Are atmospheric flow patterns favorable for summer extreme weather increasing?

By: Dr. Jeff Masters , 2:45 PM GMT on March 11, 2013

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In 2010, Russia baked through its most intense heat wave in recorded history, one that killed over 55,000 people. At the same time, intense rains deluged Pakistan, bringing that nation its worst natural disaster in its history. The following year, it was the United States' turn for extreme heat, as the nation sweltered through its third hottest summer on record, and Oklahoma suffered the hottest month any U.S. state has ever recorded. The U.S. summer of 2012 was even more extreme. Only the Dust Bowl summer of 1936 was hotter, and drought conditions were the most extensive since the 1930s. All of these events--and many more unusually extreme summer months in recent decades--had a common feature, said scientists at the Potsdam Institute for Climate Impact Research (PIK) in Germany, in a research paper published in March 2013 in Proceedings of the National Academy of Sciences. According to the authors, "each time one of these extremes struck, a strong wave train had developed in the atmosphere, circling the globe in mid-latitudes. These so-called planetary waves are well-known and a normal part of atmospheric flow. What is not normal is that the usually moving waves ground to a halt and were greatly amplified during the extreme events. Looking into the physics behind this, we found it is due to a resonance phenomenon. Under special conditions, the atmosphere can start to resonate like a bell. The wind patterns form a regular wave train, with six, seven or eight peaks and troughs going once around the globe". Using a complex theoretical mathematical description of the atmosphere and 32 years of historical weather data, the scientists showed that human-caused global warming might be responsible for this resonance phenomenon, which became twice as common during 2001 - 2012 compared to the previous 22 years.


Figure 1. Drought-damaged corn in a field near Nickerson, Nebraska, Aug. 16, 2012. The great U.S. drought of 2012 was the most extensive U.S. drought since the 1930s Dust Bowl. Damage from the 2012 drought is at least $35 billion, and probably much higher. The associated heat wave killed 123 people, and brought the U.S. its second hottest summer on record. (AP Photo/Nati Harnik)


Figure 2. Business was slow at the Lake Conroe, Texas jet ski rental in 2011, thanks to the great Texas drought and heat wave of 2011. Texas endured its driest 1-year period on record in 2011, and had the hottest summer ever recorded by a U.S. state. July 2011 in Oklahoma was the hottest month any U.S. state has ever recorded, and the contiguous U.S. had its third hottest summer on record. The total direct losses to crops, livestock and timber from the drought, heat wave, and record fires of the summer of 2011 are estimated at $12 billion, with a death toll of 95. Image credit: wunderphotographer BEENE.


Figure 3. Tourists wear protective face masks as they walk along the Red Square in Moscow, Russia on Aug. 6, 2010. Moscow was shrouded by a dense smog that grounded flights at international airports and seeped into homes and offices, due to wildfires worsened by the city's most intense heat wave in its history. The heat wave and fires during the summer of 2010 killed over 55,000 people in Russia and decimated the Russian wheat crop, causing global food prices to spike. (AP Photo/Mikhail Metzel)

Two fundamental atmospheric flow patterns may be resonating more often due to global warming
Earth's atmosphere has two fundamental patterns. One is a series of wave-like troughs and ridges in the jet stream called planetary (or Rossby) waves, which march west-to-east at about 15 - 25 mph around the globe. The other pattern behaves more like a standing wave, with no forward motion, and is created by the unequal heating of the equatorial regions compared to the poles, modulated by the position of the continents and oceans. A number of papers have been published showing that these two patterns can interact and resonate in a way that amplifies the standing wave pattern, causing the planetary waves to freeze in their tracks for weeks, resulting in an extended period of extreme heat or flooding, depending upon where the high-amplitude part of the wave lies. But what the Potsdam Institute scientists found is that because human-caused global warming is causing the Arctic to heat up more than twice as rapidly as the rest of the planet, the two patterns are interacting more frequently during the summer. During the most recent eleven years, 2002 - 2012, there were eight Julys and Augusts that showed this unusually extreme resonance pattern (this includes the U.S. heat wave of July - August 2012.) The two previous eleven year periods, 1991 - 2001 and 1980 - 1990, had just four extreme months apiece. Global warming could certainly cause this observed increase in the resonance phenomenon, but the researchers cautioned, "The suggested physical process increases the probability of weather extremes, but additional factors certainly play a role as well, including natural variability. Also, the 32-year period studied in the project provides a good indication of the mechanism involved, yet is too short for definitive conclusions. So there's no smoking gun on the table yet--but quite telling fingerprints all over the place."



Figure 4. The northward wind speed (negative values, blue on the map, indicate southward flow) at an altitude of 300 mb in the mid-latitudes of the Northern Hemisphere during July 2011 and July 1980. July of 2011 featured an unusually intense and long-lasting heat wave in the U.S., and the normally weak and irregular waves (like observed during the relatively normal July of 1980) were replaced by a strong and regular wave pattern. Image credit: Vladimir Petoukhov.

