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

Since Hurricane Oscar officially fizzled out as a tropical cyclone on Tuesday, there is now no tropical development in the Atlantic basin, and the National Hurricane Center says no further tropical development is expected over the next seven days.

However, don't be discouraged by the tropics just yet, as there are signs that the break could be short-lived.

A lot of air is currently sinking into the atmosphere over the Caribbean and the Gulf of Mexico, which is inhibiting tropical development. But the long-term outlook of the Madden-Julian Oscillation – a global pattern that alternates areas of rising and descending air every 30-90 days – suggests that rising air will return to the Caribbean around late October and early November.

That would coincide with the return of the Central American cyclone that helped produce Hurricanes Helene and Milton and, more recently, Tropical Storm Nadine.

What is the Central American Vortex?

“Now at the very end of the month we're seeing this low pressure that's starting to form eerily similar to the Central American Vortex,” says FOX weather meteorologist Steve Bender. “But this one is right above the heart of the Caribbean. So there’s all this tropical moisture to take advantage of.”

These conditions would make for favorable tropical development somewhere in the Caribbean, and if a storm were to form there would be three main scenarios it would need to follow, depending on the surrounding atmospheric control patterns we would expect at this time of year.

Most of the time, these hurricanes pose no threat to the Lower 48, but occasionally a storm system can come from the deep tropics and hit Florida or deliver a fleeting blow to the East Coast.

Tropical Formation Scenario 1: High pressure acts as a barricade for the US

The first possibility is that strong high pressure remains anchored over the southeastern United States and acts as a barricade protecting American coasts.

This pattern would mimic what just happened with Tropical Storm Nadine and would direct any tropical cyclone westward into Central America and possibly back into the Eastern Pacific.

Tropical Formation Scenario 2: On the trail of Oscar

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

This scenario would push tropical cyclones eastward over Cuba and the Greater Antilles, where it would eventually mimic Hurricane Oscar by interacting with the jet stream and becoming a post-tropical system as it is pushed into the open Atlantic.

Tropicalization Scenario 3: The East Coast of the US is more vulnerable

This scenario would be most worrisome for the US. In this case, a ridge forms too far west over the U.S. to cause strong blocking, while a strong ridge of high pressure builds in the central Atlantic.

“You're dealing with two high pressure systems that are spreading (potential storms) along the East Coast,” Bender said. “And as it continues, we may begin to see the impact areas that are already feeling massive impacts from Hurricane Helene.”

The long-range forecast models begin to see some signals of tropical development in the southern Caribbean around October 29, with even more signals of development days later.

“My concern would be the first day of November … we're a long way from that (into the future) … and there's going to be a lot of fluctuation at that point,” Bender said. “Climatologically, this is where we would normally expect these to form… but there is still a lot of potential activity ahead.”

The waters in the Gulf of Mexico are finally cooling down

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

For the first time in more than a year, the Gulf's average water temperature has fallen below average, due to a combination of cold fronts, persistent winds and the churning effects of hurricanes Milton and Helene.

The last time temperatures were average was in June 2023. However, the current average is still around 81 degrees – still warm enough for tropical development.

Water temperatures in the Caribbean will remain near record levels well into the mid-80s.

Hurricane season officially runs until November 30th

In an average season, two additional named storms occur in the last weeks of October and November, one of which becomes a major hurricane.