Blocking highs contribute to unusually hot July in the Great Plains

From NASA Goddard, something reminiscent of last year’s blocking high for the heat wave in Russia.

NASA Satellite Observes Unusually Hot July in the Great Plains

Andrey Savtchenko and Adam Voiland NASA’s Goddard Space Flight Center, Greenbelt, Md.

Much of the United States sweated through an unusually humid heat wave during July, a month that brought record-breaking temperatures to many areas across the Great Plains. As temperatures soared, NASA satellites observed the unusual weather from above.

The Atmospheric Infrared Sounder (AIRS), an instrument launched on the Aqua satellite in 2002, is unique in its ability to yield highly accurate data about the troposphere, the lowest layer of the atmosphere and the part that most directly affects life on Earth.

Hot temperatures struck Texas and Oklahoma particularly hard, AIRS observed. Large swaths of both of these states persistently experienced highs above 100° F (311 K) during the day for the month of July. Nights offered only minimal relief with low temperatures averaging close to 90° F (305 K) for the month. That’s about 20° F warmer, both day and night, than the average July temperatures for the past eight years of AIRS observations.

surface temperature anomaly maps Night and day time temperatures during July were significantly warmer than has been typical over the last eight years. As seen in the top graphic, the heat remained anonymously over much of the country at night. (Credit: NASA/Goddard Earth Science Data and Information Center)

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AIRS also offered clues about what may have caused the persistent heat spell. Domes of high atmospheric surface pressure (corresponding to the red colors in the figure below) normally intensify in the summer over both the Atlantic and Pacific oceans. However, AIRS data shows they were abnormally strong in July.

atmospheric surface pressure map An area of high pressure in the North Atlantic likely helped fuel the heat wave. (Credit: NASA/Goddard Earth Science Data and Information Center)

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Meanwhile, AIRS data for the month of July (below) reveals a clock-wise vortex of winds (shown with arrows beow) driven by the high pressure in the North Atlantic. The vortex continuously pumped hot and humid air from the tropics through the heart of the Gulf of Mexico and into much of the continental United States throughout July.

wind map from AIRS data Note the hot tropical air being pumped towards Texas and Oklahoma. (Credit: NASA/Goddard Earth Science Data and Information Center)

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The jet stream, which typically produces loops around low-pressure areas that break off and brings cooler air and precipitation, offered little relief. As seen below, the flow of the jet stream (approximated by green and yellow) instead consistently bulged over the high-pressure aloft over the United States (shown in red).

AIRS jet stream map Note the unusual bulge in the jet stream over the center of the country. (Credit: NASA/Goddard Earth Science Data and Information Center)

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AIRS data are distributed by the Goddard Earth Sciences Data and Information Services Center at NASA Goddard Space Flight Center, Greenbelt, Md. AIRS is managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena. GOES-5 is a product of the Global Modeling and Assimilation Office at Goddard Space Flight Center.

Related Links

› NASA Data Reveals Anomalously Hot Summer

› About the Goddard Earth Sciences (GES) Data and Information Services Center (DISC)

› About the Atmospheric Infrared Sounder (AIRS)

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August 31, 2011 3:55 pm

I spent 3 July weeks in Nebraska. The heat didnt bother me, it was the humidity

Peter Miller
August 31, 2011 4:02 pm

While northern and western Europe has had one of the coolest summers on record.
I guess it’s either weather or climate which is to blame.
Of course, alarmists will ignore Europe and concentrate their scare stories on events in the eastern US and Canada. Also, Europe didn’t have any hurricanes this summer!! Mind you, it rarely does.

Theo Goodwin
August 31, 2011 4:03 pm

Yep, I have seen this before, especially in the period 1980-85 or so. The culprit is high pressure that will not move. Texas and Oklahoma roasted this year as they have before. It is not unprecedented by any means. However, the colors on this map do not tell an accurate tale.
St. Louis enjoyed a moderate to cool summer, as did every city north of St. Louis. For two weeks in mid-August, St. Louis temperatures ran in the high 80s. That is May weather for St. Louis. August in St. Louis usually runs above 90 for the entire month. I expect a return to severe winters.

August 31, 2011 4:08 pm

WHat? It’s not global warming? Say it ain’t so….

August 31, 2011 4:27 pm

So is this weather pattern just random variation or does it have a cause and therefore is likely to return at increased frequency?