Commentary
The new Potsdam Institute paper gives us a mathematical description of exactly how global warming may be triggering observed fundamental changes in large-scale atmospheric flow patterns, resulting in the observed increase in unusually intense and long-lasting periods of extreme weather over the past eleven years. The paper also adds important theoretical support to the research published in 2012 by Dr. Jennifer Francis of Rutgers University, which found that the amplitude of Earth's planetary waves had increased by over 100 miles (161 km) in summer over the past decade in the Northern Hemisphere. Dr. Francis theorized that this change was connected to increased heating of the Arctic relative to the rest of the Earth, due to the observed decline in late spring Northern Hemisphere snow cover. Humans tend to think linearly--one plus one equals two. However, the atmosphere is fundamentally non-linear. What may seem to be modest changes in Earth's climate can trigger unexpected resonances that will amplify into extreme changes--cases where one plus one equals four, or eight, or sixteen. In some cases, when you rock the boat too far, it won't simply roll a bit more, it will reach a tipping point where it suddenly capsizes. Similarly, human-caused global warming is capable of pushing the climate past a tipping point where we enter a new climate regime, one far more disruptive than what we are used to.

Julys and Augusts since 1980 when quasiresonant extreme conditions were observed
The Potsdam Institute's research lists sixteen July and August periods since 1980 that have had extreme atmospheric flow patterns due to quasiresonance. These months featured severe regional heat waves and destructive floods in the Northern Hemisphere midlatitudes, detailed below. Half of these months occurred in the most recent 11-year period, 2002 - 2012. During most of these extreme months, there was not a moderate or strong La Niña or El Niño event contributing to the extremes. Summers when a La Niña or El Niño event was present are listed in parentheses, based on the Oceanic Niño Index (ONI).

July and early August 2012: Catastrophic floods in China and Japan, as well as record-breaking temperatures during heat waves in the United States and southern Europe (weak summer El Niño)

July 2011: Record heat wave in the United States, resulting in the fourth warmest July on record nationally and the driest conditions in the southern United States ever (weak summer La Niña)

July/August 2010: Russian heat wave and the Pakistan flood, with the strongest and most persistent extreme weather conditions and the highest death tolls from heat waves and floods ever for these two regions (strong summer La Niña)

July 2006: Temperatures higher than 100°F for only the second time in Britain’s history and much of Europe experiencing a serious heat wave (weak summer El Niño)

August 2004: Much of northern Europe hit by very low winter-like temperatures and sporadic snowfalls (moderate to strong summer El Niño)

August 2003: European summer 2003 heat wave, causing a highly persistent drought in western Europe (weak summer El Niño)

August 2002: Catastrophic Elbe and Danube floods (strong summer El Niño)

July 2000: Destructive floods in northern Italy and the Tisza basin and a simultaneous heat wave in the southern United States, smashing all-time high-temperature records by that time at many sites (strong summer La Niña)

July/August 1997: Disastrous Great European Flood, which caused several deaths in central Europe, and the destroying floods in Pakistan and western United States (strong summer El Niño)

July 1994: Very strong heat wave in southern Europe, with a national temperature record of 47.2°C set in Spain (weak summer El Niño)

July 1993: Unprecedented great flood in the United States that reigned over the country from April (weak summer El Niño)

July 1989: Unusually intense and unprecedented widespread drought in the United States (weak summer La Niña)

August 1987: Severe drought in the southeastern United States (strong summer El Niño)

August 1984: Continuation of the severe heat of summer 1983, with serious drought in the United States (weak summer La Niña)

July and August 1983: Very dry conditions, severe heat, and substandard crop growth (5–35% below normal) in the Midwest United States (weak summer El Niño)

Links
Petoukhov, V., Rahmstorf, S., Petri, S., Schellnhuber, H. J. (2013), "Quasi-resonant amplification of planetary waves and recent Northern Hemisphere weather extremes" Proceedings of the National Academy of Sciences, (Early Edition) [doi:10.1073/pnas.1222000110]. No subscription required, but understanding this article requires a graduate-level understanding of the mathematical theory of atmospheric dynamics. Try reading instead this easy-to-read description of the paper by the authors, published at http://theconversation.edu.au.

Press release issued in March 2013 by the Potsdam Institute for Climate Impact Research (PIK), "Weather extremes provoked by trapping of giant waves in the atmosphere."

In this 40-minute lecture presented in 2013 at the University of Arkansas, Dr. Jennifer Francis of Rutgers University explains the linkage between warming in the Arctic due to human-caused global warming and an observed shift in Northern Hemisphere jet stream patterns.

Linking Weird Weather to Rapid Warming of the Arctic, a March 2012 article by Dr. Jennifer Francis in the Yale Environment 360.

Francis, J.A., and S.J.Vavrus, 2012, "Evidence linking Arctic amplification to extreme weather in mid-latitudes", GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L06801, doi:10.1029/2012GL051000, 2012

Jeff Masters

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Quoting VR46L:


Rookie , I never meant a slight on you , I really didn't !

