The three questions… Case Study #1. U.S. tornadoes

The news from the Nation’s Midwest over the past few days has been tragic. Early-season tornadoes wreaking death and destruction across a wide swath. Just yesterday? Dozens killed in three states. Scenes of the destruction and interviews with the survivors dominate the papers, the news networks and the internet this morning. After a mild winter over much of the country, memories of last year’s tornado season are returning with a rush. The pain for those who have lost loved ones and homes – everyone and everything they’ve lived for – is unimaginable. Words are inadequate.

Yesterday’s post gave a little background on the three questions posed in the blog masthead:

What kind of world is likely if we take no deliberate action?

What kind of world do we want?

What kind of world is possible if we act effectively?

Today, briefly, to honor the memory of those who lost their lives yesterday, let’s reason through how we might answer these questions as they apply to tornadoes here in the United States. Please forgive me for this necessarily individual view. The operative word in the questions is we, that is, all of us. Please offer your differing perspectives and ideas.

What kind of world is likely if we take no deliberate action? We all know the answer to this one. In meteorology, persistence is the best forecast. The United States, by virtue of its geography and its climate, has a lock on the world’s tornadoes. Most of them and especially most of the truly dangerous ones, occur here. We average over 1000 a year. Population in the region of greatest risk is going up. Property exposure is rising as well. If we take no action to improve building construction, if we fail to provide safe rooms or tornado shelters on a home-by-home and building-by-building basis (think schools, hospitals, etc.), the loss of life and property may fluctuate year-on-year, but long-term, it’s going to rise.

Note that we discuss the built environment prior to discussing improved warnings. If warnings do not improve…that is, (1) the accuracy of the meteorological (tornado) forecasts themselves (track location, timeliness, characterization of intensity, beginning and end of the event, and so on) and (2) the communication of that risk over “that last mile,” so that it reaches people in a form that breaks through their daily routines and prompts action…then again, the death toll will continue to rise.

But even if warnings continue to improve (and thanks to the NOAA’s National Weather Service, and those university researchers and those private-sector engineers and weather service providers, warnings are improving a lot), if those who receive the warnings don’t recognize or don’t have life-preserving actions/options, the loss of life will continue to rise. A tornado warning does little good for those without a safe room or tornado shelter. The ordinary interior room in a home is of limited value. A basement? Not bad…if you’re lucky enough to have one. Climbing in the bathtub?  Better than nothing, but of limited value.  A tornado shelter for your mobile home park? Not bad, if it’s maintained, if there’s room for everyone, and if you and your family are going to be disciplined enough to run to it in the rain and hail, even on those occasions when the warning might prove to be a false alarm.

We’re increasingly urbanized – concentrating more people more tightly into small geographic areas. This trend is new (that is to say, it’s occurring over decades rather than centuries (plural). So the number of encounters between tornadoes and urbanized areas has to date been small. But over time, more such encounters will come. And when they do, the loss of life and property will hit levels that seem unimaginable today. Picture the loss of hundreds of lives and billions of dollars from individual tornadoes. Such events are now hardwired into our future.

There’s more pain and suffering in the forecast.

What kind of world do we want? We know the answer to this one as well. Let’s begin though, by taking one possible “want” off the table. Some of us might want a world with no tornadoes. But tornadoes are a collateral feature to the storms that bring the Midwestern and southeastern United States much of their needed growing-season rainfall. Furthermore, while these same storms are destroying property and taking lives, they are creating economic opportunity. Called storm-chasing, it’s really eco-tourism by another name. Google the expression; you’ll find lots of companies and individuals waiting to give you the thrill of a lifetime…seeing a tornado up close. Does this seem callous? Just remember those same Rocky Mountain snowstorms that used to kill the early settlers trying to make their way to California’s gold rush fields today support a burgeoning ski industry. So natural extremes – not just tornadoes but hurricanes and winter storms and hail, floods and droughts and wildfire, and even earthquakes and volcanic eruptions – are beautiful in their own way. Their power and majesty inspire our awe. It’s the disasters – the catastrophic disruptions of human affairs – that are tragic and ugly.

Tornadoes are part of the real world, and therefore non-negotiable.

So, given the reality of tornadoes, what kind of world do we want? Well, we don’t want to live in underground bunkers. We want a world where our homes are above ground and have lots of glass and offer splendid views in fair weather, but morph into bunkers when danger threatens. We want ample and affordable insurance coverage and we want protection for our treasured irreplaceable possessions such as photographs, etc. We want watches and outlooks with long lead times and timely warnings that actually reach us when we’re in harm’s way and at the same time guide us to take life- and property-preserving steps.   Maybe we’d even like enough advance notice to evacuate as a family, along with the cat and the dog.

Not going to happen – but establishes the direction we want to go, doesn’t it?

Which brings us to…

What kind of world is possible if we act effectively? Well, it turns out that we might be able to get pretty far down this road. But speaking of roads, forget evacuation. Too great a risk of being trapped and vulnerable in gridlock on impassable roads and streets. Shelter-in-place is the practical option.

