Hurricanes have been on our minds recently, with the start of the season just a month away. As we wrote Wednesday, the last time a major hurricane made landfall in the United States was Hurricane Wilma in the record-setting season of 2005, when it roared ashore in southwest Florida as a category 3 with powerful sustained winds of 120 mph.
But since then, it’s been a quiet decade on the major hurricane front. Although the landfall record gets muddy before the early 20th century, this is the first time since hurricane record-keeping began in 1851 that the United States has gone so long without at least a category 3 landfall. The previous streak was eight years, from 1861 to 1868.
“There’s been a lot of talk about how unusual the string is, and we want to quantify it,” said senior scientist Timothy Hall of the NASA Goddard Institute for Space Studies, the lead author of a new study published by the American Geophysical Union that tries to do just that.
The researchers used a statistical hurricane model to simulate the years 1950 to 2012 a thousand times to understand the range of possibilities in the North Atlantic ocean basin. Using the statistical hurricane landfalls from the model, they were able to conclude that the average wait time for a major hurricane drought is 177 years.
So why are we in this 177-year drought situation at the moment? It really does appear to be luck — or coincidence, if you prefer. “When we looked qualitatively at the nine-year drought, they aren’t inactive seasons,” Hall said. “I don’t believe there is a major regime shift that’s protecting the U.S.”
The study points to four reasons why researchers don’t think there’s been any meaningful or detectable change in hurricane seasons that would lead to fewer U.S. landfalls. First, since the record-breaking season of 2005, Atlantic hurricane seasons have been average as measured by accumulated cyclone energy. “The 2006-2014 annual mean ACE is 97,” they write, “compared to a 1951-2000 mean of 93.”
There also have been plenty of major hurricanes in the Atlantic since 2005 — it’s just that none of those hurricanes were category 3 or stronger if and when they made landfall. The researchers point to the seasons of 2008 and 2010, both of which had five major hurricanes, and 2011, which had four.
They also point to the activity south of the border — the Caribbean and Mexico have seen more than their fair share of major hurricanes, including five major hurricane landfalls in Cuba since 2005. And finally, hurricanes Ike and Gustav in 2008 were nearly major on the Saffir-Simpson scale, and were incredibly destructive for the coasts of Texas and Louisiana.
Now with El Niño conditions — unfavorable for Atlantic hurricanes — strengthening in the tropical Pacific, we wonder whether our string of good fortune will continue one more year, but it’s best to prepare before our luck runs out.