Tropical storm forecast to bring strong winds and heavy rain to Hawaii this weekend

A tropical storm is expected to deliver strong winds and heavy rain to Hawaii this weekend, particularly to the Big Island and Maui, as it passes south of the island chain.

The U.S. National Weather Service on Thursday evening issued a tropical storm watch for Hawaii County, which includes all of the Big Island, in anticipation of Tropical Storm Hone.

In an 8 p.m. advisory, the weather service said the storm was located about 770 miles (1,240 kilometres) east-southeast of Hilo and about 980 miles (1,575 kilometres) east-southeast of Honolulu. The storm was moving west at 14 mph (23 km/h) with maximum sustained winds of 40 mph (65 km/h).

The August storm has evoked memories of the powerful hurricane south of Hawaii that helped fuel a deadly wildfire that destroyed Maui’s Lahaina town last summer, but the weather service said Thursday that Hone was not creating the same conditions.

Separately, to Hone’s east, Hurricane Gilma was moving west across the Pacific, but it was too early to tell whether it would affect the islands.

Hone, which means “sweet and soft” in Hawaiian and is pronounced hoe-NEH, was expected to bring sustained winds of 20 to 30 mph (32 to 48 km/h) and gusts of 50 mph (80 km/h) to Maui and the Big Island. Oahu and Kauai were forecast to get slightly weaker winds.

The Big Island’s east coast and southeastern corner were expected to get four to eight inches (10 to 20 centimetres) of rain Saturday night through Sunday night. Maui could get two to four inches (five to 10 centimetres) of rain.

These predictions could change depending on the storm’s course. Late Thursday, the storm was about 815 miles (1,310 kilometres) east-southeast of Hilo. It was moving west at 16 mph (26 km/h).

The Aug. 8, 2023, Lahaina fire was fueled by powerful winds whipped up by a combination of a hurricane passing some 500 miles (800 kilometres) to the south and a very strong high pressure system to the north of the islands. The U.S. National Weather Service issued a red flag warning at the time, something it does when warm temperatures, very low humidity and strong winds combine to raise fire danger.

Laura Farris, a U.S. National Weather Service meteorologist in Honolulu, said some drier air was expected to move in to the western end of the state this weekend, which presents some concerns about fire risk.

“But it’s not even close to what we saw last year,” Farris said.

The pressure system to the north is not as strong now as last year and the tropical system to the south is a storm not a hurricane, said Pao-Shin Chu, a University of Hawaii professor and the state’s climatologist.

“We do see something similar but not as dramatic as the Lahaina case we saw last year,” Chu said.

Hurricane Gilma was packing maximum sustained winds near 120 mph (193 km/h), making it a Category 3 hurricane. It was slowly moving west. The U.S. National Weather Service said Gilma was expected to slowly weaken this weekend.

The cause of Lahaina blaze, the deadliest in the United States in over a century, hasn’t been determined, but it’s possible it was ignited by bare electrical wire and leaning power poles toppled by the strong winds.

To reduce the risk of wildfires, the state’s electric utilities, Hawaiian Electric and the Kauai Island Utility Cooperative, have since started shutting off power during high winds and dry conditions.

Last year, Maui County officials failed to activate outdoor sirens that would have warned Lahaina’s people of the approaching flames. They instead relied on a series of sometimes confusing social media posts that reached a much smaller audience.

Amos Lonokailua-Hewett, who took over as the new administrator of the Maui Emergency Management Agency on Jan. 1, said in the event of a wildfire threat, his agency would send alerts over radio and television broadcasts, via cellphones and with the sirens.

The sirens sound a steady tone and no message.

“The outdoor warning siren is typically used when there is an imminent threat to public safety and the situation requires the public to seek more information,” Lonokailua-Hewett said in an emailed statement.