The Weather Prediction Center's Winter Weather Experiment: Past Successes, Ongoing Challenges, and Future Plans

During the past 13 years, the Weather Prediction Center - Hydrometeorology Testbed (WPC-HMT) has led the annual Winter Weather Experiment (WWE). The WWE examines forecast challenges associated with heavy snowfall and mixed precipitation during the cool season, across a variety of scales from mid-latitude cyclones to lake-effect snow bands. In past years, the WWE has studied forecast cases of interest either in real-time or retrospectively. Key findings and results from WWE include enhancements to the National Blend of Models, and testing of improved snowfall accumulation variables and winter specific verification metrics for convection allowing models (CAMs), all while strengthening collaboration between WPC and individual Weather Forecast Offices (WFOs).

Currently, WPC-HMT is focused in large part on the evaluation of ongoing CAM deterministic and ensemble forecast development with the Rapid Refresh Forecast System (RRFS) ensemble. However, numerous challenges remain for evaluation of experimental CAM forecasts of winter weather. For example, gridded analyses of snow often have large uncertainties, and point observations of snowfall and precipitation types must be carefully quality controlled and contextualized to be useful for model verification. Snowfall is especially difficult to verify due to processes such as melting and settling affecting observations.

In this presentation, the recent history and successes of the WWE are reviewed along with ongoing forecast evaluation challenges. The remainder of the presentation focuses on aspirational goals to continue refining the WWE to meet the needs of WPC, WFO meteorologists, and the CAM ensemble development community. This will include highlighting ongoing projects that will expand the scope of WWE activities into forecast messaging and impacts of heavy winter precipitation on transportation.