Many state DOTs use winter-focused Weather Severity Indices (WSI) (aka Severe Weather Indices (SWI) or Storm Severity Indices (SSI)) to aid in performance measurement and management of winter maintenance operations. These states also employ Road Weather Information Systems (RWIS) and other meteorological data for reporting current conditions, forecasting weather impacts to the transportation system, and determining the appropriate response. Developing WSIs is a data-intensive process, and the methods used vary greatly for each developed WSI. While general guidance on how to develop a WSI is available , many of the more complex issues – such as how to accurately identify, capture, and incorporate blowing and drifting snow into WSIs – have not yet been determined.

The objective of this project is to create a working group of experts to serve to advance the state of the practice of weather severity indices (WSI). The project will develop a whitepaper on the current state of the practice, identify issues with WSIs, and identify lessons learned in the process of development. The effort will result in the coordination and assemble the volunteer working group to review the state of the practice of WSIs, known issues, and work to identify methods to solve these issues. This is a joint research effort with the National Center for Atmospheric Research, and is sponsored by the Aurora Pooled Fund research program/Iowa Department of Transportation.