Washington Windstorms: Seasonality and Relationship to ENSO

Powerful windstorms, such as the Columbus Day Storm of October 1962 and the Inauguration Day Storm of 1993, pose a great threat to the state of Washington (WA). The strongest windstorms are those that receive names and have historically occurred during the neutral phase of the El Niņo-Southern Oscillation (ENSO). However, there have been too few of these named storms to establish a definitive statistical relationship with ENSO. To examine this issue further, a more rigorous study has been performed using hourly wind observations from 1948-2013 for twelve ASOS stations throughout the state. The seasonality of the wind data was analyzed, as well as the relationship to ENSO. These results indicated that strong winds can occur year-round, especially in eastern WA where the seasonal cycle of winds is less apparent. Using the top 0.1% of all hourly wind observations, different statistical procedures were considered to determine a relationship between wind and ENSO. The analysis revealed a less pronounced relationship between wind storms and ENSO, as the phase of ENSO is an indicator for the likelihood of windstorms at only four of the twelve stations.