August 31, 2011 4:36 pm

Perhaps it would be good to get a comment from Anthony Lupo. He is an expert on Blocking and maintains an archive of events of blocking here And occasionally provides some commentary for ICECAP.

August 31, 2011 4:58 pm

Meanwhile, the same data show that western third of the continental US has been experiencing consistently cooler weather. No mention of unusual widespread coolness by Andrey Savtchenko and Adam Voiland of NASA’s Goddard Space Flight Center?
If we include Alaska in the cool weather part of the US, then more like half the US has been cooler even though half has been warmer. What a stunner of unusual climate.
I’ve been experiencing the cooler west coast, and it’s very noticeable. We’ve had very few of the shorts-and-t-shirt evenings characteristic of mid-to-late Summer (San Francisco excepted. SF never has shorts-and-t-shirt evenings in the Summer).
One also wonders about that isolated little pink pixel in California’s day-time Mohave Desert record (Plate 2). Maybe it’s the record of one of the more sterling climate stations assessed by the WUWT volunteer brigade?

Theo Goodwin
August 31, 2011 5:06 pm

“The vortex continuously pumped hot and humid air from the tropics through the heart of the Gulf of Mexico and into much of the continental United States throughout July.”
Maybe “The vortex” is some special deal, but there is a pump into LA, MS, AL, GA, and FL that works all year around. For example, if Memphis is hit by a cold front in January, the warm air from the Gulf will recover its ground in 48 to 72 hours, except on some rare occasions. Growing up in Atlanta, I had not encountered packed snow on a sidewalk until moving to St. Louis in my twenties. For Southerners, someone needs to explain what is special about warm air pumped from the Gulf.
And, yes, that pump from the Gulf explains one half of the forces that make the area from LA through GA a tornado alley.

August 31, 2011 5:13 pm

And here in the PNW and N. California, we had a very cool summer.
In most places in N. CA, we had the coolest summer on record, period.
Nothing is moving, and the 4 Corners H. Pressure cell is beaten back to the Southwest from it’s normal position.

August 31, 2011 5:43 pm

Searingly Hot in the Great Plains, kind of like when Lewis and Clark trudged though it.

James Sexton
August 31, 2011 5:59 pm

NASA Satellite Observes Unusually Hot July in the Great Plains!!!!!! —————– Released on the 31st of August. 😐
All they had to do was call and ask me about the weather. They could have gotten that information out ……hmm, let’s see……… uhmm oh I dunno, about a month and half earlier!! And we’re worried about funding the NWS? I’m thinking there’s a bit more savings to be had elsewhere.
BTW, the heat experienced in SE Kansas was right at the same as 1980. I remember it well. My first year in recollection without A/C.

J. Felton
August 31, 2011 5:59 pm

Peter Miller says
“While northern and western Europe has had one of the coolest summers on record.”
* * *
Add Western Canada to that as well. I live on the West Coast and the weather has been nothing but rain and fog up until mid August. Same with friends up North.
But newspapers here kept bringing up articles about how hot it was, until somebody finally showed them that their ” Country Wide heat wave” was anything but.

August 31, 2011 6:11 pm

“the heat remained anonymously …”
Ah yes. The heat that dare not speak its name.
(But I’ll tell you its name: Weather.)

Anything is possible
August 31, 2011 6:19 pm

You’ve got to love the way the Mercator projection makes Greenland look bigger than the USA, when it is actually less than a quarter of the size. It lets Jim run amok with his pink crayon all over the Arctic, even though there is very little data up there…..
It’s all about presentation, people!

Don K
August 31, 2011 6:33 pm

Daytime temperatures of 100F are twenty degrees warmer than normal in Texas? Have the folks who wrote this press release ever been to Texas or Oklahoma in the Summer? I know the region has had a hot Summer and I sympathize with the folks there. But their normal Summer is searingly hot. Wikipedia tells me that the monthly average highs in Austin in July and August are around 95F. If anything, that seems a bit low.

August 31, 2011 6:36 pm

Pat Frank-I think that’s a pretty typical La Nina pattern. For the Continental US, much of the US is warming during a La Nina, but the West/Left Coast tends to be cool, especially the Pacific Northwest.
As for Alaska, that is also the typical pattern for a La Nina. The States along the Pacific in the US are very responsive to fluctuations in Pacific temperature patterns. Notice the Huge swing in temperatures Alaska experienced in 1976-77 at the time of the “great Pacific Climate Shift”:
It is associated with a general shift to stronger El Nino tendency at that time. La Nina on the other hand, cools Alaska, so a relative absence of them produced a warmer regime in Alaska.

