After Hurricane Iselle surprised forecasters Wednesday by gaining strength, it may now become the first hurricane to make landfall in Hawaii since Iniki 22 years ago.

The storm was on a course to slam into Hawaii island Thursday and unleash sustained winds of 60 to 70 mph with gusts to 95 mph, forecasters said.

But projections show the storm should weaken as it moves west and south of Maui County Thursday night and Oahu and Kauai on Friday, packing 35- to 45-plus mph winds with locally higher gusts.

"The volcanoes of the Big Island will do a number on the system," said Mike Cantin, National Weather Service meteorologist. "So what it looks like on the other side — that’s something we will be looking at closely."

All of the islands, he said, should prepare for 5 to 8 inches of rain and up to a foot of rain in some locations, especially in windward areas, with flash flooding a possibility.

"People need to understand this is a large system and the impacts will reach far from the center," he said.

Making matters worse, another storm, Julio, grew into a Category 1 hurricane late Tuesday and is following in the wake of Iselle a couple of days to the rear. But forecasters expect it to weaken and become a tropical storm when it nears Hawaii Sunday or later.

Attesting to the warmth of its tropical waters, the Central Pacific on Wednesday was home to another hurricane, Genevieve, which was moving away from the state to the southwest.

As for now, Hawaii island will take the brunt of Iselle, including an estimated 1 to 2 feet of storm surge, forecasters said.

On Maui, Mayor Alan Arakawa on Wednesday

declared a state of emergency for the county until further notice. All nonemergency county employees will work a half-day Thursday, with county offices scheduled to close at noon.

The Hawaii County Civil Defense Agency on Wednesday warned coastal residents and those in areas prone to surf and surge impact to take precautions.

"All residents are encouraged to use current favorable weather and this time to prepare and to secure all property before the effects of the hurricane begin," the agency said in a statement.

Hawaii island and Maui County public schools will be closed Thursday and Friday. All beach parks on those islands were closed Wednesday and will remain so until conditions improve.

Winds are expected to be strong enough to take down trees, hurl tree branches and do significant damage to homes, Cantin said.

"It’s not a major hurricane, but enough to blow things around," he said, adding that the residents of the east side of the island should consider boarding up windows.

In Hilo, bottled water, toilet paper and beer were still for sale Wednesday night, but businesses and residents were taking precautions. The Seaside Hotel along Hilo Bay had plywood covering its lobby and restaurant windows and the open-air lobby was empty of its usual furniture.

Dustin Kaneshiro was enjoying the calm, still night air outside the hotel.

"We get plenty false alarms," he said. "Hopefully, we’ll get lucky this time, too."

For Oahu and Kauai, Cantin described the expected winds of up to 45 mph as being equal to the most powerful winter storms. "We’ll see downed power lines and power poles," he said.

The Coast Guard issued a high-wind warning for all commercial ports on Hawaii island and in Maui County, saying winds would be at least 40 mph. The agency advised commercial vessels and large, oceangoing barges to leave Hilo by 4 a.m. Thursday, Kawaihae by 7 a.m., Kahului by 9 a.m. and Kaunakakai, Molokai, by noon.

And it urged all pleasure craft to seek sheltered waters.

Swells on Hawaii island were expected to reach 15 to 25 feet, while Maui County will experience 12- to 18-foot waves, with 10- to 15-footers on south-facing shores Friday, forecasters said. Oahu and Kauai can expect 10- to 15-foot waves to hit east-facing shores, with southern shores seeing the same on Friday.

"It’s going to be choppy, rough surf," Cantin said. "There won’t be any clean sets. Definitely dangerous conditions. You don’t want to be going out on the water."

The Honolulu Emergency Management Department issued a statement cautioning Oahu residents not to let down their guard:

"It is vital that you do not focus on the exact forecast track. Forecast movement, direction and speed are only estimates. Even small errors in the forecast track can mean major differences in where the worst conditions will occur.

"Be ready to evacuate if necessary. Heed the advice of local officials and comply with any orders that are issued. Persons living near the shore should be prepared to evacuate quickly should building surf threaten."

Andrea Geron and her family had their bags packed and ready Wednesday morning if and when authorities give the word to evacuate their Edgewater Drive home on the ocean at Iroquois Point.

"The totes are just inside the door, ready to grab and go," she said.

Geron, looking at some modest waves lapping up on the beach next to her home, said she wasn’t really nervous about the storm. She said that’s a function of paying attention to authorities, using caution and being prepared.

She said her husband was coming home from work early Wednesday to help move lanai furniture and other outdoor items inside.

"As long as you’re prepared and listen to the warnings, you’ll be OK," she said, adding that the family with two girls, a baby and a dog is ready, if necessary, to head to the pet-friendly public shelter at Campbell High School in Ewa Beach.

Down the road, Jason Dahl was busy talking to a cable installer. He had moved into his oceanfront home Tuesday and said it could have been better timing, considering the threatening storm.

On the other hand, Dahl, a Coast Guard helicopter rescue swimmer, said he’s endured hurricanes in Florida and New Jersey and he knows what to expect.

"Usually a Category 1 hurricane never affects anything — although I’ve never been this close to the ocean, so I don’t know," he said.

Cantin said forecasters were expecting to see greater weakening of Iselle from typical Central Pacific wind shear overnight Tuesday, but the eye of the storm stayed intact, allowing the system to strengthen slightly and maintain its Category 1 strength of 74 to 95 mph.

"We don’t expect it to get much stronger than it is right now," he said. "But there still is some uncertainty there. You’ve got to realize this is not an exact science."

A ridge of high pressure is keeping Iselle on track and headed in Hawaii’s direction at a pace of 16 mph.

Gov. Neil Abercrombie and members of his Cabinet joined Wednesday’s news conference at the Central Pacific Hurricane Center on the Manoa campus of the University of Hawaii.

"We feel very confident the state is ready to go," he said. "We’re coordinated. We’re collaborative on this. What everyone needs to do is pay no attention to speculation. Remember to stay focused."

Abercrombie earlier signed an emergency proclamation allowing for easier access to emergency resources at state and federal levels by activating the state Major Disaster Fund for disaster relief. He said it will allow the state "to move swiftly with focus" to address needs of the storm.

State Emergency Management Administrator Doug Mayne urged residents to muster up a disaster kit with seven days of food and water. He also urged families and businesses to have a plan, rehearse the plan and stay informed.

"The kit is a big thing," he said. "It’s very difficult for everyone to go out last minute. And that’s what we’re seeing now."

Regarding Saturday’s primary election, the governor said "all campaign hats are off" and he and his lieutenants will follow protocols to ensure smooth voting.

ENLARGE PHOTO.

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Star-Advertiser staff writers Dan Nakaso and Nanea Kalani contributed to this report.