Maui County and Oahu residents can expect storm activity to increase overnight and into Friday, the city Department of Emergency Management said based on an advisory from the National Weather Service.

Heavy rainfall, strong winds, hail and frequent periods of lightning are forecast with the storm being at its peak sometime Friday afternoon, the city said.

Gov. Neil Abercrombie today signed a supplemental disaster proclamation to extend emergency functions for Oahu and Kauai, in response to the expected heavy rains and flooding tonight through the weekend.

Lydgate Park and the Wailua Golf Course will be closed again Friday, Kauai County said. Weather permitting, the golf course is expected to open to walk-in golfers only on Saturday. Officials will reassess both facilities Friday.

The intense bands of showers are expected to move quickly over Oahu as the storm system moves west over the state through Saturday.

Maui, Molokai, Lanai, Oahu and Kauai are under a flash flood watch until 6 a.m. Saturday.

Rain fell on Maui at a rate of 3.5 to 4 inches an hour, near Waiehu, about seven miles northwest of Kahului this afternoon.

Forecasters say the weather system near Maui will move west and bring the chance of heavy showers and thunderstorms to Maui this afternoon and to Kauai by tonight.

Since the ground is already saturated from earlier rains, forecasters say any additional rainfall could produce flash floods and more landslides.

Heavy rains created flooding and debris problems on Highway 450 on Molokai overnight. Police said the highway was impassable at several locations including the Kaunakakai gulch, just west of Kaunakakai. The highway was also closed over the Kawela gulch, the Kamalo gulch, about 2 miles east of Kamalo and at mile marker 14.

Molokai firefighters responded to a flooded home on Kamehameha V Highway in east Molokai at about 12:30 a.m. and help residents secure their belongings after a couple woke to find water almost up to their knees, a Maui County spokesman said.

The Department of Education said Kilohana School on Molokai was closed today because of the weather and road conditions.

Windward Maui from Hana to Kahakuloa also got heavy rains overnight.

The storm moved over the channel between Maui and Hawaii island later in the morning, where hail and strong winds were reported.

The forecast today calls for mostly cloudy skies with windward and mauka areas, with some showers blown over to leeward sides by strong tradewinds of 15 to 30 mph, with gusts of 40 mph. Rains are forecast to increase tonight. Thunderstorms are possible after midnight, forecasters said.

Conditions should start improving on Sunday, although rain is still in the forecast.

Kauai County officials are asking real property owners who sustained flood damage to file a claim for remission of taxes on their real property. To be eligible, the claim must be based on the direct result of flood waters overflowing the banks or walls of a river or stream, not from flooding that may be due to inadequate drainage or areas prone to ponding.