The tornado season of 2008: climate change to blame? And, tropical update

By: Dr. Jeff Masters , 5:07 PM GMT on May 27, 2008

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Residents of Parkersburg, Iowa continue to assess damage and clean up from the tornado that killed six people on Sunday. The tornado was rated EF-5, the highest possible rating for a tornado. An EF-3 tornado also hit Hugo, Minnesota on Sunday, killing one person. Only five new tornado reports occurred yesterday, and severe weather is expected to remain relatively low for the next two days. A new storm system is expected to bring an enhanced chance of severe weather to the upper Midwest beginning Thursday. The deaths Sunday push this year's tornado death toll to 110. This makes 2008 the 12th deadliest tornado season since 1950, and the deadliest since 1998, when 130 deaths were recorded. Assuming that the Parkersburg, Iowa tornado was an EF-4 or EF-5, there have been nine violent EF-4 or EF-5 tornadoes this year. This is the most since 1999, when 13 such twisters were recorded. The total (preliminary) number of tornadoes so far this year is 1191. I doubt that we will break the all time record of 1817 tornadoes in a year, set in 2004, but 2008 may vault into second place if we can top 1998's 1424 tornadoes. Could this year's tornadoes be a sign of climate change?


Figure 1. Tornadoes deaths in the U.S. by year since 1950. Year 2008 deaths are as of May 26.

Well, let's be clear that human-caused climate change is occurring, and will significantly affect nearly all aspects of weather and climate in the decades to come. However, many of these changes will be so small or gradual that they will not become detectable until many decades hence, since there is a large natural variability in weather. As I noted in my February blog, Are tornadoes getting stronger and more frequent?, there is new research that predicts that we may see an increase in the severe thunderstorms that spawn tornadoes by the end of the century. However, the computer modeling efforts that predict this rise in severe weather are just beginning, and much more research remains to be done before we can believe these preliminary results.

Will we be able to detect changes in tornado frequency if they occur?
We won't be able to detect changes in tornado frequency due to climate change, unless there is a very large change. We need a technology that can detect all tornadoes, all the time in order to be able to evaluate changes in tornado frequency. Doppler radar can only "see" perhaps 50% of all tornadoes, and many of those it detects never touch down. Thus, we rely on human observers to spot tornadoes, or look for buildings that got in the way of a tornado, using the damage pattern to identify a tornado. If there are no humans around to see a tornado, and if a tornado does not encounter any structures, it will go unrecorded. As the population increases and more buildings are erected, tornado reports will increase. This factor alone can account for the observed increase in total tornadoes since 1950 (Figure 2).

Is there evidence that strong and violent tornadoes are increasing?
Strong tornadoes (EF2 and EF3 on the Enhanced Fujita Scale) and violent tornadoes (EF4 and EF5, or F4 and F5 on the pre-2007 Fujita Scale), which make up less than 25% of all tornadoes, cause a large fraction of the tornado deaths. These storms are less likely to go uncounted, since they tend to cause significant damage along a long track. Thus, the climatology of strong and violent tornadoes may offer a clue as to how climate change may be affecting severe weather. Unfortunately, we cannot measure the wind speeds of a tornado directly, except in very rare cases when researchers happen to be present with sophisticated research equipment. Tornadoes are categorized using the Enhanced Fujita (EF) scale, which is based on damage. So, if a strong or violent tornado happens to sweep through empty fields and never destroy any structures, it will not get a rating. Thus, if the number of violent tornadoes has actually remained constant over the years, we should expect to see some increase in these storms over the decades, since more buildings have been erected in the paths of tornadoes.

However, if we look at the statistics of strong and violent U.S. tornadoes since 1950 (Figure 2), there does not appear to be any increase in the number of these storms. In fact, there appears to be a decrease, although the quality of the data base is probably not good enough to say this with confidence. It appears likely that climate change has not caused an increase in the strongest tornadoes in recent decades. I believe we can blame 2008's nasty tornado season on an unusually far south loop that the jet stream has taken this year over the U.S., thanks to natural variability in the weather.


