Could tropical troubles be brewing in the final month of hurricane season?

With Hurricane Oscar officially weakening into a tropical cyclone on Tuesday, the Atlantic Basin is now devoid of any tropical development, with the National Hurricane Center saying no further tropical development is expected over the next seven days.

However, don’t let your guard down in the tropics just yet as signs emerge that the break could be brief.

There is currently a strong atmospheric drawdown over the Caribbean Sea and Gulf of Mexico, which is limiting development in tropical regions. But the long-term outlook for the Madden-Julian Oscillation—a global pattern that cycles through areas of rising and falling air every 30 to 90 days—suggests that rising air will return to the Caribbean around late October and early November.

This would coincide with the return of the Central American Gyre, which had a hand in creating Hurricanes Helen and Milton and, more recently, Tropical Storm Nadine.

WHAT IS THE CENTRAL AMERICAN GYRE?

“Now we’re getting low pressure at the very end of the month that’s starting to form eerily similar to the Central American Gyre,” says FOX Weather meteorologist Steve Bender. “But this one is right over the heart of the Caribbean. So you have all this tropical moisture that can be used.”

These conditions will favor favorable tropical development somewhere in the Caribbean, and if a storm occurs, it will develop in three main scenarios depending on the environmental control patterns we expect at this time of year.

Most of the time, these cyclones pose no threat to the Lower 48, but sometimes a storm system can emerge from the deep tropics and hit Florida or deliver a glancing blow to the East Coast.

Tropical Formation Scenario 1: High Pressure Acts as a Barricade for the US

The first option is for strong pressure to remain in the southeastern US, acting as a barricade protecting the American coastline.

This model will mimic what just happened with Tropical Storm Nadine and will steer any tropical cyclone west into Central America and possibly back into the eastern Pacific.

Tropical formation scenario 2: in Oscar’s footsteps

In this pattern, the blocking ridge of high pressure would be centered further west, over the Deep South or Texas, still shielding the U.S. from any tropical storms but allowing the jet stream to cross the Atlantic.

This scenario would cause tropical cyclones to move eastward through Cuba and the Greater Antilles, where they would eventually mimic Hurricane Oscar by interacting with the jet stream and developing into a post-tropical system, expelling into the open Atlantic.

Tropical Feature Scenario 3: US East Coast More Vulnerable

This scenario would be the most worrying for the United States. In this case, a ridge forms too far west over the US to provide significant blocking while a powerful high pressure ridge forms in the central Atlantic.

“You’re seeing two high pressures that are kind of spreading (any storms) along the East Coast,” Bender said. “And as it tracks, you can start to see those areas of impact that have already seen huge impacts” from Hurricane Helen.

Long-range forecast models begin to pick up some signals of tropical development in the southern Caribbean around October 29, with more development signals emerging a few days later.

“My concern is the first day of November…we’re a long way (into the future)…and there’s going to be a lot of volatility at this point,” Bender said. “From a climatological perspective, this is where we would typically expect you to see these forms… but there’s a lot of potential activity ahead.”

Gulf waters have finally cooled

There was some good tropical news in the Gulf of Mexico this week.

For the first time in more than a year, average Gulf water temperatures fell below average, thanks to a combination of cold fronts, persistent winds and the devastation of Hurricanes Milton and Helen.

The last time temperatures were average was June 2023. However, it is currently still averaging around 81 degrees – still warm enough for tropical development.

Sea temperatures in the Caribbean Sea remain at near-record levels, reaching the mid-80s.

Hurricane season officially runs through November 30th.

In an average season, the last weeks of October and November typically produce two more named storms, one of which becomes a major hurricane.