Rain pounds Oahu, triggering landslides, flooding ahead of kona storm

HONOLULU (CN) — Unrelenting downpours have soaked parts of Oahu, submerging roads, stranding vehicles and triggering a landslide as the island braces for a kona storm.

The National Oceanic and Atmospheric Administration has issued a flood watch from 6 a.m. Wednesday until 8 p.m. Friday for the city and county of Honolulu.

By Monday, relentless rains had snarled traffic already: A landslide forced the closure of one lane on the Kailua side of the Pali Highway tunnel and authorities told drivers to expect delays due to the landslide and flooding on the roadway. On Oahu's Windward side, the H-3 Freeway was flooded where it merges with Kamehameha Highway.

Kona storms, a type of seasonal cyclone in the Hawaiian Islands, get their name from the winds in the westerly "kona" direction that form them — distinguishing them from the trade winds blowing in from the northeast that dominate Hawaii.

A familiar phenomenon between October and April, kona storms tap into the abundant moisture from the warm tropical waters surrounding Hawaii. This moisture then interacts with the islands' topography, often resulting in heavy downpours that can drench the region.

In addition, a series of long-period south swells will affect the islands starting Tuesday and continuing into the weekend. Surf along south-facing shores is expected to remain well above summertime averages during this extended south swell event.

Residents and visitors should exercise caution, avoid unnecessary travel and stay tuned to local weather updates.

National Weather Service radars showed heavy rains continuing to fall Monday afternoon over Windward Oahu. Some areas of Oahu saw 8 inches of rain accumulate in under 6 hours.

Local weather teams and the NWS issued alerts for Windward Oahu on Monday due to the persistent heavy rains.

The alerts came after a wet weekend for much of the state. Showers were particularly heavy at times along the eastern slopes of Oahu and Maui, as well as the southeastern slopes of the Big Island.

Separately, Kamehameha Highway at Waikane Valley was also impassable due to heavy flooding. Honolulu firefighters rescued 15 people whose vehicles were stranded or submerged in the area.

A downpour of water and major leaks were also reported at Ala Moana Center near the Jungle Fun attraction. The threat of additional rainfall looms as an unstable weather pattern approaches the islands.

South winds associated with an approaching kona low are expected to bring deep tropical moisture to all islands starting on Wednesday, along with heavy rain, thunderstorms and strong gusty winds, increasing the risk of flooding statewide.