Heavy rain and thunderstorms caused flooding on Kauai and the severe weather is expected to reach Oahu and other islands Friday.

The National Weather Service issued a flash flood warning for Kauai until 7:15 a.m. Friday as rain, falling at rates of 2 to 3 inches an hour, pounded the island.

Kuhio Highway is closed near the Hanalei bridge and the Red Cross opened Hanalei Elementary School as an emergency shelter.

Water levels at the north and south forks of the Wailua River are rapidly rising and may produce flash flooding in the Wailua area. Kauai officials said.

Water covering Kuamoo Road from the Wailua River forced tourists to evacuate a vehicle early this morning, a county official told the National Weather Service.

Flooding was also reported in the Waimea Theater building.

In the 24-hour period ending at 5 a.m., more than 8.7 inches of rain fell at the North Wailua Ditch; 6.7 inches was recorded at Mount Waialeale and nearly 5.4 inches fell at the Princeville Airport.

Earlier Thursday night, forecasters issued then canceled a flood advisory for the Big Island. The advisory was posted at 7:18 p.m. and canceled at 10:15 p.m. for Kapaau, Mahukona and Kukuihaele.

Forecasters canceled a special marine warning which was issued because of a strong thunderstorm with gusty winds, lightning and hail west and northwest of Kauai.

A weather system with cold air in the upper atmosphere is moving across the state from the west and colliding with warm, moist tropical air from the south, creating the potential for severe weather, said Jon Jelsema, a meteorologist with the Honolulu office of the National Weather Service.

Hail could form, along with strong wind downdrafts and thunderstorms. The system could also bring snow to Mauna Kea and Mauna Loa Friday afternoon through Saturday night.

Jelsema said the greatest potential for severe weather on Oahu will be Friday afternoon when daytime heating is at its peak.

The forecast for Good Friday calls for mostly cloudy and hazy weather with showers and thunderstorms likely on Kauai. Scattered showers and isolated thunderstorms are possible on Oahu Friday morning and likely in the afternoon, the weather service said. The Big Island should see scattered showers in the morning and showers and thunderstorms likely in the afternoon.

The chance of rain on Oahu will linger through Saturday.

But there could be some good news for those bothered by heavy vog.

Northeast winds behind the weather system, combined with rains “knocking some of the vog out of the air should mean clearer air on Saturday,” Jelsema said.

Most of the rain should clear Oahu by Easter Sunday.

But relief could be brief.

Another weather system could bring more showers, although not as heavy, Monday and Tuesday.

On Thursday afternoon, the National Weather Service issued then canceled a flood advisory for Oahu prompted by heavy rain over the Waianae and Koolau mountains.

Forecasters said rain was falling on Oahu this afternoon at rates of 1 to 2 inches per hour.

The flood advisory was posted just before 2 p.m. and ended at 4:45 p.m.