Figure 2. Total, strong and violent tornadoes in the U.S. by year since 1950. The year 2008 (not pictured) has had 128 strong or violent tornadoes as of May 26, according to Wikipedia.

Possible development in the Western Caribbean or Eastern Pacific late this week
A weak low pressure area (Invest 90E) has developed in the Eastern Pacific off the coast of Guatemala, near 10N 90W. This low has the potential to develop into a tropical depression by the end of the week, according to the UKMET model. Other models, such as the GFS, Canadian, and ECMWF, foresee that this area of disturbed weather will not have time to develop before moving northwards over Central America by the end of the week, bringing heavy rains to the region. Once over land, this low might move over the waters of the Western Caribbean and allow a tropical depression to form, as predicted by the GFS model. The NOGAPS model, in contrast, predicts that a tropical depression will form in the Western Caribbean south of Cuba, with no development in the Eastern Pacific. Given the persistence of these computer models over the past week in developing something in the region, I'd put the odds of a tropical depression forming within 7 days at about 40% in the Eastern Pacific, and at 20% in the Western Caribbean. There is a lot of wind shear predicted to prevail near or over the Western Caribbean late this week and early next week, reducing the odds that any such development could hold together long enough to affect the U.S. Regardless, residents of Guatemala, El Salvador, Honduras, Belize, and southern Mexico can expect heavy rains and possible flash flooding late this week from this system.


Figure 3. Area of disturbed weather over the Eastern Pacific that is forecast by some models to develop into a tropical depression. The NHC Graphical Tropical Weather Outlook is a good tool to track this disturbance.

I'll have an update by Wednesday afternoon.

Jeff Masters

New Hartford (snp4u)
Missing House, if found call Dennis and Carla
New Hartford
New Hartford (snp4u)
car pile up
New Hartford
Supercell near Pratt, Kansas (MikeTheiss)
Nice structure on upercell east of Pratt, Kansas. Photo copyright Mike Theiss.
Supercell near Pratt, Kansas

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588. Drakoen
11:37 PM GMT on May 27, 2008
585. nash28 11:37 PM GMT on May 27, 2008
LOL Extreme! Just wait for 90L! The GFDL will be so happy to stretch its legs, we'll have a CAT4:-) Kidding of course.


ROFL yea. Well there is some consensus on the broad EPAC low weakening and or dissipating so we will see.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
587. extreme236
11:37 PM GMT on May 27, 2008
James Franklin at the NHC also uses a bit of humor, but not as much nor as humorous as Avila's comments.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
586. TerraNova
7:34 PM EDT on May 27, 2008
Some Luxion Avila humor:

LOL; altough I must say that I prefer Franklin when it comes to humorous NHC discussions. Honestly can you imagine getting up in the morning, logging on to the NHC site, and reading this? I'd think i'm in some crazy dream. For example...

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION KYLE DISCUSSION NUMBER 78
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT WED OCT 09 2002

OH...OH...OH...OH...STAYIN ALIVE...STAYIN ALIVE. WITH NO TIME TO
SPARE...KYLE GENERATED SOME DEEP CONVECTION TO THE SOUTHEAST OF THE
CENTER...
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585. nash28
11:36 PM GMT on May 27, 2008
LOL Extreme! Just wait for 90L! The GFDL will be so happy to stretch its legs, we'll have a CAT4:-) Kidding of course.
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584. pearlandaggie
11:36 PM GMT on May 27, 2008
580. totally agreed, nash!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
583. extreme236
11:35 PM GMT on May 27, 2008
578. Drakoen 11:35 PM GMT on May 27, 2008
LOL The GFDL just wants to dissipate it. I want to see if it will be able to pick up the other area of low pressure in its run.


