Heavy rain, hail and lightning are expected to continue on Oahu until at least 11:45 a.m., National Weather Service forecasters said. Hail was reported in Niu Valley and Aina Haina at about 9:30 a.m. Hail was also reported in Waimanalo this morning.
Oahu is under a flash flood warning. Forecasters also extended the warning for hard-hit Kauai until 11:15 a.m.
The warning for Oahu included Aina Haina, Palolo, Niu Valley and Kuliouou.
A flash flood warning means flooding is imminent or occurring in streams. Affected residents in low-lying area should move to higher ground. Forecasters warn people not to cross flowing or rising water in vehicles or on foot.
Besides the warning, a flash flood watch remains in effect for Niihau, Lanai, Kahoolawe, Maui and other parts of Oahu and Kauai until 6 p.m. today.
No widespread power outages were reported after thunder and lightning strikes on Oahu overnight, although damage to underground cables affected homes and businesses in Waianae and Hawaii Kai.
A small pocket of homes in Hawaii Kai — about 35 — were without power this morning.
About 200 homes and businesses in Waianae lost power beginning at 8 p.m. Monday, but HECO said power was restored around 3:30 a.m.
Traffic near the Halona Blowhole was being contra-flowed this morning because of fallen rocks on Kalanianaole Highway.
The heavy rains also caused a mudslide that closed Diamond Head Road between Makalei Place and the Diamond Head Lighthouse at about 1:38 this morning. The road reopened before 7 a.m.
The weather service also reported two waterspouts in the Kaiwi Channel between Molokai and Oahu at 6:43 and 7:24 a.m. Forecasters issued a special marine warning for the area because severe thunderstorms could form more waterspouts.
On Kauai, Mayor Bernard Carvalho declared the county a disaster area on Monday.
For the 24-hour period ending at 8 a.m. today, National Weather Service rain gauges showed 14 inches of rain in Wainiha, 11.73 inches in Opaekaa Stream, 11.48 in Hanalei and 8.04 in Lihue. Nearly 17 inches of rain fell on Hanalei in the 24-hour period ending at 11 p.m. Monday. Kapahi recorded 13.6 inches.
On Oahu, 7.4 inches fell at the Waihee pump station in Windward Oahu and nearly 6 inches fell in Ahuimanu Loop. The Lyon Arboretum in Manoa recorded 4.9 inches.
Several Kauai schools — Hanalei School; Kilauea Elementary School; Kapa’a Elementary School; Kapa’a Middle School; Kapa’a High School; Kamehameha Schools’ Anahola Preschool; ; and Island School — are closed today because of closed roads and flooding.
Radar also showed more heavy rain over the north- and east-facing slopes of the Garden Island just after 5 a.m. Forecasters say stream levels, though declining, remain elevated and the ground is soaked.
Several roads remained closed, including the Hanalei Bridge, which has been flooded since Saturday night. Debris and floodwaters remained on portions of Kuhio Highway in Haena, near Lumahai, near the Kalihiwai Bridge and near Kilauea. The Kapaa Bypass Road and Kamalu Road in Wailua also remain closed.
County officials said the Wailua Golf Course is closed today and will also be closed tomorrow because of flooding.
At last report, three holding areas were open including: Waioli Church in Hanalei; Church of the Pacific in Princeville; Kapaa Middle School; and Lihue Neighborhood Center.
Forecasters say thunderstorms and heavy rains should gradually begin to lessen tonight into Wednesday, as the weather system responsible for the unstable conditions gradually moves away and weakens.
But the threat of thunderstorms and more heavy rain remains in the forecast today and tonight and there could be more flooding because the ground is soaked.