Hawaii under state of emergency as hurricane approaches

US President Donald Trump on Thursday declared a state of emergency in Hawaii, releasing disaster funds as powerful Hurricane Lane bears down on the archipelago's Big Island.

US weather authorities said Lane had weakened slightly to a Category 4-storm but was still packing maximum sustained winds of 130 miles (215 kilometers) per hour, threatening torrential rains, high winds and dangerous surf.

The National Oceanic and Atmospheric Administration warned in its latest advisory that Lane could produce "excessive rainfall" that would deluge the islands into the weekend, "leading to significant and life-threatening flash flooding and landslides."

Trump had earlier urged Hawaiians to hunker down and prepare for Lane, while the US Navy said it was deploying some of its Hawaii-based ships and submarines to avoid getting trapped when Lane hits.

Residents were stocking up on water, food and emergency supplies as Lane was tracking some 230 miles (370 kilometers) southwest of Kailua-Kona, a town on the west coast of the Big Island.

Forecasters said the slow-moving storm would generate large swells in the coming days that would produce "very large and damaging surf" on shorelines facing west and south, likely triggering "significant coastal erosion."

Sea levels in that area were expected to rise as much as two to four feet above normal tide levels, prompting a storm surge and "large and destructive waves."

Lane's center was expected to sweep very close or over Hawaii's main islands later Thursday or Friday, the NOAA said.

The storm's wind power was expected to weaken into the weekend, but forecasters warned it would remain a hurricane as it approaches the islands.

Governor David Ige had already on Tuesday declared a state of emergency on the Big Island to help provide relief for damage from the hurricane.

"Hurricane Lane is not a well-behaved hurricane," he said in a statement. "I've not seen such dramatic changes in the forecast track as I've seen with this storm.

Hurricanes rarely make landfall in Hawaii and the last major storm to strike the state was nearly three decades ago, when Hurricane Iniki barrelled into the island of Kauai, leaving six people dead and causing billions of dollars in damage.

FEMA associate administrator Jeff Byard said authorities were bracing for the worst, stocking up on emergency food and water and readying shelters.

"We have emergency food in the form of MREs (Meals Ready-to-Eat) and water that are currently on all four counties of the state," he said

Byard said FEMA was also working with utility companies to co-ordinate the repair of any damaged power infrastructure.