(BIVN) – A Flash Flood Watch is in effect for the entire State of Hawaiʻi.

For the Big Island, the Flash Flood Watch is in effect through Saturday evening, the National Weather Service says. The Honolulu-based forecasters say:

Deep tropical moisture will spread northward over central and eastern islands today, with conditions becoming unstable as an upper level trough approaches from the west. This is expected to lead to the development of showers and thunderstorms from Oahu eastward to the Big Island this afternoon, with the threat for showers and thunderstorms continuing through Saturday evening. Light winds will remain over the area during this time and this will be supportive of slow moving showers and storms, which could lead to heavy rainfall and flash flooding. The most likely time frame for the heavy rainfall and potential flooding appears to be during the afternoon and evening hours both today and Saturday.

“A Flash Flood Watch means that conditions are favorable for flash flooding,” the National Weather Service stated. “Flash flooding is LIFE THREATENING. Do not cross fast flowing water in your vehicle or on foot. Monitor later forecasts and be prepared to take action if a Flash Flood Warning is issued. If you experience heavy rain or rising water, head to higher ground immediately.”