MIAMI (AP) _ Tropical Storm Erika, with top sustained winds of 60 mph over the open Atlantic on Thursday, was not expected to strengthen to hurricane strength anytime before the weekend.

``Right now it doesn't look too promising,'' said Brian Maher, a forecaster at the National Hurricane Center in Miami. ``It's kind of like a sit and watch period.''

The storm was 370 miles east-southeast of Antigua Thursday night, moving west at about 21 mph. It was expected to continue on that course and posed no immediate threat to land, Maher said.

The islands of Antigua, Montserrat, Barbuda, Nevis, St. Kitts and Anguilla were under a tropical storm watch Thursday night. A tropical storm warning was posted for the Dutch side of St. Maarten, Maher said.

Erika formed Wednesday during what is typically the busiest period of the hurricane season, the first two weeks of September. The season has been quiet so far.

More than a month has passed without a named storm or depression. Hurricane Danny caused severe flooding and scattered damage along the coast of Alabama in July before moving north as a tropical storm and drenching other Southern states.