Rainfall from a dissipated post-tropical cyclone Wali began to hit East Hawaii on Saturday, prompting the National Weather Service to issue an early morning flash flood watch that previously hadn’t been due to go into effect until that evening.
A flood advisory for the eastern half of the island went into effect from 2:15 p.m. to around 4 p.m. Saturday as weather radar picked up thunderstorms and rainfall as heavy as two inches an hour over slopes from Glenwood to Pohakuloa and lower Puna areas.
It promised to be only the beginning of a wet few days.
Weather Service forecaster Maureen Ballard described the effects as “initial moisture.” The band of rain-producing disturbance stretches some 400 miles to the east, Ballard said.
“We expect more and possibly heavier rains now to Monday,” she said.
At 3 p.m. Saturday, there were no reports of storm-related issues from fire or police personnel, and rains in Hilo were mild to moderate, said Civil Defense administrator Darryl Oliveira.
“So far, so good,” said Oliveira.
Waikoloa Village was experiencing moderate rain Saturday evening, but it was not clear how heavily impacted the leeward areas might be.
“It is reaching higher elevations,” Ballard said of the rainfall, “and it’s just a matter of time before it comes over.”
A statewide flash flood watch was in effect through 6 p.m. Monday. Forecasters predict up to a foot of rain in some areas through Monday. Residents are being cautioned to stay away from streams, drainage ditches and low-lying, flood-prone areas. Heavy rainfall was expected to cause hazardous driving and poor visibility.