Will hurricane season end with a whimper? Watch La Niña, scientists warn.

·4 min read

There hasn’t been much happening in the tropics since Hurricane Sam dissipated on Oct. 5.

This is rare for the Atlantic in October. It’s just the third time since 1995 the tropical Atlantic did not have a single active storm from Oct. 6 to Oct. 27, according to Colorado State researcher Phil Klotzbach. It’s also great news for Tampa Bay, which is most susceptible to tropical systems on the back end of a hurricane season that runs from June 1 to Nov. 30.

Does this mean the 2021 hurricane season is coming to an early end?

Not necessarily, says meteorologist Rick Davis of the National Weather Service in Ruskin. While no named storms are present, he pointed to a “potential tropical cyclone” off the New England coast. The system has just a 40 percent chance of formation, but Davis said it shows this hurricane season isn’t wrapped up just yet.

“We just had the 100-year anniversary of Tampa Bay’s last major hurricane a few days ago,” Davis said. “Just because things have been quiet here doesn’t mean they’ll stay that way. This is the time of year Tampa Bay has the highest chance of a direct hit or close call.”

History backs up Davis’ statement. The last storm to bring significant damage to the Tampa Bay area was Tropical Storm Eta, which passed the Pinellas County coast in November before making landfall at Cedar Key a year ago.

Late-season storms are more likely to strike near Tampa Bay because prevailing winds move farther south as cold fronts stretch into the Gulf of Mexico. These fronts push systems that would strike New Orleans or Texas earlier in the year toward Tampa Bay instead.

Some forecasting models are “hinting” at a possible tropical system forming in the western Caribbean in the next week or so, Kotzback told the Tampa Bay Times. It’s too early to tell in what direction a storm would head.

Either way, seasonally weakening wind shear in the Caribbean Sea may contribute to another storm’s formation through early November, Klotzbach said.

A quiet end to the season would contrast with its start. With a month to go, there have been 20 named storms, seven hurricanes and four major hurricanes in 2021. Twelve named storms is the average for the past 30 years.

One sign that this season may still have some life was the arrival of La Niña this month. The weather phenomenon in the Pacific Ocean often leads to more favorable conditions for storms in the Caribbean Sea and the Atlantic Ocean by suppressing the level of wind shear available to break up storms.

“La Niña is associated with reductions in vertical wind shear in the Caribbean and tropical Atlantic,” Klotzbach told CNN this month. “Too much shear is typically what ends the Atlantic hurricane season, so La Niña can extend the active part of the season.”

This was the case a year ago. A La Niña phenomenon was the catalyst for a hyperactive end to the season, Klotzbach said, which included two destructive hurricanes — Eta and Iota — that formed in November. Both storms formed and rapidly strengthened in the southern Caribbean Sea, where storms most commonly form this time of year because storms off the coast of Africa rarely make it across the Atlantic now, Klotzbach said.

Davis agreed and said people in the Tampa Bay area should remain vigilant because “a storm can pop up at any time” in the Caribbean this time of year.

While keeping one eye on the tropics, Davis advised using the other to watch for the first real cold front of fall coming later this week. Tampa Bay is forecast to have low temperatures dipping into the upper 50s starting Friday and lasting through early next week.

Before you reach for your sweatshirts and flannels, though, throw on a rain jacket. Thunderstorms are expected to enter the region Thursday ahead of the front.

“We usually get our first real cold front the second week of October, and we had a small front two weeks ago,” Davis said. “But this is the real fall weather people look for.”

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