* WHAT...Life-threatening rip currents due to breaking waves up to 6 feet and occasionally higher.

* WHERE...North facing beaches of Puerto Rico, and Culebra. Easternmost St. Croix.

* WHEN...Through at least 6 AM AST Thursday.

* IMPACTS...Rip currents can sweep even the best swimmers away from shore into deeper water, where it becomes difficult to return to safety.