Its just that I am of the opinion that when people talk of reducing CO2 they really should in their own life practice what they preach . And I don't believe it is trollish , I have seen several good weather bloggers ask this Question , But you are one of the few that will disclose . I believe it sets an example and leans more credence to your argument. Personally I read your posts and take them on board . To me you are an example of you can catch more flies with honey than vinegar (ie People who are not believers that it is 100% man fault would be more inclined to read your point of view than those who tend to be insulting and patronizing)


No worries, VR46L. We have had enough conversations that I did not take anything in a negative way because I knew you do not intend it to be negative. You are inquisitive on many subjects and this will serve you well. Never be reluctant to learn more than what you know now. The best way I found to learn is through conversations with others. ... Talking to myself never got me anywhere that didn't involve men in white smocks and carrying butterfly nets. :)

Member Since: August 24, 2010 Posts: 0 Comments: 4745
662. etxwx
Quoting Some1Has2BtheRookie:


I believe that what bappit is saying that no one individual's efforts will help to mitigate the CO2 on a global scale. When someone asks, "Well, what are you doing to mitigate the CO2?" is trolling. (Look up the definition of "blog troll")


(Edited Rookie's post to just address the above part.)
For me, it often boils down to the way the question is worded. On a written forum, people have no facial expressions or body language to read to help them interpret the person's intent or tone. If someone says "I'm curious to know what individuals can do to reduce their carbon foot print. Do you have some examples?" it carries a different tone than "Well, what are you doing to mitigate the CO2?"
Member Since: Posts: Comments:
If only we could live in the world of the 15-day GFS forecast. I would love to see this. Look at the high-quality moisture this thing would be tapping into.

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Quoting MAweatherboy1:
18z GFS showed a rather curious system form over the Gulf of Mexico at the end of the run today. It starts out as a weak low here:



Then becomes a slightly stronger storm as it approaches and crosses over FL:







Is there any way the system depicted there could be tropical/subtropical? Or am I just way to anxious for hurricane season, lol?

Notice the gradient of 500 mb heights that pass through the system. That's a tell-tale sign of a baroclinic system.
Member Since: Posts: Comments:
659. VR46L
Quoting Some1Has2BtheRookie:


I agree with you that one should be willing to practice what they preach. You have no idea of what I do on a personal basis and your asking me what I do by means of a blog sight is bit pointless, do you not agree? I could tell that I ride a bicycle everywhere I go, but I do not.

Here is what I "preach":

1. Consume less.

2. Plan trips for the shortest route and combine as many errands as possible into one trip.

3. Recycle all that I can.

4. Repair what is repairable instead of discarding.

5. Donate what is still unusable but I no longer need or want.

6. Adjust your thermostat.

7. Keep your tires properly inflated.

8. Keep your vehicle(s) properly tuned.

9. Drive within the speed limit.

10. Replace your car with a more mileage efficient car when it your car is due to be replaced.

11. Replace incandescent light bulbs with CFL or LED bulbs.

12. Wash clothes in the coldest water possible.

13. Wash a full load of clothes at a time without over loading the washer.

14. Dry clothes no longer to get them dry.

15. Do not completely dry clothes that will be hung in a closet.

What do I actually practice? ALL of the above.

What do I plan to further do to lessen my carbon footprint? I am always looking for ways to further reduce my carbon footprint.

I find it very interesting that you that lower your carbon footprint even though you do not seem to believe there are reasons to do so in order to mitigate the CO2 emissions. Perhaps you have discovered what I have? When you do these things it saves you a lot of money! Should this be incentive to do so, then this is incentive enough.


Rookie , I never meant a slight on you , I really didn't !

Its just that I am of the opinion that when people talk of reducing CO2 they really should in their own life practice what they preach . And I don't believe it is trollish , I have seen several good weather bloggers ask this Question , But you are one of the few that will disclose . I believe it sets an example and leans more credence to your argument. Personally I read your posts and take them on board . To me you are an example of you can catch more flies with honey than vinegar (ie People who are not believers that it is 100% man fault would be more inclined to read your point of view than those who tend to be insulting and patronizing)
Member Since: March 1, 2012 Posts: 0 Comments: 6927
Quoting MAweatherboy1:
18z GFS showed a rather curious system form over the Gulf of Mexico at the end of the run today. It starts out as a weak low here:



Then becomes a slightly stronger storm as it approaches and crosses over FL:







Is there any way the system depicted there could be tropical/subtropical? Or am I just way to anxious for hurricane season, lol?


the 12z CMC has the same run







the cyclone phase analysis doesnt go out that far in the run so I am not able to see if its warm core or not
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting Some1Has2BtheRookie:


Before I click, I err on the side of caution, what is the link to the "cleverbot"? Is this from last year where "cleverbot" carries on a nonsensical, but humorous conversation with you?
yes
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Quoting interstatelover7166:
Remember:
Link Click it. I dare ya.


Before I click, I err on the side of caution, what is the link to the "cleverbot"? Is this from last year where "cleverbot" carries on a nonsensical, but humorous conversation with you?
Member Since: August 24, 2010 Posts: 0 Comments: 4745
18z GFS showed a rather curious system form over the Gulf of Mexico at the end of the run today. It starts out as a weak low here:



Then becomes a slightly stronger storm as it approaches and crosses over FL:







Is there any way the system depicted there could be tropical/subtropical? Or am I just way to anxious for hurricane season, lol?
Member Since: Posts: Comments:
Quoting allancalderini:
You can add me if you want 16 or 17 tropical storms 8 or 10 hurricanes and 3 to 5 majors.
I'm for 18 t.s. 9 hurricanes 4 majors
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Remember:
Link Click it. I dare ya.
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Quoting trHUrrIXC5MMX:
SURVEY

I have been thinking on trying to come up with a list of all the possible outcomes for the Atlantic tropical activity.

