Scientists link California droughts and floods to distinctive atmospheric waves


BOULDER, Colo. — The crippling wintertime droughts that struck California from 2013 to 2015, as well as this year’s unusually wet California winter, appear to be associated with the same phenomenon: a distinctive wave pattern that emerges in the upper atmosphere and circles the globe.

The high- and low-pressure regions of wavenumber-5 set up in different locations during January 2014, when California was enduring a drought, and January 2017, when it was facing floods. The location of the high and low pressure regions (characterized by anticylonic vs. cyclonic upper-level air flow) can act to either suppress or enhance precipitation and storms. The black curves illustrate the jet streams that trap and focus wavenumber-5.
CREDIT Image by Haiyan Teng and Grant Branstator.

Scientists at the National Center for Atmospheric Research (NCAR) found in a recent study that the persistent high-pressure ridge off the west coast of North America that blocked storms from coming onshore during the winters of 2013-14 and 2014-15 was associated with the wave pattern, which they call wavenumber-5. Follow-up work showed that wavenumber-5 emerged again this winter but with its high- and low-pressure features in a different position, allowing drenching storms from the Pacific to make landfall.

“This wave pattern is a global dynamic system that sometimes makes droughts or floods in California more likely to occur,” said NCAR scientist Haiyan Teng, lead author of the California paper. “As we learn more, this may eventually open a new window to long-term predictability.”

The finding is part of an emerging body of research into the wave pattern that holds the promise of better understanding seasonal weather patterns in California and elsewhere. Another new paper, led by NCAR scientist Grant Branstator, examines the powerful wave pattern in more depth, analyzing the physical processes that help lead to its formation as well as its seasonal variations and how it varies in strength and location.

The California study was published in the Journal of Climate while the comprehensive study into the wave patterns is appearing in the Journal of the Atmospheric Sciences. Both papers were funded by the National Science Foundation, which is NCAR’s sponsor, as well as by the Department of Energy, the National Oceanic and Atmospheric Administration, and NASA.

The new papers follow a 2013 study by Teng and Branstator showing that a pattern related to wavenumber-5 tended to emerge about 15-20 days before major summertime heat waves in the United States.

Strong impacts on local weather systems

Wavenumber-5 consists of five pairs of alternating high- and low-pressure features that encircle the globe about six miles (10 kilometers) above the ground. It is a type of atmospheric phenomenon known as a Rossby wave, a very large-scale planetary wave that can have strong impacts on local weather systems by moving heat and moisture between the tropics and higher latitudes as well as between oceanic and inland areas and by influencing where storms occur.

The slow-moving Rossby waves at times become almost stationary. When they do, the result can be persistent weather patterns that often lead to droughts, floods, and heat waves. Wavenumber-5 often has this stationary quality when it emerges during the northern winter, and, as a result, is associated with a greater likelihood of persistent extreme events.

To determine the degree to which the wave pattern influenced the California drought, Teng and Branstator used three specialized computer models, as well as California rainfall records and 20th century data about global atmospheric circulation patterns. The different windows into the atmosphere and precipitation patterns revealed that the formation of a ridge by the California coast is associated with the emergence of the distinctive wavenumber-5 pattern, which guides rain-producing low-pressure systems so that they travel well north of California.

Over the past winter, as California was lashed by a series of intense storms, wavenumber-5 was also present, the scientists said. But the pattern had shifted over North America, replacing the high-pressure ridge off the coast with a low-pressure trough. The result was that the storms that were forced north during the drought winters were, instead, allowed to make landfall.

Clues to seasonal weather patterns

Forecasters who predict seasonal weather patterns have largely looked to shifting sea surface temperatures in the tropical Pacific, especially changes associated with El Niño and La Niña. But during the dry winters of 2013-14 and 2014-15, those conditions varied markedly: one featured the beginning of an El Niño while the sea surface temperatures during the other were not characteristic of either El Niño or La Niña.

The new research indicates that the wave pattern may provide an additional source of predictability that sometimes may be more important than the impacts of sea surface temperature changes. First, however, scientists need to better understand why and when the wave pattern emerges.

In the paper published in Journal of the Atmospheric Sciences, Branstator and Teng explored the physics of the wave pattern. Using a simplified computer model of the climate system to identify the essential physical processes, the pair found that wavenumber-5 forms when strong jet streams act as wave guides, tightening the otherwise meandering Rossby wave into the signature configuration of five highs and five lows.

“The jets act to focus the energy,” Branstator said. “When the jets are present, the energy is trapped and cannot escape.” But even when the jets are present, the wavenumber-5 pattern does not always form, indicating that other forces requiring study are also at play.

The scientists also searched specifically for what might have caused the wave pattern linked to the severe California drought to form. In the paper published in the Journal of Climate, the pair found that extremely heavy rainfall from December to February in certain regions of the tropical Pacific could double the probability that the extreme ridge associated with wavenumber-5 will form. The reason may have to do with the tropical rain heating parts of the upper atmosphere in such a way that favors the formation of the wavenumber-5 pattern.

But the scientists cautioned that many questions remain.

“We need to search globally for factors that cause this wavenumber-5 behavior,” Teng said, “Our studies are just the beginning of that search.”


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April 6, 2017 1:35 pm

Is this in any way like Judith Curry et al’s Stadium Wave?

