The Math Behind Tornado Outbreaks

Posted by Daniel on July 6, 2011

photo of tornadoAfter watching this year’s outbreak of violent tornadoes and the tragic toll they imposed on countless lives, I decided to research these tragic twisters and their future likelihood.   Partly for my own peace of mind and to assist in making an informed purchase decision regarding a tornado shelter for my home.    Here’s what I found…

According to the National Oceanic and Atmospheric an Administration, most tornadoes (around 77%) in the U.S. are considered weak (EF0 or EF1) and about 95% of all U.S. tornadoes are below EF3 intensity. The remaining small percentage of tornadoes are categorized as violent (EF3 and above). Of these violent twisters, only a few (0.1% of all tornadoes) achieve EF5 status, with estimated winds over 200 mph and nearly complete destruction. However, given that on average over 1000 tornadoes hit the U.S. each year that means that 20 can be expected to be violent and possibly one might be incredible (EF5)

Obviously after the 2011 tornado season, we can see that averages aren’t all what they are cracked up to be.  Thus, if you are going to build a tornado shelter, do you want to keep your family safe from 95% of tornados or do you want to include the 0.1% (F5) in your protection plans, too?  I don’t know about you, but I’m not taking any chances on that 0.1%.

While researching tornado outbreaks I couldn’t help but think of their similarities to financial planning.  After evaluating all possibilities most retirees and their advisors opt for the portfolio that will survive the majority of their predictions (a market bump of an F1 to F2 – 95% protection).  Leaving themselves extremely vulnerable when (not if) an F4 or F5 market correction occurs.  No wonder there are so many people unhappy with their advisors and investments.

My conclusion… I’m in the market for a solid tornado shelter to keep my family safe regardless of what percentile my address happens to reside on.




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