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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687. extreme236
12:55 AM GMT on May 28, 2008
Hey STORMKAT/STORMTOP's weather office just sent me a Weather Alert email saying his office predicts a Cat 5 NOLA hit...
Member Since: August 2, 2007 Posts: 19 Comments: 19234
684. pearlandaggie
12:52 AM GMT on May 28, 2008
now Michaael, let sleeping dogs lie! :)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
683. juniormeteorologist
12:52 AM GMT on May 28, 2008
what i meant to say is Georgetown, SC..it is also below sea level, and when it rains for 10 minutes the city floods out completely..and hugo did devasting damage to Georgetown, SC...
681. nrtiwlnvragn
12:51 AM GMT on May 28, 2008
90E drifting east

...INITIAL CONDITIONS...
LATCUR = 9.8N LONCUR = 88.7W DIRCUR = 90DEG SPDCUR = 3KT
LATM12 = 10.0N LONM12 = 90.0W DIRM12 = 109DEG SPDM12 = 3KT
LATM24 = 10.2N LONM24 = 91.3W
WNDCUR = 25KT RMAXWD = 150NM WNDM12 = 25KT
CENPRS = 1006MB OUTPRS = 1009MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
Member Since: September 23, 2005 Posts: 14 Comments: 11179
680. extreme236
12:50 AM GMT on May 28, 2008
672. juniormeteorologist 12:45 AM GMT on May 28, 2008
Caneaddict you are not the only one..they have been predicting another major storm to hit south carolina, and category 4 or 5 I believe..Hugo was a terrible storm to the economy and I truly beleive that this year Tampa and Myrtle Beach, SC will have a major hurricane that smashed head first into the city, leaving devasting destruction, worser than Katrina.


Woah that might be a little too dramatic there...Katrina's effect was so devastating because NOLA is highly vulnerable to hurricanes. Although I have no doubt that a Tampa/Myrtle Beach hit would be very bad, I'm not sure it would be worse than Katrina.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
679. pearlandaggie
12:50 AM GMT on May 28, 2008
Michaael, not here....as they would say heer in Texas...startin' to furget wut a guud sterm is like!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
676. pearlandaggie
12:46 AM GMT on May 28, 2008
Bastardi seemed to lie at the other end of the spectrum, seeking to scare the bloody daylights out of viewers. Even on Friday, long after the [National Weather Service] forecast had moved well east of Galveston, Bastardi was still calling for a direct hit on Galveston and Houston. By Friday evening, when the storm neared land, he called for landfall near Port Arthur at 150 mph, nearly category-5 strength. At landfall Rita's winds were 120 mph, and considerably lower in Galveston.

IMHO, that Bastard(i) was partly responsible for the evacuation fiasco! very irresponsible...
Member Since: September 14, 2007 Posts: 3 Comments: 3963
675. JRRP
12:47 AM GMT on May 28, 2008
659. CaneAddict 12:32 AM GMT on Mayo 28, 2008

656. extreme236 12:27 AM GMT on May 28, 2008
Lots of active convection



Yeah, The caribbean is becoming more moist.

Does this convection can that the Carib does not warm very much?

Member Since: August 16, 2007 Posts: 0 Comments: 5834
673. weatherblog
12:46 AM GMT on May 28, 2008
The Eastern Pacific TWO says 90E is moving eastward/eastnortheast. So, maybe it'll cross into the caribbean? (Even though the models say otherwise)
Member Since: July 10, 2006 Posts: 27 Comments: 1623
672. juniormeteorologist
12:45 AM GMT on May 28, 2008
Caneaddict you are not the only one..they have been predicting another major storm to hit south carolina, and category 4 or 5 I believe..Hugo was a terrible storm to the economy and I truly beleive that this year Tampa and Myrtle Beach, SC will have a major hurricane that smashed head first into the city, leaving devasting destruction, worser than Katrina.
671. extreme236
12:45 AM GMT on May 28, 2008
Joe B. and his Rita hype:

