Updating a Climatology of Extreme Snowfall Events in the United States

Snowfall extremes are important to understand, primarily because they can disrupt economic functions, particularly logistics and transportation concerns, including roadways, air and rail. In addition, businesses and schools can have impacts on their operations during periods of heavy, intense snowfall. The National Oceanic and Atmospheric Administration (NOAA), to support the Federal Emergency Management Agency (FEMA), have maintained climatologies of 1-day, 2-day, and 3-day snowfall events for U.S. Counties using the NOAA’s cooperative observer program (COOP). This network has been in existence since 1890 and includes volunteers who manually measure snowfall every day. Over the past few decades, there have been efforts to collect these measurements through additional networks, including the Automated Surface Observing System (ASOS), as well as the Community Collaborative Rain, Hail and Snow (CoCoRaHS) network. In addition, improvements have been made to archive these varying networks through the Global Historical Climatology Network – Daily (GHCN-D) dataset, which includes an automated suite of quality assurance to ensure data integrity. Because of the recent technological advancements, there is a need to update this climatology in order to not only use the latest and most complete data, but also evaluate the importance of these indices in a changing climate. This presentation highlights the process by which snowfall extreme values are collected and validated for every county, including lessons learned and methods to improve quality assurance procedures for future ingest.