The National Weather Service has issued a flash flood warning for Oahu until 3 a.m. Sunday.

At 12:52 a.m., radar indicated extremely heavy downpours and thunderstorms have redeveloped across the windward sections of Oahu during the past hour, and rainfall rates of 2 to 4 inches per hour were occurring. Stream levels remain very high and many streams are rising further. Additional flash flooding is expected. Kamehameha Highway remains closed at Waikane Stream.

Runoff from earlier heavy rainfall will continue to cause flash flooding during the next few hours.

Locations in the warning include but are not limited to Ahuimanu, Hauula, Waimanalo, Kailua, Maunawili, Kaneohe, Waikane, Kaneohe Marine Base, Laie, Waiahole, Kahaluu and Punaluu.

Heavy rains are expected across the island chain as a strong upper-level trough moves over the state.

The approaching weather system combined with the westward exit of a weak surface trough near Maui resulted in moist, unstable conditions, prompting the National Weather Service to issue a flash flood watch for all islands through Monday.

Heavy showers and thunderstorms hit the eastern half of the state today. On Hawaii island, the heaviest rainfall was detected in the Pahoa area, where gauges recorded 4.12 inches of rain in the 24-hour period ending today at 5:45 p.m. Heavy rainfall also was recorded at Pali (3.2 inches) and Kapapala Ranch (2.46).

A winter weather advisory is also in effect for Hawaii island summits above 10,500 feet, effective through Monday.

According to the NWS, snow accumulations of 2 to 4 inches, with localized amounts up to 6 inches, are expected.