The threat of heavy showers and thunderstorms as Tropical Storm Niala approaches the state has prompted a flash flood watch for the Big Island that will go into effect Friday evening.
National Weather Service forecasters say a surge of deep tropical moisture north of the storm will approach the Big Island by Friday night and remain in place through the weekend. Heavy showers and thunderstorms will favor eastern and southern slopes, however, the rainfall may reach other areas of the island. Individual showers may be relatively brief, but “extreme accumulation” will be possible anyway if showers train over a given location. Overall coverage of the island should start relatively small Friday, but expand significantly on Saturday.
The watch will remain posted through Monday. Forecasters say the threat of heavy rain will diminish as the very moist air mass moves west away from the Hawaiian Islands next week.
A flash flood watch means that conditions may develop that lead to flash flooding.