August 31, 2011 6:51 pm

I was wondering if this same sort of heat bubble setup in Texas could be remotely related to the event that happened last year in western Russia.
When things are moving less progressively (some say teleconnections slow down in solar mins) there is the tendency toward more extremes…more extreme heat and cold.
Norfolk, VA, USA

August 31, 2011 6:59 pm

Yabut, look at the high arctic day & night!

Bernie McCune
August 31, 2011 7:08 pm

The blocking high pressure has shut down our normal August monsoons here in southern New Mexico again. It was also bad a couple of summers ago. But we along with Texas are now experiencing extreme drought conditions. Arizona and even northern NM are still in a monsoonal flow so it is localized. We’ve had no tropical storms remnants from the Gulf of Mexico nor the tropical Atlantic giving us any relief. It’s like some giant door out there has slammed shut and stopped all this moist flow into the area.
It probably can be blamed on climate (tropical cycles) as we had some very serious drought conditions here in the southwest before in the 1950s. To me periods greater than 30 or 40 years are climate significant. Those of 4 or 5 to 10 years are probably weather.

August 31, 2011 7:13 pm

This is interesting, thanks Anthony – and am wondering why there hasn’t been more screaming from the CAGW crowd about TX-OK ‘blocking high’ as per Russia. Its real I think – and these maps help document; confirmation bias perhaps – but it sure is hot in Texas. And its going to take a long time to recover…

Bernie McCune
August 31, 2011 7:17 pm

Oh and clouds do make a difference. Normally we get lots of rain and clouds in August so that temperatures are very rarely in the 100s. This year and two years ago we had weeks of 100 or very near 100 temps (no clouds lots of sunshine). I think Willis’ regulator is correct but unfortunately it is broken here in southern NM this year.

Mike McMillan
August 31, 2011 8:07 pm

savethesharks says: August 31, 2011 at 6:51 pm
I was wondering if this same sort of heat bubble setup in Texas could be remotely related to the event that happened last year in western Russia.

Careful, sharky. Them’s mighty close to fightin’ words.
Mike in Houston

B. McCune
August 31, 2011 9:04 pm

I should have said we have had no tropical Pacific storms either (rather than tropical Altlantic).

August 31, 2011 9:57 pm

Hottest July in Oklahoma history also hottest in U.S. history
This pattern happens as La Nina goes neutral. But this time it was stronger than what I’ve seen in the past. It was a bitter, snowy winter south of Branson, MO in Arkansas. I lost pines to 6ft and a number of arborvitae to the heat wave. Will have to wait and see about some large hardwoods. Still, it was not quite like Oklahoma. Everything got hit hard there. Thought I was going to be able to wade clear across a wide part of Lake Eufaula.
I still see a set up like the 1930’s. If volcanic drops from comparable levels then willingly shall change my mind.

August 31, 2011 11:25 pm

IIRC, there was also a period a few years ago in which Las Vegas had a heat wave – also tied into a blocking high.
Can’t remember the year – and the report was hidden in a seasonal summary. Wish I had kept a record of where I saw it. It seems to fit in perfectly with this post.
Gives me something to look for…

September 1, 2011 2:41 am

“The vortex continuously pumped hot and humid air from the tropics through the heart of the Gulf of Mexico and into much of the continental United States throughout July.”
There you have your problem. moist air is like a blanket. It does not let the heat escape from your body and in the same way it lets not escape the heat from the surface. People near a warm sea know the difference (I live in Barcelona) if the wind comes from sea or from land specialy during the night. If the night is warmer the day starts warmer so it is not difficult to get higher average temperatures. It is ‘bad’ for us but plants love it The problem for a plant is hot dry air.

John Marshall
September 1, 2011 2:49 am

We have had a high pressure region over the UK for the past few days with well below average temperatures and 8/8ths cloud cover due to— over convection. That is a new one on me since convection is a temperature controlled heat loss situation how ‘over convection’ occurs I have no idea. More like a quiet sun and less energy flowing down to the surface.

Stephen Wilde
September 1, 2011 3:23 am

More blocking means a cooling global climate system.
Less blocking means a warming global climate system.
Measuring the point of balance where one segues into the other is the real task for the future.

