Tropical Storm Irene was expected to intensify Friday and possibly reach hurricane strength as it approached the U.S. East Coast, forecasters said.

Irene's potential threat to land was still uncertain, as its path had shifted east, according to forecasters at the National Hurricane Center (search) in Miami. Forecasters said the storm could strike the coast anywhere from South Carolina to New Jersey.

Irene's top sustained winds increased to about 60 mph, and forecasters said conditions appeared favorable for the storm to strengthen. Hurricanes sustain winds of at least 74 mph.

At 5 a.m. EDT, the storm's center was located about 325 miles south of Bermuda (search) and about 795 miles southeast of Cape Hatteras, N.C. (search).

It was moving northwest near 15 mph, though it was expected to slow down, forecasters said.

Normally, there are only two named storms by this time in the Atlantic hurricane season. Irene became the earliest ninth named storm in the season, which began June 1 and ends Nov. 30, when it developed Sunday.