The tornado season of 2008: climate change to blame? And, tropical update
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
Missing House, if found call Dennis and Carla
Nice structure on upercell east of Pratt, Kansas. Photo copyright Mike Theiss.
Reader Comments
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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...
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.
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...
Again, see Barry circa 2007 which taught all of us a thing or two about the ULH:-) Taught me something that's for sure!
Plttttttttttttttttttttttttttttttttttttttttttt...
LOL
A real Blogeer Holds fast and steady and wrings out hiz or Her pernt.
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.
Heart attack and aggressive person on premises:-)
I am just kidding:-)
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".
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.
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.
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.
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.
/but i still want to know how to pronounce "Luxion"!! LOL
looks like the epac storm has been
coming together
may cross over to the carribean
wait and see
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
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...
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.
Link
Link
Link
LOL Extreme! Just wait for 90L! The GFDL will be so happy to stretch its legs, we'll have a CAT4:-) Kidding of course.
LOL I was thinking that the GFDL would want to dissipate 90L if it forms before June 1st kind of like a "Its too early for this to happen and I'm not done hibernating yet" type of thing :-)
I dont Publish them.
That 3rd Link is a Texas blog.
Imagine that.
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.
LOL I was thinking that the GFDL would want to dissipate 90L if it forms before June 1st kind of like a "Its too early for this to happen and I'm not done hibernating yet" type of thing :-)
GFDL wants to tackle one of those Cape Verde's.
Maybe one year the 12th named storm will be "Luxion", then no one will be able to pronounce it, kind of like "Georges"!
Link
The GFDL wants to develop the Caribbean system too! But puts it into the BOC.
ROFL I just noticed that. The NHC ran it with the intention of seeing what it wanted to do with 90E and instead it told us the Caribbean system develops.
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