Hurricane Erin was downgraded to a Category 3 hurricane early Sunday as a tropical storm warning was issued for the Turks and Caicos Islands and winds and heavy rains whipped the Virgin Islands and Puerto Rico.

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, raising the risk of flash floods, landslides and life-threatening sea swells.