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 tomorrow night.

The storm that began Dec. 11 caused flooding from Waialua to Windward O'ahu, 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.

Today, the city was wrapping up a cleanup project at Maunawili Stream at the end of Aloha Oe Drive.

"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 department's landscape and road maintenance sections have been clearing culverts and under bridges, said Department of Transportation spokeswoman Tammy Mori.

The National Weather Service said a cold front will reach the main Hawaiian Islands late tomorrow and move down the island chain to Maui through Sunday 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.