The storm was about 20 miles southeast of Little Cayman, the National Hurricane Center said. It was moving northwest at about 15 mph.

Rafael is strengthening and will likely become a hurricane by Tuesday night as it batters the western Caribbean on the first leg of an uncertain journey toward the US Gulf Coast.

SAN JUAN, Puerto Rico (AP) — Tropical Storm Rafael strengthened into a Category 1 hurricane on Tuesday as it swirled past the Cayman Islands and chugged toward western Cuba.