The only way I am able to do it is by having anyone who would like to participate to shout out their forecast. I have a list where Im putting it all together in alphabetical order, in that way we all can compare our forecasts with each other...

So what I would like to know is if any is willing to give their own forecast of the possible named storm, hurricanes and major hurricanes we could see this year in the Atlantic basin.

I'll add all the ones I get or remove the ones you ask me to. So far I have some, a broader list would be great...

Again I'll remove anyone who doesn't want to be on it or add in.

I have some thus far... who else wants to participate?
If you want to go to my blog to tell me as for more privacy it's fine with me...



I'll keep updating it as soon as I can
You can add me if you want 16 or 17 tropical storms 8 or 10 hurricanes and 3 to 5 majors.
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Quoting VR46L:


I Dont agree with you I was always brought up to believe Do as I say , not as I do. is Hypercritical . And setting an example is key to spreading the word not posting insults at people who believe that it is part man fault . I honestly know you don't do that, but I seriously don't believe it is trollish to ask questions about Carbon footprint .



I am actually proud of my footprint , I have no car for 6 years, have not flown in 10 .Walk most places and reduce reuse and recycle in all instances so I do my bit . about the only thing that I waste is electric as I love the internet and spend too long on it .


I agree with you that one should be willing to practice what they preach. You have no idea of what I do on a personal basis and your asking me what I do by means of a blog sight is bit pointless, do you not agree? I could tell that I ride a bicycle everywhere I go, but I do not.

Here is what I "preach":

1. Consume less.

2. Plan trips for the shortest route and combine as many errands as possible into one trip.

3. Recycle all that I can.

4. Repair what is repairable instead of discarding.

5. Donate what is still unusable but I no longer need or want.

6. Adjust your thermostat.

7. Keep your tires properly inflated.

8. Keep your vehicle(s) properly tuned.

9. Drive within the speed limit.

10. Replace your car with a more mileage efficient car when it your car is due to be replaced.

11. Replace incandescent light bulbs with CFL or LED bulbs.

12. Wash clothes in the coldest water possible.

13. Wash a full load of clothes at a time without over loading the washer.

14. Dry clothes no longer to get them dry.

15. Do not completely dry clothes that will be hung in a closet.

What do I actually practice? ALL of the above.

What do I plan to further do to lessen my carbon footprint? I am always looking for ways to further reduce my carbon footprint.

I find it very interesting that you that lower your carbon footprint even though you do not seem to believe there are reasons to do so in order to mitigate the CO2 emissions. Perhaps you have discovered what I have? When you do these things it saves you a lot of money! Should this be incentive to do so, then this is incentive enough.
Member Since: August 24, 2010 Posts: 0 Comments: 4745
650. txjac
Geez, somtimes when I read these comments I feel so intellectually challanged. Wish I had the time to understand half of what is said here ...
I'm usually working as I read posts (yes even now when it's well past). I really dont have a lot of left over time to read up and try to understand it all ...usually my searches are work related.

Thanks to all of you that put up with me ..your patience is greatly appreciated
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Rossington-Collins Band - Don't Misunderstand Me

Can't You See
Member Since: February 29, 2012 Posts: 0 Comments: 5917
Quoting VR46L:


I fail to see how a question about carbon footprint is trolling .

IF you are big into believing that man is 100% cause . then you should set an example to people who dont completely buy into it !

Also every little helps if you cut down your emission ..

Also its good for the environment even if you do not believe its 100% mans fault .

The enormity of CO2 pollution makes questions about any individual's carbon footprint a non sequitur to the discussion. One might as well ask any number of other personal questions. Asking irrelevant personal questions is trolling.

Member Since: May 18, 2006 Posts: 10 Comments: 6061
Quoting ncstorm:


Great comment VR..I like Rookie, he is very fair and I have never seen him put any poster down, also quite funny as well.

However, if the people who are passionate about global warming and saving the planet refuse to provide their own examples about what they are doing to help our planet, then its going to be real hard to convince someone who doesnt believe in GW. I hardly see that trolling in asking someone what steps they are taking. I have been lurking in Rood's blog and reading some of the "nicer" comments and skipping over the beating of the chest ones. I will say lately I have been keeping an open mind now about global warming..not saying I buy in it just yet but I'm not putting up a shield anymore..I'm taking baby steps over here, however when I see negative comments directed at people such as I who may be turning an eager ear to listen to the other side, it makes the shield come back up..I still have my own personal views about earth but I also am listening which is something I havent done in the past...
When it comes to empirical science, I guess I've never understood those who say, "I'd believe in or support X, but some of the people who do say mean things sometimes, so I just can't." As humans, emotions obviously play some part in every decision we make. But deciding whether we support, say, climate change, or evolution, or the Big Bang, or the existence of black holes--really shouldn't be based upon whether we've felt slighted by someone who does, or whether someone who does was hypocritical in our eyes. (And vice versa, of course.) No, it should be based solely on whether we agree with the preponderance of the evidence: the mountains of observational data collected by thousands of people over many years, along with the peer-reviewed interpretations of those data. Nothing more.

