Tropical Storm Erin has formed on a path toward the Caribbean and is expected to strengthen to a hurricane later in the week as it passes by Puerto Rico. Most models forecast the storm turning upward into the Atlantic Ocean, but a few see the storm continuing onward to the U.S. mainland.

Tropical Storm Erin formed on Monday and is expected to become a hurricane, and possibly a major hurricane, later this week.

Brief: Tropical Storm Erin is likely to become a hurricane in the next 48 hours, according to the National Hurricane Center on Aug. 12.