Although dozens of powerful hurricanes have formed in the Atlantic Basin during the past decade, the last time a major hurricane with winds exceeding 110 mph struck US shores was when George W. Bush was president during the stormy summer of 2005.
So as we head into the time of year that author Ernest Hemingway referred to as “a more dangerous summer” when powerful hurricanes most often form, there’s an obvious question being asked by meteorologists and coastal dwellers on the Gulf and Atlantic coasts: Will this be the year that the remarkable hurricane-free streak—the longest since record-keeping started in 1851—is ended?
Five named storms have already formed this year, but none reached the threshold for designation as a major storm. The most recent was Hurricane Earl, whose strongest winds reached 80 mph. Still, Earl killed at least 65 people during its trek across the Caribbean Sea and southern Gulf of Mexico from August 2 to August 6.
Seasonal forecasters think there will be plenty more storms roaming the Atlantic during the late summer and fall. Forecasters at Colorado State University predict 11 more named storms will form before hurricane season ends November 30. CSU thinks five of those storms will become hurricanes, and two of those storms will have winds exceeding 110 mph.
The National Oceanic and Atmospheric Administration predicts 12 to 17 named storms—including the five earlier storms—will form. As many as four of those storms could become major hurricanes, the NOAA forecast said.
Meteorologist Phil Klotzbach at Colorado State University says there are several factors in place that could make for a stormy late summer. Seawater temperatures in the area where hurricanes most often form are quite high, and upper level winds that could disrupt hurricane formation may not be as powerful as in recent years.
Meteorologist Bob Henson with Weather Underground thinks the Atlantic could become active in a few weeks, and the summer of 2016 could be “back-loaded” with frequent hurricanes forming.
“Even in the wake of Hurricane Earl, there is still a great deal of oceanic heat across the Caribbean and around the Bahamas that a hurricane approaching the U.S. could draw on,” Henson said.
And that’s where the U.S. luck avoiding hurricanes could be tested.
“It’s just luck that has kept the storms away” from the U.S. for the past 10 years, Klotzbach says. And unfortunately, luck can’t be factored into hurricane forecasting.
“There’s no way to gauge luck,” he says.
There are a few technicalities that have contributed to the storm-free streak. First, the three devastating hurricanes that made landfall during the past decade have been just under major-storm status. Hurricane Sandy, which did catastrophic damage from Virginia to New York, was not a major hurricane when it made landfall in New Jersey in October 2012. And neither were Hurricane Irene, which struck North Carolina in 2011, and Hurricane Ike, which hit Texas in 2008.
But it’s not that monster storms haven’t formed in the past decade. In fact, an average of about three major hurricanes have formed each summer since 2005. And that’s where the luck has come into play. Weather patterns have steered 27 major hurricanes away from the US since Hurricane Wilma struck Key West, Florida in October 2005.
Hurricanes draw their energy from seawater that has been heated to at least 80 degrees Fahrenheit, and waters in parts of the Atlantic Basin—which includes the Caribbean Sea, Gulf of Mexico, and Atlantic Ocean—have usually reached this milestone by August.
That’s also the time of year that thunderstorms known as “tropical waves” come rolling off the coast of western Africa. These waves, which originate near the Cape Verde Islands, can be hurricane seeds. If conditions are right as they rumble across the Atlantic, they can gain strength, pick up circulation imparted by the rotation of the Earth, and intensify into tropical storms.
Eventually, if conditions allow, the tropical storms can strengthen into hurricanes with winds of at least 74 mph. They become major hurricanes if their winds reach 111 mph. A major hurricane can cause catastrophic damage if it comes ashore at a coastal city.
Hurricanes tend to travel in a northwestward direction as they cross the Atlantic, and sooner or later they’re likely to turn more directly northward.
The key to whether a hurricane will make landfall is where it makes that inevitable turn to the north. And that’s where weather patterns come into play. A low-pressure system parked over the East Coast can push a hurricane northward, Klotzbach says. Upper-level winds known as the jet stream can steer a hurricane out to sea and keep it away from shore, he said.
But these weather patterns are constantly changing, and it’s all but impossible to predict whether they’re going to be in place during the hurricane season. Klotzbach said he and other researchers have tried to figure out a way to predict the presence or absence of steering currents during hurricane season, but couldn’t do it. “It’s a tricky problem,” he said. “I wish it were easier.”
Listen to author Willie Drye discuss his IPPY-Award-winning latest book, For Sale-American Paradise: How Our Nation Was Sold An Impossible Dream in Florida, with Frank Stasio on WUNC’s “The State of Things,” and with Joseph Cooper on WLRN’s “Topical Currents.”