Yesterday the Washington coast was hammered by an potent combination of extraordinarily large and powerful waves, which coincided with a reasonably high astronomical tide and some storm surge. You can see these processes coming together (high tide was at roughly 1pm) in the video above, compiled from a webcam mounted on Kalaloch Lodge on Washington's Central Coast. This webcam is looking straight out the mouth of Kalaloch Creek, a small coastal creek, towards the ocean. In the video you can see waves pulsing into Kalaloch Creek, mobilizing and transporting the massive jams of wood that line the beach and creek mouth there. This storm led to at least one death, and a raft of incredible videos, photos and stories from along the coast.
How extreme were these waves? Pretty darn extreme. The Cape Elizabeth Buoy has been measuring waves just offshore of the Washington Coast since 1987, providing hourly estimates of significant wave height and other wave and weather parameters. To date the bouy has accumulated over 200,000 wave observations going back almost 20 years. The bouy estimated a peak significant wave height for this event of 9.9 m at 12:50 pm. There are only 14 larger wave observations on record, all associated with the "Great Coastal Gale" of December 3-5 2007. I've plotted significant wave heights from Cape Elizabeth below, as a time series (top), and a histogram (bottom).