Rain of up to 2 inches an hour fell on Waikane Stream, causing the stream to reach flood levels and prompting a flash flood warning for Oahu for about two hours this morning. The warning was lifted, but forecasters say residents should be prepared for more localized heavy rain through Sunday morning.

Moist air blown in by the strong trade winds is mixing with a weather system in the upper atmosphere to create unstable weather and the potential for heavy showers, National Weather Service forecasters say.

“The combination is bringing in this rainy weather pattern,” said Anthony Reynes, a forecaster with the Honolulu office of the National Weather Service. “At any time you can experience localized heavy rain. The public should stay informed, just in case we issue a warning in your area.”

The upper level weather system is closer to Maui and Hawaii island, which are both under flash flood watches through Saturday.

But Reyes said the potential for heavy showers also exists on the other islands.

The showers are favoring windward and mauka areas because they are being blown in by the trade winds. But rain could also hit leeward areas.

About 3.8 inches of rain fell in the northern Koolaus at  the Oahu Forest Reserve in the 24 hour period ending at 11 a.m. About 3.1 inches was recorded at the H-3 tunnel rain gauge and Manoa saw about 2 inches of rain.