SAN JUAN, Puerto Rico: Hurricane Erin strengthened into a Category 2 storm on Friday as it approached the northeast Caribbean, prompting forecasters to warn of possible flooding and landslides.

The storm is expected to remain over open waters, although tropical storm watches were issued for Anguilla, Barbuda, St. Martin, St. Barts, Saba, St. Eustatius and St. Maarten.

Heavy rains were forecast to start late Friday in Antigua and Barbuda, the US and British Virgin Islands and southern and eastern Puerto Rico. Up to 10 centimeters are expected, with isolated totals of up to 15 centimeters, according to the National Hurricane Center in Miami.

The hurricane center also warned of dangerous swells but said the threat of direct impacts in the Bahamas and along the east coast of the United States “appears to be gradually decreasing.”

The storm was located 405 kilometers northeast of Anguilla as of the hurricane center’s 11 p.m. EDT advisory. It had maximum sustained wind speeds of 160kph and was moving west north-west at 27kph.