AREAS AFFECTED : CENTRAL OREGON COAST; NORTH OREGON COAST ...HIGH SURF ADVISORY IN EFFECT FROM 9 AM SATURDAY TO 1 PM PDT SUNDAY... The National Weather Service in Portland has issued a High Surf Advisory, which is in effect from 9 AM Saturday to 1 PM PDT Sunday. * SEAS...Combined seas building to near 20 feet Saturday morning, then peaking at 25 to 30 feet in the afternoon and evening. Isolated higher waves possible. Seas expected to fall below 20 feet Sunday afternoon. * IMPACTS...Waves will run up much higher on beaches than normal. These powerful waves can sweep people off jetties and other exposed rocks. The waves can easily move large logs and other beach debris. Bar crossings and the surf zone will be dangerous due to strong currents and breaking waves.