Hurricane Lane drenched Hawaii Thursday ahead of its arrival in the island state, prompting US President Donald Trump to declare a state of emergency as landslides and flash flooding left roads blocked.
The National Weather Service said Lane -- located about 200 miles (320 kilometers) south of Hawaii -- remained a powerful category four hurricane, packing winds in excess of 130 miles per hour.
The eye was expected to sweep very close to or over the islands, 2,000 miles southwest of the mainland US, sometime later Thursday.
Up to 12 inches (30 centimeters) of rain have already fallen, according to federal authorities, with 30 inches expected in the worst-hit areas over the coming four to five days.
"Someone once told me it wasn't raining when Noah built the Ark," American Red Cross vice-president Brad Kieserman told a news conference in Washington.
"That means that readiness is important -- readiness to make sure we can fulfill our responsibility and the critical infrastructure lifelines."
Emergency teams have set up 16 evacuation centers, with a further 19 due to open throughout the day, authorities said, as Trump urged Hawaiians to hunker down and prepare for the worst.
"Our teams are closely coordinating with the state and local authorities. You are in our thoughts!" Trump tweeted.
Brock Long, chief of the Federal Emergency Management Agency (FEMA), said: "We are extremely concerned about the potentials for inland flooding, landslides occurring and damage to the transportation, communications infrastructure."
Residents across the state were stocking up on water, food, gasoline and emergency supplies as Lane drew nearer.
"Last couple of days it's been like this -- it's been busy," said Chris, an employee at a gas station in Haleiwa, on the north shore of Oahu island -- the location of the capital Honolulu.
"We have been just constantly getting cars filling up. Everybody is in a panic mode right now -- everyone is filling up gas, gas cans, propane cans and all that."
Landslides and flooding caused by the first rainstorm partially blocked several roads on Big Island, according to local media.
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 were expected to rise as much as two to four feet above normal tide levels, prompting a storm surge and "large and destructive waves."
Surfers were observed taking advantage of the calm before the storm to get out on their boards one last time Wednesday before the ocean got too violent.
Bracing for the worst
Lane's wind power was expected to weaken into the weekend, but forecasters warned it would remain a hurricane as it approaches Hawaii.
The US Coast Guard said 57,000 US military personnel already stationed in Hawaii stood ready to launch search and rescue missions, and provide logistics and medical support.
Governor David Ige declared a state of emergency Tuesday on 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.
Federal officials have been working with Hawaiian utility managers to keep a close eye on the power grid, a major vulnerability in Puerto Rico last year when it was hit by Hurricane Maria, a Category 4 storm.
Hurricane-related deaths in Puerto Rico have been estimated at as many as 4,600 people, largely because prolonged and widespread power outages and washed out roads prevented access to health care, according to US researchers.
The government of Puerto Rico, a self-ruled US territory, has put the toll at 1,427.