FORT LAUDERDALE — Hurricane season started with fear-inducing fury, but there’s a chance the final six weeks close with a feeble whimper.
You never want to tempt Mother Nature, especially after 2021 became the seventh consecutive year to have a named storm before the June 1 start of hurricane season.
But meteorologists think the Atlantic will be quiet for the next week, possibly two — and even until the Nov. 30 end of hurricane season.
Wind shear, a feature that rips storms apart, is the primary reason.
“You can’t rule out a system developing somewhere,” AccuWeather meteorologist Randy Adkins said, “but it seems unlikely we’re going to have a very active end to the season.”
La Niña, the weather pattern usually associated with an active storm season, has started but hasn’t fully taken hold yet, according to meteorologists.
“That trend toward La Niña has been slow in going,” AccuWeather senior meteorologist Dan Kottlowski said. “It’s not like last year. Last year, we went into a La Niña much faster, so the state at which we go into a La Niña may be very critical as to how it impacts the shear pattern across the tropics.”
Kottlowski said La Niña’s slow development has allowed wind shear from the westerlies, high-level winds that travel from west to east, to become prominent.
“The westerlies have been dipping into the Gulf of Mexico, down even into the Caribbean and off the southeast coast of the United States more effectively this year than last year,” Kottlowski said. “That creates vertical wind shear, which blows the tops off of thunderstorms, which then either hinders or prevents tropical development, or even tropical maintenance.”
Strong wind shear usually exists in the eastern Atlantic at this time of year, but for this week, and likely next week, it’ll also be in the western Caribbean and Gulf of Mexico.
On top of that, water temperatures begin to cool in the eastern Caribbean in October. That, along with wind shear, means storms rolling off Africa’s west coast are less likely to complete the journey across the Atlantic and to the United States.
October storms, especially those forming after the Oct. 15 end of the rainy season, are more likely to develop closer to home. Water in the western Caribbean and Gulf of Mexico doesn’t reach its peak warmth until late September or early October, which is why that region hosts much of the storm development.
“This time of year, you kind of want to look in the western Caribbean Sea,” said Dr. Steven Lazarus, meteorology professor at Florida Institute of Technology. “That water is not only super warm, but it’s also deep. So, we are in that transition period.”
The bad thing for Florida is those storms tend to travel north and then head east. Worse, as seasons change and the jet stream dips farther south, the steering currents tend to guide storms toward Florida more than to, say, Texas or Louisiana.
Florida is somewhat of a magnet for late-season storms. Two of the most notable were Hurricane Michael, which made landfall on Oct. 10, 2018, in the Florida Panhandle as a Category 5 storm, and Hurricane Wilma, which made landfall in South Florida on Oct. 24, 2005, as a Category 3 storm.
“You definitely can’t let your guard down at this time of year,” Adkins said, “particularly in Florida.”
The 2021 hurricane season has been active with 20 named storms, seven hurricanes and four major hurricanes.
August’s revised projection from the National Oceanic and Atmospheric Administration was 15 to 21 named storms, seven to 10 hurricanes, and three to five major hurricanes.
There’s a chance the current storm numbers will not increase much because cool, dry air is starting to arrive, which is good for preventing hurricane development.
“You’re starting to see the pattern, the pattern that the air is a little cooler,” said Nick Shay, ocean sciences professor at the University of Miami, “and once we start to get cooler drier air, hurricane season really tails off.
“There’s an old wives’ tail that says once we get that first full-fledged cool front or cold front to penetrate down over Miami and in the Bahamas and the northwest Caribbean, hurricane season pretty much comes to an end. ... In general, that’s a fair statement.”
- By Chris Perkins, South Florida Sun Sentinel