Example: I've talked with some very obnoxious types who, like me, are firm supporters of the scientific consensus that cigarette smoking causes lung cancer. I mean, very obnoxious types, people with whom I'd rather not waste one minute of my time. But that fact doesn't make me want to run out and smoke a carton of Marlboros. That would be tremendously illogical, no?

One's scientific "belief" (for lack of a more fitting word) should always stem from evidence, not emotion.
Member Since: November 8, 2009 Posts: 4 Comments: 13551
Yes Rookie is one of those passionate believers in GW who doesn't go around harassing or insulting people because they don't see eye to eye with him.I have seen him discuss climate change with a more mature approach than others(who's name will not be mentioned but know who they are).Defetially a valued member here.
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645. Skyepony (Mod)
Member Since: Posts: Comments:
644. VR46L
Quoting ncstorm:


Great comment VR..I like Rookie, he is very fair and I have never seen him put any poster down, also quite funny as well.

However, if the people who are passionate about global warming and saving the planet refuse to provide their own examples about what they are doing to help our planet, then its going to be real hard to convince someone who doesnt believe in GW. I hardly see that trolling in asking someone what steps they are taking. I have been lurking in Rood's blog and reading some of the "nicer" comments and skipping over the beating of the chest ones. I will say lately I have been keeping an open mind now about global warming..not saying I buy in it just yet but I'm not putting up a shield anymore..I'm taking baby steps over here, however when I see negative comments directed at people such as I who may be turning an eager ear to listen to the other side, it makes the shield come back up..I still have my own personal views about earth but I also am listening which is something I havent done in the past...


Thank you NCSTORM , I agree with you . I have real respect for Rookie !

I will send you a mail as to the rest of your comment:)
Member Since: March 1, 2012 Posts: 0 Comments: 6927
Pretty solid slug of rain moving through my area now:

Member Since: Posts: Comments:
MesoWest Jurupa Valley CA US SGXWFO, Riverside, California (PWS)
Updated: 2:49 PM PDT on March 12, 2013
Clear
85 °F
Clear
Humidity: 20%
Dew Point: 39 °F
Wind: 2 mph from the WNW
Wind Gust: 7.0 mph
Pressure: 29.96 in (Steady)
Heat Index: 82 °F
Visibility: 10.0 miles
UV: 4 out of 16
Pollen: 8.40 out of 12
Pollen Forecast new!
Clouds:
Clear -
(Above Ground Level)
Elevation: 794 ft

I have 83.5 here right now (high)
Member Since: February 29, 2012 Posts: 0 Comments: 5917
Quoting VR46L:


I Dont agree with you I was always brought up to believe Do as I say , not as I do. is Hypercritical . And setting an example is key to spreading the word not posting insults at people who believe that it is part man fault . I honestly know you don't do that, but I seriously don't believe it is trollish to ask questions about Carbon footprint .



I am actually proud of my footprint , I have no car for 6 years, have not flown in 10 .Walk most places and reduce reuse and recycle in all instances so I do my bit . about the only thing that I waste is electric as I love the internet and spend too long on it .


Great comment VR..I like Rookie, he is very fair and I have never seen him put any poster down, also quite funny as well.

However, if the people who are passionate about global warming and saving the planet refuse to provide their own examples about what they are doing to help our planet, then its going to be real hard to convince someone who doesnt believe in GW. I hardly see that trolling in asking someone what steps they are taking. I have been lurking in Rood's blog and reading some of the "nicer" comments and skipping over the beating of the chest ones. I will say lately I have been keeping an open mind now about global warming..not saying I buy in it just yet but I'm not putting up a shield anymore..I'm taking baby steps over here, however when I see negative comments directed at people such as I who may be turning an eager ear to listen to the other side, it makes the shield come back up..I still have my own personal views about earth but I also am listening which is something I havent done in the past...
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting aspectre:
Looking down at the top of the sinkhole that swallowed the golfer yesterday

Only the thick interlocking roots kept the turf strong enough to very temporarily take his weight.
And ya hafta take a look at what happens after...

...a kid takes a $1 bet to splash a parking lot pothole puddle. If you haven't "been there, done that" at least once in your life, ya'll never really understand

I have bad luck. If I were to be given money after jumping into a small pothole, I would.

...except with my luck, it would grow and deepen right as I was jumping.
Member Since: July 6, 2010 Posts: 113 Comments: 32267
Looking down at the top of the sinkhole that swallowed the golfer yesterday

Only the thick interlocking roots kept the turf strong enough to very temporarily take his weight.
And ya hafta take a look at what happens after...

...a kid takes a $1 bet to splash a parking lot pothole puddle. If you haven't "been there, done that" at least once in your life, you'll never really understand . Accompanying story
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Quoting Levi32:
Well now I have reservations about the claim that vertical instability was actually below normal in the MDR in 2010, which is the only truly active year where the lower instability seemed contradictory.

