Oregon Sea Grant

There has been little documentation of storm surges along the coast of the U.S. Pacific Northwest (PNW), generated by extratropical storms. A 44-year record of measured tides on the central Oregon coast has been analyzed to determine the hourly non-tidal residuals, which were further analyzed to separate the storm-surge component from the enhanced winter water levels of the seasonal cycle, which can amount to 0.5 m during El Niños. The results document that surge levels have reached 1.4 m, with as many as 15 significant occurrences during a winter, having been greatest during the late 1960s and early 1970s. Although storm intensities and measured wave heights have been increasing over the decades, there has not been a corresponding increase in surge levels and frequencies. Although small compared with surges generated by eastcoast Northeasters, the PNW surge events can produce 10s of meters of dune retreat, representing a significant erosion hazard.