Reply to  rovingbroker
April 6, 2017 4:27 pm

This is not new. Blocking highs, the Ridiculously Resilient Ridge, have been know about years. But it’s nice to see NCAR is studying weather, which affects us all, instead of climate change, which so far has had no noticeable effect on anyone. The small increase in global average temperature that occurred over the past 40 years would be undetectable by the average human if it happened over the course of five minutes in a room they were sitting in.

Stephen Richards
Reply to  Thomas
April 7, 2017 1:14 am

But you don’t need NCAR to do that job. Just shut them down and leave weather to NOAA.

Jimmy Haigh
April 6, 2017 1:36 pm

And CO2’s effect on all of this? Zilch.

AGW is not Science
Reply to  Jimmy Haigh
April 7, 2017 12:28 pm

Yes, it was quite amazing not to see the genuflection to the climate change BS show up in the papers (at least as summarized here). And refreshing, as it’s such transparent BS when they do it.

Reply to  AGW is not Science
April 7, 2017 5:28 pm

…and amazingly, “specialized models” that appear at first blush to have some actual predictive power, instead of the same old models which have been falsified repeatedly. They actually admitted that there are parts of this phenomenon that are unexplained and that they know need more study (without speculating that it was caused by CAGW and it worse than we thought). How refreshing.

Sounds like these folks actually have somehow been instilled with some science rather than just a healthy dose of politic and advocacy. Based on the trash that has come out of this agency over the recent decade, I didn’t know my home town NCAR had any of that science-thingy left.

Must be new hires (/sarc).

Thomas Homer
April 6, 2017 1:40 pm

from the article: “The slow-moving Rossby waves at times become almost stationary.” …

And how do atmospheric tides impact these ‘stationary’ waves?

April 6, 2017 2:01 pm

In other words – weather!

And these jerks get paid for this crap?

Reply to  Paul Homewood
April 6, 2017 2:40 pm


Another Scott
Reply to  Paul Homewood
April 6, 2017 3:58 pm

I would be glad to see my tax dollars go to research like this. I wholeheartedly agree with them when they say more study is needed.

Reply to  Another Scott
April 6, 2017 4:37 pm

Yeah, this is my kind of research. At least they didn’t try to connect any of their research to CAGW. Jet stream research is good stuff!

I would like to see a diagram of these five pairs of highs and lows they are talking about. I don’t see five pairs on the nullschool website.

Reply to  Paul Homewood
April 6, 2017 8:44 pm

And after all of this: The slow-moving Rossby waves at times become almost stationary. When they do, the result can be persistent weather patterns that often lead to droughts, floods, and heat waves.

They missed cold snaps , blizzards, fog, hurricanes, cyclones etc. Please send more money so we can continue our studies. ( Actually our predictions failed on purpose anything to do with cooling or any words that could say those dreaded words.)

Reply to  Paul Homewood
April 7, 2017 1:24 am

Do you want better weather forecasts or not?

Samuel C Cogar
Reply to  Roy
April 7, 2017 4:41 am

The best you can ever hope for is …… almost better weather forecasts,

Reply to  Roy
April 7, 2017 6:12 am

No apparently asybot just wants to bitch about all weather and climate research because he doesn’t like global warming. He believes in ignorance because it does not conflict with his ideology.

Being able to understand these patterns better can be useful in providing warnings to people about what is coming. If you know a drought is coming and it will last for quite awhile, you can modify your behavior (i.e., use less water) to better conserve what you have.

Ignorance, contrary to some here, is not bliss.

Reply to  Roy
April 7, 2017 9:46 am

My second biggest gripe about the global warming nonsense (the first being the trillions wasted) is the way it has turned many against even good science and models in general.

April 6, 2017 2:02 pm

Looks like Rossby is a popular fellow. There was a paper recently published that had Rossby waves in the Sun’s “atmosphere” contributing to sunspots or lack thereof and Rossby waves are in on the El Niño’s.

Reply to  rbabcock
April 6, 2017 8:57 pm

I have once heard of them occurring in ocean currents. I doubt they exist only in Earth’s atmosphere. I think one other place they occur is in the hexagon pattern I have seen in a photo of one of Saturn’s polar regions.

Reply to  Donald L. Klipstein
April 6, 2017 10:37 pm

They do occur in the oceans as well as the atmosphere. The restoring force for Rossby waves is the rotation of the earth. They can occur, in principal, in any fluid (atmosphere or ocean) on a rotating planet.

Stephen Wilde
Reply to  David Small
April 6, 2017 11:06 pm

I would expect Rossby type waves to be involved in internal ocean oscillations.

Reply to  rbabcock
April 7, 2017 1:21 am

Scientists are herds with buzzwords, just like the media. When I was a cancer researcher there was a two year window when p53, angiogenesis and gene therapy were the buzzwords every grant proposal needed.

Rossby Waves are getting their 15 minutes right now, I guess.

Reply to  rtj1211
April 7, 2017 12:55 pm

That’s because humans are prone to fads (madness and wisdom of crowds). Scientists are human, after all, so they are not immune (nor are medical practitioners).

Samuel C Cogar
Reply to  rbabcock
April 7, 2017 5:38 am

Rossby waves, ……. HUH?

And just what is the primary difference between …… Rossby waves and Sound waves?

