The Winter Storm Severity Index for Alaska: Development and Arctic Testbed Evaluation

Abstract Alaska has unique climatological and geographical considerations for winter services provided by the National Weather Service. Correspondingly, there is a lack of impact-based decision support products and services provided to core partners and stakeholders in Alaska as compared to those in the contiguous United States. The Winter Storm Severity Index (WSSI)—an operational product that produces a graphical representation of the location and severity of anticipated societal impacts from forecasted winter weather conditions—is one such product that is available in the contiguous United States but is not available in Alaska. In an effort to expand the winter services in Alaska, a prototype WSSI for Alaska was developed and subsequently evaluated within the Arctic Testbed and Proving Ground in Anchorage, Alaska. The development of this prototype (including components and thresholds) and feedback gathered from the testbed evaluation are detailed in this article. This process serves as a successful proof of concept of applying the framework of an existing operational forecast product (i.e., the WSSI) to a specific region (i.e., Alaska) based on targeted input and feedback from professional partners, stakeholders, and local forecasters. Significance Statement The Winter Storm Severity Index is a National Weather Service product available in the contiguous United States that depicts the severity of potential societal impacts associated with the winter forecast. Bringing the product to Alaska requires careful consideration of the unique needs of Alaskan stakeholders. This paper describes the initial development of the product for Alaska and its evaluation with forecasters in Alaska within the Arctic Testbed and Proving Ground.