An upper level disturbance will combine with an area of moisture to trigger possible heavy rain and thunderstorms for Maui and the Big Island into Wednesday.

The National Weather Service in Honolulu has issued a flash flood watch for Maui until 6 a.m. Wednesday, and for the Big Island until 6 p.m. Wednesday.

There’s also a winter weather advisory for Haleakala above 9,000 feet until 6 a.m. Wednesday for freezing rain and a chance of snow showers. An advisory is also posted for the summit areas of Mauna Loa and Mauna Kea for freezing rain and snow showers, also above 9,000 feet, until 6 p.m. Wednesday.

The main concern will come from heavy rain and thunderstorms that could anchor over the windward slopes of the Valley Isle and the Big Island.

The threat of heavy showers should diminish by midday for Maui and Wednesday evening for the Big Island. A cooler drier airmass will move in statewide by Thursday.