Because it too, knows a Caribbean system will form lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
582. floridastorm
11:33 PM GMT on May 27, 2008
hey guys
looks like the epac storm has been
coming together
may cross over to the carribean
wait and see
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581. pearlandaggie
11:34 PM GMT on May 27, 2008
576. no skin off of my back, man. i try not to be rude to anyone and i do my best not to take offense. it's cool!!

/but i still want to know how to pronounce "Luxion"!! LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
580. nash28
11:33 PM GMT on May 27, 2008
It just goes to show everyone that even the most SEASONED hurricane specialist can and WILL have his/her ass kicked from time to time. Those who can admit that they have no idea over a certain storm or situation have my utmost respect.
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579. extreme236
11:34 PM GMT on May 27, 2008
573. nash28 11:33 PM GMT on May 27, 2008
I love it Extreme!!!!!

That's why I love that man! He is human, and isn't afraid to show it in the discussion, which is more than I can say for most Mets.


Exactly! lol He makes the discussions entertaining and he definatly isn't like those mets who make a discussion as boring as possible.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
578. Drakoen
11:34 PM GMT on May 27, 2008
LOL The GFDL just wants to dissipate it. I want to see if it will be able to pick up the other area of low pressure in its run.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
577. Patrap
6:31 PM CDT on May 27, 2008


Does Global Warming Change Hurricane Intensification Rates?

Felix and Humberto Leave A Question Link

These are the facts when it comes to rapid intensification in the Atlantic -- but can we generalize further about them? Jeff Masters, pretty much the chief expert among hurricane bloggers, puts it like this:

No scientist has published a paper linking rapid hurricane intensification rates with global warming. While the cases of Humberto and Felix are certainly unique, the year 1969 also had two storms that were very similar in their intensification rates. A quick look I did at historical intensification rates doesn't show any noticeable trends, and I think that the rapid intensification rates of Felix, Humberto, and Wilma the past three years are not far enough outside the statistical norms that we need to invoke climate change as an explanation. Still, it does leave one wondering, and climate change could be affecting hurricane intensification rates.

But how might it be affecting them? What would the mechanism of action be? Masters doesn't say, but I'm going to assume that he means more heat stored in the ocean creates an environment more conducive to rapid strengthening. But that raises some obvious questions: Is there an upper limit imposed by physics on how fast strengthening can occur? And do our data totally limit us in saying anything more about trends in intensification rates at the current juncture?

To answer these questions, the "Storm Pundit" will be canvassing hurricane experts for more illumination about how global warming may affect hurricane rapid intensification rates -- a subject that may well inspire much more scientific research in the near future. Stay tuned.





Member Since: July 3, 2005 Posts: 428 Comments: 129841
576. extreme236
11:33 PM GMT on May 27, 2008
Oh and Pearlandaggie that comment I made may have come off a tad rude but the overall point as was making is that when a GW discussion even starts up on here all it leads to is name calling and other crap and I know you were probably just making a quick point. Sorry if it seemed rude.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
575. nrtiwlnvragn
7:33 PM EDT on May 27, 2008
GFDL

000
WHXX04 KWBC 272329
CHGQLM
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR

TROPICAL DEPRESSION INVEST 90E

INITIAL TIME 18Z MAY 27

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


FORECAST STORM POSITION

HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)

0 10.1 90.4 360./ .0

STORM DISSIPATED AT 0 HRS AT THE ABOVE PSN.
Member Since: September 23, 2005 Posts: 15 Comments: 11343
574. pearlandaggie
11:32 PM GMT on May 27, 2008
so for those of us "less-educated" dolts, how DOES one pronounce "Luxion"?? :)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
573. nash28
11:32 PM GMT on May 27, 2008
I love it Extreme!!!!!

That's why I love that man! He is human, and isn't afraid to show it in the discussion, which is more than I can say for most Mets.
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572. moonlightcowboy
6:31 PM CDT on May 27, 2008
LOL, Pearland. I've been monkeying with a way to post those RAMSDIS loops with a direct link from comments. I did it last year, but forgot. Just now remembering how to do it.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
571. extreme236
11:28 PM GMT on May 27, 2008
Some Luxion Avila humor:

On a Wilma discussion:
"First of all, I could not believe it. Nobody in their right mind would have expected this drop in pressure."