That is, ……. other than the literal fact that one can easily observe the former but not the latter.

HA, has anyone considered researching the Sound waves that propagate through the atmosphere as a result of being created by “thunder-boomer” storms ….. to find out if said Sound waves are predictive of future “thunder-boomer” storms and/or the latitudinal direction and speed of said “future thunder storms”?

Investigating those “thunder-boomer” Sound waves could very well be the basis of future “long term” weather reporting, ………………… RIGHT?


April 6, 2017 2:02 pm

So, is this weather or climate? Either way, this is what I’d like NCAR to actually research and publish results on.

Reply to  RHS
April 7, 2017 12:57 pm

Weather is what we live in, must survive and adapt to. Climate is a statistical summary of the previously realized weather. In other words, climate is what you’ve seen. Weather is what are now and will see. “Whatever will be, will be ….”

April 6, 2017 2:07 pm

Breaking news: weather is caused by differences in atmospheric pressure!

April 6, 2017 2:11 pm

I blame this kind of junk news on our education system and the media. People no longer look at synoptic charts. Even the weather on the TV news used to present the synoptic chart. Now it’s just a map of temps and little sun or cloud cartoons.

Reply to  AP
April 6, 2017 4:21 pm

Agree a WHOLE lot; +googol, at least.

April 6, 2017 2:14 pm

They just had to throw that extreme events thing in there…….

April 6, 2017 2:16 pm

Okay, but I doubt this will impact the rate of non-planning in California and the finger pointing of climate change policy hacks.

Tom Halla
April 6, 2017 2:23 pm

Models from NCAR that actually describe weather patterns? I thought they stopped doing such things./s

April 6, 2017 2:24 pm

Dubious research. Climate models do not regionally downscale, and fine resolution weather models go awry 5 days out, even on big stuff like hurricanes and cyclones. This tweener fails on both counts.

Stephen Wilde
April 6, 2017 2:31 pm

The variable behaviour of the jet stream tracks, consequent changes in so called ‘blocking’ patterns and associated changes in global cloudiness resulting in global warming or global cooling has been my hobby horse here and elsewhere for the past ten years or more.
The truth is that solar variations affect the atmospheric circulation from above and over the poles whereas ocean oscillations affect the atmospheric circulation from below and towards the equator.
It is the interplay between the two influences that leads to natural climate change over multidecadal periods of time.
Depending on that interplay the gradient of tropopause height between equator and poles is affected which allows the switch between jet stream zonality or meridionality.
Zonality is associated with less clouds and global warming whereas meridionality is associated with more clouds and global cooling.
Nothing to do with CO2 at all.

Brett Keane
Reply to  Stephen Wilde
April 6, 2017 3:21 pm

Stephen, using your work, and the knowledge that the blob and El Nino should expand the atmosphere, I was able to successfully predict what has happened the last two years in both hemispheres. That is, more zonal, then less so and more meridional. Our NZ NIWA, snowflakey as it is, is now talking about wavenumbers too. Tender buds of Spring in their minds maybe. I suppose we should encourage them…..

Stephen Wilde
Reply to  Brett Keane
April 6, 2017 3:45 pm

Yes, Brett, that sounds right as an example of the bottom up equatorial oceanic effect.
For the top down solar effect we can look at the last sola\r minimum around 2010 which produced the coldest UK December for 100 years due to persistent blocking.
The degree of zonality / meridionality and/or the level of global cloudiness would work as diagnostic indicators for net warming or cooling but there is still a huge problem for regional seasonal predictability because the Earth’s rotation and the landmass distribution continually moves the position of the dominant blocking systems around longitudinally and latitudinally from season to season..

Reply to  Stephen Wilde
April 6, 2017 4:17 pm

re: “The variable behaviour of the jet stream”

Dog wags tail or vice versa; which came first, the low pressure center moving onshore with a leading trough with embedded ‘jet’ at the boundary, or the jetstream itself.

I don’t think you can treat the so-called ‘jet’ as an independent, freely-existing entity just as the tail of the dog requires the dog to exist.

Reply to  _Jim
April 6, 2017 4:26 pm

The jets and the high/low pressure cells are part of a single phenomenon.
The power of the jets threading between the cells is related to the pressure gradients created by the differing physical characteristics of the adjoining air masses.

Reply to  Stephen Wilde
April 6, 2017 9:02 pm

Regarding: “Zonality is associated with less clouds and global warming whereas meridionality is associated with more clouds and global cooling.”

What about hemispheric warming and cooling? Does this mean the jet stream pattern in one hemisphere would be more zonal in summer and more meridional in winter?

Reply to  Donald L. Klipstein
April 6, 2017 9:10 pm

I can see how an aspect of solar variation other than TSI and that affects cloud formation might cause the jet stream pattern to change due to change in a factor (other than temperature) that affects cloud formation. This reminds me of the “Hale winter” phenomenon that has been claimed to exist, where harsh winters have (or are claimed to have) some tendency to occur in/around England and eastern North America every other minimum of the ~11-year solar cycle.

Reply to  Donald L. Klipstein
April 6, 2017 10:28 pm

That is well established in meteorology.

