HONOLULU (KHON2) -- The National Weather Service has issued a flood watch for all main islands through Sunday afternoon. Get Hawaii's latest morning news delivered to your inbox, sign up for News 2 You According to officials, a low aloft will move over the island throughout the weekend, creating a "very unstable atmosphere." Affected islands will experience heavy rain and thunderstorms, especially in the windward area. Heavy showers and thunderstorms possible this weekend In addition to a flood watch, the NWS has issued a high surf advisory for all east-facing shores until 6 p.m. on Saturday. Reports said waves could reach between eight to 12 feet in the morning and will decline to seven to 10 feet by the afternoon. Spooktacular picks: Top 10 must-watch horror flicks to scream your way through the Halloween season Beachgoers should proceed with caution as breaking waves and strong currents will make swimming dangerous.