Tropical Storm Erin is barreling toward Puerto Rico and could become the season’s first hurricane before the week’s end.

Currently sweeping through the Atlantic, Erin is on track to impact Puerto Rico, the Leeward Islands, and the U.S. and British Virgin Islands. According to a Thursday night advisory from the National Hurricane Centre, the system is expected to develop into a “large and formidable major hurricane” as early as Friday.

Forecast models indicate that Erin will strengthen into a Category 1 hurricane on Friday, with “rapid intensification” likely to push it to Category 3 status by Saturday afternoon.