East Hawaii’s wettest month of the year is producing a combination of welcome news and not-so-welcome news.
The entrance to Waipio Valley was closed due to flooding Monday, and a large albizia tree fell over early in the morning along Highway 132 in Pahoa, blocking both lanes, closing the road, and knocking out Hawaii Electric Light Co. power lines.
Meanwhile, however, drought-stricken areas continue to see a bit of a comeback, or at least a reprieve, from dry conditions that have persisted for more than five years.
Heavy rains hit multiple sites across the island over the weekend, with a rain gauge on Kawainui Stream — an area that typically puts up the biggest numbers on the island — collecting nearly 18 inches of rain in the 72-hour period from Friday at 8 a.m. to Monday morning. Hilo International Airport saw a combined total of 3 inches, Laupahoehoe got 3.3 inches, Waimea collected 2 inches, Honokaa and Kamuela both received more than 5, and Pahoa collected 1.5. Even typically dry areas on the leeward side saw some rain, including Kahuku Ranch and Kapapala Ranch, with 1.1 inches and 1.7 inches, respectively.
Hydrologist Kevin Kodama with the National Weather Service in Honolulu said the rainfall wasn’t anything out of the ordinary, historically speaking.
“This is normal seasonal rainfall,” he said. “March is the wettest month of the year, and this March, after beginning kind of on the dry side, we’re now seeing the rainfall of that spring transition.”
Last month, continuing improvements in rainfall removed the “severe drought” designation from Hawaii Island for the first time since July 2008.
“Large-scale weather systems during February have produced enough rainfall to build on previous improvements in drought conditions,” according to a National Weather Servcie drought statement from early March. “These rain events managed to reach the leeward areas of Maui and the Big Island, which have been hit the hardest by drought.”
Hawaii Island had various locations listed over the years as being in severe drought, classified as D2, according to the U.S. Drought Monitor. The monitor classifies areas between D1, or Moderate Drought, and D4, or Exceptional Drought. Extreme Drought, or D3, is found in state only on western Molokai in the area serviced by the Kualapuu Reservoir and is solely due to long-term irrigation water use restrictions, according to the National Weather Service.
The drought update added that areas of Moderate Drought, or D1, have continued to recede on the Big Island and Maui. As of March 6, moderate drought was found from the lower leeward South Kohala slopes to the Humuula Saddle and the upper slopes of Mauna Loa.
On the windward side of the island, the trade winds are blowing again, Kodama said, and that means heavy rain.
“The prevailing wind is driving the rain,” he said. “We didn’t see the trades for a little while, and that’s what gives the windward side all the rain.”
The weekend soaking meant trouble for Waipio Valley, where swollen rivers and streams flooded the road leading down into the valley, closing it to all traffic but that of Waipio residents, according to Darryl Oliveira, administrator of Hawaii County Civil Defense. The road remained closed Monday.
Eight stranded hikers were airlifted to safety Sunday morning after spending the evening in Waipio Valley because they were unable to walk out when water levels rose. The group was found along the Hi‘ilawe waterfall trail after being reported overdue. No one was injured.
“They’ve had a lot of rain out there and the slope is still draining out,” Kodama said. “The road going into Waipio Valley goes into the stream, and it doesn’t take much to close it.”
Also this weekend, one lane was blocked on Hawaii Belt Road at Kawalii Gulch due to a landslide that delayed traffic for two to three hours.
Meanwhile, in Pahoa, Highway 132 closed early Monday morning to traffic for more than 11 hours after an albizia tree collapsed onto the road about 0.2 miles west of Nanawale Boulevard. When the tree fell, it took out powerlines across the road, according to Kristen Okinaka, spokeswoman for HELCO.
The tree fell at 3:18 a.m., she said, knocking out power to 789 customers. Work to restore power began at 4:24 a.m., and by 11:45, all affected customers had regained their electricity.
The road was reopened to the public around 2:15 p.m., according to Civil Defense.
Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.