Some changes are afoot in our weather as a cold front approaches the state from the northwest. Winds will become light and variable Sunday with afternoon sea breezes triggering some interior clouds and pop-up showers. Then a moisture convergence band ahead of the front will form over Oahu, Maui County and the Big island, bringing the possibility of heavy showers and flash flooding. There could also be strong or severe isolated thunderstorms ahead of and along the front. Because of this, a Flash Flood Watch will be in effect from 6 a.m. Monday through 6 p.m. Tuesday for Oahu, Maui County and the Big Island.
Winds will also become more southerly and then southwest by Monday, reaching breezy speeds and spreading volcanic haze from the Big Island. The Kona winds could become quite gusty downslope of the usual windward areas of Kauai and Oahu. The front itself will bring some moderate rain over north and west areas of Kauai Sunday night and Monday and push the convergence band of heavy showers and thunderstorms back over Maui and the Big Island.
Surf will be rising close to advisory levels for north, west and south facing shores, while surf for east shores is falling with the diminishing trade wind speeds. The northwest swell is forecast to peak Sunday or Monday, with another swell rolling in Tuesday and Wednesday. There's a chance for warning-level surf for north and west shores near the end of the week.