A slow-moving front making its way across the Big Island has brought steady rain to the northeastern portion of the island this week and will continue to impact areas as far south as Ka‘u as it continues its overnight track.
As of 5 p.m. Tuesday, the National Weather Service issued a flood advisory from Volcano to South Point, with radar indicating rain falling at a rate of about 1 inch per hour.
“We’re just getting some moisture that’s sort of coming in with those trade (winds) and getting wrapped around onto the southeast portion of the island,” NWS meteorologist Matt Foster said Tuesday.
The rain is part of a system that has been moving eastward for days, albeit at a slow pace.
Rain in the northeast has been “persistent,” this week, Foster said.
“We just have north winds that are keeping that moisture up there on the slopes.”
The 24-hour rain amount for Laupahoehoe by Tuesday afternoon was at 4.52 inches, according to data from local rain gauges. Honokaa had received 2.99 inches and Waimea 1.51 inches. The gauge at Kawainui Stream, south of Pepeekeo, had recorded 2.11 inches.
On Tuesday, state Department of Transportation crews were called out to clear Highway 19 after a landslide at Kaawalii Gulch dislodged large boulders, blocking the Hilo-bound lane just north of Laupahoehoe.
“If there’s a lot of rain up there it kind of loosens the materials,” said Sal Panem, DOT district engineer for Hawaii County.
And with the ground already saturated, it doesn’t take much for the mud and rocks to give way, Civil Defense administrative officer John Drummond said.
The steady rain also can create flood conditions.
“When we have these rain events, it can happen without much notice,” Drummond said.
“Take your time as far as driving is concerned,” Foster said. “It doesn’t take that much floodwater to pick up a vehicle and carry it away.”
Email Ivy Ashe at iashe@hawaiitribune-herald.com.