About Epsilon:
"There are no clear reasons, and I am not going to make one up, to explain the recent strengthening of Epsilon."

About Zeta:
"As you can see...I ran out [of] things to say."

About Ernesto:
"Since neither I nor the [forecast] models are good enough to precisely know if Ernesto will have an intensity of 64 knots at landfall...which is the border between hurricane and tropical storm intensity and 4 knots above the forecast...a hurricane watch has been issued for a portion of the coast".

About Juliette:
"If some of the dynamical models have their way...Juliette could meet her less-than-Shakespearean demise sooner than indicated in the official forecast".
Member Since: August 2, 2007 Posts: 19 Comments: 19234
570. moonlightcowboy
6:29 PM CDT on May 27, 2008
RAMSDIS IR3 WV LOOP
Member Since: July 9, 2006 Posts: 184 Comments: 29610
569. pearlandaggie
11:29 PM GMT on May 27, 2008
but MLC, i thought RAMSDIS was offline unless you had a password! LOL ....just kidding!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
568. moonlightcowboy
6:27 PM CDT on May 27, 2008
RAMSDIS 4km IR FLOATER #1 LOOP.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
567. pearlandaggie
11:27 PM GMT on May 27, 2008
564. the last link had to do with ocean cycles and hurricanes, in case one would want to take a peek at it...
Member Since: September 14, 2007 Posts: 3 Comments: 3963
566. nash28
11:27 PM GMT on May 27, 2008
Well.. sniffle sniffle.... Dr. Masters started it!!!1 Sniffle Sniffle...

I am just kidding:-)
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565. pearlandaggie
11:26 PM GMT on May 27, 2008
lol, nash! if even ONE person bothers to read those papers and decides that maybe the debate is still on, then i'll have done my little part :)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
564. extreme236
11:25 PM GMT on May 27, 2008
We were talking about the weather and then a GW post comes up...that conversation is a storm that spins up faster than any hurricane ever could.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
563. moonlightcowboy
6:24 PM CDT on May 27, 2008
LOL, sporte! Yeah, seems to have been mostly civil today, doesn't it? That'll change, ugh! It's been hot, but not so humid today, dry.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
562. nash28
11:24 PM GMT on May 27, 2008
Yeah, I am doing my best to stay out of the 4th ring of hell also known as the MMGW smackdown. My blood pressure rises to levels so high that any day now the hospital I work at will be calling both a Code Blue AND a Code 4...

Heart attack and aggressive person on premises:-)
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561. pearlandaggie
11:23 PM GMT on May 27, 2008
Pat, i'm sorry, but i'm not following you on that one. i'm pretty tired and pretty slow (more like usually slow) today!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
560. sporteguy03
11:21 PM GMT on May 27, 2008
MLC,
How is it in your area? Here it is great low humidity. It was nice that we have not seen Charlie Brown on the blog today so far.
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559. Patrap
6:22 PM CDT on May 27, 2008
556.

Plttttttttttttttttttttttttttttttttttttttttttt...

LOL

A real Blogeer Holds fast and steady and wrings out hiz or Her pernt.
Member Since: July 3, 2005 Posts: 428 Comments: 129841
558. nash28
11:21 PM GMT on May 27, 2008
You're right MLC. The UL winds bite right now.. However, if the ULH can position itself over the Low properly, even a 45kt wind shear value will be blocked.

Again, see Barry circa 2007 which taught all of us a thing or two about the ULH:-) Taught me something that's for sure!
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557. Drakoen
11:20 PM GMT on May 27, 2008
The NOGAPS isn't like the GFS in the 120hr frame. The NOGAPS is producing a weakness between the lower the mid level ridge one over Texas and one out in the Atlantic. A trough will move in between.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
556. pearlandaggie
11:14 PM GMT on May 27, 2008
Well, let's be clear that human-caused climate change is occurring

Of course, I beg to disagree...

