UPDATE: 7:50 p.m.

The National Weather Service has extended a flood advisory for Oahu to 10:30 p.m. tonight.

Rain is continuing to fall near Waimanalo and Hawaii Kai, with rainfall rates of about 1 to 3 inches per hour as of 7:30 p.m., the weather service said.

Locations in the advisory include, but are not limited to: Honolulu, Waimanalo, Mililani, Marine Corps Base Hawaii in Kaneohe, Hawaii Kai, Palolo, Kahaluu, Ahuimanu, Salt Lake, Kailua, Manoa, and Maunawili.

A flash flood watch is also in effect for all islands, through late tonight for Kauai and Niihau and through Saturday night for Kahoolawe, Lanai, Maui, Molokai, Oahu, and the Big Island.

The rain is being caused by moist air spreading over the islands and an unstable atmosphere.

6:00 p.m.

A flash flood warning has been replaced by a flood advisory for Oahu.

The National Weather Service said radar showed heavy rain falling at a rate of about 1 1/2 inches per hour over central Oahu near Whitmore Village at about 5:45 p.m.

Locations in the advisory include Honolulu, Mililani, Wahiawa, Waialua, Schofield Barracks, Salt Lake, Manoa, Wheeler Field, Kunia, Kapolei, Waikele, and Kalihi.

Meanwhile, the weather service is warning about a thunderstorm capable of producing waterspouts about 8 nautical miles west of Ilio Point on northwest Molokai. Waterspouts with wind gusts of 34 knots or greater may form in the Kaiwa Channel and Oahu windward waters. The waterspout warning is in effect until 7:45 p.m.

A flash flood watch also remained in effect for Kahoolawe, Lanai, Maui, Molokai, Oahu, and Hawaii island through Saturday morning, the weather service said.

Kauai and Niihau are under a flash flood watch through late tonight.

The weather service said a moist and unstable atmosphere is producing flooding rains. Winds are light so heavy showers may become stationary.

4:16 p.m.

The National Weather Service has issued a flash flood warning for Oahu until 7 p.m.

At 4:05 p.m., radar showed heavy rain near Waimalu, falling at a rate of about 2 inches an hour, the weather service said.

“Flash flooding is expected to begin shortly,” the weather service said.

Locations in the warning include Waipio, Waipahu, Pearl City and Aiea.

3:35 p.m.

A flood advisory for the eastern side of the Big Island has been issued until 6:15 p.m.

“At 3:07 p.m., radar indicated heavy rain near Hilo. Rain was falling at a rate of one and one half inches per hour,” according to the National Weather Service in Honolulu.

The advisory includes Hilo, Hawaiian Acres, Orchidlands Estates, Glenwood, Pepeekeo, Keaau, Hawaii Volcanoes National Park, Volcano, Laupahoehoe, Ookala, Hawaiian Paradise Park and Pahoa.

The entire state remains under a flash flood watch.

2:50 p.m.

Much of Maui is under a flood advisory until 5:30 p.m. today, according to the National Weather Service.

“At 2:31 p.m., radar indicated heavy rain along the north shore of Maui near Haiku,” the advisory said. “Rain was falling at a rate of one and a half inches per hour.”

The advisory includes Kahului, Kahakuloa, Puunene, Haliimaile, Pauwela, Waikapu, Kipahulu, Paia, Makawao, Wailuku, Waiehu and Haiku-Pauwela.

2:15 p.m.

The National Weather Service in Honolulu has issued a flood advisory for portions of the east side of Hawaii island until 4:30 p.m. today.

“At 1:26 p.m., radar indicated heavy rain near Hawaiian Acres,” the flood advisory said. “Rain was falling at a rate of 1 and a half inches per hour.”

The advisory includes Volcano, Hawaiian Acres, Orchidlands Estates, Hawaiian Paradise Park, Glenwood, Pahoa, Hawaii Volcanoes National Park and Mountain View.

PREVIOUS COVERAGE

A flash flood watch is in effect for Kauai and Niihau through tonight and the rest of the state through Saturday evening as a storm system west of the islands moves eastward.

Forecasters with the National Weather Service in Honolulu said this morning that the system “will move from west to east across the area today through Saturday, bringing the potential for heavy rainfall and thunderstorms to the island chain.”

The potential for showers and thunderstorms is most likely this afternoon and evening for Kauai and Niihau, forecasters said. For Oahu to the Big Island, the threat continues until Saturday evening with “the most likely time frame for the heavy rainfall and potential flooding appears to be during the afternoon and evening hours both today and Saturday,” according to the weather service’s flash flood watch.

A watch means that conditions are favorable for flash flooding, which can be life-threatening, they warned, adding “do not cross fast-flowing water in your vehicle or on foot.”

”Remnant moisture” from the system “may combine to bring a wet and showery pattern to windward areas Monday through the middle of next week, with showers reaching leeward areas at times as well,” forecasters said.