Flash Flood in Honolulu County, Hawaii

Heavy rain began falling over the Koolau mountain range early in the morning and became anchored through most of the day. Widespread flooding occurred over much of the Koolau Mountains and eastern areas of Oahu. The following event summary includes a list of impacts that the flooding caused. A man in Kaneohe reported forty inches of water in his backyard with twenty inches of water in his house along the Keeahala Stream. The Kokokahi Gymnasium was reportedly flooded according to the broadcast media. Flood waters reportedly inundated homes in the neighborhoods bordered by the Likelike and Kamehameha Highways downstream of the Hoomaluhia Botanical Gardens. A business was flooded on Kamehameha Highway at the confluence of Opaeula Stream and Helemano Stream. The Likelike off ramp from the H3 Kaneohe-bound was closed due to flooding, and cars were flooded up to their windows. As a result, residents had to be rescued from their vehicles. A family on Kaneohe Bay Drive reported that rapid flood waters washed away the stairs leading up to their home. According to the City and County of Honolulu, a wastewater spill at the Ahuimanu Preliminary Treatment Facility occurred due to heavy rainfall and resulting inflow and infiltration into the wastewater system.

A cold upper level trough along with deep moisture and southeasterly winds allowed heavy rainfall to develop over the Koolau mountain range of Oahu, over Kauai, and over windward portions of Maui. On Oahu, the heavy rain developed and remained persistent for several hours, which led to flooding and flash flooding over the eastern and northern portions of the island. Particularly the Koolau Mountain Range was impacted. Portions of Maui and Kauai also experienced flash flooding.