State and city crews are still removing debris left from flooding that hit O'ahu in mid-December, but officials believe they're prepared for the quick-moving storm that's expected to drench the Islands starting tonight.

December's storm caused flooding from Waialua to Windward Oahu, Waipahu to the Wai'anae Coast and left behind tons of debris, but the worst of it under city care has been removed, said city spokesman Bill Brennan.

Yesterday, the city was wrapping up a clean-up project at Palapu Stream at the end of Aloha 'Oe Drive in Maunawili.

"There is still work to be done by the city crews to clear debris from city drainage ways, and work is ongoing," he said.

All week, state crews have been fixing potholes to mitigate any effects from the expected rain, and personnel from the Transportation Department's landscape and road maintenance sections have been clearing culverts and under bridges, said spokeswoman Tammy Mori.

The National Weather Service said a cold front will reach the main Hawaiian Islands tonight and move down the island chain to Maui through tomorrow before weakening. Heavy showers and possible thunderstorms may occur.

"We expect rainfall across any one particular area will be limited by the rather rapid frontal speed, minimizing the threat of significant flooding," the weather service said.

In the past, clogged streams have been blamed for severe flooding that caused millions of dollars in damage, including a 2004 storm that sent Manoa Stream surging through homes and Hamilton Library at the University of Hawai'i.

On the Leeward side, city streams were inspected and have been cleared of debris, Brennan said.

"We are checking with the rural district on the status but I believe the city streams have been cleared and are in good shape," Brennan wrote in an e-mail.

Whenever a significant storm threatens, the state has a standard response, Mori said.

"Equipment is positioned around the island, gassed up and ready to go," Mori said. "Crews are on standby."

Although the state works to keep its culverts and bridges cleared year-round, a contractor was hired to help with the effort after the Dec. 11 storm, Mori said.

She said Kunia Road, closed since the December storm, should reopen next week and that the state had shored up the road with 4,000 tons of material.

Brennan said the city is also clearing debris from beaches in the Kiapoko Ditch area in Waialua, Hau'ula and La'ie, and from Makaha beaches.

Some privately owned streams and ditches that were affected by the storm have not been cleared, but the National Guard, state Civil Defense and the city Department of Emergency Management are working together to coordinate debris removal in those areas, he said.

State and city road crews are also removing debris from beneath bridges, sharing equipment and manpower, Brennan said.

Brennan said according to city law, stream owners are responsible for maintaining their stream area and keeping it clear of obstructions or blockages that could impede stream flow.