...HIGH SURF WARNING IN EFFECT UNTIL 6 PM HST FRIDAY FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI OAHU MOLOKAI AND NORTH FACING SHORES OF MAUI... ...HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST FRIDAY FOR WEST FACING SHORES OF THE BIG ISLAND... .An extra large long period northwest (320-340) swell will build this morning, peak this afternoon, then gradually fade through Friday afternoon. Surf heights will swiftly rise to above warning criteria along all exposed north and west facing shores. * WHAT...Surf building to 30 to 40 feet along north facing shores of Niihau, Kauai, Oahu, Molokai, and 20 to 30 feet along north facing shores of Maui. Surf building to 25 to 35 feet along west facing shores of Niihau and Kauai, and 20 to 30 feet along west facing shores of Oahu and Molokai. * WHERE...North and west facing shores of Niihau, Kauai, Oahu, Molokai, and north facing shores of Maui. * WHEN...Until 6 PM HST Friday. * IMPACTS...High. Expect very strong breaking waves and powerful currents. Waves breaking in channel entrances may make navigating the channels dangerous.