September 1, 2011 5:34 am

In contrast, N Europe has had one of the coldest summers of the last 20 or 30 years.
Also, noticed on BBC Breakfast show. Presenter to weatherman:
“What’s happened to your Global Warming? – Oh, I am not supposed to ask that, am I?”
Typical of the Biased Broadcasting Corporation’s guidelines.

Pull My Finger
September 1, 2011 6:02 am

Not to be a tool, but that isn’t a mercator projection. Greenland looks much, much larger in a mercator which maintains true bearing between any two points, making it outstanding for navigation. I’m pretty sure the above map a Miller Cylindrical which is similar to a mercator in that it is a cylindrical projection, but it compromises true direction (rhumb line) to reduce magnitude distortions at the high latitudes. Using inappropriate projections is a huge pet peeve of mine. It’s very, very easy to distort the truth with maps.
But yes, you’re correct in that it is a terrible projection to use for this purpose. There are numerous projections that are much more appropriate for displaying a continental map and there is software that can change projections in a matter of milliseconds these days. Back in the early days of computers changing projections was a monumental task.

Anything is possible says:
August 31, 2011 at 6:19 pm
You’ve got to love the way the Mercator projection makes Greenland look bigger than the USA, when it is actually less than a quarter of the size. It lets Jim run amok with his pink crayon all over the Arctic, even though there is very little data up there…..

Pull My Finger
September 1, 2011 6:04 am

Here’s a really good resource for map projections. Used the hard copy to train new employees back when I worked in a map library.

Pamela Gray
September 1, 2011 6:35 am

I’m reading “Battle Cry Of Freedom”, a very thorough chronicle of the Civil War, penned by James McPherson. It covers the decades before and I am assuming, after the Civil War as well as the war itself. There is mention here and there of hot weather similar to the above. I would not say this is unusual. It is easily explained and happens not unusually during La Nina and La Nada conditions under the cold regime we apparently are in regarding ENSO long term oscillations. It includes the cold in the western portions of the US.

September 1, 2011 7:26 am

Here in Oklahoma, we set a national record in July, 2011 with an overall average temperature of 89.1F degrees, 2 degrees higher than Texas during the same month. 89.1F is the highest monthy average ever recorded in the US, beating out interestingly enough the old record set in the 1950’s by…Oklahoma.
I guess we just can’t catch a break.

September 1, 2011 7:29 am

The heat in the great plains may have been caused by the exceptionally dry winter we had here in Texas. Soil conditions in April resembled those normaly found only in August. Lack of humidity means increased solar insolation. By June the ground the ground was too hot to walk barefoot on and my tap water was warm enough to shower in without using hot water.

September 1, 2011 8:53 am

I concur, Ack. It isn’t the heat that has been terrible, it’s been the humidity.

September 1, 2011 9:04 am

This is what Piers Corbyn predicted was it not?
See my special Piers corbyn page at the website
linked to the name “Axel” above. Click it now !
Choose Corbyn Vs Met Office page from the
Quick Page Menu button. (top left of each page)

Interstellar Bill
September 1, 2011 9:30 am

Can we stop calling temperatures ‘hot’ or ‘cold’?
Temps are numbers, that is to say abstract objects,
not physical, heat-generating objects.
It’s the air that’s hot or cold, humid or dry.
Temps are high or low, which are merely metaphors for greater or lesser.

Theo Goodwin
September 1, 2011 10:05 am

Interstellar Bill says:
September 1, 2011 at 9:30 am
Well said! But the idiom rules. We will never eliminate “The temperature here is freezing!” And that is OK with me. (TV meteorologists are another matter entirely. They should know better and speak better.)

Theo Goodwin
September 1, 2011 10:11 am

Stephen Wilde says:
September 1, 2011 at 3:23 am
“More blocking means a cooling global climate system.
Less blocking means a warming global climate system.”
Do you have the evidence near at hand? In other words, could you elaborate a bit?

September 1, 2011 11:17 am

I planted a row of Leland Cypress as a wind break because I’m at 2200 ft. up on a ridge and the winter wind is a bear. In 6 years many of them are 18-20 ft. tall, they grow fast and are as tough as the Mohorovičić Discontinuity! The big ice storm of 2009 didn’t break them down. Heavy snowstorms and this drought didn’t bother them at all. They are a perfect snow fence, catching the blowing snow into a drift. I’m going to plant some more of them for sure.