Stephen Wilde
Reply to  Donald L. Klipstein
April 6, 2017 11:04 pm


Reply to  Stephen Wilde
April 6, 2017 9:15 pm

Stephen, if California was 20-25 degrees further south than it is now?. The mid west would be a tropical forest. To me the deserts of Chili and Peru along their coast lines are very similar a thin line of coastal area and the a high mountain range. Would the current jet stream pattern still hold? I am asking because of an ongoing discussion I have with a “warm” supporter that just doesn’t seem to understand the importance of these cycles and the need for water in the whole of the SW American continent to be addressed with better retention ( instead of bullet trains to nowhere), BTW do you have a site I can hook up to? Thanks.

Stephen Wilde
Reply to  asybot
April 6, 2017 11:03 pm

Lengthy changes in jet steam tracks are indeed equivalent to shifting a location latitudinally relative to the permanent climate zones.
Thus the South West USA moves between the Mediterranean climate zone and the Subtropical Desert climate zone over multidecadal periods of time such as the periods of transition between the MWP, LIA and modern warm period. That is why there are periods of lengthy extreme drought and much wetter periods in the historical records for California.

I have a site here:

Note that the latitudinal shifting of the permanent climate zones represents the Earth’s negative response to any change in radiation input to or output from the climate system. Such shifting is the process of convection correcting for radiative imbalances so as to maintain the hydrostatic equilibrium of the atmosphere at a temperature determined by atmospheric mass and the strengh of the gravitational field. Conduction from the surface to our mostly non radiative atmosphere combined with the resulting convective overturning are the true cause of the greenhouse effect, not radiative imbalances.
In so far as GHGs create a radiative imbalance the climate zones shift imperceptibly to restore balance and maintain the initial temperature.
Sun and oceans apparently shift the climate zones by as much as 1000 miles latitudinally over the course of the millennial solar cycle (MWP to LIA to date) whereas I would expect our CO2 output to require a shift of less than a mile to maintain balance.

Reply to  Stephen Wilde
April 8, 2017 10:15 pm

Thanks for the link to your site, i WILL learn!

Stephen Wilde
Reply to  asybot
April 6, 2017 11:15 pm

I should add that anything that affects global albedo will alter system temperature despite the climate zone shift because a change in albedo mimics the effect of a change in the power of the sun by altering the proportion of solar energy able to enter the oceans. Hence the importance of cloudiness changes.
GHGs would only alter system temperature in so far as they change global albedo and that seems to be insignificant compared to the effect of solar and ocean variability on global cloudiness.
The Svensmark cosmic ray hypothesis is not necessary in my hypothesis but cosmic rays do serve as a useful proxy for solar variability.

Don K
April 6, 2017 2:58 pm

A paper that admits it is speculative, doesn’t blame CO2 or global warming, for anything, and doesn’t assert that we are all gonna die if we don’t do something NOW. What’s not to like?

And I would point out that there is reasonably persuasive evidence that in the centuries before human record keeping in the Western US, there were periods of drought that lasted decades. That’s something that California and the West in general seem totally unprepared to deal.with. Anything that might shed light on that is surely worth investigating.

Reply to  Don K
April 7, 2017 12:27 pm

Don K,
Any paper that doesn’t claim ‘The science is settled’, and then stick its fingers in its ears and go ‘Na-na-na. Can’t hear you! Na-na-na!’ is to be welcomed.

As noted above, some of this is a delicate repackaging of blocking highs, etc.
But it is still, to me, research.

There are forces, and interactions, that we do not understand [some we probably do not know, ‘unknown unknowns’ as it were] – so finding out more about them will improve short-term [under four days] weather forecasting.
And if that even means I can, occasionally, not take a brolly up to London Town, with confidence, it is good.

Your last paragraph simply oozes common sense.
Has California deemed common sense an ‘endangerment attitude’ yet?
Rather than keeping population & water demand down, so encouraging good folk to leave California.
Is there method in their madness after all?

I touched down, once, in LA, on an Auckland-London Heathrow flight; returning is not on my bucket list.

Roy Spencer
April 6, 2017 3:24 pm

I don’t see much new here. This type of research goes back to the 1960s at least. Basic atmospheric dynamics. They proposed a study and had to say” something” in their report.

Stephen Wilde
Reply to  Roy Spencer
April 6, 2017 3:48 pm

Hello, Roy.
I agree that they are referring to phenomena first noticed in the 1960s. However, causation was never established and that is my area of interest which they are now tentatively exploring.
By the way, would you be kind enough to restore my posting privilege at your site?
I am now aware of your ‘trigger points’ and will endeavour to avoid them.

Another Scott
Reply to  Roy Spencer
April 6, 2017 4:02 pm

“back to the 1960s” nothing wrong with bringing it to the 2010s and trying to improve our understanding.

Reply to  Another Scott
April 7, 2017 8:31 am

Roy is correct here. I taught my first course in weather/climate in 1967. The basis of climate, especially seasonal climate, was the general circulation of the atmosphere. This paper almost seems like a reawakening in the basics after the hiatus revolving around complex ocean atmospheric modelling and the politicalization of the science. We knew the basics of semipermanent latitudinally based pressure systems, and major air masses that formed and were moved around by changes in the zonal/meridional oscillations in major wind systems. These patterns still exist – they can be followed every year – and they vary every year. Two years ago when the US had few tornadoes, the Canadian prairies had more than usual. The position of the jet, and waves in the jet simply brought the contact zone between contrasting air masses further north than typical. All the “storm chasers” were in our motels that summer (I think they may become a new indicator for meteorology). We have added a lot of knowledge over the last 40 years but have failed to tie things together.

