The Big Island should brace for a pasting of rain and wind, and the leeward side is no exception.
Iselle failed to weaken as predicted and continued toward Hawaii Island as a Category 1 hurricane Wednesday afternoon. Winds could reach 70 mph with gusts to 85 and Iselle could dump a foot of rain when it hits in mid to early afternoon Thursday, National Weather Service forecasters say.
A storm surge of 1 to 3 feet, combined with an afternoon high tide and 15 to 22 foot waves may swamp coastal areas, and high winds may damage buildings, according to a hurricane warning issued for Hawaii Island. Located about 255 miles east-southeast of Hilo, Iselle was packing 80 mph sustained winds which extended 35 miles from the center as of 8 a.m. Thursday. Tropical storm force winds extended in a 140 mile radius as the hurricane headed west-northwest at 17 mph.
Schools, agencies, businesses and parks closed with the hurricane’s approach, and Gov. Neil Abercrombie signed an emergency proclamation ahead of the oncoming weather.
“Folks need to understand this is a large system and significant impacts will be seen far away from the center,” said NWS meteorologist Mike Cantin at a press conference in Honolulu.
Forecast winds, he said, “are significant enough to take down trees and do substantial damage to homes as well.”
Unanchored structures are particularly at risk and objects left outdoors could become wind-driven projectiles dangerous to humans. The entire island chain was also under a flash flood watch, with mudslides and dangerous torrents of water possible in some areas.
The island’s two high peaks can’t be counted on to break the effects for West Hawaii, said Ray Tanabe, acting regional director for the National Weather Service in the Pacific Region.
While the peaks may exert some blocking effects, “the shape of the island may increase some impacts from accelerating downslope winds,” Tanabe said.
The funneling effect may be felt particularly in Waikoloa and Kawaihae, he told West Hawaii Today.
Winds are expected to peak Thursday evening, then decline toward midnight on the east side of the island and around sunrise Friday on the west side.
“Winds should be significant enough to take down trees and do substantial damage to homes as well,” Cantin said.
High surf — reaching 22 feet Thursday — ahead of the hurricane is expected to pound windward coasts and potentially flood low-lying areas.
“We don’t recommend anyone being near the coastline as this makes landfall,” Tanabe said.
The Hawaii County Civil Defense early Thursday urged residents in coastal areas and areas prone to surf and surge impact are advised to take precautions. Areas of concern for initial high surf impact include Punaluu in the Kau area, Kalapana, Phoiki, Kapoho in the Puna area, and Keaukaha in Hilo.
Hurricane Iselle weakened briefly Tuesday but restrengthened early Wednesday morning, with a clearly defined eye re-emerging. The annular shape of the hurricane has been resistant to the effects of shear and drier air. The sea surface temperature beneath Iselle was 78 degrees — marginal for supporting the system — but wind shear effects were also low Wednesday, and the window for Iselle to weaken was closing as the hurricane bore down on Hawaii County at 18 mph as of 8 p.m. Wednesday.
“We didn’t see anything that was going to take a big bite out of Iselle,” Tanabe said Wednesday afternoon. “The primary factor has been the shear. We expected shear to have more of an impact.”
People should finish their storm preparations by Thursday morning at the very latest, Tanabe said.
“When those winds arrive, you don’t want to be out there taking chances,” he said.
Civil Defense asks that all residents remain off the roadways and to anticipate possible power outages and interruptions in telephone and other communication systems. The public is advised to complete all necessary preparations by noon Thursday.
The National Weather Service is also watching Hurricane Julio, which is not expected to weaken much as it approaches. The hurricane, about 1,235 miles east of Hilo, had 105 mph winds Thursday morning as expected to come abreast the island on Sunday. The storm is moving west around 17 mph.
“Right now the track has it sliding by to the north of the islands, but that could change,” Tanabe said. “We’ll deal with Iselle first, put some Band-Aids on and then focus on Julio.”