"NO CHANGES ON TRACK. LANDFALL NEAR GLS, THEN SLOW MOVE UP I-45 CORRIDOR. STORM TRAP SET AND BACKING SOUTHWESTWARD TOWARD MEXICO TO FOLLOW. ANOTHER POST LATER, BUT MAJOR DISASTER SCENARIO MAY COME TO PASS...EVEN BEYOND THE OBVIOUS OF 930-950 MB HURRICANE HIT."
Member Since: August 2, 2007 Posts: 19 Comments: 19234
670. nash28
12:43 AM GMT on May 28, 2008
Gotta run again guys... Chicken was fantastic. Now, gotta run to CVS for the wifes prescription. BBL.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
669. pearlandaggie
12:42 AM GMT on May 28, 2008
Dear God!!!! They oughta know better than to propogate scare tactics like that! Denis Phillips needs to take it down several notches.

four words for you nash...

Joe Bastard(i) and Rita!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
668. nash28
12:42 AM GMT on May 28, 2008
Bottom line is, YES, the time and the 87+ year luck WILL RUN OUT one day. But to say that the this might be the year, as if it WILL be the year is just silly at best.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
667. nash28
12:41 AM GMT on May 28, 2008
Dear God!!!! They oughta know better than to propogate scare tactics like that! Denis Phillips needs to take it down several notches.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
666. pearlandaggie
12:41 AM GMT on May 28, 2008
just remember CaneAddict...

All models are wrong...some are useful!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
665. extreme236
12:40 AM GMT on May 28, 2008
661. CaneAddict 12:34 AM GMT on May 28, 2008
It is quite scary how on this show i am watching on channel 11 Accuweather news, They are stating that the NHC thinks within the very near future that a major hurricane will make its way through Tampa Bay....Our last major hurricane was in 1921. They are also stating this year could be the year.


Accuweather is mentioning that because they want to make sure everyone knows that if that happens they were the first to tell you lol
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664. pearlandaggie
12:39 AM GMT on May 28, 2008
CaneAddict...i knew so folks in Tampa when Charlie was headed their way. now that was a close call!
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663. CaneAddict
12:38 AM GMT on May 28, 2008
200 Comments Sort: Newest First - Order Posted Filter: Show All Show Bad Show Below Average Show Average Show Good Show Best

662. pearlandaggie 12:37 AM GMT on May 28, 2008
661. i hear ya buddy...and i even washed my car this weekend! i thought that was a sure bet! we sure could use some tropical moisture without the wind!
Action: | Ignore User


Sure can!
Member Since: October 5, 2007 Posts: 3 Comments: 2151
662. pearlandaggie
12:37 AM GMT on May 28, 2008
661. i hear ya buddy...and i even washed my car this weekend! i thought that was a sure bet! we sure could use some tropical moisture without the wind!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
661. CaneAddict
12:34 AM GMT on May 28, 2008
It is quite scary how on this show i am watching on channel 11 Accuweather news, They are stating that the NHC thinks within the very near future that a major hurricane will make its way through Tampa Bay....Our last major hurricane was in 1921. They are also stating this year could be the year.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
660. beell
12:32 AM GMT on May 28, 2008
657.
Hey Pearland, In Crosby here. The whole thing just stopped on a dime and went poof like a pre h-season model run...
OK, that was a bad joke. Sorry.
Member Since: September 11, 2007 Posts: 143 Comments: 16651
659. CaneAddict
12:32 AM GMT on May 28, 2008

656. extreme236 12:27 AM GMT on May 28, 2008
Lots of active convection



Yeah, The caribbean is becoming more moist.
Member Since: October 5, 2007 Posts: 3 Comments: 2151
658. extreme236
12:30 AM GMT on May 28, 2008
655.

lol I didn't even notice that
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657. pearlandaggie
12:28 AM GMT on May 28, 2008
654. yeah, but no gottie rain in the southern part! it's been dry as a bone for a while.
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656. extreme236
12:27 AM GMT on May 28, 2008
Lots of active convection

Member Since: August 2, 2007 Posts: 19 Comments: 19234
655. pearlandaggie
12:27 AM GMT on May 28, 2008
651. why is it, so often, when people try to make hurricane humor they get the rotational direction wrong? (not a poke at you extreme, just pointing that out)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
654. beell
12:27 AM GMT on May 28, 2008
Texas got clouds.
Valid 6:45PM CDT/23:45Z
Photobucket
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653. pearlandaggie
12:24 AM GMT on May 28, 2008
650. you know, the sad part is THAT IS ACTUALLY the wind sensor on the Mars lander...except that...

