History doesn’t seem to give the United States good odds. We haven’t gone three years without a hurricane making landfall on the U.S. mainland.
That’s one reason forecasters wonder whether the United States will make it through the season that starts today and ends Nov. 30 without a hurricane strike. There’s a lot working against extending the lucky streak.
Experts say this is a period when the tropics are hyperactive and produce hurricanes like a factory.
Since 1995, hurricane activity picked up after a relative lull in the number of storms that lasted from the 1970s through the early 1990s, said Stanley Goldenberg, research meteorologist with the Hurricane Research Division.
“In 1995, we saw the activity go way up, and it stayed up,” he said.
Hurricane activity, mainly affected by water temperature in the Atlantic Ocean, swings between calm and active periods, each lasting several decades.
These active periods could be especially troublesome for the Tampa Bay area.
In addition to more storms in general, these active periods produce more storms from the Caribbean, which can pose a greater threat for Florida’s west coast.
Since 1995, the number of Caribbean-spawned storms has increased five times, Goldenberg said.
“The Caribbean has seen a tremendous increase in activity during these periods,” he said.
Also, the number of major hurricanes with winds more than 110 mph in October is increasing from an average of one every 10 years in the past to one a year.
Late-season storms, which frequently come from the Gulf of Mexico or the Caribbean, tend to move eastward toward Florida rather than west like early season storms do.
“As we see more of the October storms, there’s more chance for one to hit the west coast,” Goldenberg said.
Experts say there will be plenty of storms to take aim at the coastline this year, mirroring last season, which produced 15 storms, eight of which became hurricanes.
Four of those became Category 3 storms or larger.
Forecasters from the National Oceanic and Atmospheric Administration and hurricane researcher William Gray, a Colorado State University professor, are close on their estimates, in the neighborhood of about a dozen tropical storms. Of those, six to eight will become hurricanes and two of those major storms.
Although the predictions do not say whether any of those storms will hit the area, more storms mean more chances for one to wade ashore.
“No one will predict landfall,” Gray said. “It’s impossible. But most land-falling storms occur in active years.”
The forecasts support the idea of more activity than the average season, which has nine tropical storms and six hurricanes – two of those becoming major storms.
The Return Of El Nino
The forecasts might have been higher if water in the Pacific Ocean wasn’t growing warmer, possibly leading to El Nino conditions.
El Nino causes shifts in the jet stream that can tear apart developing hurricanes or keep them from becoming as powerful.
But few of the experts expect the weather phenomenon to have a major impact on the number of storms this year. It’s not forecast to be a repeat of the one that stunted the 1997 season.
“This one is so slow developing, and it’s expected to be weak,” said Max Mayfield, director of the National Hurricane Center in Miami. He said the NOAA forecast might have been slightly higher, though, if the El Nino was not forming.
And even if El Nino is more powerful than predicted, its growth by the middle of the summer may be too late to do much good.
“There’s also a lag in the atmosphere of a month before it has any effect,” Mayfield said.