Dan Sutter and I have a new book released this week from AMS Books and the University of Chicago Press.  You can order the book from AMS Books at:

Deadly Season: Analysis of the 2011 Tornado Outbreaks

A Tornado Visits My Hometown

I’m an economist who studies natural hazards.  Over the last few years, tornadoes have dominated that research agenda.  It’s a fascinating topic for social scientists and most of the time I can separate the emotions of a horrifying event allowing me to conduct dispassionate analysis.  But yesterday the research came home.  Both my wife and I went to high school in Arlington, Texas.  Most people know Arlington as the home of the Texas Rangers, Six Flags and now the Dallas Cowboys.  But for those of us who were raised there, it’s home like any town is home.  We know the streets, not as markers on a map but places in our lives.  We remember when the mall was an open field as well as the name of the local college before it was subsumed into one of the state university systems.  As I was watching TV coverage of the tornadoes, it became clear that my home town had been struck by the very monster I have spent the last 10 years studying.  It’s not the first tornado to hit Arlington, or the DFW metroplex, for that matter, but it was the first time since the incredible and horrifying death toll from last year’s tornado season.  It also happened as the National Weather Service is conducting an effort, known as Weather Ready Nation, to help prepare for future outbreaks.  I’ve been involved in that effort and I have no doubt that yesterday’s outbreak will become one of the talking points.  The main point for the researcher in me is that a tornado outbreak hit a major population area and as of now, there are no fatalities.  Over 6 million people live in the Dallas/Ft. Worth metropolitan area.  By some estimates somewhere between 6 and 12 tornadoes touched down, some large enough to send 5 ton tractor trailers into the air like match sticks.  Significant to major damage occurred in Kennedale, Arlington, Lancaster and Forney, all suburbs on the southern and eastern side of the DFW metroplex but across a 50 mile swath.  This is the nightmare scenario that keeps forecasters and emergency managers up at night.  And when the previous season saw death tolls in the hundreds, it brings a keen focus to bear.  Teams of engineers will descend on my home town in the ensuing days to assess the storm path and damage.  They should talk to Dale Stubblefield, who went to high school with my wife and me.  He posted an eye witness account on Facebook with a description of the path, the damage he witnessed but most importantly the speed with which the neighborhood began the process of recovery.

“The damage to the neighborhood is heart breaking. We were lucky and had minor damage, a broken window, some roof damage, we lost a tree and our fence. Our neighborhood got nailed. The tornado crossed 287 at Sublett, turned north and passed Corey Elementry creating havoc. It crossed I-20 and blew up homes as it headed to St. Barnabus Church up on the hill. The pre-school was in session with over 85 kids as the storm ripped off the roof of the chuch education building and then ripped though my neighborhood before hitting a nursing home on Green Oaks. 

Help was immediate. The Martin HS football team came in by the truckloads and started stacking fence panels, moving brush and helping a family move their valuables out of their home. Members of St. Barnabus, even though their church had been heavily damaged brought food and drinks to those working to secure homes. Wow - what a day.”  

More Thoughts on the Tornado Outbreak of 2011

I've just completed  participating in a conference sponsored by the Geneva Association where I presented my thoughts on this years tornadoes.  In preparing for the presentation, I used our casualty models to see if this year suffered from any of the vulnerabilities we had identified that will inflate fatalities.  The answer to that question is yes.  Compared to previous outbreaks, this one occurred predominantly in the southeast which has the highest fatality rate from tornadoes than any other region.  As an example, the fatality rate for the US is .45 per million calculated using data from 1950-2010.  Mississippi has a fatality rate of 2.8, six times the US average.  Secondly, there is a greater proportion of mobile homes than previous outbreaks.  As a comparison, consider the tornadoes of 1953, the last year we suffered more than 500 deaths.  For the counties affected by those tornadoes, the percentage of mobile homes in the housing stock was 6 tenths of one percent.  It was 10 percent for the counties affected by this years tornadoes.  Our research confirms the observation that you are 10 times more likely to die in a mobile home struck by a tornado than a permanent home.  As more mobile homes are in the path of the tornado, higher casualties will likely follow.  Finally, one third of this years fatalities occurred on a weekend including the tornado in Joplin.  We have found that casualties are significantly higher on either Saturday or Sunday than during the week.  People are safer in the buildings they work or go to school in than they are in their own homes.  I used our casualty model to estimate the change in fatalities for the Joplin tornado if it had occurred on a Monday rather than a Sunday and found the expected fatalities would have been reduced by 23%.

