A flash flood watch issued Monday by the National Weather Service is in effect for Kauai, Niihau and Oahu through this afternoon.

The weather service said deep tropical moisture combined with increasing instability associated with an upper low moving into the area will support periods of heavy showers and a few thunderstorms. Showers could become heavy at times, potentially leading to flash flooding.

“With heavy showers expected to move over the islands from the south, some normally dry leeward areas will receive heavy rainfall,” the weather service said. “This includes urban areas of Oahu, which are more susceptible to flooding problems.”

A flash flood watch means that conditions are favorable for flash flooding.

The city Department of Emergency Management will issue emergency public information over TV, radio and official social media channels.