UPDATE: 6 p.m.

A flood advisory for Oahu has been canceled, but a flash flood watch will remain in effect through 6 a.m. Sunday for Kauai, Niihau and Oahu.

4:30 p.m.

A flood advisory is in effect for Oahu until 7:15 p.m. tonight.

Radar this afternoon indicated heavy rain across portions of Windward Oahu and across the Koolau mountains from Kualoa Ranch to Waimanalo. Rain was falling at a rate of 1 to 2 inches per hour, according to the National Weather Service.

The National Weather Service has canceled the flash flood warning for Kauai, but a flash flood watch will remain in effect through 6 a.m. Sunday. A flash flood watch is also in effect for Niihau and Oahu.

Kauai County reported that Kuhio Highway near Hanalei Bridge remains closed in both directions. The south end of Kapaa Bypass Road is also closed. All other roads have been opened.

The county reported that 20 residents have taken shelter at Kapaa Middle School.

A county news release said that heavy rain led to an estimated 20,000-gallon wastewater spill at the Wailua Wastewater Treatment Plant this morning. The wastewater flowed into Lydgate Park and was contained around 9 a.m. Signs have been posted to inform the public to stay out of the affected area.

The traffic signal at Rice Street at Umi Street is currently under repair after being damaged from this morning’s weather. The signal facing Umi Street and Hoolako Street is flashing red, which means it is functioning as a stop sign.

The NWS said an upper low will trigger heavy rainfall and potential thunderstorms in parts of the state through Sunday. Trade winds will focus rain on windward and mauka areas. By Sunday night, drier and more typical trade winds should return to the islands.

10:03 a.m.

The Kauai Police and Fire Departments earlier today evacuated residents out of severely flooded areas, including Wailua River View Estates and lower Haleilio Road.

Police also closed multiple roads today due to heavy ponding and flooding along the roadways and urged motorists to avoid driving through the area “unless absolutely necessary.” Police reported opening Kuamoo Road, Wailua Bridge and Rice Street just before 10 a.m. today.

“Kuhio Highway by the Coconut Marketplace is still flooded. Traffic is being redirected but it’s still very slow going in the area and there is heavy pounding on the roadways. It’s not advisable to drive through at this time unless absolutely necessary,” according to a Facebook post.

The following roads remain closed:

>> Kuhio Highway at Papaloa Road in the vicinity of the Coconut Marketplace. Police are attempting to open the gate at mall to redirect traffic;

>>Northbound lane of Kapaa Bypass Road;

>> Southbound stretch of the Kapaa Bypass Road from the roundabout;

>> Road to the Kauai Beach Resort and Villas;

>> South end of the Kapaa Bypass Road is completely flooded and impassable;

>> Haleilio Road in Wailua;

>> Kuamoo Road in the vicinity of Coco Palms;

>> Keapana Road in Kapaa;

>> Kamalu Road in Wailua;

>> Weliweli Road in Koloa.

“Please don’t drive if you don’t have to,” the Facebook post said. “For updates on road conditions and closures, please call 241-1725. Please do not call 911 unless you have an emergency.”

Meanwhile, the National Weather Service in Honolulu has issued a flood advisory for Oahu until 12:15 p.m.

At 9:09 a.m., the radar showed heavy showers falling at rates of up to 2 inches per hour along the central and northern portions of the Koolau Mountains.

“Additional heavy rainfall is expected through the morning, and since grounds are already saturated, rapid rises in streams are possible along windward Oahu and the north shore,” the advisory said.

Locations in the advisory include but are not limited to the following areas:

>> Ahuimanu

>> Maunawili

>> Kaneohe

>> Kahuku

>> Waikane

>> Laie

>> Waiahole

>> Kahaluu

>> Punaluu

>> Whitmore Village

>> Heeia

>> Haleiwa

>> Kahana Valley State Park

The advisory may be extended if heavy rain persists.

9:44 a.m.

The flash flood warning has been extended for Kauai County until 12:30 p.m.

At 9:17 a.m., the radar indicated diminished rainfall across the island, but Kauai Civil Defense reported that the bridges across the Hanalei and Wailua rivers remain closed as a result of increasing flooding or debris floating in dams.

Forecasters warned of flooding in drainages, streams, rivers, roads, properties and other low-lying areas. Landslides are possible in steep terrain and closures of public roads are possible in some areas, according to the statement.

The warning may be extended if heavy rain showers persist.

7:43 a.m.

The National Weather Service in Honolulu today has issued a flash flood warning for Kauai County, and a flash flood watch for Oahu, Kauai and Niihau.

At 7:31 a.m. today, the radar showed heavy rainfall at a rate of 2 to 4 inches per hour falling across the northern through the eastern portion of Kauai. The warning expires 9:30 a.m. today.

“Heavy rainfall also continues within a thunderstorm just southeast of Lihue. Bridges across the Hanalei and Wailua rivers remain closed either to high water or to debris dams,” according to the warning for Kauai County.

Meanwhile, forecasters said heavy rain and thunderstorms will be possible on Oahu through tonight, so the watch will remain in effect until late tonight. The watch expires 6 a.m. Sunday.

“An upper low will approach from the northwest will bring unstable atmospheric conditions across the western end of the state,” the advisory said.

Conditions are favorable for flash flooding, which is life threatening, the advisory said.

“Do not cross fast flowing water in your vehicle or on foot. Monitor later forecasts and be prepared to take action if a Flash Flood Warning is issued. If you experience heavy rain or rising water, head to higher ground immediately,” according to the advisory.