Emerging disturbance in Atlantic runs into some trouble

Atlantic hurricane season is starting to pick up the pace. Tropical Storm Bill formed off the eastern coast of the United States Monday night, and concerns continued for tropical development in the Gulf of Mexico. Thousands of miles away, another feature began making waves on the opposite end of the ocean.

A section of the far eastern Atlantic that is often hostile to tropical systems this time of the year was being closely scrutinized by AccuWeather forecasters. A tropical wave emerged off the African coast over the weekend and was situated to the south of the Cabo Verde islands.

The tropical wave off the coast of Africa is one of the strongest if not the strongest of the year thus far, according AccuWeather Hurricane Expert Dan Kottlowski. This wave has been designated as Invest 94L.

However, the wave had become less robust on Tuesday. The system was more disorganized when compared to earlier this week and shower and thunderstorm activity had decreased, according to the National Hurricane Center.

This visible satellite image shows the tropical wave as a collection of clouds off the coast of western Africa Tuesday afternoon, local time. The disturbance has become less organized when compared to Monday. (RAMMB/CIRA)

A tropical wave is an area of scattered showers and thunderstorms that tracks across the Atlantic Ocean from Africa to the Caribbean and Central America, especially during the height of tropical season.

Kottlowski added that the tropical wave was visible on satellite surrounded by dry air and dust from the Saharan Desert.

Dry air ingested into a developing tropical system can inhibit the development of showers and thunderstorms and cause the feature to dissipate.

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This dust can play a role in whether or not this tropical wave develops into a more organized tropical system in the coming days.

"There is a low chance that 94L develops later this week as it tracks westward across the eastern and into the central Atlantic," said AccuWeather Senior Meteorologist Dan Pydynowski. By this weekend, 94L will move into a zone of higher wind shear and dry air which would limit its potential for further tropical development."

A massive area of dust can be seen to the west of the tropical wave in the Atlantic Basin on June 14, 2021.

Other factors that can contribute or hinder tropical development are sea-surface temperature and winds that change speed and direction at different levels of the atmosphere, known as wind shear.

According to Kottlowski, the sea-surface temperatures ahead of the tropical wave are marginal for development. However, once this wave reaches about 50 degrees west, about halfway across the ocean, it will run into much warmer water, but it may also have to deal with increased wind shear.

Kottlowski also added that where the center of the tropical low forms in relation to 10 degrees north can also determine if an organized system develops or not. If the low forms to the north, it will remain in the marginally warm water, but if it forms farther south it will be located over even warmer water.

The feature will continue tracking to the west this week and can bring enhanced showers and thunderstorms to the eastern Caribbean this weekend or early next week.

While tropical waves can routinely form off the coast of western Africa in early June, a variety of conditions typically inhibit them from strengthening into tropical storms or hurricanes at this part of the season.

Dust, marginal water temperatures and wind shear typically prevalent in the eastern portions of the main development region during the beginning of hurricane season can hinder tropical cyclone formation, explained Kottlowski.

"Only two tropical depressions have ever formed that far east before July 1," stated AccuWeather Senior Weather Editor Jesse Ferrell.

Storms are more likely to form in the Caribbean Sea or the Gulf of Mexico as a gyre develops over the region. Along with Tropical Storm Bill and this tropical feature near Africa, AccuWeather meteorologists are also tracking a potential tropical system in the Gulf of Mexico. Following the quiet start to the season during the first two weeks of June, some tropical experts have compared the burst of activity to something that's more likely to occur in September.

Hurricane season officially runs from June 1 to Nov. 30. This year AccuWeather meteorologists predicted another active season with more storms than normal expected to strike the United States.

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