Here's the 500mb relative humidity anomalies for Jul-Oct 2010:



Notice how most of the dry air is actually south of the region where storms develop. The African Easterly Wave corridor is plenty moist, and we obviously had a big Cape Verde season. It's very possible the dry air to the south is a result of an active wave train pulling the ITCZ farther north than normal.

Now remember SSD is our only source of "vertical instability" data, since they have created a metric for it (there are many possible metrics to measure stability).

Note where they define "tropical Atlantic" to be:



Now seeing as how this region extends all the way to the equator, it's easy to see how, due to the overlap with the region of dry air south of 10N during 2010, that vertical instability averaged below normal during the hurricane season over that region:



However, was it actually below normal in the MDR? I now doubt that.

Good point.

It is still odd to me that the net instability over the central tropical Atantic was below average. Yeah the main instability was focused over the MDR and likely caused more stability over the region from 10N on south to the equator, but the fact that the region as a whole experienced below average instability is still puzzling.
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And hey, look, for the top 9 ACE years, Jul-Oct 500mb relative humidity was actually below normal south of 10N, similar to 2010 (which is excluded from these top ACE years).

2010 was a bit drier overall than its fellow top ACE years, but I think the region defined as the tropical Atlantic by the SSD weighted the vertical instability measurements downward.

Member Since: Posts: Comments:
Well now I have reservations about the claim that vertical instability was actually below normal in the MDR in 2010, which is the only truly active year where the lower instability seemed contradictory.

Here's the 500mb relative humidity anomalies for Jul-Oct 2010:



Notice how most of the dry air is actually south of the region where storms develop. The African Easterly Wave corridor is plenty moist, and we obviously had a big Cape Verde season. It's very possible the dry air to the south is a result of an active wave train pulling the ITCZ farther north than normal.

Now remember SSD is our only source of "vertical instability" data, since they have created a metric for it (there are many possible metrics to measure stability).

Note where they define "tropical Atlantic" to be:



Now seeing as how this region extends all the way to the equator, it's easy to see how, due to the overlap with the region of dry air south of 10N during 2010, that vertical instability averaged below normal during the hurricane season over that region:



However, was it actually below normal in the MDR? I now doubt that.

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Dry air weakened it substantially, and wind shear finished the job.

Member Since: July 6, 2010 Posts: 113 Comments: 32267
634. VR46L
Quoting Some1Has2BtheRookie:


I believe that what bappit is saying that no one individual's efforts will help to mitigate the CO2 on a global scale. When someone asks, "Well, what are you doing to mitigate the CO2?" is trolling. (Look up the definition of "blog troll")

"IF you are big into believing that man is 100% cause . then you should set an example to people who dont completely buy into it !" - This is another trollish comment. Setting examples for safe flying, swimming or driving habits are not based upon if you believe in them or not. You may not believe in them but when you do not practice them you are putting everyone within your reach at risk. When you do this on a global scale you are putting everyone on the globe at risk. .. Have you never reasoned through the thought that one should always err on the side of caution? Do you understand the ramifications when you do not do so and more than just you are being put at risk?


I Dont agree with you I was always brought up to believe Do as I say , not as I do. is Hypercritical . And setting an example is key to spreading the word not posting insults at people who believe that it is part man fault . I honestly know you don't do that, but I seriously don't believe it is trollish to ask questions about Carbon footprint .



I am actually proud of my footprint , I have no car for 6 years, have not flown in 10 .Walk most places and reduce reuse and recycle in all instances so I do my bit . about the only thing that I waste is electric as I love the internet and spend too long on it .
Member Since: March 1, 2012 Posts: 0 Comments: 6927
Quoting Levi32:
627. TomTaylor

Well I think the mechanism would not be the global temperature itself but the time-change of the global temperature. If the global temperature is rising (or at least the tropics temperature), since the atmosphere hasn't had the opportunity to evaporate more moisture from the ocean yet, its relative humidity will drop. Once the global temperature comes back down (like during a La Nina), the air will have more moisture than before, and the cooling temperatures will cause it to condensate.

This is why the worst Atlantic hurricane seasons come when there was an El Nino during the preceding winter which drops off into a La Nina (e.g. 2010). The cooling atmosphere in the tropics while the Atlantic SSTs are still warm causes enhanced moisture condensation. The opposite is true when global/tropics temperatures are warming as the hurricane season starts.

However, that doesn't explain 2010 being drier than normal, which again leads me to postulate an SAL problem.
Yeah perhaps. And yeah, the Sahel influence must also be considered but it seems that Sahel Precipitation is on the upswing. Will be interesting to see how this graph evolves over the coming years

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Quoting Levi32:


Here, I made you a quick 'n dirty plot of monthly Reynolds. The correlation with active and inactive Atlantic hurricane seasons is pretty obvious.

Yess, got the plot out of ya.

Thanks Levi
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627. TomTaylor

Well I think the mechanism would not be the global temperature itself but the time-change of the global temperature. If the global temperature is rising (or at least the tropics temperature), since the atmosphere hasn't had the opportunity to evaporate more moisture from the ocean yet, its relative humidity will drop. Once the global temperature comes back down (like during a La Nina), the air will have more moisture than before, and the cooling temperatures will cause it to condensate.

