Tropical Storm Irene (search) became better organized and stronger Thursday as it moved closer to the East Coast, but any landfall was still days away.

"We're forecasting it to become a hurricane in a few days," said James Franklin, a hurricane specialist at the National Hurricane Center (search) in Miami.

Irene is expected to move toward the East Coast from Georgia to Virginia (search) over the next five days, though it was still too soon to tell what kind of threat Irene could pose to land, Franklin said.

"It certainly doesn't look like the main threat is Florida, but stranger things have happened. ... It may well turn sharply enough [to the north] to not make landfall," he said.

Irene had top sustained winds near 40 mph, just above the 39 mph threshold for tropical storms. Hurricanes sustain winds of at least 74 mph.

At 11 a.m. EDT, Irene was about 515 miles south-southeast of Bermuda and moving west-northwest near 17 mph, forecasters said.

Irene broke records Sunday as the earliest ninth named storm in the Atlantic hurricane season, which began June 1 and ends Nov. 30. Normally, only two named storms have formed by this time in the season.

It weakened to a depression Monday, but regained tropical storm strength Wednesday.