U.S. weather forecasters say Hurricane Irene, the first Atlantic hurricane of the 2011 season, has strengthened as it takes aim at the Bahamas and is expected to intensify.

The National Hurricane Center in Miami said in its latest bulletin Monday that Irene had grown into a Category 2 storm on the five-point scale of hurricane intensity. Forecasters said the storm now had winds of 160 kilometers per hour and was located about 210 kilometers east of Puerto Plata in the Dominican Republic. It was moving toward the west-northwest.

The hurricane center forecasted the core of the storm would go just to the north of the Dominican Republic and Haiti. The storm was expected to move near or over the Turks and Caicos Islands and the southeastern Bahamas on Tuesday, and near the central Bahamas early Wednesday.

Forecasters also predicted Irene would move northwest along the east coast of Florida later in the week before possible landfall as a major hurricane in South Carolina.

The Federal Emergency Management Agency, or FEMA, is urging people along coastal areas of the southeastern U.S. to closely monitor the hurricane and prepare for potential severe weather in the coming days.

Irene intensified into a hurricane over Puerto Rico before dawn Monday, flooding streets, knocking down trees and cutting power to about 1 million residents. There were no reports of serious injuries.

Puerto Rico's governor, Luis Fortuno, declared a state of emergency to mobilize aid from the U.S. federal government. Schools, government offices and businesses in the territory remained closed Monday.