Two Tropical Waves Crossing the Atlantic, Neither are a Threat

Jun 24, 2021
Originally published on June 25, 2021 9:34 am

Update as of 9:30 AM Friday:

The National Hurricane Center has decreased the chances of tropical storm formation from 40 percent to 20 percent over the tropical Atlantic over the next 5 days. The strong tropical wave near the coast of Africa could still develop next week, but it will be slow to occur, if it happens at all. It remains no immediate threat to land areas.

Update as of 9:30 AM Thursday:

Two robust tropical waves are moving across the Atlantic Ocean this week, with both showing at least a hint of developing. However, neither are expected to become a threat to the United States in the next five to seven days.

The first wave of interest was located a few hundred miles east of Barbados Thursday morning, where thunderstorm activity had recently flared up. Forecasters at the National Hurricane Center (NHC) have kept chances of tropical cyclone formation very low with this wave, and say only an "increase in shower activity and gusty winds" were expected as moves across the Lesser Antilles on Friday. Upper-level are likely to be too strong for development with this wave as it moves through the Caribbean this weekend, but some of the tropical moisture associated with it may eventually reach the Gulf of Mexico next week.

A second tropical wave appeared stronger and more organized on satellite data as it was emerging off the west coast of Africa Wednesday. Long range forecast models suggest some gradual tropical development may occur with this feature as it traverses the central Atlantic Ocean over the next five days. The National Hurricane Center said there is a 40 percent chance it could develop into a depression or named storm as of their Thursday morning update.

Climatology argues against a tropical storm or hurricane originating east of the Lesser Antilles in late June, as less than 4% of them have done so since 1851. However, both disturbances this week have proven to be stronger than normal for this time of year. Tropical waves that originate over Africa tend to dissipate quickly in the central Atlantic until oceanic and atmospheric conditions become more favorable in late summer or early fall.

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