WEST PALM BEACH, Fla. – In the spring of 2015, the global atmospheric force El Niño began mustering a formidable strength. The meteorological event, one of the strongest on record, efficiently raged through hurricane season to dissolve burgeoning storms.
And with the storm season whimpering to an end on Monday, 2015 marks an unprecedented 10 years since a hurricane has hit Florida.
But the lack of landfalls this year doesn’t mean there weren’t a few tense moments.
Tropical Storm Ana popped up May 8 nearly a month before hurricane season’s official June 1 start date. August’s Hurricane Fred was the first hurricane to hit the Cape Verde Islands since 1892. Tropical Storm Erika drove some South Florida residents to board up the windows when it was forecast to be a Category 1.
Florida declared a state of emergency for Erika, but the August storm never reached hurricane strength.
“This was a below-average season, but not astonishingly below,” said Tim Hall, a senior scientist at NASA Goddard Institute for Space Studies. “It’s just that the storms didn’t make a U.S. landfall.”
There were 11 named storms in the Atlantic this season, four of which became hurricanes.
The strongest, Hurricane Joaquin, was the 10th named storm. It formed Sept. 27 hundreds of miles southwest of Bermuda, and wasn’t given much chance of developing into a major threat.
But Joaquin defied forecasts, accelerating to a Category 4 hurricane with 155 mph winds. It raked the Bahamas and is blamed for the deaths of 33 people who were aboard a cargo ship that sank en route to Puerto Rico from Jacksonville, Fla.
“I’m sure there will be a lot of studies about what was missed with Joaquin and why it ramped up so much,” Colorado State University researcher Philip Klotzbach said.
The National Oceanic and Atmospheric Administration 2015 hurricane forecast predicted a 90 percent chance of a below-average season. Its August predictions were for six to 10 named storms, one to four hurricanes and zero to one major hurricane.
The average hurricane season has 12 named storms, six hurricanes and three major hurricanes.
While the sheer number of named storms in 2015 was more than originally forecast, the four hurricanes were within the predicted amounts. But forecasters didn’t expect two major hurricanes.
Besides Joaquin, tiny hurricane Danny in August proved to have an unexpected punch. It reached Category 3 strength before weakening to a tropical storm 520 miles east-southeast of the Leeward Islands.
“In terms of counts, it’s been really close to an average season,” said Hugh Willoughby, a research professor at Florida International University and a retired veteran of the NOAA hurricane division. “But what really counts is ACE.” Accumulated cyclone energy is a measure of a hurricane’s strength and duration.
The ACE for 2015 was about 65 percent of the median between 1981 and 2010, and nearly half that energy was generated by Joaquin.
That means that while a respectable number of storms formed, El Niño weakened them before they could develop.
Torn apart by El Niño
“A tropical cyclone is like a haystack,” said Rob Gutro, deputy news chief and manager for NASA’s hurricane Web page. “When it faces vertical wind shear from El Niño, winds blowing in different directions, it falls apart.”
El Niño is a periodic warming of the water across the eastern path of the Pacific Ocean. The warm water makes radical shifts to rainfall patterns, suppressing showers over Indonesia and moving them to the eastern part of the Pacific.
There, strong thunderstorms form, which influence wind patterns in the upper atmosphere, reducing wind shear in the Pacific and increasing it in the Atlantic.
The Eastern Pacific has had 18 named storms this season, including 12 hurricanes. Hurricane Patricia, which barreled into Mexico in late October, is the strongest hurricane ever tracked by the National Hurricane Center with sustained winds of 200 mph.
Dennis Feltgen, a meteorologist and spokesman for the National Hurricane Center, said officials there adjusted communication techniques after getting grief about Tropical Storm Erika’s forecast.
Feltgen said while the media relayed the uncertainty in the forecast, there was so much attention given the storm that it ramped up anxiety.
It’s too early to tell what the 2016 hurricane season will bring, but it’s almost certain there won’t be a strong El Niño.
“Ten years without one lousy hurricane, that’s just phenomenal to me,” CSU’s Klotzbach said. “That kind of streak can’t continue forever.”