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Busy Start to Tropical Season Fueled by Warm Atlantic

9 Jul 2017, 2:32 pm

With four tropical cyclones in the Atlantic so far this season, it’s been a busy start to the Atlantic basin’s hurricane season, and there’s a big factor helping play a role in it.

Warmer than average sea-surface temperatures along the belt of typical tropical development in the Atlantic Ocean is aiding an unusually active start to the Atlantic basin’s hurricane season. Four storms have already formed in the Atlantic basin so far in 2017, including three tropical storms, a figure not usually seen until mid-August.

But while the number of tropical cyclones is impressive so early in the season, it’s the location of their formation that’s potentially even more striking. Two of the four storms have formed directly from tropical waves originating off the west coast of Africa, a prime development ground usually looked to in August or September rather than June or July. It’s in this area where sea-surface temperatures are consistently running about 2-to-6° Fahrenheit (1-3° Celsius) above average. Take a look at this map from WeatherBell.com, and pay close attention to the orange and red areas between the Lesser Antilles islands, in the middle-bottom portion of the map, and the west coast of Africa, on the far right side of the map:

The so-called Cape Verde season or a Cape Verde tropical storm or hurricane is one that starts near this chain of remote islands, located roughly 400 miles off the west coast of Africa. Fueled by storms moving east-to-west across the Atlantic, wind shear and dry air from the Saharan Desert usually limits development in the early-to-mid portion of the Atlantic season, but so far, storms have been able to modestly overcome both factors. The warm sea-surface temperatures add heat, energy and moisture to the system, likely contributing to this active pattern.

This was a significant factor in noted Colorado State University tropical researcher Dr. Phil Klotzbach raising his seasonal forecast last week.

That said, the short-term forecast appears relatively tranquil, with no storm development expected in the Atlantic this week.

A tropical cyclone, for the record, is classified as either a tropical depression, a tropical storm or a hurricane.

As always, stay with WeatherNation for the latest on the tropics.

For WeatherNation: Meteorologist Chris Bianchi

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