SAN JUAN, Puerto Rico — Hurricane Erin exploded in strength to a Category 5 storm in the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.

Erin’s sustained winds increased to 70 mph, just 4 mph shy of hurricane strength. The hurricane center said Erin should continue to strengthen through the weekend, when it should be moving near or north of the Leeward Islands, according to the official forecast path.

The National Hurricane Center (NHC) has warned that Tropical Storm Erin is expected to strengthen and could become a major hurricane over the weekend as it shifts just north of the northern Leeward Islands,