HAUULA, Hawaii -- Forecasters at the National Weather Service issued a flash flood watch for Kauai, Oahu and Niihau on Friday.

Oahu was downgraded from a flash flood warning. However, forecasters said there is a threat of more rain southwest of Oahu that could go ashore. The grounds are already saturated with rains from the past few days.

Mudslides, rushing water and other problems kept crews busy and Kamehameha Highway closed in several spots throughout day and night on Thursday.

Forecasters have kept Oahu under a flash flood warning until 12:30 p.m. Friday. The National Weather Service also placed Kauai under a flash flood watch.

Early Friday morning, a waterfall pounded Pali Highway on the Kailua-bound side after the second tunnel.

Authorities closed the Pali Highway on the Kailua-bound side is closed by Waokanaka Street because of that waterfall. Drivers were forced to use alternate routes such as Likelike Highway or the H-3 Freeway.

The Red Cross opened an evacuation shelter in Hauula Thursday afternoon at the Hauula Chapel of the Church of Jesus Christ of Latter-Day Saints. The address there is 54-208 Hauula Homestead Road. Another shelter opened at the Brigham Young University Hawaii campus in Laie.

Officials suggest taking extra clothes, bedding, food and water, and any medications needed.

Pets are not allowed. The shelter will be open indefinitely.

The heavy rain shut down several schools on Thursday. Those schools will remain closed on Friday, Department of Education officials said.

Schools Closed Friday:

Kahuku Elementary School

Kahuku Intermediate and High School

Kaaawa Elementary School

Hauula Elementary School

Laie Elementary School

The DOE is also considering closing Sunset Elementary School, but it was not sure Thursday afternoon.

Pooling, flooding and water runoff are problems at each of the campuses. A DOE spokesman said there are no reports of any serious damage at the schools.

The road closures and dangerous conditions lasted through the day and into the evening. Officials warned motorists to avoid the area.

"We're advising everyone who lives on that side to stay away and make arrangements to stay elsewhere this evening if at all possible," Oahu Civil Defense administrator William Balfour said. "If you absolutely have to get to that side, be prepared for road closures and extended periods of waiting."

Cars made their way through all the standing water along parts of Kamehameha Highway. However, the few allowed through soon came to another halt.

All morning long on the windward side, officials kept closing Kamehameha Highway sporadically. As soon as cars got past one point, they would have to come to a stop while more debris was cleared from the roadway up ahead. Some motorists had been trying to get home since before 7 a.m.

"Well, we're going to see how long it takes. We don't want to be here all day," Kaneohe resident Briana Pocock said.

After already overworked crews were able to clear a large tree that blocked the highway, the traffic started moving again.

"You know, our crews have been dealing with everything from mudslides to, you know, this huge tree that just fell down on the highway," Department of Transportation spokesman Scott Ishikawa said.