Updated

The National Hurricane Center says Tropical Storm Don has formed in the Atlantic Ocean.

Forecasters say the storm is about 485 miles east-southeast of Barbados and 595 miles east of Trinidad on Monday afternoon. It has maximum sustained winds of 40 mph and is moving west at 17 mph.

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A tropical storm warning is in effect for Grenada. A tropical storm watch is in effect for Barbados, St. Vincent and the Grenadines, and St. Lucia.

An Air Force Reserve crew found the storm small and well-defined but not particularly well-organized. Don is expected to dissipate within 72 hours.