"Category 7" Hurricane Patricia Threatens Western Mexico. The hurricane is generating astonishing sustained winds of 200 mph, according to the 10 a.m. advisory from the U.S. National Hurricane Center. The Saffir-Simpson hurricane wind scale rates hurricanes on a scale of 1-5, depending on the maximum sustained winds. The strongest hurricanes,More
Like a cyclonic photobomber, Hurricane Patricia stormed onto the scene last week and overshadowed a major hurricane milestone.
Saturday marked the 10-year anniversary (that would be the tin anniversary for you traditionalists) since the U.S. saw its last major hurricane make landfall. That’s 3,652 days since the U.S. had a Category 3 or larger storm make landfall.
But talking about a major hurricane drought comes with some caveats, particularly as the U.S. coastal population grows and more people who have never experienced a hurricane in any form move to coastal areas. With climate change expected to increase the number of major hurricanes and sea level rise exacerbating their impacts, it’s more important that coastal communities get up to speed and be prepared for the damage large storms can cause.
The U.S. major landfall drought might just be luck. The date was Oct. 24, 2005. Kanye West and Jamie Foxx topped the Hot 100. And Hurricane Wilma cut across the southern tier of Florida as a Category 3 hurricane, causing an estimated $21 billion damage.
Since then, Kanye’s star has risen, but the U.S. hasn’t dealt with a major landfalling hurricane.
There’s been some research into the topic and the main driver appears to be plain old luck. The findings, published earlier this year in Geophysical Research Letters, show that a major landfall drought this length should statistically occur roughly once every 177 years.
James Elsner, a hurricane researcher at Florida State University, said hurricanes are somewhat more likely to come in bunches in Florida — the nation’s most hurricane-prone state — compared to before the 1960s. That means the state is also seeing longer gaps between hurricanes.
So the current drought is certainly an oddity, but not completely unheard of. Since Wilma, the Atlantic has seen 64 hurricanes form including 26 major hurricanes. Averaged annually, that’s right about what you’d expect for the basin. And that hasn’t stopped storms like Hurricane Joaquin from inflicting major damage on other countries in the Atlantic basin.
Wind might not be the best measure of “major.” Using winds as the only measure of a storm’s major-ness misses rain and storm surge, which can drive flooding and the majority of the damage associated with hurricanes. Hurricane Sandy and Irene were both Category 1 storms (and in Sandy’s case, it wasn’t even technically a hurricane when it made landfall) yet they both cost billions.
“Every tropical cyclone is unique,” Steven Bowen, a meteorologist at re-insurer Aon Benfield, said. “As Hurricane Sandy showed the world, just because a storm does not have an official declaration of being a ‘major’ hurricane at Category 3 or above intensity does it mean that consequential societal impacts cannot occur.”
That storm caused an estimated $67 billion in damage when it made landfall in the Northeast nearly three years ago, with the vast majority due to flooding and not the storm’s Category 1-level winds. Katrina, the most costly storm in U.S. history, also caused most of its $150 billion in damage from flooding due to storm surge.
Modern monitoring and aircraft reconnaissance may also be allowing scientists to see the major hurricane drought in more detail than in other periods during the historical record.
“Clearly there have been changes over the years in the ability to a define major hurricane with Sandy being a recent example,” Elsner said.
In the preceding decades, Elsner said it’s possible Sandy would’ve been classified as a major storm based on its low pressure at landfall and subsequent widespread damage.
Conversely, wind speeds are not as exact as you might think. They're estimates — albeit good ones — that come with a bit of uncertainty and a single mile per hour in either direction can mean the difference between a major and minor hurricane.
Susan Tolwinski-Ward, a data scientist at AIR Worldwide, said that the uncertainty in those estimates coupled with such a thin line between major and not could mean the difference of up to three major landfalling hurricane a year one way or the other. Using the uncertainty in those measurements and nothing else, 1993-2003 could in theory be another 10-year major hurricane drought, a finding published in a recent study in the Bulletin of the American Meteorological Society that Tolwinski-Ward was not a part of.
"That 'drought' would give the current 'drought' very recent precedent," she said.
This discord is in part why some scientists have argued for a more holistic approach to both defining major hurricanes as well as warning the public of the risks specific storms pose.
The National Hurricane Center (NHC) started issuing storm surge maps in 2014 in large part due to the damage Sandy’s surge brought to the Northeast. And after confusion with Hurricane Erika’s forecast last month, the NHC has begun to issue key points about storms in its forecasts to help the public (and perhaps overeager journalists) better convey the risks and uncertainties associated with specific storms.
The drought could breed complacency, which is bad news for coastal residents and insurers. The Atlantic basin is only one of seven major cyclone basins and it isn’t even the most active. The western Pacific tends to see the most storms, dubbed typhoons in that region, and has been a big reason that 2015 has set a record for the number of Category 4+ storms in the northern hemisphere.
But the Eastern Seaboard and Gulf of Mexico are some of the most heavily-insured locations in the world.
Coastal counties in those regions are also home to an estimated 85 million people as of 2003, a number expected to continue rising as six of the 10 fastest-growing coastal counties are in the region, a trend driven in part by older people moving to the coast in their retirement years.
When you add in climate trends including sea level rise, which can increase the height of storm surge, and projections of fewer but more intense hurricanes, you have a recipe for increased vulnerability and losses in these regions in the future.
“History also tells us that every storm from a tropical storm to a Category 5 has its own unique characteristics and any landfalling storm has the potential to be quite costly,” Bowen said.
This article has been updated.