The active element of the instrument is an extremely lightweight Kapton tube hanging in Kevlar fibres. Images taken of the instrument will show the deflection of the Telltale due to the wind. A mirror is mounted below the active part to enable better direction information.


i kid you not....
Member Since: September 14, 2007 Posts: 3 Comments: 3963
652. nrtiwlnvragn
12:23 AM GMT on May 28, 2008
648. ATS3

Don't think so. N44RF is not scheduled to complete rework until fall of 08.
Member Since: September 23, 2005 Posts: 14 Comments: 11179
651. extreme236
12:22 AM GMT on May 28, 2008
I just found out that Florida is now warning their guests about the potential dangers of the state:

Member Since: August 2, 2007 Posts: 19 Comments: 19234
650. JLPR
8:20 PM AST on Mayo 27, 2008
647. jaja lol haha funny =P
I need to put one of those rocks on my backyard lol =D
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649. extreme236
12:19 AM GMT on May 28, 2008
647. pearlandaggie 12:17 AM GMT on May 28, 2008
hey extreme, you need to think more high-tech...like NASA does...


ROFL
Member Since: August 2, 2007 Posts: 19 Comments: 19234
648. ATS3
12:12 AM GMT on May 28, 2008
WILL NOAA HAVE ONE NEW P3 FOR THIS SEASON?
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647. pearlandaggie
12:16 AM GMT on May 28, 2008
hey extreme, you need to think more high-tech...like NASA does...

Member Since: September 14, 2007 Posts: 3 Comments: 3963
646. pearlandaggie
12:14 AM GMT on May 28, 2008
atmoaggie...hey buddy, did miss something!?!?! LOL :)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
645. extreme236
12:11 AM GMT on May 28, 2008
We will just have to wait and see what happens. We should just predict the tropics like the NWS does:

Member Since: August 2, 2007 Posts: 19 Comments: 19234
644. atmoaggie
12:07 AM GMT on May 28, 2008
My God... LOL!!!


Obviously you also have no clue... CO2 from your breath orginally came from the air (if you eat plants or animals that ate plants, unless you eat crude oil - ick). In other words, there is no effect at all from breathing. If anything, CO2 is actually removed from the atmosphere by humans as it is incorporated into their bodies (carbon is a basic element for life), many of which are also overweight; not to mention that they are usually preserved and buried in such a way that their remains don't reenter the environment, at least not for decades or longer (not sure how good embalming is as a preservative).


I have a terrific clue, STL. This would achieve your goals. If 40something% of Americans, most of the Europeans, all of the others that are so thoroughly convinced the "science" is complete ceased to be, then the solution they were all looking for would come to fruition. Might be the only solution that would actually have an effect.

So if you are destroying the earth and gullible/arrogant enough think about the solutions that might actually work then ask yourself if you are sure the "science" is settled or if the real science has only begun.
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643. Tazmanian
5:08 PM PDT on May 27, 2008
Parkersburg Tornado Rated EF5


www.crh.noaa.gov/crnews/display_story.php?wfo=dmx&storyid=14909&source=0
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642. WPBHurricane05
8:04 PM EDT on May 27, 2008
wplg local 10 hurricane special is on also

i think max mayfield will come on soon
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641. hahaguy
8:03 PM EDT on May 27, 2008
for all of you in the wptv viewing area they are having a hurricane special its on now
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640. Thundercloud01221991
12:00 AM GMT on May 28, 2008
thank you for the link
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639. IKE
7:01 PM CDT on May 27, 2008
638.

OK.
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638. extreme236
12:00 AM GMT on May 28, 2008
I guess when they made the HWRF they ran it through all the 2005 storms and compared it to the GFDL and found it to be about 30% more accurate or something like that.
Member Since: August 2, 2007 Posts: 19 Comments: 19234

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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.

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