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)
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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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888. weatherboykris
2:30 AM GMT on May 28, 2008
Yeah vortix. Why are you trying to start something? We're just talking weather here, for once with no arguments.
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887. weatherblog
2:28 AM GMT on May 28, 2008
877. Drakoen 2:24 AM GMT on May 28, 2008
875. weatherblog 2:23 AM GMT on May 28, 2008
867. Drakoen 2:18 AM GMT on May 28, 2008
GFDL, GFS, NOGAPS vs. UKMET, ECMWF

Also, versus the HWRF...(just pointing out)

the HWRF is psycho. I was thinking about giving it its own category lol.


lmao...yeah, the HWRF and CMC seem related.
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886. nash28
2:29 AM GMT on May 28, 2008
Dude. Statements like that are EXTREMEMLY uncalled for, and you know it.

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885. kmanislander
2:29 AM GMT on May 28, 2008
Quikscat this evening places the low at 87W and 9 N approx

Link
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883. BahaHurican
10:29 PM EDT on May 27, 2008
882.

Yup. Time for me to head to bed . . .
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881. weatherblog
2:25 AM GMT on May 28, 2008


The NOGAPS takes it in a very interesting path, but I doubt it'll survive the mountains of Honduras.
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880. BahaHurican
10:24 PM EDT on May 27, 2008
874. moonlightcowboy 10:23 PM EDT on May 27, 2008


Thanks mlc, couldn't remember, I'm so beat ;o). That would put another upward pulse of the MJO in the area around the beginning of July, when I think TS formation potential would be on the rise for a variety of other reasons.
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879. nash28
2:26 AM GMT on May 28, 2008
G'night all. I am exhausted and done.

More tomorrow.
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877. Drakoen
2:24 AM GMT on May 28, 2008
875. weatherblog 2:23 AM GMT on May 28, 2008
867. Drakoen 2:18 AM GMT on May 28, 2008
GFDL, GFS, NOGAPS vs. UKMET, ECMWF

Also, versus the HWRF...(just pointing out)


the HWRF is psycho. I was thinking about giving it its own category lol.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
876. BahaHurican
10:22 PM EDT on May 27, 2008
Ya'll, I'm just too beat to make much of a contribution tonight, so I'm headed to bed. Maybe tomorrow . . .
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875. weatherblog
2:20 AM GMT on May 28, 2008
867. Drakoen 2:18 AM GMT on May 28, 2008
GFDL, GFS, NOGAPS vs. UKMET, ECMWF


Also, versus the HWRF...(just pointing out)
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874. moonlightcowboy
9:13 PM CDT on May 27, 2008


LOOP


I think Baha's obs is on the money, too. Much of this convection is associated with the ITCZ and a result of the MJO pulse, too. Yes, there's some rotation, and a low; but, there's lots of converging air in the area from lots of directions. But, you can see some higher tops firing, too. We may get something, but I still don't seeing moving towards the CONUS anytime soon with dry air and searing high pressure.

- Baha, my understanding is the MJO cycles every 30-40 days.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
873. Drakoen
2:20 AM GMT on May 28, 2008
866. kmanislander 2:18 AM GMT on May 28, 2008
Guys

there is a ULL over Guatemala driving 90E due E

Take a look

Link


That was expected from the HPC. Good eye though!
Member Since: October 28, 2006 Posts: 57 Comments: 30830
872. BahaHurican
10:13 PM EDT on May 27, 2008
I am not seeing the same Jp from 2006 and 2007. U sort of like another "eye".


Huh???

What is this, ID theft game or something?

BTW, while a lot of "reglars" are in the blog, PLEASE, my friends, let us keep the troll action to a minimum. We have a few summer season posters who aren't really interested in weather; let's not get ourselves banned because we are not using those BUTTONS. . . . I think this is setting up to be a very interesting season, and it will be much more interesting if we are all here, able to "battle out" the more interesting nuances of each current, past, or future system, potential system, former system, and revitalized, memorialized, homogenized system . . .
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871. Drakoen
2:18 AM GMT on May 28, 2008
865. jphurricane2006 2:18 AM GMT on May 28, 2008
damn my math sucks, either way my point doesnt change, and it better move north or it would run into panama anyway, also how do we know that jump east isnt a relocation, weak systems do that


I don't prefer either way necessarily.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
870. Weather456
10:17 PM AST on May 27, 2008
855. jphurricane2006 10:13 PM AST on May 27, 2008
the steering showed a system could move east yesterday

but really a .2 degree movement south and .3 movement east is hardly a movement at all and could easily happen in weak steering


from 90E to 88.7E is a shift of 1.3 degrees east.

