As emergency shelters opened, rain began to pour and cellphone alerts went out, the approaching hurricane started to feel real for Hawaii residents.

Hurricane Lane was forecast to continue its northwest turn into the islands Thursday, which would make it the most powerful storm to hit Hawaii since Hurricane Iniki in 1992.

"Everyone is starting to buckle down at this point," said Christyl Nagao of Kauai. "Our families are here. We have businesses and this and that. You just have to man your fort and hold on tight."

Officials opened shelters on the Big Island and on the islands of Maui, Molokai and Lanai on Wednesday. They urged those needing to use the Molokai shelter to get there soon because of concerns the main highway on the south coast of the island could become impassable.

On the island of Oahu, which was put on a hurricane warning late Wednesday, shelters were scheduled to open Thursday. Officials were also working to help Hawaii's sizeable homeless population, many of whom live near beaches and streams that could flood.

Hawaii Emergency Management Agency Administrator Tom Travis said there's not enough shelter space statewide and advised those who are not in flood zones to stay home.

Officials warned the limited shelter space should be a "last resort" and aren't designed to withstand winds greater than about 40 mph (64.3 kph).

"Whenever possible, the public should plan to shelter in place or stay with family or friends in homes outside of these hazard areas that were designed, built, or renovated to withstand anticipated conditions," the city and county of Honolulu said in a news release.

NBC News tweet

Hurricanes are ranked 1 to 5 according to what is known as the Saffir-Simpson Hurricane Wind Scale. Hurricane Lane is at category 4, which means winds from 130 to 156 mph (251 kph).

The Big Island was already starting to see Lane's first effects, Gov. David Ige said at a news conference Wednesday.

The hurricane's outer rain bands were bringing showers to some parts of the island, said Matt Foster, a meteorologist with the National Weather Service.

The eastern side of the island picked up nearly 3 inches (7.62 centimeters) of rain in three hours, Foster said.

Melanie Davis, who lives in a suburb outside Honolulu, said she was gathering canned food and baby formula.

"We're getting some bags of rice and of course, some Spam," she said of the canned lunch meat that's popular in Hawaii.

She was organizing important documents into a folder — birth and marriage certificates, Social Security cards, insurance paperwork — and making sure her three children, all under 4, have flotation devices such as swimming vests — "just in case."

Public schools were closed for the rest of the week and local government workers were told to stay home unless they're essential employees.

Meteorologist Chevy Chevalier said Lane may drop to a Category 3 by Thursday afternoon but that would still be a major hurricane.

Mike Seidel tweet

"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."

The central Pacific gets fewer hurricanes than other regions, with about only four or five named storms a year. Hawaii rarely gets hit. The last major storm to hit was Iniki in 1992. Others have come close in recent years.

"We're planning on boarding up all our windows and sliding doors," Napua Puaoi of Wailuku, Maui, said after buying plywood from Home Depot. "As soon as my husband comes home — he has all the power tools."

Puaoi was 12 when Iniki hit Hawaii.

"When it did happen, I just remember, pandemonium, it was all out craziness," she said.

Unlike Florida or Texas, where residents can get in their cars and drive hundreds of miles to safety, people in Hawaii are confined to the islands.

Instead, they must stay put and make sure they have enough supplies to outlast prolonged power outages and other potential emergencies.

The Federal Emergency Management Agency has several barges with food, water and supplies that it moved into the region ahead of Hurricane Hector, which skirted past the islands more than a week ago, according to FEMA Administrator Brock Long.

The U.S. Navy was moving its ships and submarines out of Hawaii. All vessels not currently undergoing maintenance were being positioned to help respond after the storm, if needed.