UPDATE: Tuesday

The flood watch for Oahu, Kauai and Niihau has been canceled.

Forecasters said the low pressure system west to northwest of Hawaii that brought heavy showers to the western islands Monday will weaken over the next 24 hours.

Monday 8 p.m.

The flood advisory for the island of Kauai has been canceled.

Radar showed that the heavy rain over the island has diminished and flooding is no longer expected, the National Weather Service said.

Kauai, Niihau and Oahu remain under a flood watch through 6 a.m. Tuesday.

5:30 p.m.

The flood advisory for Oahu has been canceled but another for Kauai is in effect until 8:15 p.m.

“At 5:08 p.m., radar indicated heavy rain over Kauai, especially over interior and southeast portions of the island. Rain was falling at a rate of 1 to 2 inches per hour within the heaviest showers,” the National Weather Service’s latest advisory said.

The advisory covers Lihue, Kapaa, Kalaheo, Kekaha, Princeville, Kilauea, North Fork Wailua Trails, Alakai Swamp Trails, Lawai, Omao, Kokee State Park, Hanalei, Wailua Homesteads, Wainiha, Hanapepe, Na Pali State Park, Koloa, Haena, Waimea and Wailua.

Kauai, Niihau and Oahu remain under a flood watch through late tonight.

4 p.m.

A flood advisory is in effect for Oahu until 5:45 p.m. today due to excessive rainfall.

The National Weather Service in Honolulu reports minor flooding on roads, poor drainage areas and in streams. “Ponding of water in urban or other areas is occurring or is imminent,” forecasters report.

At 2:41 p.m., the radar indicated heavy rain falling at a rate of 1 to 2 inches per hour over Oahu mostly over urban Honolulu and the interior and leeward areas of the island.

Some locations that will experience flooding include Honolulu, Waipio, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, Waipahu, Aiea, Kunia, Halawa, Waiahole, Waikane, Schofield Barracks, Salt Lake, Kahaluu, Moanalua, Ahuimanu, Iroquois Point and Ewa Beach.

Meanwhile, a flood watch has been extended for Oahu, Kauai and Niihau through late tonight.

“The potential for locally heavy showers and a few thunderstorms will persist across the western end of the state, as an upper-level disturbance to the west produces unstable conditions,” according to the forecast.

EARLIER COVERAGE

Oahu, Kauai and Niihau are under a flood watch through this afternoon as a storm system passing the islands brings the threat of heavy rain and possible thunderstorms.

“The potential for locally heavy showers and a few thunderstorms will persist today, especially over the western end of the state, as an upper-level disturbance produces unstable conditions,” the National Weather Service said this morning.

During the flood watch, “flood prone roads and other low lying areas may be closed due to elevated runoff and overflowing streams. Urban areas may receive more significant flooding and property damage due to rapid runoff,” forecasters said.

The storm system doused Windward Oahu Sunday night, putting the area under a flash flood warning for several hours. The weather service said three vehicles were stranded in knee-deep water near Waikane Valley Road, Sunday night and Kamehameha Highway was closed in both directions near Waikane Valley Bridge due to flooding.

The storm system is expected to pass the islands by Tuesday, with showers primarily favoring windward areas through the rest of the week. Trade winds may become disrupted once again next weekend as a front approaches the region.