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News / Nation & World

Warm Atlantic waters concern hurricane forecasters

‘Very small changes actually matter a lot,’ researcher notes

By Jack Prator and Michaela Mulligan, Tampa Bay Times
Published: February 26, 2024, 6:02am

TAMPA, Fla. — Hurricane season is still months away, but warm winter waters in the Atlantic Ocean are already concerning some forecasters.

Water temperatures in the north Atlantic Ocean currently rival those normally seen during the summer months. By some estimates, this type of heat would be seen only once every 142,000 years.

Researchers say we are reaching the Atlantic Ocean’s winter peak — the first week of March typically marks the coldest water temperatures of the year, and experts say the unseasonably warm waters will only get hotter after that.

On Florida’s west coast, the Gulf of Mexico has cooled off after a blistering summer that recorded hot tub-like temperatures. While a strong El Niño was responsible for warming Gulf waters just a few months ago, it has also boosted winter storms, whipping up winds and lowering surface temperatures.

But experts expect that as the summer approaches and El Niño wanes, Gulf waters will warm up again.

Jeff Masters, a hurricane scientist formerly with the National Oceanic and Atmospheric Administration, put it simply: “The planet is record-warm right now, and the planet’s oceans are record-warm.”

He says there are two factors contributing to the intense heat in the Atlantic: The El Niño pattern left water temperatures at least 10 degrees warmer than usual. And a weak Bermuda-Azores High — a high-pressure system hanging over the ocean — means the trade winds are weaker. That translates to less wind stirring up waters, which stifles any cooling effect.

Masters said that because of the Loop Current, which brings warm water from the Caribbean Sea to Florida’s coast, the Gulf is closely tied to the rest of the Atlantic.

“If the Caribbean is warm, then that warmth is going to find its way into the Gulf of Mexico,” he said.

‘It’s happening’

Hurricane expert Brian McNoldy said the warmest temperatures are concentrated in the main hurricane development region of the Atlantic, from Africa to the Caribbean Sea. Temperatures in the region are similar to what experts would expect to see around the beginning of the hurricane season, he said.

“It’s exceptionally unlikely that what we’re seeing is happening — but it’s happening,” said McNoldy, a senior research associate at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science.

Long-range forecasts that look at possible sea-surface temperatures in July, August and September show temperatures could remain more than a few degrees above normal.

“They don’t sound like big numbers, but for an ocean and things in the tropics, very small changes actually matter a lot,” McNoldy said.

Should the warm Atlantic sea-surface temperatures stick around, warm waters could stir up storms at the start of hurricane season, he said.

A similar batch of ingredients was in place last year when two early-season storms formed off the coast of Africa: Tropical Storm Bret and Tropical Storm Cindy.

McNoldy told The Tampa Bay Times back then that storms forming in that area of the Atlantic was unusual in June. If the warm waters stick around as predicted this year, storms could have the juice to get up and running early again, he said.

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More concerning than high surface temperatures is the Atlantic’s ocean heat content, a measurement of deeper warm waters. It’s pivotal to forecasting hurricane intensity and is now unseasonably high in both the Atlantic and the Gulf.

“I’m anticipating we’re going to have near-record or possibly record ocean heat content this coming hurricane season,” Masters said. “Because right now, there’s so much hot water going down to great depths right through the Atlantic.

“The oceans have a long memory and they’ve got a lot of heat, and so they’re going to keep on giving off that heat to the weather over the next few months.”

Hurricanes act as a sort of heat engine, Masters said. They take heat energy from the ocean and convert it into wind energy. That means the more heat that is available, the stronger a hurricane can get. Deep, warm water can also negate the cooling effects of winds that may otherwise weaken a strong tropical storm.

The highest temperatures driven by an El Niño typically lag about three months after the weather pattern has peaked, Masters said. This year’s El Niño reached its zenith last month, so he expects the warmest weather to show up around May.

“We’re pretty confident that it’s going to be a record stretch of weather globally into the summer,” he said.

While all signs point to a particularly intense hurricane season, Masters said it’s too early to panic.

“February is really too early to get too whipped up about the potential for a hyperactive hurricane season,” he said.

Masters said two weather events could work against the warm waters expected this season and lower storm risk.

If a large amount of Saharan dust blows across the oceans, it would reflect sunlight, shade waters and cool surface temperatures. Another possibility is a natural shift in wind patterns over the Atlantic, kicking up the trade winds and stirring up waters.

“But here we are in February, so we have no idea how that’s going to play out when it comes to hurricane season,” he added.

Another big question ahead of hurricane season is what factors are at play that could push storms our way.

Masters compared the unseasonable Atlantic temperatures this year to previous ones. There were 12 hurricanes whipped up in 2010 — the third-most-active season on record. But none of those made landfall in the U.S., Masters said.

“It didn’t matter that it was an active year as far as being in the U.S. goes, because the steering currents were favorable,” he said. “So an active year doesn’t necessarily mean a bad year if the steering currents are your friend.”

Last year, the globe was experiencing an El Niño during the hurricane season, which typically stymies activity. This year, El Niño’s counterpart, La Niña, could fall into place just as the season begins.