A flash flood warning is in effect for parts of Oahu

HONOLULU (HawaiiNewsNow) – The National Weather Service has issued a flood warning for all islands through Sunday afternoon.

By Sunday, an upper-level disturbance will spread across the state, creating a very unstable atmosphere that can easily trigger heavy showers and thunderstorms, especially over windward areas.

For Oahu, the flash flood warning has been extended until 1:15 p.m

At 10:16 a.m., radar indicated heavy rain over central and eastern Oahu, including communities in urban Honolulu. The rain fell at a rate of 1.5 to 3 inches per hour and was particularly heavy from Halawa to near Pearl City.

Rain flooded several areas around Oahu, from Manoa to Halawa, Saturday morning.

More than 7.5 inches of rain fell in Maunawili between 3 a.m. and 9 a.m., according to the National Weather Service. Manoa recorded just over 5 inches of rain during the same period, with most of it falling after 6 a.m

Periods of heavy rainfall over already saturated ground can quickly lead to runoff and flash flooding. Water levels in already elevated streams could rise quickly with additional heavy rain.

The Ala Wai Canal was one of many waterways filled with runoff and debris Saturday morning.

Water could flood some roads, including Kamehameha Highway. Flash flooding is likely to continue.

Locations that will experience flash flooding include Honolulu, Waipio, Waiahole, Waikane, Pearl City, Aiea, Kahaluu, Halawa, Ahuimanu, Mililani, Waikele, Moanalua, Salt Lake, Wahiawa, Kaaawa, Waipahu, Wheeler Field, Kunia, Punaluu and Kalihi.

A flash flood warning was previously in effect for the island of Maui. Windward East Maui recorded the most precipitation, with West Wailuaiki's rain gauge recording 4.8 inches during the six-hour period ending at 9 a.m. Hana recorded just under 10 inches.

The Hawaii News Now weather team has marked Saturday and Sunday as first alert weather days for all islands.

The combination of heavy rain and high surf has also led to the closure of the Bayfront Highway in Hilo as large waves washed debris across the roadway.

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