The system is expected to pass north of the islands this evening and tomorrow.

Flash flood warnings were issued this morning for Kaua'i, O'ahu and Moloka'i. The warning for Moloka'i has been dropped to a flash flood watch. Elsewhere across the Islands flash flood watches remain in effect for all islands except the Big Island.

On Kaua'i, downpours over the center of the island were raising water to near the flood stage in both the Hanalei and Wailua Rivers. The flash flood warning for Kaua'i was to remain in effect until 2:15 p.m.

National Weather Service forecaster Nezette Rydell said that the service was also watching closely the development of specific conditions that could support tornado development on Kaua'i and O'ahu. Those conditions had not yet developed at midday, but could develop during the afternoon or early evening.

"There is a possibility that the National Weather Service could issue a tornado watch or tornado warning," the service said in a special statement.

"This is still an uncertain situation and by no means is it certain to develop."