An upper-level disturbance in the atmosphere created heavy showers and thunderstorms over the Big Island today and will bring rain north to O'ahu as early as this afternoon but definitely by tomorrow, the National Weather Service forecast today.

A flash-flood watch for the Big Island was extended through late this afternoon and a winter-storm watch for Big Island summits will be in effect through Thanksgiving.

Winds will remain light until Thursday, lead forecaster Bob Farrell said.

"I'm looking at a more of a tradewind pattern by Thursday and most of the rain should be on the Ko'olaus but it won't be excessively heavy," Farrell said. "There could be sprinkles eleswhere over the city."

No flooding is expected on O'ahu, he said.

Overnight lows will continue to be brisk with temperatures in the high 60s to low 70s. Daytime highs will be in the high 70s to low 80s.