NWS calls rain, storms over Windward Oahu 'unusual phenomenon'

HONOLULU (HawaiiNewsNow) - Update 5:50 a.m.

The National Weather Service describes last night's severe weather event on the Windward Side to Hawaii News Now as 'an unusual phenomenon.'

A cell of rain showers sat right over the Waikane and Kahana Valley areas and quickly intensified into a thunderstorm, then dumped enough rain over the region that the Waikane Stream rose seven feet in about an hour.

Forecasters say it's fairly rare for a system like this one to remain in one place for so long.

Update 11:45 p.m.

Honolulu Police say Kamehameha Highway has been reopened in Waikane.

Update 11:30 p.m.

The National Weather Service has cancelled the flash flood warning that was posted for Windward Oahu. However, at last check, Kamehameha Highway was still closed in both directions in Waikane as the Waikane Stream washes across the roadway.

Update 10:45 p.m.

Heavy rains have diminished over Windward Oahu, but the National Weather Service reports that streams are still very high in Waikane, Waiahole and Kahana Valley. Kamehameha Highway remains closed at Waikane. The Flash Flood warning remains in effect.

Update 10 p.m.

Heavy showers have diminished in coverage in the since 9:30 p.m....though additional heavy rainfall is possible across Windward Oahu. Kamehameha highway remains closed in Waikane due to flooding...and streams in Kahana valley...Waikane...and Waiahole remain very high.

Update 9:30 p.m..

A nearly stationary thunderstorm over Windward Oahu continues to focus very heavy rainfall in the Kahana Valley and Waikane areas.

Recent radar estimates indicate rain rates in excess of 3 inches per hour in the heaviest downpours in Waikane Valley. The Waikane stream has risen over 7 feet in the past hour, and Department of Emergency Management has reported that Kamehameha Highway is closed in Waikane. This is a dangerous situation.

Locations in the warning include but are not limited to Punaluu. Kahana, Waikane, Waiahole, Laie and Hauula.

This warning may need to be extended beyond 11:30 p.m. if Flash Flooding persists.

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