I like the concept of top-down bottom-up influence. The interplay of the two adds a third dimension, and likely plays a role in the intensity and positioning of major pressure/wind fields. These, in turn, determine where contrasting air masses meet and produce our daily weather. Convection within an air mass adds another layer. This paper is fine but not new. It illustrates a much needed renewal of interest in basic concepts. Increasing knowledge ENSO, PDO, AMO etc., especially when newbies like “the blob” show up, eventually will fill in some blanks. At times I get the feeling we have become lost in the “physics” of climate science at the expense of moving forward with an understanding of what actually happens. The pertinent questions that physics will have to answer at some point likely will evolve from synoptic understanding. And adjusting to weather events (adaptation) will come from synoptic analysis – not theory.

April 6, 2017 3:31 pm

I thought omega,and other, blocks were already a well-known phenomenon.

Stephen Wilde
Reply to  Andrew Pearson
April 6, 2017 3:48 pm

Yes, but causation has never been properly explored.

el gordo
Reply to  Stephen Wilde
April 7, 2017 3:41 am

Stephen the subtropical ridge in the SH appears to be weakening, with low pressure troughs too far south for this time of year.

Could this behaviour be categorised as a regional cooling signal?

Stephen Wilde
Reply to  Stephen Wilde
April 7, 2017 4:10 am

In the sourthern hemisphere a cooling signal would be cold air masses moving more northward than usual in a more meridional jet stream pattern.

el gordo
Reply to  Stephen Wilde
April 7, 2017 4:57 am

OK thanks Stephen, it seems nothing unusual is happening.

Stephen Wilde
Reply to  Stephen Wilde
April 7, 2017 5:28 am

Not yet, the system currently seems in balance as evidenced by ‘the pause’. We need the sun quiet enough for long enough to cut off the supply of energy into the oceans that has been feeding the recent El Ninos.
Shouldn’t be much longer though.
The next step should be jetstream meridionality increasing further along with global cloudiness and a shift of all the climate zones towards the equator.
It is a slow, irregular process due to system inertia and chaotic variability.

el gordo
Reply to  Stephen Wilde
April 7, 2017 2:30 pm

‘…..and a shift of all the climate zones towards the equator.’

A reasonable assumption, so we can safely say BoM is wrong when they state that extra human induced CO2 is intensifying the subtropical ridge.

April 6, 2017 3:56 pm

Stationary Rossby’s? I don’t think. Seen these waves. The leave miles-long white trails criss-crossing land and cities and states from California to Texas, the east coast. And day long milky skies. Things that look like clouds, sometimes. Had to breakout a snapshot to show the kids what I meant by white puffies. And blue skies. Really blue skies. These waves are worldwide, they tell me. Got the field glass out one day and looked. Could of sworn I saw a tanker with . . . oh, wait . . . I’m thinking of something other than a Rossby . . . This weather thing is so confusing . . . sorry.

Reply to  Wrusssr
April 6, 2017 9:18 pm

Wrusssr, Did you ever see any pictures of the skies over the USA the 2 days post 911, Could be on the net but I remember for fact amazingly clear sky.

Nigel in Santa Barbara
April 6, 2017 3:57 pm

Can someone post a link to the actual NCAR study?

April 6, 2017 4:10 pm

Damn. These “Scientists” at the National Center for Atmospheric Research (NCAR) are good …

/snark and sarc

We’ve seen this ‘odd’ wave pattern since they came on the scene in 2015 when they delivered heavy record rains and numerous cold fronts (during summer) ever since here in Texas. I can’t recall a year (2016 in particular) when we had several cold (okay, ‘cool’) fronts move through the DFW area in the month of JULY.

Even my Mom in Michigan has said “this weather is screwy.”. No kidding Mom … NCAR agrees.

Reply to  _Jim
April 6, 2017 9:19 pm

Normal American weather is “acting normal” enough for people to think there is such a thing as normal American weather.

Most Americans (and many in many other countries) are in the northern temperate zone. The word “temperate” works like the word “flammable”. Flammable and inflammable mean the same thing. Temperate means intemperate, not temperant. The temperate zones, especially the northern one, are where the weather has a temper. (Elsewhere the weather has temper tantrums less often, but that still happens.)

Reply to  Donald L. Klipstein
April 7, 2017 1:12 pm

Um, no, NOT quite.

There is a reason meteorologist’s label cold fronts in Texas in July as “rare”, because, they are, “normally”. The usual extent to which they reach is as far south as Oklahoma, where they are seen by us, in Texas, to ‘die out’.


Do you understand that, have I made that clear yet?

April 6, 2017 4:49 pm

What this tells me is that there’s a finite amount of stormy weather available in the temperate latitudes whose distribution across the globe varies as standing waves of high and low pressure guide storms to particular regions, moreover; there are several meta-stable configurations of standing waves guided by the jet stream and which chaotically flip between each other.

