Rafael is forecast to strengthen Tuesday and will likely become a hurricane over the next 24 hours as it batters the western Caribbean on the first leg of an uncertain journey toward the US Gulf Coast.

The National Hurricane Center forecasts Tropical Storm Rafael to grow into the season’s 11th hurricane on Tuesday as it moves toward Cuba with winds and storm surge expected to affect the Florida Keys this week.

Tropical Storm Rafael is forecast to become a hurricane in the northwestern Caribbean near the Cayman Islands before making landfall in Cuba.