The windward side of the Big Island received a cloudburst Sunday night, and while Hilo and vicinity are known for rainy weather, the downpour was notable because September is the dry season for most of Hawaii.
The deluge wasn’t the usual trade-wind showers, according to National Weather Service forecaster Derek Wroe.
“It was kind of an odd situation,” he said. “There was kind of a disturbance in the middle portion of the atmosphere, and that had drawn up quite a bit of moisture around it, so that really enhanced the trade-wind showers. Actually, enhanced is kind of subdued term for what happened. It actually created quite a bit of rainfall. A lot of places got over five inches overnight on the windward side.
“It was quite a soaking, but thankfully, that’s the end of it.”
In the 12-hour period ending at 8 a.m. Monday, the National Weather Service gauge at Honolii Stream registered 6.66 of rain. Hakalau measured 6.43 inches, Papaikou Well reported 5.56 inches, and Saddle Quarry had 5.52 inches.
And although not every gauge reported 5 inches or more, other locations received at least their fair share of precipitation.
Keaumo, at about 5,500-feet in elevation, received 4.11 inches of rain, while north of Hilo, Laupahoehoe measured 4.67 inches of rain and Honokaa recorded 4.19 inches.
Kulani, on the slopes of Mauna Loa, had 3.55 inches. Piihonua, upslope from Hilo, reported 3.62 inches, and Hilo International Airport saw 3.18 inches fall on its tarmac.
The only leeward sites to record significant rainfall during that 12-hour period were in Ka‘u.
Kapapala Ranch received 3.59 inches, while 2.94 inches fell on Pahala.
The east end of Wood Valley Road in Ka‘u was closed in both directions because of flooding. It was reopened to traffic midafternoon Monday.
Email John Burnett at jburnett@hawaiitribune-herald.com.