So it's no wonder that we have now exceeded the largest annual death toll since records were kept beginning in 1950.  Or is it that simple?  I also spoke at the AMS Broadcast Meteorology Conference last month.  Some of the comments I heard from people expressed shock at the casualties but also questioning the value of the warnings that have been celebrated for minimizing casualties.  That started me thinking about how I could test whether or not the warnings were effective.  Keep in mind that the Joplin tornado had 24 minutes lead time.  One way to examine this notion is to compare the fatality rate from this years tornadoes with another outbreak.  Again, consider 1953 which had a similar number of killer tornadoes, 41 versus 56 this year, had a similar number of affected counties, 72 versus 75 this year, a similar percent of F-3 plus tornadoes, 78% versus 79% this year, and a similar number of fatalities, 519 versus 537 this year.  The population of the affected counties in 1953 was 3.9 million giving that outbreak a fatality rate of 167 per million.  Affected counties in this years tornadoes is 8.2 million giving this year a fatality rate of 35 per million, half the rate of  1953.  Can the entire difference be attributed to better warnings?  No, I don't believe so, but it is clear that something profound has changed in the last 60 years and the obvious candidate is the investment we have made in our warning system as well as the enhancement in communication technology that we enjoy today.

There is no argument that we have experienced a terrible tragedy.  But it's my belief that the death toll could have much higher if not for the investment by and the efforts of the National Weather Service and the forecasters that have trained to warn residents of the danger of approaching tornadoes.

How Could This Happen?

            April of 1974 was a very special month for me.  I met, then asked to my senior prom the young woman who has now been my wife of 33 years.  But April of 1974 has a tragic history for it was on April 3, 1974 that hundreds of people died in what was one of the worst days for tornado fatalities.  Since that time, Doppler radar was installed and increased dramatically the accuracy and timeliness of tornado warnings.  Communication technology has improved beyond anything we imagined in the 1970’s and this has allowed warnings to be disseminated quickly and to virtually anyone with a TV, radio, computer or even cell phone.  As a result, casualties from tornadoes have dropped to an annual average of about 60.  Not until April of this year have we witnessed any tornado event which killed more than 100 people.  So it’s not surprising that we are shocked when we see the death tolls from the tornadoes of the last 6 weeks.  For the first time since 1953 we have exceeded 500 fatalities and by the time this season is over, we may top that total of 519.

            Some are asking if we had bad warnings for these storms.  The answer to that question is a resounding no.  Joplin had over 20 minutes of warning and the same has been true for each of the horrific events that our country has endured.  In fact, a good argument can be made that without our current warning technology and the expertise of our forecasters, the death toll would have much, much higher.  It is true that an EF-5 tornado which makes a direct hit on a home is going to kill and injure anyone inside regardless of the lead time these unfortunate souls had before it struck.  But keep in mind, that not all of the tornadoes we have experienced have been that strong and even the ones that were, may not have been that strong for the life span of the tornado. 

            So how could this happen?  Is it climate change or just bad luck?  I am not a climate scientist, so I will leave that question for more qualified researchers.  But I do have some insight into why this year has been one that we will likely never forget.  First, it has been almost 50 years since we have seen an outbreak of this magnitude.  And over that time we have come to believe that outbreaks of this size are so rare that we just don’t consider that they could happen in our lifetime.  But, 50 years is a blink of an eye to Mother Nature.  Our records and oral history only go back a few hundred years at best.  The Midwest was not aggressively settled until the latter part of the 19^th century so our experience with tornadoes is limited.

            Secondly, we have increased the population in vulnerable areas dramatically.  Land that was once uninhabited is now crammed with subdivisions.  When my wife and I attended the prom in 1974 the Dallas/Ft. Worth area consisted of 2 counties, Dallas and Tarrant.  It now stretches across 10 counties with a population of about 6 million.  The same can be said for Oklahoma City, Kansas City, Little Rock and other metropolitan areas in “Tornado Alley”.

            Finally, part of the reason is truly nothing more than bad luck.  Even with the increased population, there are still vast areas of rural land.  An EF-5 tornado that plows through a corn field kills nothing more than the fruits of a farmer’s labor.  A financial blow but not a human tragedy.  Tornadoes go where they do and if they cross human settlement, bad things are going to happen.  It is not the act of an angry god but the unfortunate consequence of living with a sometimes violent environment.   

Tornadoes in Oklahoma

Once again, central Oklahoma is the bull’s-eye for an outbreak of killer tornadoes. I have more than a professional interest any time a tornado passes through Oklahoma having spent 4 years living and working there. Additionally, our son still lives in Oklahoma City, so any time we hear of severe weather in that region, it catches our attention. Preliminary reports are that 5 people lost their lives and another 10 are in area hospitals with severe injuries. The death toll may rise of course, but it could have been a lot worse. Tornadoes are common there and most people have had experience with them and know what to do. One anecdote from this event reported on CNN.com illustrates that. The tornado struck a large truck stop on Interstate 40 east of OKC. Workers rushed everyone in the building into the safest room they had, the cooler. Travelers also sought shelter at the truck stop in one of the coolers or the restrooms. The tornado struck the truck stop ripping off the roof and overturning tractor trailers but no one was killed at this location.

