Hurricane Ana is approaching Hawaii, producing high waves along some shorelines, heavy rains that prompted a flood advisory, and winds strong enough for officials to urge caution.

The center of the powerful Pacific storm was about 155 miles southwest of the Big Island as it passed late Friday night and about 245 miles from Honolulu, the National Weather Service said.

There was little chance for hurricane conditions on the islands, but a tropical storm watch remained in effect throughout the archipelago and winds were expected to reach nearly 40 mph, forecasters said.

Waves were expected to crest to 10 to 15 feet on both the North and South shores of Hawaii’s islands late Saturday and to remain tall through Sunday.

Late Friday, the National Weather Service issued a flood advisory for parts of the Big Island until shortly after midnight, saying rain was falling in some areas at a rate of 2- to- 3-inches an hour.

Ana became a Category 1 hurricane earlier in the day when it was about 230 miles south of Hilo.

Hurricane Ana is approaching Hawaii with heavy rains that prompted a flood advisory (photo AP)

Shortly before midnight, it had maximum sustained winds of 85 mph and was churning along its course at 13 mph.

Swells were picking up on the Big Island’s south shores Friday afternoon, with 15-foot waves seen in Pohoiki Bay.

About 6 to 8 inches of rainfall were expected, although some isolated areas could get up to a foot of rain.

Gov. Neil Abercrombie proclaimed an emergency to help the state respond to the storm.

The Hawaii chapter of the American Red Cross planned to opened evacuation shelters on the Big Island at noon. Island Air planned to suspend its Maui and Lanai flights Saturday afternoon and all flights Sunday, but airports remained open.

On Oahu, buses and trash pickup remained on their normal schedule. Less rain was expected than previously predicted, but officials remained concerned about high surf, storm surge and flooding, Honolulu Mayor Kirk Caldwell said.

Camping permits on Oahu were revoked for the weekend, but most parks remained open except for Hanauma Bay, which will be closed on Sunday.

The weather service issued a flash flood watch for the entire state from Friday through Sunday, indicating flooding is possible anywhere in the archipelago.

Ana (AH – nah) is expected to lose power as it moves northwest along the island chain.