The Experimental Winter Storm Outlook (WSO) Snowfall and Freezing Rain uses WPC’s (Weather Prediction Center’s (WPC's) winter weather ensemble suite to depict the probability of exceeding event-based NWS Winter Storm Warning criteria for both snow and freezing rain for the Day 1-4 period within the contiguous United States (CONUS). The products consist of four individual 24-hour outlooks issued on the night shift by 0900 UTC (one each for Day 1, 2, 3 and 4 with 1200 to 1200 Coordinated Universal Time (UTC) valid times). The underlying data for the probabilities of exceeding local warning criteria is produced for each 6-hour time step. These four outlooks will be subsequently updated on the day shift by 2100 UTC for the same valid times. In addition to the four individual days, a summary product is issued that depicts the maximum probability across all time ranges (Days 1 to 4).

The Experimental Winter Storm Outlook(WSO) is based on a combination of the WPC's Probabilistic Winter Precipitation Forecasts (PWPF) and local National Weather Service (NWS) snow and ice warning criteria. Therefore, the WSO provides an early alert to hazardous winter weather conditions in a similar fashion to other national center outlooks, and also assists with NWS Winter Storm Watch and Warning decision making. The WSO will exploit a robust winter weather ensemble specifically tuned to Weather Forecast Office (WFO) Winter Storm Warning criteria. This year, in anticipation of implementing a modernized snow criteria that involves a migration from 12- and 24-hour criteria to a new event-based version (a qualifying winter storm event will be considered to be no longer than 48 hours), the WSO will be informed by the proposed new criteria. Therefore, the outlooks will now depict the probability of exceeding event-based Winter Storm Warning criteria for snow over the next four days for any given location in the contiguous United States (CONUS). PWPF, already utilized by WFOs across the NWS, forms the foundation of WPC’s WSOs while WFOs retain Winter Storm Watch issuance responsibility.

Link to Graphical Web Page: https://www.wpc.ncep.noaa.gov/wwd/wso/

Link to data download(shapefile): https://www.wpc.ncep.noaa.gov/wwd/wso/shp/

Link to metadata: https://www.weather.gov/gis/IDP-GISRestMetadata

Questions/Concerns about the service, please contact the DISS-GIS team

You can provide feedback at: https://www.surveymonkey.com/r/winterstormoutlook2022-2023