My research with Dan Sutter on tornadoes reveals that had this event happened overnight, the death toll would have been much higher. Even a well warned tornado, can be overlooked by residents simply because they were not awake to hear the warning. Additionally, after the sun goes down, tornadoes are difficult to see and even when a warning has been given, some residents want to visually confirm the warning for themselves before they heed the warning. Just to give a sense of the value of tornado warnings, Harold Brooks and Chuck Doswell of the National Severe Storms Laboratory estimate that prior to the National Weather Service issuing tornado warnings the fatality rate from these storms was 1.8 per million. Today it is .11. This suggests that fatalities, without our current warning system could be more than 16 times higher than they were today. So instead of 5 fatalities we could be looking at the potential of having almost 100 from this event. Tornadoes are scary partly because of the power they posses but also because of their unpredictable nature. But, we are fortunate to have a dedicated, professional staff of forecasters who provide valuable warnings and do indeed save lives.

You Can't Fight Mother Nature

It is perhaps ironic, but a researcher in natural hazards, finds himself at the mercy of a natural hazard.  I am talking about the Iceland Volcano, which has not had any fatalities, but may prove fatal to some businesses in Europe, most notably, airlines and the travel industy.  Today is the fifth day of closed airspace over Europe.  I was supposed to be presenting research in Munich on Friday, travel to Bratislava for a Fulbright Lecture, then take the night train from Vienna to Zurich for another conference.  Well, let's just say that plans have changed, at least somewhat.  Munich and Bratislava were cancelled but I do plan to make it to Zurich, but by train, from Oslo.

This event is certainly a lesson for modern society.  The disruption in air travel has created absolute chaos in a number of areas.  Passenger travel is the obvious one, but for many there are alternatives, like my changing to a train, which is easy to do in Europe.  But there are other areas that will be hurt as well.  Delivery of goods, particularly perishable goods are in real trouble.  It has been very easy for urban areas to have fresh fruits and vegetables available year round.  We simply had them flown from warmer regions with lower labor costs.  But, without air service, that produce will rot in warehouses.  An event like this reminds us of how vulnerable that delivery system is.  The airline industry in Europe was in a precarious state to begin with.  For some airlines, the loss of business could be the last straw.  My cancelled flight was on SAS.  SAS announced that if the disruption continued into this week, which it has, they would begin laying off 2500 workers.  BBC is reporting that as an industry, airlines are losing $200 million a day.  This is day five, so that would make the costs to the airlines at $1 billion.  But, it occurs to me that a bigger concern to the airlines could be the realization on the part of travelers of the inherent uncertainty of flying.  The last time this volcano erupted was in 1821 and it erupted on and off for almost 2 years.  As travelers take this into consideration when making their plans, will it cause them to consider alternatives, like ferries and the train?  Will it cause travelers from other continents, like North America to stay home rather than taking the risk of being stuck across an ocean from home?  The last thing the European economy needs now is a reduction in tourism.  Greece is perilously close to defaulting on their sovereign debt, while Portugal and Spain are not far behind.  Our world is inter-connected in ways that are not obvious until something like this happens.

Bottom line, you can't fight Mother Nature.

Landslides

     

The project I am developing while in Norway deals with the socio-economic consequences of landslides.  Most of my work, up until now, has focused on wind hazards, tornadoes and hurricanes.  Before my arrival in Norway, Uganda suffered serious damage and fatalities from a landslide and just yesterday 95 souls were lost in the mudslides that occurred in Brazil.

In the US, the US Geological Survey estimates that in an average year 1 to 2 billion dollars worth of damage are attributed to landslides and over 25 lives are lost.  This is damage and casualty totals similar to tornadoes, yet landslides do not receive the same amount of attention in the media.  My project will merge data on landslides and some of the precipitating events such as thunderstorms and wildfires with demographic data to attempt to create a damage profile of this hazard.  The data on landslides has been obtained from a hazard database maintained by the University of South Carolina called SHELDUS¹.  My thanks to Susan Cutter and her colleagues in compiling this data for researchers to use.

Before I left for Norway, I was interviewed for a short syndicated television segment on tornado warnings.  The first station to pick it up is WCPO in Kentucky.  Here is the link:

Tornado Warnings

This week I will be presenting my research to the Economics Department at the University of Gothenburg, in Gothenburg, Sweden.

¹Hazards & Vulnerability Research Institute (2009). The Spatial Hazard Events and Losses Database for the United States, Version 7.0 [Online Database]. Columbia, SC: University of South Carolina. Available from http://www.sheldus.org "


Landslide Photographs are provided by the International Centre for Geohazards, a research centre of the Norwegian Geotechnical Institute.