Hurricane Irene, growing dangerous by each passing day, left the northwestern Caribbean, triggering high waves and heavy downpours which left about one million people in the dark in Puerto Rico. According to official storm predictions, the United States' Southeast region is under threat of a potential landfall towards the end of the week.

Puerto Rico Governor Luis Fortuno declared a state of emergency and asked people to remain indoors and avoid downed power lines, flooded streets and other hazards. There were no reports of deaths or major injuries from the region.

Hurricane Irene is expected to grow more dangerous as forecasters predict the storm to intensify into a major Category 3 hurricane by Thursday afternoon. At that juncture, Irene will be near Andros Island and about 130 miles southeast of Miami and Fort Lauderdale, with a wind speed of 115 mph.

While South Florida remains a potential landfall spot, latest computer model trends, predicted an increasing threat level for the Carolinas.

Dennis Feltgen, a spokesman for the hurricane center, said Irene's projected path paralleling the Florida coast meant that a slight wobble or delay in an expected northward turn could push the powerful core from offshore onto a densely developed shoreline, Miami Herald reported.

The stakes are high because it would take just a slight shift in the track to the left to make a dramatic change in the impact of the storm in a hugely populated area,'' he said.

A low pressure trough over eastern U.S. will potentially shift Irene's track to the east, reducing the risk of a direct landfall in densely populated South Florida but raising the risk in the Carolinas, reports said.

The storm is tracking north of all the big islands in the Caribbean now, said meteorologist Brad Panovich of WCNC-TV in Raleigh, N.C. This is significant because now the storm will have little interference as it moves towards the U.S. This also means a shift in the track east squarely puts the Carolinas in the strike zone.

I would prepare now along the entire South and North Carolina coasts, he added. Preparing for the worst and hoping for the best is the goal here. Get your supplies and plan together today through Wednesday. Thursday we'll know who needs to activate that plan. If you wait you'll be fighting crowds for supplies late week.

Florida residents were asked to stay prepared and ensure essential supplies including batteries, drinking water and food.

South Carolina officials also warned residents to track the storm closely. It has been six years since a hurricane hit the South Carolina coast, said Joe Farmer of the state Emergency Management Division, according to an MSNBC report.

Irene menaced the Dominican Republic and Haiti but since the storm's worst winds and rains remained north of the island, the threat of deadly flooding was reduced. Nevertheless, authorities worried about the approximately 600,000 Haitians still living in Port Au Prince tent cities after the 2010 earthquake.

Puerto Rico Emergency Operations Director, Mauricio Rivera, told The Miami Herald that by late Monday afternoon, more than half the island still had no electricity and 28 percent of the population was without running water. The island of Vieques remained completely without power.

I call what we had an 'almost-hurricane,'  Rivera said. It brought a lot of rain, a lot of wind, and quite a few electrical poles fell and so did trees. The situation is returning to normal. It's raining, but mostly just drizzling.''

According to reports, Oscar winning actress Kate Winslet and others escaped uninjured when Richard Branson's home on his private isle in the British Virgin Islands was destroyed by fire after being struck by lightning. About 20 people, including Winslet and her young children, were staying in Branson's eight-bedroom house on Necker Island when the fire broke out around 4 a.m., said reports.