This is why the worst Atlantic hurricane seasons come when there was an El Nino during the preceding winter which drops off into a La Nina (e.g. 2010). The cooling atmosphere in the tropics while the Atlantic SSTs are still warm causes enhanced moisture condensation. The opposite is true when global/tropics temperatures are warming as the hurricane season starts.

However, that doesn't explain 2010 being drier than normal, which again leads me to postulate an SAL problem.
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Quoting TomTaylor:
How does this match up to other years?

Positive anomaly is nice but it doesn't really us anything if it isn't put in context.


Here, I made you a quick 'n dirty plot of monthly Reynolds. The correlation with active and inactive Atlantic hurricane seasons is pretty obvious.

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Quoting TomTaylor:
I got your mail, thanks for the response. The problem with the vertical instability is definitely a result of the dry air in the mid to upper levels of the atmosphere.

In recent years when instability has been lacking (used July-Oct of the last five years below) the low to mid levels of the atmosphere have been warmer than normal, while the upper levels have been around average -- this would tend to favor above average vertical instability. Moisture plots, however, are much more telling for the lack of vertical instability. Over the last three hurricane seasons, the tropical Atlantic has incredibly dry. Here are three very telling plots


Total Precipitable Water Anomaly




500mb RH Anomaly




300mb RH Anomaly



The problem with that is the fact that if we look at the same products for the 2003-2007 time period, we get similar results.

EDIT: I see you added more, so scratch this comment.

Surface Precipitable Water Anomalies:



500mb Relative Humidity Anomalies:



300mb Relative Humidity Anomalies:

Member Since: July 6, 2010 Posts: 113 Comments: 32267
Looks like WA15 is gonna stay wet for a while with this one...
Member Since: September 9, 2010 Posts: 5 Comments: 1034
Quoting Levi32:


Maybe, but remember 2010 had an even higher SST anomaly in the MDR both pre-season and during the season than we are likely to see this year, yet vertical instability was below normal over much of the tropical Atlantic during the height of the hurricane season, despite the high ACE year we had.

I was talking to Tom earlier about this. I'm not entirely sure what has been causing low vertical instability since 2010. It could be that despite favorable SSTs, African dust has been at a higher concentration than normal, thus drying out the mid-troposphere and increasing stability. However, I don't know of a dataset that quantifies this, so I don't know how SAL in recent years compares with history.
I got your mail, thanks for the response. The problem with the vertical instability is definitely a result of the dry air in the mid to upper levels of the atmosphere.

In recent years when instability has been lacking (used July-Oct of the last five years below) the low to mid levels of the atmosphere have been warmer than normal, while the upper levels have been around average -- this would tend to favor above average vertical instability. Moisture plots, however, are much more telling for the lack of vertical instability. Over the last three hurricane seasons, the tropical Atlantic has incredibly dry. Here are three very telling plots


Total Precipitable Water Anomaly




500mb RH Anomaly




300mb RH Anomaly





The next part of the problem is finding what is causing that. I went through nearly all the different oscillations and indices and it turns out mean global temperature appears to have the best correlation with dry air over the Atlantic. Below I have plotted the correlation between global mean temperatures and the same three variables (TPW, 500mb RH, 300mb RH).


Global Mean Temperature Correlated with Total Precipitable Water




Global Mean Temperature Correlated with 500mb Relative Humidity




Global Mean Temperature Correlated with 300mb Relative Humidity





These correlations not only match up, but they show almost the exact same patterns. With TPW the dry anomaly is most evident in the MDR. With 500mb RH, the dry anomaly over the last few years extends from the coast of Africa to the Lesser Antilles -- the exact same region where global temperatures have a negative correlation with 500mb RH. With 300mb RH, the dry anomaly is most evident in the Caribbean, but also extends over the MDR. Sure enough, the global temperature has it's strongest negative correlation in these same regions. Keep in mind a negative correlation between global temperatures and RH means that when temperatures are warm (positive anomaly), RH tends to be low (negative anomaly).


Hard to draw concussions without a mechanism, but the correlation sure is high...makes you wonder.
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Quoting yonzabam:


Well, rising air over the US means sinking air elsewhere. Sinking air = low vertical instability.

I don't know how far east this effect would extend, but tropical storms in the east to mid Atlantic have developed 'normally' the past two years, but failed to ramp up in the western section.
No, drought over the Plains would be a sign of sinking air. Sinking air over the Plains would promote rising air elsewhere.
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Quoting VR46L:


I fail to see how a question about carbon footprint is trolling .

IF you are big into believing that man is 100% cause . then you should set an example to people who dont completely buy into it !

Also every little helps if you cut down your emission ..

Also its good for the environment even if you do not believe its 100% mans fault .


I believe that what bappit is saying that no one individual's efforts will help to mitigate the CO2 on a global scale. When someone asks, "Well, what are you doing to mitigate the CO2?" is trolling. (Look up the definition of "blog troll")

"IF you are big into believing that man is 100% cause . then you should set an example to people who dont completely buy into it !" - This is another trollish comment. Setting examples for safe flying, swimming or driving habits are not based upon if you believe in them or not. You may not believe in them but when you do not practice them you are putting everyone within your reach at risk. When you do this on a global scale you are putting everyone on the globe at risk. .. Have you never reasoned through the thought that one should always err on the side of caution? Do you understand the ramifications when you do not do so and more than just you are being put at risk?
Member Since: August 24, 2010 Posts: 0 Comments: 4745
Quoting Levi32:


Well just because the SST anomaly difference between the tropical Atlantic and the rest of the tropics is positive doesn't necessarily mean that the tropical Atlantic is warmer than normal. It could be colder than normal, but if the rest of the tropics were even more colder than normal, the difference would still be positive.

