unable to read a map from the article showing that much of the US had lower than normal temperature. That was the first map in the article.

Being unable to read must be a hindrance in your life. I am sorry for you.

Reply to  griff
December 13, 2021 7:51 am

So climate change caused a weather system to pick up warm humid air from the Gulf of Mexico and move it over much of the eastern US?

As someone who lives in the American south, I can assure you that getting Gulf air is nothing unusual, at any time of year.

As to your other claims, extreme events are happening all the time. When they don’t strike populated areas, they aren’t covered by the news.

griff, just because you are incredibly ignorant, don’t assume everyone else is.

Reply to  griff
December 13, 2021 7:54 am

When shown a chart that proves that an event is happening less often, griff just echoes the Guardian and declares that it is happening more often.

Tom Abbott
Reply to  griff
December 13, 2021 8:36 am

“The chances of all this ‘just happening’ in one 6 months is off the scale. Isn’t it?”

No, it’s just weather, Griff.

Next you will be claiming the snowfall and rainfall occurring right now in the western U.S. is caused by CO2.

Remember how you were claiming the drought in California was caused by CO2? Well, stay tuned.

Look at all this moisture being brought into the western U.S.,39.82,264

It looks like the bulk of the U.S. is south of the jet stream so they will experience mild weather for a few more days. Mild weather doesn’t mean it can’t snow. 🙂

The position of the jet stream is what determines whether you are warm or cold, and whether storm fronts are severe or not, not CO2.

Reply to  griff
December 13, 2021 8:40 am

There has been warm weather many times in America a country you live around 3,500 away from. This has been pointed out many times by Tony Heller who posts many examples of it as the chart shows below that it was over 70F in many areas in December 1951


Number of F3-5 in Winter in long term decline


You meanwhile ignored what Dr. Spenser stated that Tornado counts in America is in long term DECLINE to a record low in 2018.


Reply to  griff
December 13, 2021 11:09 am


Is there ANYTHING that “climate change” can’t do?

Reply to  TonyG
December 13, 2021 11:16 am

I asked climate change to make my bed this morning.
I’m still waiting.

Clyde Spencer
Reply to  TonyG
December 13, 2021 11:56 am

I can answer that question. It can’t make fools be reasonable.

Reply to  TonyG
December 13, 2021 1:27 pm

It can’t/won’t stop the seasons from happening, stop weather from happening, stop natural disasters from happening, etc. It’ll still get cold during the winter and warm during the summer. There will still be snowstorms, tornadoes, hurricanes, droughts, floods, boring weather, etc. just like there would be if climate change were occurring slower than it is today. What will change is the frequency, spatial distribution, temporal distribution and magnitude of those events.

Reply to  bdgwx
December 13, 2021 2:50 pm

What will change is the frequency, spatial distribution, temporal distribution and magnitude of those events.

That’s pretty vague.

Clyde Spencer
Reply to  griff
December 13, 2021 11:46 am

For random events, they should be observed most frequently clustering around the population mean. That is, approximately 95% of them within 1.96 sigma. The extreme tails of the distribution will be rare. Therefore, one may have to wait a long time to observe a ‘tail’ event. Another way of saying that is the longer a phenomenon is observed, the more likely an extreme event will be observed. Your Chicken Little responses show how little you know except what you read in the biased ‘news’ media and parrot back here as ‘evidence’ of your beliefs. In essence, you are Cherry Picking.

Reply to  griff
December 13, 2021 4:04 pm

I know Bojo is bonkers, but I didn’t know Griff as a British resident caught the Bojo disease.

ie. Commenting on things he knows nothing about, on just about every country in the world he has never visited.

All he needs is a G/F like princess nutnut and we could understand why this fool keeps spouting crap, but we don’t even know F-A about Griff, apart from he’s just a public fool.

December 13, 2021 12:57 am

But, but, but…

The unusually cold weather, just like all unusual weather, is caused by global warming. I thought everybody knew that.

December 13, 2021 3:47 am

Kind of figures. Tornadoes and hurricanes are fueled by temperature differentials.

December 13, 2021 5:08 am

There you go again, Dr Roy, using facts and reality against the idiot left. You are gonna be soooo canceled. Again. Still. 220, 221, whatever it takes they are going to be very cross with you.

December 13, 2021 9:13 am

It is important to note that Dr. Spencer is talking about a warm season outbreak for May of 2019 and is not particularly relevant to the cool season outbreak for December of 2021 which was fuel by higher than average temperatures and dewpoints colocated with very high wind shear.

