The threat of thunderstorms and flooding on Oahu and Kauai has mostly passed for today. But forecasters say it could still rain on a motorcade when world leaders, including President Obama, arrive in Honolulu this week.

The National Weather Service lifted a flash flood watch for Kauai County and Oahu this morning after heavy rains moved past Kauai and a weather system in the upper atmosphere weakened.

But the National Weather Service says the weakened weather system is sticking around and could still bring rain to the islands when 20,000 government and business leaders and journalists arrive in Honolulu for the Asia-Pacific Economic Cooperation Forum meetings this week.

"We’re still going to get bands of showers which will come through from time to time and some of the downpours could be heavy," said Robert Ballard, a forecaster with the National Weather Service.

Forecasters do not expect the heavy rain and thundershowers which hit Oahu and Kauai last week. But he said the unsettled weather conditions make it difficult to predict exactly where, when and how heavy the rain will be this week.

Ballard said it’s too early to forecast what the weather will be like for the weekend, when several outdoor events are scheduled for the 21 world leaders in town for APEC, including the photo of the leaders in aloha attire Sunday afternoon.

Oahu should get a break from the cloudy skies and rain, although there is still a slight chance of heavy rain tonight.

The rain fell hard on Kauai early this morning, but skies cleared after sunrise.

At 4 a.m. this morning, radar showed heavy showers moving quickly across Kauai with rainfall rates between 1 and 2 inches per hour resulting in nuisance flooding. Forecasters issued a flood advisory for the island, which was lifted at about 7 a.m.

About 8 inches of rain fell in the Wailua Ditch in the 24-hour period ending at 8 a.m.; 6.7 inches was recorded at Mt. Waialeale and about 3.3 inches fell in Wainiha. Kapahi, Wailua, and Moloaa Dairy all recevied about 3 inches of rain.

The heavy rains also prompted the state Department of Health’s Clean Water Branch to issue a brown water advisory for Kauai, from Na Pali State Park to Kilauea.

The public is advised to stay out of flood waters and runoff due to contaminants from overflowing cesspools and sewer manholes, as well as animal fecal matter, dead animals, pathogens, chemicals and associated flood debris.

If water is cloudy or brown, stay out, the Clean Water Branch advised.