By Malia Mattoch McManus
HONOLULU (Reuters) - Tropical Storm Ana, churning across the central Pacific with sustained winds of up to 70 miles per hour (113 kph), was expected to strengthen into a hurricane on Wednesday as it closed in on Hawaii, with landfall possible this weekend, forecasters said.
The last hurricane to hit Hawaii was a Category 4 storm, Iniki, which lashed the island of Kauai in September 1992 with winds of more than 140 miles per hour (225 kph), killing six people and causing damage estimated at $2.4 billion.
Ana, about 680 miles (1,100 km) southeast of Hawaii's Big Island on Wednesday morning, is a comparatively weaker system, with maximum sustained winds expected to top out at about 90 mph (145 kph), just below the upper limits of a Category 1 storm, National Weather Service meteorologists said.
Tropical storms get classified as hurricanes when their maximum sustained winds reach 74 mph (119 kph), a level Ana was expected to reach by Wednesday night, forecasters said.
"It's probably going to become a hurricane before the day is out," said Dennis Feltgen, a meteorologist for the National Hurricane Center in Miami.
Tropical storm-force winds extended outward by up to 65 miles (100 km) from Ana's center, with large swells from the storm expected to hit the eastern shores of Hawaii's main islands by late on Thursday, the Hurricane Center reported.
If Ana remains on a track to hit Hawaii, it could make landfall on the Big Island by late Friday night or early Saturday morning, said Matthew Foster, a meteorologist with the Central Pacific Hurricane Center in Honolulu.
Hawaii residents were being urged to stockpile provisions and to make sure they had an evacuation plan if necessary.
"We're advising all residents to have seven days' worth of supplies, food, medication, water," said Peter Hirai, deputy director for emergency management in Honolulu.
"There might be a perception ... that the Big Island will block this storm, but we're telling people not to take this storm lightly. It could become a hazardous situation over the weekend."
In August, Tropical Storm Iselle pummeled the Hawaiian Islands with high winds and heavy rain, forcing hundreds of people to seek shelter and knocking out power to more than 20,000 residents.
A second storm tracking right behind, Julio, passed hundreds of miles north of Hawaii.
The last recorded hurricane to hit Hawaii before Iniki in 1992 was the Kohala Cyclone in 1871.
(Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Mohammad Zargham and Sandra Maler)