(CNN) Tropical Storm Karen formed early Sunday, and a tropical storm warning has been issued for St. Vincent and the Grenadines, along with Grenada and its territories, the National Hurricane Center said.

Karen is about 105 miles northwest of Grenada, with maximum sustained winds of 40 mph, the center said in its latest advisory.

A tropical storm warning means that tropical storm conditions are expected somewhere within the warning area.

A tropical storm watch has been issued for the US Virgin Islands, Puerto Rico - including Vieques and Culebra - and the British Virgin Islands, according to the advisory.

Karen is forecast to continue moving in a west-northwest direction Sunday, away from the Windward Islands, and move across the eastern Caribbean Sea Sunday night and Monday.

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