Update 3:56 p.m.
The National Weather Service canceled a flash flood watch for Oahu at about 3:45 p.m.
A flash flood watch remained in effect for Maui, Molokai and Lanai through tonight, as officials noted that a strong cold front is expected to bring heavy showers and thunderstorms to Maui County.
Update 3:10 p.m.
A flash flood watch is in effect through the afternoon for Oahu, Kaui and Niihau, and into the night for Maui County.
The National Weather Service canceled an earlier flash flood warning for Oahu that was initially extended to 4:30 p.m.
Update 1:30 p.m.
The National Weather Service extended a flash flood warning for Oahu until 4:30 p.m. today.
At 1:24 p.m., Doppler radar indicated heavy rainfall falling at a rate of 2 to 3 inches per hour and thunderstorms over Honolulu, the southeastern Koolau mountains and the windward coast of Oahu.
The Waikane and Punaluu streams have reached the flood stage and will cause flash flooding along Kamehameha Highway, weather officials said.
Locations of the warning include but aren’t limited to Honolulu, Maunawili, Kailua, Waikane, Hawaii Kai, Salt Lake, Kaneohe, Waiahole, Moanalua, Halawa, Kaneohe Marine Base and Waimanalo.
Update 1 p.m.
Honolulu police closed Diamond Head Road in both directions between Diamond Head Lookout and Coconut Avenue due to fallen debris.
Update 10:30 a.m.
The National Weather Service at 10:28 a.m. issued a flash flood warning for Oahu until 1:30 p.m. which may need to be extended if heavy rain continues.
Locations of the warning include but aren’t limited to Honolulu, Maunawili, Kailua, Waikane, Mililani, Hawaii Kai, Salt Lake, Kaneohe, Waiahole, Moanalua, Halawa and Kaneohe Marine Base.
Doppler radar at 10:24 a.m. showed thunderstorms with heavy rain falling at a rate of 2 to 3 inches per hour over Honolulu and along the south shore of Oahu. The heavy rain also extends across the windward side of the island from Hauula to Makapuu Point.
A flash flood warning means that flooding is imminent or occurring in streams and low lying areas.
Weather officials are urging the public to move to higher ground immediately.
Update 8:23 a.m.
The National Weather Service at 7:56 a.m. issued a special marine warning for the Kaiwi Channel, windward and leeward waters of Oahu and windward waters of Maui County until 8:45 a.m.
Radar at 7: 56 a.m. showed strong thunderstorms capable of 39 mph winds about 7 nautical miles southwest of Honolulu Harbor and 7 nautical miles northwest of Ilio Point on Molokai, moving northeast at 28 mph.
Mariners can expect gusty winds, high waves, lightning and heavy rain.
Weather officials are urging boaters to find safe harbor immediately.
Update 7:50 a.m.
The National Weather Service at 7:36 a.m. extended the flash flood advisory for Oahu until 11 a.m. and for Kauai until 10:45 a.m.
Doppler radar at 7:29 a.m. showed increasing showers over west and south shores of Oahu, falling at a rate of 2 to 3 inches per hour, but moving quickly.
On Kauai, radar indicated decreased rainfall across the entire island, but light to moderate rain will continue to fall throughout the morning.
Weather officials are urging the public to avoid streams, drainage ditches, and low-lying areas prone to flooding and not to cross fast flowing or rising water.
Update 6:23 a.m.
A strong thunderstorm will roll through the island of Oahu today, according to the National Weather Service.
Weather officials at 5:52 a.m. spotted the strong thunderstorm from Wahiawa to Waipio moving northeast at 25 mph with the possibility of winds reaching an excess of 40 mph.
Locations affected include Kunia, Schofield Barracks, Pearl City, Waikele, Waipahu, Mililani, Wahiawa, Wheeler Field, Kapolei, Makakilo, Waiahole, Kahaluu, Waikane, Ewa Beach, Whitmore Village, Helemano Housing and Kahana Valley State Park.
The National Weather Service also issued a flash flood advisory for the island of Oahu until 8 a.m. and for the island of Kauai until 7:45 a.m. The advisory may extend if heavy rain persists.
Doppler radar at 5:02 a.m. showed a large area of heavy rain moving over Oahu from the west, with rainfall ranging from 1 to 2 inches per hour.
Locations of the advisory include Honolulu, Kailua, Waikane, Mililani, Waialua, Hawaii Kai, Salt Lake, Kaneohe, Waiahole, Moanalua and Halawa.
On Kauai, radar at 4:29 a.m. showed heavy showers moving across the island at a rate of 1 to 2 inches per hour. Locations of the advisory include Lihue, Kapaa, Kalaheo, Kekaha, Princeville, Kilauea, Wailua Homesteads, Barking Sands, Waimea, Moloaa, Anahola and Kokee State Park.
A flash flood watch is still in effect for Niihau and Kauai through this afternoon, and for Maui County from 8 a.m. through late tonight.
The National Weather Service in Honolulu has issued a flash flood watch for Niihau, Kauai and Oahu through Saturday.
“A cold front and passing upper trough will approach from the northwest tonight and bring the potential for locally heavy rain bands and thunderstorms across the western half of the state after midnight tonight and through the day Saturday,” forecasters said.
Kauai is expected to get heavy rain after midnight followed by Oahu Saturday morning, they said. “The front is expected to weaken as it reaches Maui County late in the day Saturday, but there is a chance this flash flood watch could extend into Maui County Saturday evening.”
Heavy downpours could cause streams to overflow, leading to life-threatening flash flooding, forecasters said.
Beyond Saturday, the forecast calls for the stormy conditions to dissipate on Sunday, with possible showers over the central islands.
Forecasters predict another cold front could bring showers Tuesday through Wednesday to the western and central part of the state.