A Flash Flood Watch will be in effect Monday morning through Tuesday afternoon for Oahu, Maui County and the Big Island. Southerly winds ahead of an approaching cold front will draw up deep tropical moisture with heavy showers and isolated thunderstorms. The front will reach Kauai Monday, pushing the unstable area of moisture back over the eastern end of the state through Tuesday.
Light winds will become strong southwest Kona winds as the front approaches, then shift to cool northwest and then north winds as the front passes. Gusty south winds ahead of an upper disturbance will boost winds for the Big Island summits, with a High Wind Watch posted from Monday evening through Tuesday afternoon. Southwest winds of 45 to 60 miles per hour with localized gusts over 70 miles per hour are possible.
Conditions may not be right to go to the beach, but surf will be just below advisory levels for north, west and south shores. North shores are forecast to peak at 10 to 14 feet, west shores at 6 to 10 feet and south shores at 5 to 7 feet. The south swell should persist through Wednesday. A big northwest swell could bring warning level surf near the end of the week.