Interestingly enough, what this is also telling me is that the standing waves are more stable at higher temperatures since the summer California pattern is more like the drought pattern and mostly constant. We aren’t talking about a few degrees C difference but the much larger difference between summer and winter in the temperate latitudes, moreover; I suspect it has more to do with increased solar energy and not the specific temperature. Also note that in the tropics where the temperatures are even warmer, the inter-tropical convergence zone guides storms in a mostly linear fashion around the equator.

It would be interesting to see the patterns in the S hemisphere and if the same 5-wavenumber behavior develops. In the S hemisphere, the temperate region is much more like an ideal water world. In addition, storm systems tend to circumnavigate the globe, much like in the inter-tropical convergence zone, so it could might be an N-wave number pattern circumnavigating the globe (most likely 5 or 7 based on relative spacings over the Pacific).

Reply to  co2isnotevil
April 6, 2017 9:31 pm

Among storms larger than individual thunderstorms, ones in or near the ITCZ tend to have different mechanics than ones that form well away from the ITCZ and outside where the tropical easterly trade winds are prevailing. Extratropical storms are fueled mostly by horizontal temperature gradient, and ones with pressure patterns big enough to put on a weather map are often associated with jet stream curves towards the equator, going equatorward around upper level low pressure areas/troughs.

Reply to  Donald L. Klipstein
April 6, 2017 10:36 pm

Yes, and ITCZ storms are mostly thunderstorms which tend operate on a vertical temperature gradient. Both mechanisms implement heat engines, the difference being whether the driving temperature gradient is horizontal or vertical. Note however, that both storm organizations are possible anywhere.

April 6, 2017 5:09 pm

Roy Spencer is correct.
I studied Rossby Waves at Texas A&M in Air Force Basic Meteorology in 1963-1964. Sometimes there is a 3-wave pattern sometimes there is a 4 wave pattern, and sometimes a 5-wave pattern.
The trick is to figure if and when there will be a pattern change. If the pattern will not change much, the weather forecasts can sometimes be good for several days to a week, even more.
Many times when the winter pattern sets up the strongest wave is over Siberia, and the Jet Stream flow out of the North Pole flows into Central Asia and they have the coldest winter temperatures in the Northern Hemisphere, for which Siberia is so famous, or infamous.
But sometimes the strongest wave sets up over Hudson Bay and the coldest winter temperatures set up over Canadian North America; this is the infamous Polar Vortex which made so much news in recent years, but it really is what we have known from student years, as Dr Roy says, the “Polar Night Vortex.”
The trick is, for everyone, ahead of time to figure how the pattern will set up and change. To my knowledge, no one has a perfect track record on predicting this.
The Climate Prediction Center tries, and I have seen some of their papers on this, to do this with mathematics and statistics. However, since the atmosphere has that chaotic nature, and because the equations of motion have numerous terms that we do not know how to solve, those “non-linear partial differential equations” eat our lunch.
This is Judith Curry’s uncertainty monster and we have been unable to solve these equations for ~200 years.
Meteorologist Joe Bastardi has a different tack: he uses a “pattern matching” technique, observing the history of previous years’ patterns and their evolution and matching this knowledge with current patterns.
I have not kept records, but it seems as if Joe is doing at least good and probably better than the pure mathematical approach that the Climate Prediction Center uses.
This is the fundamental problem we have: We can write down the equations perfectly, but we do not know how to solve them.

Reply to  Robert Endlich
April 6, 2017 6:54 pm

I appreciate your comment, as I’ve been looking for data, timeseries, etc on wavenumber history. Is there a link where that is found or determined? Thanks.

Reply to  Bob Weber
April 6, 2017 7:56 pm

These only tell how tough this is, not what you are looking for
Geophysical Fluid Dynamics Lab:
The AMS, before they got involved in human-caused CO2-fueled global warming.
Royal Society

Robert W. Endlich

April 6, 2017 8:00 pm

Links and nice intro to zonal wavenumber, and wrt solar activity.

Gary Pearse
April 6, 2017 8:35 pm

heavy tropical rains heat the upper atmosphere in ways that develop w-5 pattern.

This looks like they are on the verge of discovering Willis’s emergent thunderstorms in the tropics. Also, I’ve been flagging the Trump Effect in climate science: not a peep about CO2 or global warming, and this from Boulderdash Atmos Research.

Stephen Wilde
Reply to  Gary Pearse
April 6, 2017 10:49 pm

Willis doesn’t deal with the top down solar effect from the poles. Nor does he extend his hypothesis to bottom up shifting of the climate zones by ocean oscillations.

Johann Wundersamer
April 6, 2017 8:45 pm

strong jet streams act as wave guides when waves guide strong jet streams.


April 6, 2017 8:52 pm

One claim I have heard many times, which I doubt, is that manmade climate change is making stationary Rossby waves more of a problem.

Johann Wundersamer
April 6, 2017 9:16 pm

But the scientists cautioned that many questions remain.

“We need to search globally for factors that cause this wavenumber-5 behavior,” Teng said, “Our studies are just the beginning of that search.”

the beginning of a long journey.

April 6, 2017 9:46 pm

The ridiculously resilient ridge vs the terribly tenacious trough. There was this forecaster at KCRA in Sacramento in the 70’s, Harry Geise, who thought he had Rossby waves in the “upper atmosphere” dialed in. Wave 5 and the numbering sequence in the illustrations is not clear to me. Often there are only four Rossby waves. Here is the 250 mb map today over mean surface pressure.
comment image

I guess I can see five waves there. Even the map projection makes a difference.
comment image

Ray in SC
Reply to  gymnosperm
April 7, 2017 11:12 am

I don’t see the waves but in the first picture I do see a mermaid swimming with a manatee. Oh, and she’s topless!

