Saturday, June 15, 2013

The Joplin Tornado Was Not EF-5 Intensity: Implications

Since the Joplin tornado of May 22, 2011, which is the only tornado to kill more than 100 people in the modern tornado warning era, the National Weather Service has contended it was the strength, as well as the size, of the storm that lead to so many deaths (158 to 161 depending on who is counting and their methodology).

For example, the National Weather Service's Joplin Service Assessment begins,

It also calls the event rare, which EF-5 tornadoes certainly are.

But, what if the tornado wasn't that strong? It appears it was not according to a new study by the American Society for Civil Engineering. While Joplin was a terrible tornado (EF-4's are major storms!), the tornado was simply not the unsurvivable high end tornado that some have made it out to be. The study talks about issues with building construction. Those issues have apparently been addressed by modifications to the Joplin building code which include the installation of hurricane clips. That should be done in new homes throughout tornado alley and I congratulate Joplin for doing so.

But, now we are back to the question, If the tornado was not as strong as first thought, why did so many die?

With the news the Joplin tornado was not extraordinarily strong, is appears to validate the case I make in When the Sirens Were Silent which is the story of the warning system's many tragic failures that day. A malfunctioning warning system that day allowed us to return to the pre-warning system level of deaths that would be expected with this type of storm.

The sirens were sounded in Joplin when it was not under a tornado warning. The sirens were not sounded when a tornado warning was eventually issued and as the tornado was approaching the city. The National Weather Service, multiple times, misreported the location and direction of movement of the storm. Finally, the tornado was invisible so people could not recognize what was approaching them.  The book explains what went wrong on a minute by minute basis with a goal of making sure it never happens again.

The book has received very good reviews and the paperback version is completely sold out. We've purposely priced the ebook version at the very low price of $2.99.

There is only one reason we don't have triple digit yearly death tolls due to tornadoes: The warning system. That is the story I tell in Warnings. But, in the rare cases when the warning system fails, the U.S. reverts to pre-warning system death tolls. That is why the meteorological infrastucture must be preserved and strengthened.


  1. Mike...Homes that have hurricane clips, I assume that will help keep the roof on? Is that a guarantee in a tornado regardless of strength? I have seen so many pictures of other places where the weather service concluded EF-4 or greater damage had occurred and the Joplin damage looked like it had suffered similar.

  2. No, it will not keep the roof on in an F-3 or stronger. But, it will in weaker tornadoes which is the great majority.

  3. Todd,

    The report indicated that while the tornado was a *strong* EF4 - like in many of the very large tornadoes the strongest winds had a small damage path - much of the damage from the tornado was F3 or weaker - and according to the report based on damage types the construction changes (which include more than just clips) would have stopped much of the damage.