26 December 2008

If Your Roof Is Gone, Does It Matter If It Was a Tornado?

Posted by Dan Satterfield

I have asked this question to myself many times.

Any Meteorologist, who works as a forecaster, will tell you that people get very upset if you tell them that the damage to their home was not caused by a tornado.  I am not sure why this is the case, it would probably make a good PhD thesis for some Psychology student!

Straight line winds can, and most of the time are, responsible for most structural wind damage. I have talked with people who no longer have a roof, and they were genuinely disappointed that it was not a tornado that took it! ESPLAIN THAT ONE RICKY!

In many cases it can be difficult to tell. The damage at Belle Mina, in Alabama on Christmas Eve, is a good example! My first thought was that it was likely straight line winds. A good rule of thumb is this: if the only damage is a mobile home, then assume straight line winds. In this case, there was some decent evidence of an EF-1 tornado. That means a 3 second wind gust of 86-110 mph.

If you have wondered how these storm surveys are done, here is a link to a power point presentation on doing storm surveys. It is courtesy of the U.S. National Weather Service.


The slides were put together by NWS Meteorologist Ernest Ostuno.