Tropical Atlantic staying busy as October winds down

The Atlantic hurricane season has just over one month left to go, but there are still plenty of chances for more storms to develop. On Wednesday, AccuWeather meteorologists were studying at least three areas of the Atlantic -- one north of Bermuda, another east of the Bahamas, and a separate area around the Caribbean -- that could generate a named storm within the next week.

From Sunday to Tuesday, a non-tropical system that was hanging around over the western Atlantic showed signs of acquiring tropical characteristics as it spun near Bermuda. However, the opportunity for this system to evolve into a tropical system has come and gone.

A very similar non-tropical storm system was located more than 500 hundred miles to the southwest of Bermuda on Wednesday. This too has been under the watchful eye of AccuWeather forecasters for over a week and will have a window of opportunity from Thursday to Saturday to acquire tropical characteristics just like the system near Bermuda at the start of this week.

This system, which was strung out over a 500-mile-long swath that extended into the Caribbean, could follow a wide range of possibilities. It could become a tropical depression or storm, become classified as a subtropical depression or storm, or not develop further at all. As of Wednesday afternoon, forecasters have raised the development risk from a low to medium chance.

A subtropical system is structured similarly to both tropical and non-tropical systems. Typically, subtropical systems are very sprawled out and contain a significant amount of dry air in their circulation. Should the system develop a defined area of circulation with winds of 39 mph or greater, it could be dubbed a tropical storm. If a circulation evolves, but with winds less than 39 mph, a tropical depression could be born.

The National Hurricane Center is the authority that makes the official call on when storms in the Atlantic meet the criteria to be labeled as tropical or subtropical storms or depressions.

However, if the developing system exhibits a significant threat to lives, property and travel in terms of heavy rainfall, AccuWeather meteorologists may refer to the system as a tropical rainstorm to help raise public awareness, provided the storm has some tropical origins and structure.

This storm is not expected to be a threat to the United States.

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"Steering breezes are likely to guide the storm, whatever it may become, toward the northeast, farther away from the Bahamas and across Bermuda to end this week," AccuWeather Senior Meteorologist Adam Douty said. "The islands of Bermuda are likely to experience a period of drenching showers, gusty thunderstorms and rough seas."

Forecasters say that conditions could become more severe in Bermuda if the system were to evolve into a strong tropical storm.

The disturbance east of the Bahamas was already producing a corridor of torrential showers and thunderstorms that extended from the northern coast of South America, northward through Puerto Rico and the United States Virgin Islands on Wednesday.

This close-up image of the tropical disturbance east of the Bahamas reveals a fire hose effect of showers and thunderstorms that was aimed at Puerto Rico and the United States Virgin Islands on Thursday morning, Oct. 27, 2022. (AccuWeather Enhanced RealVue™ satellite)

Since the relentless downpours may move little through Thursday, there is the likelihood of flash flooding and mudslides on the islands as well as river flooding in Puerto Rico.

If the pipeline of rain fails to shift in a prompt manner, a life-threatening situation could unfold.

Farther to the south, there is another area that AccuWeather forecasters have been focusing on for tropical development.

Even though the Cabo Verde portion of the Atlantic hurricane season is drawing to a close, there can still be tropical systems born from activity in this region. Disturbances that brew from the Indian Ocean and Africa travel westward across the Atlantic during the summer and early autumn. These disturbances are known as tropical waves. Over time and under the right atmospheric conditions, the tropical waves can evolve into tropical storms and hurricanes.

One such tropical wave moved off the coast of Africa several days ago and was approaching the waters to the northeast of South America. This zone has been a trouble spot and source of tropical development on a few occasions this year. Julia, Ian and Bonnie all originated in this part of the Atlantic.

As the new disturbance moves into the Caribbean late this week, there are two options for its future track.

One potential outcome is for the tropical wave to remain weak and poorly organized.

In this more likely scenario where the storm does not gain much strength, a batch of drenching showers and gusty thunderstorms would move quickly westward across the southern part of the Caribbean this weekend and head into Central America later next week, according to Douty.

On the other hand, there is a chance the system may quickly organize and strengthen into a strong tropical storm or hurricane while in the eastern part of the Caribbean. In this case, a slower and more northern track could occur with potentially significant impacts to lives and property over some of the islands in the northern Caribbean.

The risk of tropical development of the Caribbean system, like the system in the western Atlantic, has been raised from a low to a medium chance and could be pushed higher as the situation warrants.

Even when the calendar flips to a new month next week, the Atlantic could remain active. Any system that develops in the Caribbean could linger through the first several days of November.

From a historical perspective, every decade since the 1970s has had at least one year with a named tropical system in November. The notorious 2020 season had three named systems in November, including two Category 4 hurricanes.

The next three names on the list forecasters use to name tropical storms for the 2022 season are Lisa, Martin and Nicole.

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