Hurricane Irene is bearing down on the Bahamas, crossing the Turks and Caicos Islands as it also takes aim at the eastern coast of the United States.

The National Hurricane Center said in its latest bulletin Wednesday that the storm was about 655 kilometers southeast of Nassau, Bahamas, moving to the west-northwest with 155 kilometer-per-hour winds.

Officials say that on the forecast track, Irene's core will move near or over the southeastern and central Bahamas Wednesday, and near or over the northwestern Bahamas on Thursday.

The storm lashed the British territory of the Turks and Caicos Islands Tuesday.

Irene is currently a Category Two storm on the five-point scale of hurricane intensity, but is forecast to strengthen by Thursday. Forecasters say it could become a major hurricane.

Irene is the first storm to seriously threaten the United States in three years and could have an impact from Florida to New England.

Authorities have said Irene has the potential to cause flooding in the U.S. mid-Atlantic and New England regions, where soil is saturated from recent heavy rains. They also say Irene is a “very large” system whose tropical storm-force winds extend 335 kilometers from the center, bringing the entire East Coast of the United States in range of the hurricane.

The White House says officials briefed President Barack Obama on Tuesday about federal coordination with authorities in states that may be affected by the storm.

The head of the Federal Emergency Management Agency, Craig Fugate, said Tuesday FEMA also is in contact with the National Park Service in Washington about the storm's potential to disrupt a Sunday dedication ceremony for a memorial to slain civil rights leader Martin Luther King, Jr.

Meanwhile, the U.S. State Department has issued a travel warning that urges Americans to carefully consider the risk of traveling to the Bahamas and the Turks and Caicos due to the hurricane. The notice said Americans likely to be impacted by the storm and who do not have access to adequate and safe shelter, should consider leaving until Irene has passed and while commercial transportation is available.

Irene intensified into a hurricane over the U.S. territory of 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. President Obama declared an emergency in Puerto Rico late Monday, authorizing federal aid to help local authorities recover.