ULTRALONG SOLAR CYCLE 23 AND POSSIBLE CONSEQUENCES

Correlation of Carbon Dioxide with Temperatures Negative Again

re oceans becoming more acidic and is this a threat to marine life?

Nature, Not Human Activity,
Rules the Climate


Ocean Oscillations and Hurricanes

and i suppose i will bid you all a premature adieu as i'm sure this heresy will get me banned for off-topic content...
Member Since: September 14, 2007 Posts: 3 Comments: 3963
555. extreme236
11:19 PM GMT on May 27, 2008
Very impressive (TS Nakri)



Member Since: August 2, 2007 Posts: 19 Comments: 19234
554. moonlightcowboy
6:16 PM CDT on May 27, 2008


Upper level winds are not favorable. Hey, I hope I'm wrong and certainly have less knowledge than lots of you fellas in here, but conditions will have to change a good bit for any storm to develop, stack and get its act together. Lots of "ifs" yet.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
553. TerraNova
7:17 PM EDT on May 27, 2008
LMAO Pat! QUICK!!!! Someone queue Avila:-)

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DOLLY DISCUSSION NUMBER 2
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT THU AUG 29 2002

THE BELL JUST RANG IN THE TROPICAL ATLANTIC...HELLO DOLLY...

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552. nash28
11:18 PM GMT on May 27, 2008
Having to keep an eye on the chicken I do not have time to check the models... What did the 12z Euro do?
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551. extreme236
11:17 PM GMT on May 27, 2008
Well the crowd on here earlier was very Pro-EPAC earlier now the crowd is more Pro-Caribbean.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
550. Michfan
6:17 PM CDT on May 27, 2008
Looks like NOGAPS and GFS are in agreement so far.
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549. nash28
11:13 PM GMT on May 27, 2008
You are correct there MLC. If a TS spins up, which is not only possible, but probable under the ULH assuming the ULH moves in tandem with the system, given the current conditions it will be another Barry. Dry TS.
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548. Drakoen
11:14 PM GMT on May 27, 2008
543. nash28 11:13 PM GMT on May 27, 2008
You know what amazes me??? Not more than five hours ago, it was all about the EPAC. I stuck my neck out mentioning the ULH. Now, lookie here:-)


LOL thats what happens when someone posts the HPC and EPAC discussion.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
547. extreme236
11:14 PM GMT on May 27, 2008
Well nothing will develop the way it is now but its not going to stay that way.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
546. Patrap
6:14 PM CDT on May 27, 2008
The QuikSCAT problem was a data Processing error,not the Spacecrafts

QuikSCAT Storm Page Link
Member Since: July 3, 2005 Posts: 428 Comments: 129841
545. Michfan
6:11 PM CDT on May 27, 2008
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544. SpaceThrilla1207
11:12 PM GMT on May 27, 2008
MLC you downcaster.Lol

it kind of looks like the caribbean one will develop down the road, maybe in time for hurricane season's start.
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543. nash28
11:11 PM GMT on May 27, 2008
You know what amazes me??? Not more than five hours ago, it was all about the EPAC. I stuck my neck out mentioning the ULH. Now, lookie here:-)

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542. moonlightcowboy
6:11 PM CDT on May 27, 2008
Ike, I hope something does spin up and drops some rain on the se, just a depression or weak TS with plenty of wet stuff - that'd be good. Some of you fellas may see it, I just don't see it period, not, like it is now.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
540. nash28
11:11 PM GMT on May 27, 2008
LMAO Pat! QUICK!!!! Someone queue Avila:-)
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539. Drakoen
11:09 PM GMT on May 27, 2008
534. Patrap 11:08 PM GMT on May 27, 2008
I think maybe the Caribbean feature is a 07 Karen Remnant.


No its an Ingrid remnant.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
538. Michfan
6:08 PM CDT on May 27, 2008
Looks like QScat got fixed.
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