The forecast track for Tropical Storm Ana continued to shift away from the Big Island on Thursday after the system weakened overnight Wednesday.
But forecasters predict the cyclone could strengthen again and say the island should brace for storm-force winds, heavy rains, high surf and flash flooding.
“People should continue to make preparations as they’ve been advised to do,” said National Weather Service forecaster Kevin Kodama. “We’re not out of the woods by any means.”
Damaging winds of 40 mph and higher could hit the south part of the Big Island and Kailua-Kona from early Friday evening to Saturday afternoon.
Surf to 30 feet on Ka‘u and Puna shorelines and 15 feet in Kailua-Kona is expected Friday evening as Ana makes its closest approach to the island.
A 1- to 2-foot storm surge also is forecast, said Chris Brenchley, a meteorologist with the Central Pacific Hurricane Center.
The system was 400 miles southeast of South Point on Thursday evening, with tropical storm-force winds extending 60 miles from the center.
The island is under a tropical storm watch, and a flash flood watch is effective from noon Friday to 6 p.m. Sunday, with up to 20 inches of rain predicted to fall along southeast slopes. Offshore waters are under a hurricane warning effective this afternoon.
Emergency shelters are opening at noon Friday, Hawaii County Civil Defense Administrator Darryl Oliveira said during a media briefing Thursday afternoon.
“Hawaii Island will start to feel some of the impacts by 6 p.m. (Friday),” Oliveira said. “Our intent is to have shelters open well in advance of tropical storm-force conditions.”
Moderate wind shear weakened Ana to a 60 mph storm by Thursday morning, but the cyclone was forecast to strengthen briefly to hurricane status and pack 75 mph winds as it brushes past the island Friday night and Saturday.
The center of the storm is on course to pass about 85 miles southwest of South Point, then weaken as it encounters increased vertical shear from an approaching upper level trough.
Even though Ana has passed over water warm enough to fuel itself, the storm is encountering wind shear and has struggled to organize, Kodama said.
“It goes through bursts,” he said. “It organizes, then fizzles out.”
“It’s going to be moving into water that is more than warm enough, and there’s a window of opportunity for it to intensify further,” he added.
The likelihood of tropical storm-force winds is 43 percent for Kailua-Kona, 54 percent for South Point and 26 percent for Hilo.
The first signs of high surf showed up Thursday, running 10 feet at Isaac Hale Beach Park in Puna, according to Civil Defense.
Door-to-door notifications of residents in low-lying areas continued Thursday, Oliveira said, noting some of the residents don’t have a line of communication to the outside.
People living in flood-prone regions that were impacted by Tropical Storm Iselle are being urged to move to higher ground, but no mandatory evacuations are anticipated, he said.
Residents of Kapoho Vacationland were heeding that warning, according to resident Nadean Ratledge.
She said Thursday many who live along the shoreline were planning to evacuate.
The neighborhood was hit hard by Iselle in August and damage still was evident on some lots now two months later.
“We will be more careful this time,” said Ratledge, who was going to stay with neighbors on the “drier side” of the neighborhood.
“We didn’t know what was coming. Now we do.”
Puna Geothermal Venture will go offline Friday to prevent the plant from tripping offline during the storm and releasing emissions, Oliveira said. PGV released hydrogen sulfide as a safety measure following a power-related shutdown during Iselle, causing concerns among residents living nearby.
The North Kohala emergency shelter most likely will not open because the region is far enough away from the projected impact area, said Barney Sheffield, Hawaii Island’s disaster manager for the American Red Cross. It will not be clear how many other shelters will open until Friday morning.
“There is no way to tell right now,” Sheffield said. “There are so many variables depending on the storm track.”
Ana has been on a westward track and is expected to turn west-northwest Thursday, then veer west Sunday and skirt to the south of Oahu and Kauai as a tropical storm.
If a ridge north of the Hawaiian Islands weakens earlier than forecast, the storm could swing onto a more northwesterly track, bringing it closer to the Big Island, said Brenchley. If the ridge fails to weaken as anticipated, it could help steer the storm west, away from the islands.
A delay in the cyclone’s predicted turn to the northwest has been good news because it takes the track farther away from the island chain. The bad news is Ana is forecast to slow its forward speed from 13 mph to 10 mph when it passes the Big Island, and to 7 mph as it approaches Oahu.
“That’s the part that makes it dangerous,” Kodama said. “It keeps the winds and the rain around longer.”
All county and state beach parks on the Big Island, Hawaii Volcanoes National Park and public libraries will close Friday ahead of the storm.
Hawaii Electric Light Co. activated its incident management team and put staff on alert to make sure employees are ready to respond, said HELCO administrative manager Rhea Lee.
The power company has an agreement with mainland utility companies that provides mutual assistance in times of emergency, and the group has been put on notice that HELCO might need additional workers in the aftermath of Ana, Rhea said.
The cyclone has packed a lot of uncertainty, with the forecast track changing numerous times during the past few days. In Ocean View, residents seemed to be bracing against the unknown, said Gil Robinson, president of the Ocean View Community Association.
“I’ve been boarding up my own house, and some neighbors’ houses,” Robinson said. “We just don’t know.”
Tribune-Herald staff writer Tom Callis contributed to this report.
Email Bret Yager at byager@westhawaiitoday.com.
