Weather Tidbits: Winter Storm Severity Index

This Weather Tidbits explores the Winter Storm Severity Index that is used by the National Weather Service. The WSSI is a tool that forecasts the impacts of winter storms; ranging from property and tree damage to transportation and disruptions to daily life. The WSSI is measured by analyzing the potential impacts of 6 things; which are snow amount, snow load, ice accumulations, flash freeze, blowing snow & ground blizzards. The WSSI consist of 6 categories starting with no impacts. This is followed by limited impacts in baby blue; which involve small accumulations of snow or ice, minimal impacts with little inconveniences.

Minor impacts shown in yellow roughly equates to criteria for NWS advisory; that include minor disruptions and none to minimal recovery time. Moderate impacts in orange roughly equates to criteria of NWS warning; that have definite impacts and 1 to 2 days of recovery time. Major impacts in red involve significant impacts, even with preparation; and deal with several days of recovery times. Lastly, extreme impacts in purple are historic & widespread severe impacts; that involve many days to a week of recovery time.