A flood watch has been issued for Niihau and Kauai ahead of time — effective from Wednesday morning through late Wednesday night.

The National Weather Service of Honolulu said bands of showers are expected in advance of an approaching front, which may bring heavy rainfall to Kauai, and possible flash flooding.

Forecasters warn that flood-prone roads and other low-lying areas may have to be closed due to elevated runoff and overflowing streams. Also, rapid runoff may result in more significant flooding and property damage to urban areas.

Forecasters say rainfall is expected to increase across the western and central ends of the state through Thursday in advance of an approaching front, with locally heavy rainfall and possible thunderstorms potentially generating flooding concerns.

Rains are expected to expand across the isles, from west to east, through the remainder of this week.

Officials advise the public to monitor later forecasts and to be prepared to take action, if necessary.

A flood watch means that conditions are favorable for flash flooding, which is life-threatening. Officials warn the public not to cross fast-flowing water in a vehicle or by foot.