I'm gone till later
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869. cdo
2:14 AM GMT on May 28, 2008
how is Phantom Aruthor doing?
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868. nrtiwlnvragn
10:18 PM EDT on May 27, 2008
Spaghetti plots for the 00Z update. Generally a northward track.
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867. Drakoen
2:16 AM GMT on May 28, 2008
GFDL, GFS, NOGAPS vs. UKMET, ECMWF
Member Since: October 28, 2006 Posts: 57 Comments: 30830
866. kmanislander
2:17 AM GMT on May 28, 2008
Guys

there is a ULL over Guatemala driving 90E due E

Take a look

Link
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864. CaneAddict
2:14 AM GMT on May 28, 2008
854. extreme236 2:13 AM GMT on May 28, 2008
Based upon the information I have seen from the computer models and the NHC I don't think 90E will amount to much. I could be wrong but I am still leaning toward development of the Caribbean low.

Good night all!


I am also going more for the development in the Caribbean...anyway i am also out, night all!
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862. guygee
2:08 AM GMT on May 28, 2008
342. GulfScotsman 8:41 PM GMT on May 27, 2008
equation...

CO2 into the atmosphere by man made sources in the United States of America.

Loss of C02 removing forest in less developed countries.


Net effect on CO2 levels hence..

thus and therefore... the larger contribution to green house gas build up and the catostrphic global emergency know as GW. I am actually challenging anyone for a scientific, math based, equation with the US inputs to atmosphere, the mathematical scientific scrubbing capacity of x number of square miles of rainforest.

Annualized.

Comparative.

Hypothesis - deforestation in the third world contributes more to the net gain of CO2 in the atmosphere - by loss of C02 conversion, than the United States of America contributes to the GW problem.

Answers on the 10pm news. No conjecture please... real numbers.

honestly i am just curious about the "hypothesis"

================================
Source: Global and regional drivers of accelerating CO2 emissions
(See supporting data links)
Global Summary (2005):
In 2005, the cumulative global fossil-fuel emission of CO2 was C(t) = 319 GtC and the cumulative emission from the other major CO2 source, land use change (J. G. Canadell, C.L.Q., M.R.R., C.B.F., E. T. Buitenhuis, et al., unpublished data) was 156 GtC (3). Of the total cumulative emission from both sources (~480 GtC), less than half (~210 GtC) has remained in the atmosphere, the rest having been taken up by land and ocean sinks (4). For the recent period 2000-2005, emission fluxes averaged 7.2 GtC y-1 from fossil fuels and 1.5 GtC y-1 from land use change; through this period the fossil-fuel flux grew rapidly at ~3% y-1, and the land use change flux remained approximately steady. A time-dependent indicator of sink effectiveness is the airborne fraction, the fraction of the total emission flux from fossil fuels and land use change that accumulates in the atmosphere each year. Recent work (J. G. Canadell, C.L.Q., M.R.R., C.B.F., E. T. Buitenhuis, et al., unpublished data)shows that the airborne fraction has averaged 0.44 for the period 1959-2005, increasing slightly through those 47 years to an average of 0.48 for 2000-2005. This implies a slight weakening of land and ocean sinks relative to total emissions.

From: Ranking of the world's countries by 2004 total CO2 emissions from fossil-fuel burning, cement production, and gas flaring.
Source: Gregg Marland, Tom Boden, and Bob Andres, Oak Ridge National Laboratory

United States, Total Carbon Emissions, 2004:
1.650020 GtC

Secondary Source:

U.S. Carbon Dioxide Emissions from Energy Sources 2007 Flash Estimate:
U.S, Total Carbon Emissions, 2007 (est):
1.632 GtC
--------------------
Estimates of Carbon Emissions from tropical deforestation.

See:
Houghton, R.A. 2005. Aboveground forest biomass and the global carbon balance (pdf). Global Change Biology 11:945-958.
Estimates of Carbon Emissions per year:
1.5 GtC(plus or minus) 1.2 (1.2 from Gurney et al. (2002)increased by 0.3 to account for river transport (Aumont et al., 2001).

0.9 GtC(range 0.5 to 1.4) from DeFries et al. (2002).

1.1 GtC from Achard(2004).

2.2 GtC (plus or minus) 0.8 from Houghton (2003).

2.4 GtC from Fearnside(2000).

Other sources:
Gullison RE, Frumhoff PC, Canadell JG, Field CB, Nepstad DC, Hayhoe K, Avissar R, Curran LM, Friedlingstein, Jones CD, Nobre C (2007)
Tropical forests and climate change (pdf). Science 316: 985-986

Baseline case for tropical deforestation carbon emissions: ~1.5 GtC/Y

United Nations Food and Agriculture Organization (FAO) estimate, 2005: ~2.0 GtC/Y
-------
Special Note: The variability of carbon emissions from tropical deforestion can be very high due to factors such as drought and wildfires. For example, in the very strong 1997-98 El Nino year, increased forest fires released an extra 2.1 GtC(plus or minus) 0.8 to the atmosphere.
Source:
Van der Werf, G.R., J.T. Randerson, G.J. Collatz, L. Giglio, P. Kasibhatla, A. Arellano, S. Olsen, and E.S. Kasischke, 2004. Continental-scale partitioning of fire emissions during the 1997 to 2001 El Nino/La Nina period. Science, 303: 73-76.


