Officials in the northern Caribbean are warning of heavy rains and dangerous swells as Tropical Storm Erin approaches the region

The hurricane center explicitly calls for Erin to rapidly intensify before the weekend — a term used when a storm’s sustained winds get at least 35 mph stronger in 24 hours. In this case, forecasters expect Erin to leap from a Tropical Storm on Friday to a major Category 3 hurricane by Sunday.

Tropical Storm Erin has begun to strengthen and is expected to reach major hurricane intensity this weekend as it tracks just north of the Caribbean islands, where it could bring rain, gusty winds and high surf.