But in this case, yes, the positive AMO Atlantic tripole is evident.



ilke this one myself

we can see sst above normal esp. so near grenland and s of baffin island between lab/greenland some are 2.59 degrees above normal near greenland

Member Since: July 15, 2006 Posts: 174 Comments: 54353
Quoting Tropicsweatherpr:
Levi, you would think that negative NAO that has dominated for the past couple of months would tend to diminuish the sal impulses but there have been some big outbreaks this year.



Well the Atlantic is supposed to be dry this time of year. The moisture content of that air isn't terribly far below normal.

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SURVEY

I have been thinking on trying to come up with a list of all the possible outcomes for the Atlantic tropical activity.

The only way I am able to do it is by having anyone who would like to participate to shout out their forecast. I have a list where Im putting it all together in alphabetical order, in that way we all can compare our forecasts with each other...

So what I would like to know is if any is willing to give their own forecast of the possible named storm, hurricanes and major hurricanes we could see this year in the Atlantic basin.

I'll add all the ones I get or remove the ones you ask me to. So far I have some, a broader list would be great...

Again I'll remove anyone who doesn't want to be on it or add in.

I have some thus far... who else wants to participate?
If you want to go to my blog to tell me as for more privacy it's fine with me...



I'll keep updating it as soon as I can
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Quoting Levi32:
As we monitor pre-hurricane season signals, an important global link is the difference between Atlantic MDR SST anomalies and the rest of the global tropics. This is important because if the rest of the global tropics are cooler relative to normal than the tropical Atlantic (i.e. the difference is positive), then upward motion tends to focus in the Atlantic more than anywhere else in the globe (since it is the warmest relative to normal), which promotes more tropical activity.

I only have 6 days of data on here right now (will eventually accumulate to 90 days), but this graph will track the difference with daily values. Right now it is 0.309C

How does this match up to other years?

Positive anomaly relative to other basins is nice but it doesn't really us anything if it isn't put in context.
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619. VR46L
Quoting bappit:
A comment posted on the bunker fuel article:

"Every day we are fooled into thinking that climate change is a problem caused by individuals and solvable by individuals is another day we fail to move towards large-scale, coordinated, societal action."

Keep that in mind the next time someone trolls you with questions about your carbon footprint. Kale with a low carbon footprint anyone?


I fail to see how a question about carbon footprint is trolling .

IF you are big into believing that man is 100% cause . then you should set an example to people who dont completely buy into it !

Also every little helps if you cut down your emission ..

Also its good for the environment even if you do not believe its 100% mans fault .
Member Since: March 1, 2012 Posts: 0 Comments: 6927
Quoting Levi32:


Maybe, but remember 2010 had an even higher SST anomaly in the MDR both pre-season and during the season than we are likely to see this year, yet vertical instability was below normal over much of the tropical Atlantic during the height of the hurricane season, despite the high ACE year we had.

I was talking to Tom earlier about this. I'm not entirely sure what has been causing low vertical instability since 2010. It could be that despite favorable SSTs, African dust has been at a higher concentration than normal, thus drying out the mid-troposphere and increasing stability. However, I don't know of a dataset that quantifies this, so I don't know how SAL in recent years compares with history.


Levi, I came across this while searching for any historical data on the SAL. While this study does not concern the historical data on the SAL it may provide you with new information as to future weather patterns related to the SAL? See if this offers any useful information for you. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

Unfortunately, I could not find any historical data sets for the SAL.
Member Since: August 24, 2010 Posts: 0 Comments: 4745
Well it sure got hot today....71F. Good thing is, as the temperature rose the Dewpoint went down so it wasnt too bad. Breeze felt good though.
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Quoting AstroHurricane001:


Hot air rises, but DRY air sinks. The molar mass of water (18 g/mol) is lower than that of an average molecule of dry air (nitrogen and oxygen considered, 29 g/mol). A similar contradiction happens in oceanic circulation patterns.


But, if the whole column of air is dry, doesn't that mean rising air?

It seemes to me that, in your explanation, the sinking air has to be drier than the air below it.
Member Since: July 20, 2008 Posts: 0 Comments: 2928
Levi, you would think that negative NAO that has dominated for the past couple of months would tend to diminuish the sal impulses but there have been some big outbreaks this year.

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Just like I expected is windy out here...
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Quoting yonzabam:


Really? There must be a gap in my education. I thought hot air rose.


Hot air rises, but DRY air sinks. The molar mass of water (18 g/mol) is lower than that of an average molecule of dry air (diatomic nitrogen and oxygen considered, 29 g/mol). A similar contradiction by different processes happens in oceanic circulation patterns - warm oceans upwell, but oceans that experience high evaporation allow denser, saltier water to appear at the surface, causing downwelling.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.