Pop Piasa
Reply to  Ray in SC
April 7, 2017 4:14 pm

Yes it’s all giving me ideas for creative Easter egg decorating.

Reply to  Ray in SC
April 7, 2017 7:00 pm

I can see Elvis!

Reply to  gymnosperm
April 7, 2017 12:46 pm

I got the spelling right the third time.

Like Ray in SC, I am at all sure there are five waves in the first map.
A polar bear and a kangaroo, with big ears, attacking Easter Eggs? well, maybe . . . . .
And the second is something from ‘Phantom of the Opera’.


Reply to  Auto
April 7, 2017 12:47 pm

Like Ray in SC, I am (dammit) NOT at all sure there are five waves in the first map.



Coeur de Lion
April 6, 2017 11:14 pm

I do believe that Michael Mann’s upcoming paper on extreme events caused by CAGW brings in the Jet Stream. Perhaps we have convergence here? How wonderful!

Stephen Wilde
Reply to  Coeur de Lion
April 6, 2017 11:20 pm

Well, he would try that wouldn’t he.
To be persuasive he needs to say how CAGW changes the gradient of tropopause height between equator and poles in the manner observed.
Previously, CAGW was proposed only to shift the jets and climate zones poleward (more zonality) so I’d be interested to see how he proposes to deal with the more recent shift towards meridionality (since 2000 or thereabouts).
He also needs to explain the shifts of the climate zones that occurred from MWP to LIA when CAGW could not have been a factor.

Reply to  Stephen Wilde
April 7, 2017 1:16 am

What is the tropopause trend you indicated. Increasing in height at the equator ? Seasonal variation. ?

Stephen Wilde
Reply to  Stephen Wilde
April 7, 2017 4:05 am

Tropopause height between equator and poles should be envisaged as a pair of see-saws set end to end with one running longitudinally across each hemisphere and an independently moving joint or fulcrum near the equator.

Seasonal changes simply move the joint at the equator northward and southward each year. Lengthening one see-saw and shortening the other.

For longer term climate change the sun moves the troposphere height up or down above the poles and the ocean oscillations move troposphere height up or down above warming or cooling ocean surfaces (mostly near the equator).

The net interplay between the solar top down and oceanic bottom up influences on tropopause height causes the average gradient of tropopause height between equator and poles to be in constant flux.

That gradient determines how much physical space the tropospheric weather systems have in the vertical plane in which to operate between the equator and poles.

If the height above the poles drops relative to the height above the equator then the climate zones are pushed equatorward into a more meridional pattern.

If the height above the poles rises relative to the height above the equator then the climate zones are pushed poleward into a more zonal pattern.

Zonal results in less clouds and global warming whereas meridional results in more clouds and global cooling.

For a diagnostic indicator of global warming or cooling we need to be able to ascertain the degree of jet stream meridionality / zonality and / or the total global cloudiness.

Currently, the ongoing temperature pause implies that the height above the poles relative to that above the equator is setting a level of global cloudiness that results in neither warming nor cooling. That must change in due course.

Don K
Reply to  Stephen Wilde
April 7, 2017 7:22 am

“He also needs to explain the shifts of the climate zones that occurred from MWP to LIA when CAGW could not have been a factor.”

It has to do with tree rings and chicken entrails Stephen. Real science stuff. You wouldn’t understand. (Besides which, IIRC Mann doesn’t believe in either the MWP or the LIA.)

Reply to  Stephen Wilde
April 7, 2017 7:41 am

Thanks. This would then alter or influence the rosby waves ?

Reply to  Stephen Wilde
April 7, 2017 10:11 am

That’s a good description Stephen. The CO2 hypothesis has no explanation for the multidecadal expansion of the Hadley cells. And geopotential heights have been shown to depend on solar activity.

From Labitzke, K. (2001). The global signal of the 11-year sunspot cycle in the stratosphere: Differences between solar maxima and minima. Meteorologische Zeitschrift, 10(2), 83-90.

Stephen Wilde
Reply to  Stephen Wilde
April 7, 2017 11:09 am

Thanks Javier.
In due course I think it will be more fully appreciated as an accurate, basic description of the underlying mechanism for natural climate variability.
Maybe someone could put me in charge of a research project with a large budget ? 🙂

M Seward
April 7, 2017 3:09 am

And this is news??!! Rossby waves have been known about for how bloody long???

April 7, 2017 4:43 am

As far a prediction goes, it’s non-linear chaotic system.
We can say where it is now. We know (or can re-construct) where it has been in the past (via weather records).
But in a non-linear complex system, that says nothing about where it will be in say 2 years with any confidence.