Stephen Wilde
September 1, 2011 12:10 pm

Theo Goodwin says:
September 1, 2011 at 10:11 am
“Do you have the evidence near at hand? In other words, could you elaborate a bit?”
Sure, here you go:

September 1, 2011 1:00 pm

As usual the extrapolation of some NE Canada and certain Northern Europe stations makes the whole Arctic have a supposed “positive anomaly.”

September 1, 2011 2:30 pm

Yes, Texas gets hot in the summer, but it is unheard of (since record keeping started) for the Panhandle to be so hot for so long. This area varies in altitude from 2000 – 5000 feet and while we may get into the 100s for a few days, to go into the 100s for over 50 days (Amarillo) or close to 100 days (Childress, in the southeastern Panhandle just off the edge of the Llano Estacado Plateau) is exceedingly unusual. The drought has contributed to this heat and the two reinforce each other’s effects under the capping effect of that persistent high. The closest similar period I’ve found was in the 1850s-1860s, and that lasted almost 15 years, if the proxy data and peripheral records are correct. The 1950s are another similar episode, but even then there was more rain than the area has seen this water year.
I’m looking forward to a change!

September 1, 2011 6:25 pm

Given its religious nature, global warming isn’t very omnipresent, is it? Texas one year, Moscow another, Victoria in Oz the year before.
Anyone would think it was just weather, rather than a well-mixed irreversible turning-up of the control knob.

Jon Hutto
September 2, 2011 6:48 am

I wish, oh how I wish, they would not say “than normal” when referring to weather. on a day when the sun is shining, what they call ‘Warmer than normal’ is warmer than an average of sunny days, rainy days, days with a low pressure cell, days with whatever else happening. Not warmer than a normal sunny day.

September 2, 2011 7:12 am

Is the weather finally cooling off in Texas? The long-range forecasts are predicting lower temps by the start of next week.

Dave Springer
September 2, 2011 10:23 am

I’m smack dab in the center of the “heat wave” and while air temperature has been high the water temperature of Lake Travis is not abnormally high. It’s 88F at surface behind the dam (200 feet deep water there) and that’s quite normal for this time of year. I’ve seen it get to 89F in less remarkably warm summers.
The explanation for this dichotomy is pan evaporation rate. The abnormally warm air is also abnormally dry air. This raises the pan evaporation which cools the water.
This is little solace for the oppressive heat except for aquatic species which prefer cooler water but it underscores a very important point. The primary means of heating a deep body of water is sunlight during the day and the primary means of cooling is evaporation that goes on 24 hours a day.
This is true for deep inland lake whose shore I live upon and it’s true for the 70% of the earth’s surface covered by the global ocean. There is very little greenhouse gas effect over the ocean because of the different way that water is heated and cooled versus land. So-called downwelling long wave infrared reflected back to the surface by GHGs does not significantly slow down the rate of heat loss. DLIR is completely absorbed by a skin layer of water just a few micrometers deep. This absorbed energy doesn’t mix downward for a number of reasons including warmer water is less dense and rises to the surface to viscosity in the skin layer being the dominant force. All the DLIR does is raise the pan evaporation rate which actually helps cool the water by speeding up the transport of energy in latent heat of vaporization from surface to cloud where the energy is released.
This is behind so-called “missing heat” that should be in ocean according to GHG narrative but cannot actually be located. The so-called missing heat never entered the ocean in the first place but was rather transported very efficiently by water vapor rising to form clouds. Once that energy has been transported to the cloud layer then the DLIR coming from the cloud is actually impeded from reaching the surface by the GHGs between cloud and ground. GHGs are insulators and the same GHGs that insulate surface against IR cooling will also insulate the surface from DLIR coming from a warm cloud.

Dave Springer
September 2, 2011 10:34 am

TXRed says:
September 1, 2011 at 2:30 pm
“Yes, Texas gets hot in the summer, but it is unheard of (since record keeping started) for the Panhandle to be so hot for so long.”
All due to a high pressure ridge that parks itself over Texas when the Pacific ocean surface is abnormally cool. Cool moist Pacific air coming in from left coast that would normally give us rain and cooler temperatures is shunted up over the top of Texas and thus it’s as abnormally cool and wet well above Texas as it is hot and dry within Texas.
Kind of hard to reconcile record cooling in the Pacific with record level of CO2 in the atmosphere isn’t it? That would cause cognitive dissonance in my mind but evidently for the AGW bandwagon it’s no problem to ignore the facts which contradict your beliefs.

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