Flash Flood in Honolulu County, Hawaii

At approximately 800 pm HST, a mesoscale convective system was observed moving over the Kauai Channel towards Oahu. At around 900 pm HST, this mesoscale convective system moved over the west side of Oahu, then the Northern half of Oahu, and began to deliver large amounts of heavy rain. Due to the slow moving nature of this weather system, enormous rain amounts accumulated in a very short time frame. At approximately 1000 pm HST, stream levels rose above flood thresholds and reservoirs filled up. From 1100 pm HST to 200 AM HST, a massive flood wave surged through the North Shore. Multiple roads became impassable across Northern Oahu, Haleiwa became completely cut off, and multiple homes and many cars got swept away in flood waters. Many homes and cars that were not washed away were heavily damaged beyond use or habitation. Businesses were also flooded, and an ambulance was reportedly lost due to the rising flood waters. With the help of police officers, the crew escaped the ambulance through the side window. There were over 200 rescues by first responders and residents, these rescues included rescues from police, fire, national guard, and lifeguards. 10 people were taken to the ER with non critical hypothermia due to prolonged exposure to the flood waters. Much of the destruction and rescues were reported in Waialua and Haleiwa. However the damage spread to the northeast section of Oahu where multiple homes were inundated with flood waters. Over 171 million dollars in damages were reported across Oahu's public schools from the Department of Education and officials put the total costs of the storm island wide above 1 billion dollars .

A cutoff low moved in from the northwest and pulled deep tropical moisture from the south over the Hawaiian islands. This led to the development of prolonged slow moving heavy rain and thunderstorms. The heavy rain and thunderstorms caused catastrophic flooding over Oahu's North Shore and Manoa Valley.