One tornadogenesis and maintenance ingredient most people are unaware of is the wind shear component. As the planet warms CAPE (convective available potential energy) may increase in the warm season but SRH (storm relative helicity) may decrease which generally has the affect of 1) changing storm modes from discrete to clustered and 2) reducing the helical kinetic energy within the planetary boundary layer essential for low level mesocyclone maintenance and tornadogenesis. Long term this may contribute to shorter tracks, lower intensity, and less frequently tornadoes as the planet warms at least during the warm season. During the cool season the picture may be a bit different. SRH is typically much higher already in the cool season and it is the CAPE that is often lacking. But with a warming planet CAPE might be expected to gradually increase during the cool season thus leading to more frequent, longer tracked, and more intense tornadoes at least for the cool season. This is still a very active research topic and there is no real clear consensus on the future of tornadoes in the American midwest. I think right now the research leans toward tornadoes will probably continue to decline overall while the frequency and distribution of them will gradually move toward the cool season further east, but I wouldn’t really say the research is convincing yet.

Reply to  bdgwx
December 13, 2021 9:28 am

You make it sound like there is something unusual about weather fronts dragging Gulf air up into the central and eastern United States. That’s the only reason why there was warm air ahead of that front.

One of these days warmists will actually try to learn a little about weather.

Reply to  MarkW
December 13, 2021 10:40 am

MarkW said: “You make it sound like there is something unusual about weather fronts dragging Gulf air up into the central and eastern United States.”

I didn’t say that. In fact research says that the quasi resonant amplification of the polar jet could make frontal system more common in the center of the country in the cool season. That doesn’t necessarily mean SRH, CAPE, and other ingredients would colocate sufficiently for tornadogenesis, but it does mean, if true, that frontal systems will continue to be at least as common as they are today.

Reply to  bdgwx
December 13, 2021 11:18 am

History shows that the jet stream only gets wavy when it’s cold. A warmer would would be a quieter world.

Reply to  MarkW
December 13, 2021 1:21 pm

It gets more wavy during the cool season and less wavy during the warm season. That’s common knowledge. The question is…will it get more/less/same wavy during the cool season in response to Arctic amplification in the future relative to the past for the same season? The question is NOT…will it continue to get less wavy during warm season relative to the cool season in response to Arctic amplification? We already know the answer to that is yes because Arctic amplification does not prevent the seasons from occurring. In other words, it will still get cold in the winter and warm in the summer.

Reply to  bdgwx
December 13, 2021 9:31 am

BTW…there are many factors that must come together at the right time and in the right proportion for tornadogenesis to occur. I don’t want people thinking SRH and CAPE are the only factors in play. It’s way more complicated than that. I’ve not seen a lot of research into the long term future of these other factors.

Larry in Texas
December 13, 2021 9:52 am

As usual, Roy Spencer is spot on. Also as usual, our senile-old-fool of a President “Brandon” Biden makes himself look ridiculous by talking about tornadoes and climate change in the same sentence. Seldom has any President made gaffe after gaffe as this one – it’s the only real thing this President has accomplished.

Clyde Spencer
Reply to  Larry in Texas
December 13, 2021 12:01 pm

Seldom has any President made gaffe after gaffe as this one

It is evidence of his incompetence and/or senility. What is truly disturbing is the way that the MSM covers for him.

December 13, 2021 2:07 pm

Hide the decline.

December 14, 2021 7:15 pm

What’s up with using 1954 as a start date when the available data goes back to 1950? Didn’t F3-plus tornadoes fail to escape notice as far back as the National Weather Service kept comprehensive tornado records?

Mike Maguire
December 16, 2021 11:01 pm

We had another outbreak of severe storms and tornadoes again this week………and it was for the same reason as the one that happened last week.
A powerful jet stream between extreme cold to the north and warm/humid air to the south.
Powerful jet streams help maximize the lift to turn a thunderstorm into a severe thunderstorm. They also cause rotating storms and favorable wind sheer dynamics that lead to violent tornadoes.
The energy for the deep surface low pressure values with these last 2 events came from the temperature contrast between the cold to the north and warmth to the south.
Without the subzero cold in Canada during this period, the intensity of the jet stream just south of the extreme cold would have been much less………and along with that…..less severe weather and fewer, if any violent tornadoes.

Warm humid air, by itself can’t produce violent tornadoes. You need the powerful jet stream that results from having the extreme temperature gradient(from cold to the north).

Screenshot 2021-12-16 at 13-32-33 Canadian Temperature Current Conditions, covering Temperature Readings for all of Canada.png
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