Eleven-Year Major Hurricane Drought: Much More Unusual than Two Cat 4 Strikes

the statistics of rare events (like hurricanes) are not very well behaved. Let’s look at this new record, and compared it to the 11+year period of no major hurricane strikes that ended when Harvey struck Texas.

Roy Spencer

[This is a reprint (21 Sep 2017) from Dr. Roy Spencer’s blog (drroyspencer.com) in which he makes the point that two category 4 hurricanes making landfall in the same year is far more likely than the recent  eleven year period with no major hurricane landfalls that preceeded the two category 4 hurricanes.  Assuming the 177 year return period for no major hurricanes in 9 years estimated by NASA was correct, we agree with Dr. Spencer that the return period for no major hurricanes in 11 years would be 560 years.  Ed.]

Weather.com published an article noting that the two Cat 4 hurricane strikes this year (Harvey and Irma) is a new record. Here’s a nice graphic they used showing both storms at landfall.

http://www.drroyspencer.com/wp-content/uploads/irma-harvey-split-550x309.jpg
Left: Hurricane Harvey makes landfall near Rockport, Texas, on Aug. 25, 2017 | Right: Hurricane Irma makes its first landfall at Cudjoe Key, Florida, on Sept. 10, 2017 (graphic: Weather.com).

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