The National Weather Service has posted a high wind warning “over and downwind of the Kohala Mountains” until 6 p.m. Friday.
Meanwhile, most of the rest of the state, including the Big Island, is under a wind advisory, also until 6 p.m. Friday.
A strong high-pressure system north of the state will drift slowly eastward through Friday, according to the NWS. The system will drive strong and gusty trade winds that will be accelerated over the summits and downwind of hilly and mountainous terrain.
The high wind warning, which extends to the Waimea area, means sustained winds of 40 mph or greater and gusts of 58 mph or greater. Winds that speed may blow down trees and power lines and damage roofs. And travel will be difficult, especially for vehicles that present a high profile.
“We’ve actually already observed that this afternoon, up by Kohala Ranch,” said Thomas Vaughan, a forecaster for the NWS in Honolulu. “We’ve seen sustained speeds there already with winds of of 36 to 39 mph and gusts over 58, and that’s what helped us prompt that high wind warning.”
Vaughan said the wind advisory means there is likelihood of “sustained winds of 30 to 39 mph, with gusts of 50 to 57 mph.”
“There are reports of advisory-level winds already from various areas on the Big Island,” he said. “I’ve seen reports from Waikoloa, South Point, Upolu Point. I’ve also seen advisory-level winds in Kealakomo, which is on the coast if you go straight southeast from Volcano.”
According to Vaughan, the strong trades should also bring scattered showers, “especially in the windward areas of the island, in Hilo and inland of Hilo.”
Advisory-level winds are are expected for the summits and upper slopes of Maunakea and Mauna Loa.
Residents under the wind advisory could experience wind that can tear shingles from roofs, knock down tree branches, blow away tents and awnings, and make it difficult for drivers to steer, especially in vehicles that present a high profiles.
The weather service is advising preparedness, including watching out for falling tree branches when walking or driving and making sure tents and awnings are secured or taken down. Loose outdoor items should be brought inside or secured properly.
Residents also are advised to be prepared for power outages.
“We should see these higher winds tonight through (Thursday) and they should taper off Friday night,” Vaughan said.
Email John Burnett at jburnett@hawaiitribune-herald.com.