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861. Drakoen
2:14 AM GMT on May 28, 2008
JP, 90-88.7= 1.3 degree movement east.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
859. nash28
2:14 AM GMT on May 28, 2008
The GFDL last year was the most I have seen it miss the ocean standing on the pier.
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858. weatherboykris
2:13 AM GMT on May 28, 2008
Interesting solutions presented by the GFDL and HWRF this afternoon, with the GFDL seeming to favor a GFS type of solution.
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857. extreme236
2:13 AM GMT on May 28, 2008
I guess I agree with the GFDL and its run of the system lol

It seems to agree with the GFS and NGPS in a Caribbean system and on the general track.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
856. BahaHurican
10:04 PM EDT on May 27, 2008
Evening everybody. It's been a long rough day, but a light rain shower just as I got home had added a good note to the day . . .

Someone commented earlier about the MJO moving into the area, and it's really obvious in the increased convection along the ITCZ and even through this area. Other fronts over the last few weeks stirred up little rain here.

Looking at the models along w/ current conditions, I'm still not sure we'll get even as much as a named system out of that general area of disturbance; even the EPac side will need more time with continued favorable conditions. The upswing in moisture may, however, actually trigger something for the opening of the season.

Anybody has an idea when another moist period of the MJO is supposed to pass through the region? If it's in July, I can reasonably expect at least one tropical system to wind up at that time.
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854. extreme236
2:11 AM GMT on May 28, 2008
Based upon the information I have seen from the computer models and the NHC I don't think 90E will amount to much. I could be wrong but I am still leaning toward development of the Caribbean low.

Good night all!
Member Since: August 2, 2007 Posts: 19 Comments: 19234
853. taco2me61
2:07 AM GMT on May 28, 2008
832. CaneAddict 2:07 AM GMT on May 28, 2008
821. Weather456 2:02 AM GMT on May 28, 2008
jphurricane2006,

I've been reading ur post for the past days now and I cudnt help but notice that u have change. I am not seeing the same Jp from 2006 and 2007. U sort of like another "eye".

Exactly.

I totally agree...... I sit back in the back ground and just lurk sometimes aswell.....

Thanks for the great reading.....

Taco :0)
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852. nash28
2:11 AM GMT on May 28, 2008
JFV- This is a weak feature. For shallow systems, I'd follow the BAMS. The deeper one becomes, then I would give more credence to the dynamical models such as the GFDL and HWRF.
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851. Drakoen
2:11 AM GMT on May 28, 2008
847. JFV 2:11 AM GMT on May 28, 2008
WOW, it truly is moving eastward isn't? Was the NHC expecting this track Drak? Cause the models with the exception of GFDL are all taking it towards the west!


The GFS, NOGAPS, HWRF aren't taking it west
Member Since: October 28, 2006 Posts: 57 Comments: 30830
850. Weather456
10:11 PM AST on May 27, 2008
838. Drakoen 10:09 PM AST on May 27, 2008

I corrected that....I was mixing up myself..lol...kinda tired here.
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849. kmanislander
2:10 AM GMT on May 28, 2008
I feel much better now jp

I was worried for a moment LMAO
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848. nash28
2:11 AM GMT on May 28, 2008
Damnit JP!!! You beat me to it:-)

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846. nash28
2:10 AM GMT on May 28, 2008
JP has become more conservative and patient, like many of us have over the last few years around here.
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845. Weather456
10:06 PM AST on May 27, 2008
This is the 6 hr track: 90E is moving southeastward. I was going back and forth maybe becuz I'm tired but this is the moevemnt being reported on infrared imagery.


200805280000 UTC 9.8 -88.7
200805271800 UTC 10 -90
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844. Tazmanian
7:06 PM PDT on May 27, 2008
seen like 90E is puting on a show for us


this is going to be a long long season
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843. weatherblog
2:08 AM GMT on May 28, 2008
831. nash28 2:07 AM GMT on May 28, 2008
Ok, so the Low, which was hailed THE LOW earlier by everyone and their mother is moving S, SSS, SSE, SESE, ESE, EESE, ESSSSEE, or not at all...

Does that about sum up what I have missed this evening?

:-)


Perfectly! lol, but we came to the conclusion it's moving to the SE at a slow pace...
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841. nrtiwlnvragn
10:08 PM EDT on May 27, 2008
Doc just updated his blog entry on 90E
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839. nash28
2:08 AM GMT on May 28, 2008
Guys. JP is NOT another Eye. Not even close. I know JP can fight his own, but I will step in and say the man is more intelligent than you think.

BTW, how the hell are ya JP?
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838. Drakoen
2:07 AM GMT on May 28, 2008
826. Weather456 2:04 AM GMT on May 28, 2008
Sorry my post should say southwest....not southeast.


How? moving from 90W to 88.7W is east movement.
Member Since: October 28, 2006 Posts: 57 Comments: 30830

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