MIAMI, Florida -- Hurricane Bertha -- the first hurricane of the 2008 Atlantic season -- began a shift in direction Tuesday morning, a day after growing to Category 3 status, according to the National Hurricane Center.

While Bertha's power may fluctuate over the next day, the storm is expected to begin gradually weakening by Wednesday, the center said.

Bertha became a major -- or Category 3 -- hurricane Monday afternoon. A Category 3 has wind speeds of 111 to 130 mph.

As predicted, the eye of the hurricane began a shift toward the northwest and slowed a bit early Tuesday, the hurricane center said at 5 a.m. ET.

At that hour, Bertha was 675 miles east-northeast of the northern Leeward Islands and 1,035 miles southeast of Bermuda. The eye was moving toward the northwest at about 10 mph.

Bertha's maximum sustained winds were clocked at 120 mph, the 5 a.m. advisory said.

There is a very small chance Bertha will make landfall in the United States. Bermuda could be affected by the hurricane this weekend.

"It is still way too soon to determine whether or not Bertha will affect Bermuda," the center said.

The storm formed Thursday in the far eastern Atlantic, off the coast of Africa, near the southern Cape Verde Islands. It strengthened into a hurricane early Monday.

The first tropical storm of the season, Arthur, formed May 31 near the coast of Belize and dumped heavy rain on Central America and southern Mexico.