Update: Wind advisory canceled as trade winds fall below advisory thresholds

Update at 3:23 p.m. Dec. 12: The National Weather Service in Honolulu has canceled the wind advisory in effect for North and South Kohala, Kaʻū and the interior of the Big Island.

Wind speeds have lowered below advisory thresholds in those areas as trade winds have started to decrease, and will continue to do so into the weekend, while high pressure north of the state weakens.

Update at 6:54 a.m. Dec. 12: The National Weather Service in Honolulu has extended the wind advisory in effect for North and South Kohala, Kaʻū and the interior of the Big Island until 6 p.m. today as strong and gusty trade winds continue for another day.

East winds of 20 to 30 mph, with gusts up to 50 mph, are still expected in the advisory areas.

Winds this strong can cause significant damage, including tearing off shingles, and make it difficult to steer while driving, especially in high-profile vehicles.

Weather officials advise:

• Watch out for falling tree branches when walking or driving.
• Secure outdoor objects, such as tents and awnings, or take them down.
• Be prepared for power outages.
• Use extra caution when driving, especially if operating a high-profile vehicle.

Strong and gusty trade winds will continue for one more day as an upper-level low pressure system passing to the south of the state is strong enough to reflect a trough at the surface.

The area forecast discussion for Hawai’i issued by the National Weather Service in Honolulu at 3:56 a.m. today said that surface trough will combine with a moderate strength subtropical ridge just north of the state to tighten local pressure gradients and produce stronger trade winds across the islands.

These strong trades will continue to blow at advisory thresholds over and downstream of wind-favored mountain regions over the eastern half of the state.

Hawaiʻi County Civil Defense said in an email Wednesday evening that utility disruptions were being reported in areas of the island. For more information and additional power outage or other hazard updates, visit the Hawaiʻi County Hazard Impact Map.

Civil Defense says if you are experiencing high winds or utility disruptions:

• Be advised that crews are working on repairs.
• Stay clear of downed utility lines and report all hazards to authorities.
• Know that road closures can occur without notice.
• Drive with caution and be aware of debris, downed trees and utility lines.

Expect decreasing wind speeds into the weekend, however, with light and variable winds returning by next week from late Monday into Wednesday, with two passing cold fronts breaking down the ridge north of the island chain.

The wind advisory that was in effect through today for the summits of Mauna Kea and Mauna Loa was canceled as winds atop the mountains have diminished to below advisory thesholds.

Update at 3:30 p.m. Dec. 11: The high wind warning that was in effect for the summits of Mauna Kea and Mauna Loa on the Big Island has been replaced with a wind advisory as winds have decreased atop the island’s tallest peaks.

The advisory is in effect until 6 p.m. Thursday. The National Weather Service forecast office in Honlulu says the mountaintops will see east winds of 45 to 55 mph, with gusts up to 65 mph.

Winds this strong can make it difficult to steer, especially for drivers of high-profile vehicles.

Update at 9:58 a.m. Dec. 11: The wind advisory in effect for Hāmākua, North and South Kohala, Kaʻū and the interior of the Big Island was extended through 6 a.m. Thursday by the National Weather Service forecast office in Honolulu.

Winds of 20 to 30 mph, with gusts up to 50 mph, continue to be expected in the advisory areas.

The latest area forecast discussion for the state from 6:42 a.m. today said trade winds continue to strengthen in response to a pressure gradient between a high pressure ridge that has been building for the past several days to the north and a deepening mid- to upper-level low southeast of the islands moving westward, but staying south of the state, through the end of the week.

Trade winds will peak today into tonight when the pressure gradient is expected to be at its strongest.

Gusty winds will be accompanied by slightly drier conditions today and tomorrow compared with Tuesday, but while afternoon relative humidity values could briefly dip to less than 50%, the probability of reaching fire weather threshold of 45% now appears low.

So there no longer is any concern for possible fire weather conditions.