With tweaks in building codes (driven by consumer demand and our family values versus some top-down command-and-control imposition) we would find ourselves over time in better-constructed housing, with safe rooms, for only incremental cost. [Such construction is much less expensive than after-the-fact retrofits.] Then those better warnings would prompt us to take easy, familiar action (assembling in that safe room for brief periods) until the threat had passed. If we knew our kids were safe in school and the sick were safe in hospitals, then we could begin to tackle safety in the workplace and the shopping mall…you get the idea. And with insurance to cover the remaining risk, and make us whole economically…we’d be a lot better off than we are today.

We would be a Weather-Ready Nation.


Remember that threat of tornado strikes in urbanized, densely populated areas? That’s going to take more thought, and concerted action. A needed starting point? A good high-level risk assessment. We need to get started on that.

Please be safe this tornado season.

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4 Responses to The three questions… Case Study #1. U.S. tornadoes

  1. Kim Klockow says:

    Thanks for the post, Bill. Great thoughts, as always. I just have a few thoughts to add.

    With respect to present sheltering-in-place measures, for the vast majority of people, they’re actually effective. Less than 1% of the people who sheltered-in-place on May 3, 1999 died in the F-5, and if my summer GIS student’s estimates are roughly good, then ~a quarter of one percent of the exposed population perished in Alabama on 04/27 last year (an estimate that was almost indistinguishable from the April 3, 1974 outbreak rate of fatality by exposure). This might suggest that fatality is random chance when tornadoes get that intense, but outcomes can still be good overall.

    Reinforcing at least portions of our structures should alleviate the random chance worry for those sheltering-in-place, but we need to keep in mind who it is that’s most vulnerable to the preponderance of tornadoes: those who live in vulnerable structures (e.g., mobile homes, sub-standard apartments) given their socio-economic position. It doesn’t take an EF-4/5 to harm these people, but for them, the solution can’t be something that comes with additional costs that they need to bear. I think we might need to rely on something other than sheltering-in-place for these people, but it would require quite a bit of community orchestration. See the May 24, 2011 central Oklahoma case to understand the problems with people seeking alternate shelters hours ahead of time. This needs to be resolved, infrastructurally, on a community level.

    The information meteorologists provide is having a great deal of influence on the sheltering choices people are making, but in recent years, these behaviors have been changing quite a lot in some places. Some relationship between community and weather information providers may be needed to foster our best long-run outcomes.

    • William Hooke says:

      Thanks, Kim.

      Great comment and interesting statistics…a really useful contribution/addition to the discussion. Just a couple of questions…When you speak of sheltering in place, are you speaking only to structures without safe rooms or tornado shelters, or are those such a small fraction of the population that it doesn’t matter? And do you have statistics on survival rate as a function of radial distance from the center of the track? How far away from the core of the tornado in your analysis could someone be and still be included in your sample? Does that distance vary with tornado strength, or the width of the damage pattern on the ground? And finally, are you suggesting that it’s not cost-effective for people of any income level to take these extra precautions? Again, thanks.

      • Kim Klockow says:

        Hi Bill,

        Thanks for the thoughtful questions, and I’ll answer as best I am able. Sheltering-in-place during May 3 was primarily done by those without storm shelters (this is possibly covered in Biddle, M.D., 2000: Warning response and risk behavior in the 3 May 1999 Oklahoma City long track violent tornado. Preprints, 20th Conf. Severe Local Storms, Orlando FL, Amer. Meteor. Soc., 650–653. But it’s certainly covered in his dissertation that I have sitting on my desk, which might never have resulted in a publication). Detailed analysis of injuries and fatalities for the event can be found in the following WaF article: Tornado-Related Deaths and Injuries in Oklahoma due to the 3 May 1999 Tornadoes. Sheryll Brown, Pam Archer, Elizabeth Kruger, Sue Mallonee.

        I don’t have statistics on survival as a function of distance from the center of the track – I’ve not seen any studies that have done this, actually. My student took estimated track widths from (Brooks, H. E., 2004: On the relationship of
        tornado path length and width to intensity.
        Weather and Forecasting, 19(2), 310-­319.) and applied the buffers to GIS track information provided by the Huntsville and Birmingham forecast offices (for 1974, she geocoded track information provided in Fujita’s event assessment and performed the same buffering). She quality checked the GIS information from the WFOs with aerial survey raster data, and did find some issues with data provided by one of the WFOs. This is a rough estimate that’s meant to reveal bulk effects, and an error sensitivity analysis revealed that we still have trouble distinguishing the events from one another in terms of fatality rate by exposure.

        I do want to be clear that I think shelters are a wonderful idea. It’s just proven very difficult to get shelters into mobile homes/the places that are most vulnerable due to cost (not just fixed, but variable cost). Repeated attempts to push policy for this in several states have failed (Harold can tell you these stories). Simmons and Sutter demonstrate that it’s “cost effective” to have shelters in/near such vulnerable structures, but for those who can afford it (who live in well-built structures), you actually have to be pretty risk averse to build a shelter. (Direct estimation of the cost effectiveness of tornado shelters.
        Simmons KM, Sutter D., Risk Anal. 2006 Aug;26(4):945-54.). I hope this helps to answer your questions!

  2. Pingback: The human face of shelter-in-place | Living on the Real World

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