Climate Change

Storm in the pond: 5 brew in Atlantic — only the 2nd time

Peak Atlantic hurricane season is on way, and scientists may run out of names 

By Akshit Sangomla
Published: Thursday 17 September 2020
Five tropical storm systems were brewing in the Atlantic ocean at the same time for only the second time on record on September 14. Photo: National Oceanic and Atmospheric Administration

A rare climatic event occurred in the Atlantic Ocean on September 14, 2020: Five storm systems — hurricanes, storms and depressions — were brewing in the ocean at the same time for only the second time on record.

The five active storms were Hurricane Paulette, Hurricane Sally, tropical storm Teddy, tropical storm Vicky and tropical depression Rene.

The last time such an event occurred was nearly half-a-century ago, in September 1971.

It was only in August that two tropical storms — Laura and Marco — had also formed at exactly the same time, sparking fears of the Fujiwhara effect that occurs when two hurricanes combine to form a mega hurricane.

Even though the event did not happen, it did highlight the increasing threat from such rare climatic events. 

The speed at which storms have formed in the current season means that meteorologists are now close to running out of names for them. After the formation of tropical storm Vicky, there would be only one name — Wilfred — left for use.

As the coming weeks signal peak of the Atlantic Hurricane season, scientists would have to resort to the Greek alphabet for naming subsequent storms. This has happened only once before in 2005. 

Depressions, storms and hurricanes have caused significant destruction in the United States and the Caribbean islands with strong winds, heavy rainfall and storm surge, mostly along the Gulf Coast.

The slow moving tropical storm Sally, which had hit the United States Gulf coast as a category II hurricane, caused heavy rainfall and flooding in Florida and Alabama, killing one person.

It also left thousands of residents in Florida state without electricity. Pensacola city was the worst hit, with media reports quoting the fire chief of the city saying it had received four months’ worth of rains in four hours.

The unusually heavy rainfall is because of the slow pace of the storm, which means that there will be even more rainfall and flooding before it dissipates. Slow paced storms cause much more rainfall, thereby increasing the chances of flooding in the regions of impact.

Typically, a hurricane moving at around 8 kilometre per hour can cause up to 760 millimetres (mm) of rainfall. Slow movement is often caused due to the behaviour of winds circling the cyclone.

Slow moving storms and hurricanes have become a regular occurrence in the Atlantic Ocean. The category V Hurricane Dorian, which devastated the Bahamas in September 2019, was also a slow-moving storm. For some part of its journey it only moved at 1.5 kmph.

Hurricane Florence in 2018 and Hurricane Harvey in 2017 were also slow-moving storms. A research paper published in the journal Science Advances in April 2020 found that human-induced global warming might make hurricanes slower by upto 3.2 kmph by the end of the century, if the greenhouse gas emissions are not controlled in time.

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