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Hurricane season may not end on time. That’s not the only problem.

The real question is, will the western Caribbean Sea continue producing monster storms like Hurricanes Eta and Iota late into the year?

How fitting that an unprecedented hurricane season would end with an unprecedented November: Two major hurricanes formed this month for the first time in recorded history. Hurricanes Eta and Iota both slammed into the same Central American coastline miles and days apart.

But is this really the end?

Hurricane season officially ends on Monday, but scientists fear storms could continue to form beyond the “official” end date of Nov. 30.

Conditions for storm development will remain favorable in the west Caribbean Sea, said David Zierden, who runs the Florida Climate Center at Florida State University. A record 30 named storms have formed so far this year — but he believes more storms could continue developing into December.

“The potential is still there,” Zierden said. “Anytime you have 27, 28, 29 degrees Celsius sea-surface temperatures, you have enough energy for a powerful hurricane to form.”

A range of 27 to 29 degrees Celsius is about the same as 80 to 84 degrees Fahrenheit. Sea-surface temperatures in the western Caribbean were still in the upper 20s Celsius or low 80s Fahrenheit on Tuesday, according to the National Oceanic and Atmospheric Administration database.

The western Caribbean is where Eta and Iota became major hurricanes earlier this month, marking it the first time in recorded history that two storms of Category 3 strength or higher formed in November. Iota also became the latest Category 5 storm on record when it reached maximum sustained winds of 160 mph on Nov. 16 — another sign that powerful storms can still form this late in the season.

Iota was just the second Category 5 hurricane to form in November since the 1932 Cuba hurricane, aka the Hurricane of Santa Cruz del Sur, the deadliest and most destructive storm to hit Cuba in modern history.

After striking Nicaragua on Nov. 3, Eta took a curveball path to Florida and brushed by the Tampa Bay region when it made landfall at Cedar Key on Nov. 12. Iota made landfall in Nicaragua on Nov. 17 but never threatened Florida, instead dissipating after reaching El Salvador.

Zierden said that Eta’s path from Central America to Florida was no fluke, storms that form in the central and western Caribbean often turn to the north and enter the Gulf of Mexico. That means Florida, which has so far avoided a major storm strike during this busy hurricane season, isn’t in the clear yet.

Hurricane Michael is one example of why Florida needs to be on guard. When that late-season storm struck the Florida Panhandle on Oct. 10, 2018, it was the first Category 5 storm to strike the United States since Hurricane Andrew hit South Florida in 1992.

And where did Michael form? In the western Caribbean.

“When there’s activity down there we pay attention and we get ready here in Florida,” Zierden said.

Related: Hurricane Michael: What if it had hit Tampa Bay?
Satellite imagery of Hurricane Eta, overnight and into Wednesday, Nov. 11.
Satellite imagery of Hurricane Eta, overnight and into Wednesday, Nov. 11. [ NOAA ]

On paper, the Atlantic hurricane season starts June 1 and ends Nov. 30. But those dates are merely guidelines, Zierden said. Storms regularly form before and after the official dates. This historic storm season started early with two tropical storms forming in May.

Zierden said he won’t be surprised to see tropical systems develop after Nov. 30, which has happened in five seasons since 2000. Tropical Storm Zeta formed so late in 2005 — the most destructive hurricane season on record, and a year often compared to 2020 — that it did not dissipate until Jan. 7, 2006.

The main factor that determines when hurricane seasons actually start and stop is cold weather, said Florida International University hurricane researcher Hugh Willoughby.

As cold fronts begin pushing further south into the Caribbean Sea and the tropical Atlantic in November, the water cools. And hurricanes need warm water in order to form and strengthen, Willoughby said. After cooling down for the winter, sea-surface temperatures don’t fully warm up again until the start of June, which is why the National Hurricane Center designates June 1 as the start date.

The central and western Caribbean Sea is where to look for most late-season storms, said Willoughby. Atlantic storms that form off the coast of Africa and move west toward the Caribbean — what he calls “Cape Verde storms” — mostly end by mid-October.

The western Caribbean Sea is usually the last part of the Atlantic Ocean to cool off and quiet down during hurricane season. It’s the area of the tropical Atlantic that’s closest to the equator, where the variance in temperature from summer to winter is minimal. Warmer weather means warmer sea-surface temperatures, and that increases the chances that more storms will develop.

That is one of the reasons why 2020 not only set a record for most named storms but for the rapid development of storms. Willoughby called this year’s meteorological conditions “a perfect storm for the perfect storms.”

Those include warmer-than-normal sea-surface temperatures in the northern Gulf of Mexico and off the coast of Africa; an active rainy season in Sub-Saharan Africa; and the presence of La Niña in the Pacific Ocean.

La Niña is the atmospheric phenomenon that cools Pacific Ocean temperatures and affects weather patterns in the Atlantic and elsewhere. This year, its presence meant more powerful storms could form because there was little-to-no wind shear to break them up. It’s also another factor why storms formed so late into the season. The National Oceanic and Atmospheric Administration forecast that La Niña will last until February.

Global warming is another factor in hurricane seasons producing bigger storms, Willoughby said, and the current 30-year-cycle of Atlantic multidecadal oscillation, a climate cycle that also affects sea surface temperatures.

But while the potential for storms to form still exists, Willoughby believes the worst of the 2020 storm season is behind us.

He doesn’t foresee anymore Eta or Iota-like monsters this year. Instead, he predicts the western Caribbean could close out the year with a few more tropical depressions and tropical storms.

That’s in large part because — in a year that brought record-breaking heat for Florida — cold fronts are finally starting to move further south.

But the problem with trying to predict what will happen in 2020 is that it is 2020.

“If this were any other year but 2020, I would say that the satellite pictures look already what they’d look like in December and this thing would be about over,” he said.

“It sure does look good, but the experience with this year is that everything is different.”

2020 Tampa Bay Times Hurricane Guide

HURRICANE SEASON IS HERE: Get ready and stay informed at tampabay.com/hurricane

PREPARE FOR COVID-19 AND THE STORM: The CDC’s tips for this pandemic-hurricane season

PREPARE YOUR STUFF: Get your documents and your data ready for a storm

BUILD YOUR KIT: The stuff you’ll need to stay safe — and comfortable — for the storm

PROTECT YOUR PETS: Your pets can’t get ready for a storm. That’s your job

NEED TO KNOW: Click here to find your evacuation zone and shelter

Lessons from Hurricane Michael

What the Panhandle’s top emergency officials learned from Michael

‘We’re not going to give up.’ What a school superintendent learned from Michael

What Tampa Bay school leaders fear most from a storm

Tampa Bay’s top cops fear for those who stay behind

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