Upgrades to the Probabilistic Winter Storm Severity Index

The Probabilistic Winter Storm Severity Index (Prob WSSI) is a graphical depiction of societal impacts created through the use of Geographic Information Systems (GIS). Winter weather elements are combined with non-meteorological datasets (e.g., climatology, land-use, urban areas) to generate an impact forecast. 24 hour Probability of impacts are generated by the Weather Prediction Center’s (WPC) Super Ensemble (WSE), which is composed of a mix of 60 CAM and global model members, from hour 24 through hour 168 (day 7). The experimental Prob WSSI provides a classification of the likelihood of potential societal impacts due to expected winter hazards and their distribution using the following terminology: “minor,” “moderate,” “major,” and “extreme.” Informed by ensemble information, the experimental Prob WSSI allows for detailing the likelihood of potential impacts (i.e., "what is my chance of reaching a moderate impact?"). The Prob WSSI output will convey a range of likelihood of impacts thus enhancing preparedness and decision making as they pertain to winter weather. The Prob WSSI has undergone algorithmic, data availability (i.e. type) and time range changes over the past two years as it has matured from concept to experimentally operational. These updates will be covered and the future direction of the Prob WSSI will be discussed.