April 7, 2017 7:05 am

Piers Corbyn has a good YouTube on Global waves

April 7, 2017 10:00 am

Precipitation in the Santa Barbara Basin has been attributed a solar control:

The GISP2 aerosol record and variation in varve thickness at ODP Site 893 show a coherent ~2750 year cycle… Varve thickness in Santa Barbara Basin has been shown to correlate with annual rainfall, which occurs mainly during winter when prevailing winds slacken… The 2750 year cycle [in varve thickness] is tentatively attributed to an underlying 2200 year cycle in atmospheric ∆14C with a switch in correlation around 7000 year BP. The correlation with atmospheric ∆14C and with 10Be implies that this cycle is also solar in origin

Nederbragt, A. J., & Thurow, J. (2005). Geographic coherence of millennial-scale climate cycles during the Holocene. Palaeogeography, Palaeoclimatology, Palaeoecology, 221(3), 313-324.

If true, the atmospheric pattern might be related to the current solar centennial minimum (SC24-25) and there could be more unusual rain patterns during the next winters for California.

“It never rains in Southern California”, unless solar activity is low.

Stan Bennett
April 7, 2017 10:54 am

The discussion here is good from a climate/science standpoint. I think, however, this was all summed up by Steinbeck in one of his books, the comment-During the wet years in California the settlers moved out of the valleys and moved into the hills, during the dry years these farms failed and people moved back to the valleys- I think the comment was in East of Eden, but it may have been in another one of his books. Pretty well summed up the drought/wet weather of California and it stuck with me.

Ian Wilson
April 7, 2017 12:48 pm

Speaking of standing waves – I published a paper about n = 4 standing waves in the Southern Hemisphere mid-latitudes that were driven by upper atmospheric lunar tides.

Wilson, I.R.G. and Sidorenkov, N.S., Long-Term Lunar Atmospheric Tides in the
Southern Hemisphere, The Open Atmospheric Science Journal,
2013, 7, 51-76

Abstract: The longitudinal shift-and-add method is used to show that there are N=4 standing wave-like patterns in the summer (DJF) mean sea level pressure (MSLP) and sea-surface temperature (SST) anomaly maps of the Southern Hemisphere between 1947 and 1994. The patterns in the MSLP anomaly maps circumnavigate the Earth in 36, 18, and 9 years. This indicates that they are associated with the long-term lunar atmospheric tides that are either being driven by the 18.0 year Saros cycle or the 18.6 year lunar Draconic cycle. In contrast, the N=4 standing wave-like patterns in the SST anomaly maps circumnavigate the Earth once every 36, 18 and 9 years between 1947 and 1970 but then start
circumnavigating the Earth once every 20.6 or 10.3 years between 1971 and 1994. The latter circumnavigation times indicate that they are being driven by the lunar Perigee-Syzygy tidal cycle. It is proposed that the different drift rates for the patterns seen in the MSLP and SST anomaly maps between 1971 and 1994 are the result of a reinforcement of the lunar Draconic cycle by the lunar Perigee-Syzygy cycle at the time of Perihelion. It is claimed that this reinforcement is part of a 31/62/93/186 year lunar tidal cycle that produces variations on time scales of 9.3 and 93 years. Finally, an N=4 standing wave-like pattern in the MSLP that circumnavigates the Southern Hemisphere every 18.6 years will naturally
produce large extended regions of abnormal atmospheric pressure passing over the semi-permanent South Pacific subtropical high roughly once every ~ 4.5 years. These moving regions of higher/lower than normal atmospheric pressure will increase/decrease the MSLP of this semi-permanent high pressure system, temporarily increasing/reducing the strength of the East-Pacific trade winds. This may led to conditions that preferentially favor the onset of La Nina/El Nino events.

April 7, 2017 1:24 pm

It would appear that the many “laymen” posting above sincerely believe “the jet stream” to be an entity which is able to exist alone and solely by itself, without support from other determining factors such as associated Rossby constructs (waves) and associated low pressure systems.

I do hope this is NOT actually the case.

April 7, 2017 6:55 pm

High and low pressure systems are an artefact of the Global Electric Circuit.

“Point 1 Together, the earth’s surface and the ionosophere resemble a charged spherical capacitor, i.e. two oppositely charged conducting electrodes with an insulator in between. The ground is normally negatively charged during fair weather. Positive charge is found in the air between the ground and the ionosphere (the charge would normally be found on the second electrode in a typical capacitor). The positive charge is attached to small particles in the air (aerosols) and is relatively immobile (compared to air molecules due to the large size and large inertia of the particles). These are called “large ions.” Most of the positive charge is found near the ground. ”

Patrick MJD
April 8, 2017 12:47 am

“Scientists link California droughts and floods to distinctive atmospheric waves”

Seriously, they link weather events to the atmosphere? WHOA!!! Where can I find a paid job like that?

Chuck Bradley
April 8, 2017 7:51 am

If I get around to reading the actual papers, I will look for data about where and how much wet there was when CA was dry, and where and how little wet there was when CA was wet.

Gary Palmgren
April 8, 2017 7:57 am

My takeaway from this is that they found a 5 node Rossby wave pattern tends to be stationary. When the pattern is stationary, the weather in the hemisphere remains stable with some areas getting lots of rain and others getting drought. A shift in the phase, changes which areas are wet and and which are dry.

It is almost a tautology, one would would predict a stationary Rossby wave during unusually protracted wet or dry patterns. The recognition of a five node pattern seems to be new. It might be used to predict extended periods of rain or drought when it appears. They need to be bold and make predictions to test the hypothesis. Using the limited historical data is just curve fitting.

April 9, 2017 4:46 am

See what sending out them negative waves did, Moriarty?

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