Heavy rain breaks record on Kauai and likely to continue

Heavy rain throughout Hawaii on Monday — including record-breaking rainfall on Kauai — triggered a statewide flash flood watch that will last through this afternoon as road closures, brown-water advisories and power outages hit parts of the state.

The “wet, unsettled, and locally breezy weather” could possibly persist through Wednesday, the National Weather Service reported, thanks to a Kona low that sits about 600 miles west of the islands. The highest risk of flooding and strong thunderstorms is at the western end of Hawaii.

NWS reported that a record 3.55 inches of rain fell in Lihue on Monday. The record prior to Monday was set over 50 years ago, in 1968, when 3.51 inches of rain fell in Lihue in one day.

Preliminary reports for 24-hour rainfall showed that nearly 13 inches of rain fell on Mount Waialeale.

A “convergence band” — a band of clouds that can produce large amounts of rain — led to active, fast-moving and heavy showers Monday on Kauai and Oahu. Heavy showers and thunderstorms will hit the islands from the south as weather conditions continue. NWS said the thunderstorms could be capable of producing “damaging wind gusts” as the Kona low’s main convergence band approaches late today.

There is less of a threat in Maui County and on Hawaii island, but rain would likely favor southeast slopes, NWS said.

The Kona low will slowly move north Thursday and Friday, gradually reducing the chance of heavy rain from east to west. Easterly tradewinds are expected throughout the state over the weekend.

On Monday afternoon a brown-water advisory was issued for Oahu beaches on the North Shore and Windward side and for Kauai.

Heavy rain resulted in stormwater runoff entering coastal waters. The public is advised to stay out of floodwaters and stormwater runoff due to possible overflowing cesspools, sewers, manholes, pesticides, animal fecal matter, dead animals, pathogens, chemicals and associated flood debris.

The Department of Health said not all coastal areas may be affected, but to stay out if the water is brown.

On Monday afternoon a flash flood warning was canceled for Kauai after the record-breaking rainfall. The Kauai Emergency Management Agency reported that Kuhio Highway was still closed at Hanalei Bridge.

Officials warned of flooding in drains, streams, rivers, roads and other low-lying areas. Landslides are possible in steep terrain.

At 11:45 a.m. the Hanalei River gauge showed a rapid rise in water level, according to the NWS.

The most intense rainfall on Oahu was observed over Hawaii Kai and Honolulu at rates of 1 to 2 inches per hour, although preliminary reports showed the greatest 24-hour rainfall in the Mililani area, Waianae, upper Nuuanu and parts of Kaneohe.

Officials warn the public to stay away from streams, drainage ditches and low- lying areas prone to flooding. Rainfall and runoff also will cause hazardous driving conditions due to ponding, reduced visibility and poor braking action. Individuals should not cross fast-flowing or rising water in a vehicle or on foot.

A high-surf advisory has been issued for the south and east shores of Niihau and Kauai due to a combination of strong southeast winds and large seas. Surf is expected to rise to 5 to 8 feet on those shores through this afternoon.

Officials warn of strong breaking waves and rip currents, making swimming difficult and dangerous. Beachgoers should heed all advice from ocean safety officials.

A small-craft advisory also remains in place for most Hawaii waters — from northwestern Kauai to the windward Big Island — through 6 p.m. today.

About 3,000 Hawaiian Electric customers lost power in Ewa Beach on Monday night. Hawaiian Electric had restored power to about 1,600 customers in the Ewa Beach and Kapolei area who lost power earlier in the day.

Reporter Mark Ladao contributed to this report.