Hurricane Lane has weakened as it approaches Hawaii but was still expected to pack a wallop, forecasters said Wednesday.

The National Weather Service said tropical-storm-force winds could begin as early as Wednesday afternoon on the Big Island.

The hurricane was about 305 miles (490 kilometers) south of Kailua-Kona and moving northwest toward other islands.

@Space_Station

Meteorologist Chevy Chevalier in Honolulu says winds slowed overnight from 160 mph to 155 mph (259 to 250 kph), prompting a downgrade of the hurricane from a Category 5 to a Category 4.

He says it may diminish to a Category 3 by Thursday afternoon but that would still be a major hurricane.

Chevalier says that by early Friday, the hurricane is forecast to be a Category 2 with winds up to 110 mph (177 kph) and the center located west of Hawaii Island and south of Honolulu.

"We expect it to gradually weaken as it gets closer to the islands," Chevalier said. "That being said, on our current forecast, as of the afternoon on Thursday, we still have it as a major hurricane."

With winds to 130 mph (209 kph), the hurricane could cause catastrophic damage.

Hawaii residents have rushed to stores to stock up on bottled water, ramen, toilet paper and other supplies as they faced the threat of heavy rain, flash flooding and high surf.

Public schools on the Big Island and in Maui County closed Wednesday until further notice.

@HRD_AOML_NOAA Video of #NOAA42 entering the eye #HurricaneLane during the 4PM HST mission. The storm was near its peak intensity, a Category 5, at this point. Taken by L. Bucci.

Hawaii Gov. David Ige is allowing non-essential state employees on the Big Island and Maui to go on administrative leave. Employees on Hawaii and Maui islands who work in disaster response as well as in hospitals and prisons are required to report to their jobs, the governor said.

The hurricane was moving at 8 mph (15 kph), said meteorologist Melissa Nye.