Update at 1:42 p.m. Dec. 10: The National Weather Service in Honolulu has upgraded a wind advisory previously in effect for the summits of Mauna Kea and Mauna Loa on the Big Island to a high wind warning that will remain in effect through 6 p.m. Wednesday.

East winds of 50 to 60 mph, with gusts of up to 70 mph, are forecast atop the mountains, which will make travel to and at the summits difficult, chiefly for high-profile vehicles.

Winds at this strength can cause property damage. Hazardous driving conditions because of powerful crosswinds will pose a serious risk for drivers, especially for lightweight and high-profile vehicles.

Loose outdoor items should be brought inside or properly secured.

Original story posted at 8:51 a.m. Dec. 10: Steadily strengthening trade winds, expected to become breezy to strong by tonight across the state and remain there through Thursday, will likely reach already typically windier areas of the islands beginning later this morning, including those on the Big Island.

Breezy conditions could become hazardous because of the increased wind speeds, so the National Weather Service forecast office in Honolulu issued a wind advisory from 10 a.m. to 6 p.m. Wednesday for most of the Big Island.

The advisory includes Hāmākua, North and South Kohala, Kaʻū and the interior of the island.

Northeast winds of 20 to 30 mph with gusts up to 50 mph are expected in those areas.

Winds that strong can tear off shingles, knock down tree branches, blow away tents and awnings as well as make it difficult to steer while driving, especially in high-profile vehicles.

Hawai‘i County Civil Defense and National Weather Service officials advise:

• Drive with caution, especially if opering a high-profile vehicle.
• Be aware and stay clear of debris, downed trees and utility lines. Report all hazards to authorities.
• Watch out for falling tree branches.
• Secure all outdoor objects. Make sure tents and awnings are secure or take them down.
• Be prepared for power outages.

The wind advisory in effect for Big Island summits also was extended until 6 p.m. Wednesday because of the increasing trade winds, and ti might even need to be upgraded to a high wind warning.

Northeast winds of 35 to 45 mph, with gusts up to 60 mph, are forecast atop Mauna Kea and Mauna Loa, which will make travel to and at the summits difficult, especially for high-profile vehicles.

The public should consider postponing trips to the summits, if possible, until conditions improve. Otherwise, use extra caution walking and driving, and be careful opening or closing doors.

Hawai’i Volcanoes National Park reported Monday in a Facebook post that the Mauna Loa summit is closed to overnight and day use because of forecasted hazardous windy conditions during the first half of this week.

Park staff is monitoring the weather for opportunities to re-open the summit when conditions improve.

Puʻuʻulaʻula Cabin, also known as Red Hill Cabin, however, is open. The cabin is located at the 10,035-foot-elevation level and about 7.5 miles above the end of Mauna Loa Road, just off the Mauna Loa Trail.

Trade winds are strengthening as high pressure continues to build to the north of the islands, according to the National Weather Service forecast area discussion from early Tuesday morning for Hawai’i. Wind speeds will gradually decline, becoming moderate to locally breezy, heading into the weekend before finally weakening by next week.

The breezy conditions during the next few days are also raising fire weather concerns, especially on Wednesday and Thursday when winds are forecast to be their strongest.

“The only limiting factor for us to issue a fire weather watch at this time is the minimum humidities being borderline critical,” said the weather agency’s Honolulu forecast office in the area forecast discussion.

Relative humidity levels should near critical thresholds over some of the windier leeward areas of the state by Wednesday afternoon, and red flag warnings will be a possibility Wednesday and Thursday.

“We will watch the humidities today to give us a better idea of the potential for red flag warnings tomorrow and Thursday,” the National Weather Service said in its area forecast discussion.

For more information, including downed power lines or other weather-related hazards, visit the Hawai‘i County Hazard Impact Map.

To see the latest forecast, advisories, watches and warnings for your community, visit the National Weather Service Honolulu forecast office website.