Even though the United States has certainly seen its share of destructive storms over the past nine years, we haven't gotten slammed by a category three or higher hurricane in nine years -- the longest stretch in which we've been free from such monster storms since 1850. Our last major hurricane -- defined as a major storm with winds in excess of 111 miles per hour -- was Hurricane Wilma, which hit on October 16, 2005.
Just weeks earlier, Hurricane Katrina -- also a category five hurricane -- struck the US Gulf Coast and became one of the deadliest hurricanes in US history. Hurricanes Ike (2008), Irene (2011) and Sandy (2012) followed but none of them hit as a Category 3 or greater.
A new NASA study shows that such a "hurricane drought" only comes along once every 177 years.
To arrive at this conclusion, Timothy Hall, a research scientist who studies hurricanes at NASA's Goddard Institute for Space Studies in New York and Kelly Hereid, who works for ACE Tempest Re, a reinsurance firm based in Connecticut, ran thousands of computer simulations on the years 1950 to 2012.
The simulations in effect recreated 63,000 Atlantic hurricane seasons by using records of Atlantic tropical cyclones (some of which lead to hurricanes) and sea surface temperature data. The reason the researchers took this approach is because hurricane records only stretch back to 1850, which wouldn't have given them enough data to make worthwhile conclusions. The computer models gave them a much larger data set.
They concluded that our current hurricane drought -- which beats the previous eight-year record from 1861 to 1868 -- represents a sweet spot that only comes along once every 177 years on average. Their study was published in April in the journal Geophysical Research Letters.
And the reason for this lack of major hurricanes? We've pretty much just been lucky, the researchers say.
"The last nine hurricane seasons were not weak -- storms just didn't hit the US," Hall said in a statement released Wednesday. "It seems to be an accident of geography, random good luck."
Unfortunately, while the 63,000 simulated hurricane seasons helped the researchers determine the frequency of hurricane droughts, it did not help them determine how long the current one could last. In fact, according to Hall, the likelihood that one will hit every year is roughly 39 percent. So just because we've been on a stretch of good luck, it doesn't mean that it will necessarily continue. June 1 is the official start of hurricane season.
Still, in April, researchers at North Carolina State University predicted that the 2015 hurricane season will be quieter than normal, so that might lower the 39 percent figure a bit, which means we might have a shot at going a full decade without a major hurricane hitting the US.
Take THAT 1861 to 1868!