Hard Luck, Hard Lessons in Moore

May 22, 2013 · 0 comments

While we hope, pray, and provide for survivors of Monday’s tragedy in Moore, Oklahoma, it is impossible to ignore the terrible turn of bad luck this tornado represents.

In 1999 Moore was struck by what has been considered the most powerful tornado ever observed on radar–winds over 300 miles an hour aloft. That was a billion dollar disaster that claimed 36 lives. Then, in 2003, the same path of destruction was crossed again–fortunately claiming no lives. Nonetheless at the time this powerful twister was rated an F-4 on the old version of the Fujita scale. And this week…unspeakable destruction and loss of loved ones as a mile-wide-plus tornado—an EF-5 on the Enhanced Fujita scale—yet again crossed the benighted path through Moore.

People in tornado country are vulnerable. It should be as simple as that. But the people of Moore are being tested beyond any threshold of resilience we might expect from the odds.

Clearly, lightning can strike in the same place twice. The people of Moore, and of Oklahoma in general, understood that, and have been open to the advice of the weather and climate community. For example, in 2002 the greater Oklahoma City metropolis spent $4.5 million to upgrade and expand its warning siren system. The Moore area alone has a network of 36 sirens and apparently took full advantage of the 16 minute warning lead time. Furthermore, areport from Oklahoma Climate Survey’s Andrea Dawn Melvin revealed the terrible vulnerability of schools in the 1999 disaster (she presented these findings at the 2002 AMS Annual Meeting; and at the symposium for the one-year anniversary of the tornado, in Norman). In response, school districts in the state have taken her advice to heart, revising emergency plans, and in some case building or reinforcing shelters.

But making good luck out of bad is an unceasing, and apparently unforgiving task, for meteorologists and citizens alike. Preparations are rarely perfect. Even though Melvin’s report helped spur Oklahoma City and other jurisdictions to create safe rooms in schools, other cities, like Moore, did not go this far in safety preparations. The two schools damaged in 1999 were rebuilt with safe rooms, but the other schools in the district–including those destroyed on Monday–were not upgraded in this manner.

Furthermore, while the 1999 tornado was among the most thoroughly analyzed of all severe storms in history, lessons drawn about building safety were not always heeded. A Weather and Forecasting paper by engineer and storm chaser Tim Marshall showed how the damage from the 1999 Moore tornado looked like the work of extreme winds until you examined how the houses had been built. Connections between frame and foundation, roof and walls had been compromised easily because of poor construction practices. Garage doors had been uncommonly weak points, forcing otherwise fine houses to yield to the storm. Marshall concluded, “Houses with F4 or F5 damage likely failed when wind gusts reached F2 on the original F scale.”

And yet, inspecting the rebuilding in Moore 40 days after the disaster, Marshall already found numerous instances of the same construction mistakes being repeated. It was rare for builders to exceed code standards in order to strengthen houses for a repeat tornado.

Unfortunately nature did repeat. While construction improvements would not prevent failure of a house in the worst case scenario, there are a lot of tornadoes in which safety can be improved by using the right kinds of fasteners, improving shelters, updating sirens, and the like. Monday’s disaster goes far beyond the placement of hardware and planks, but that is not the point. These tornadoes are a reminder  that all this happened before and can happen again.

Pray that hard luck finally ends for Moore, but remember that we are a community that must keep on learning hard lessons.