Characteristics of the Best and Worst HRRR Forecasts for Banded Snow Over the Past 3 Winters

Banded snowfall occurs frequently each winter in the United States, yet forecasting its location is a challenge. A small error in forecast location can cause a significant change in snow accumulation within a short distance. For each snow system over the past 3 years, the value of the reflectivity that is 1.25 standard deviations above the mean is calculated. This value is then used to measure the length and width to determine if a snow band is present. There are 373 instances that meet this criteria. Each instance is ranked by how closely it matches with the HRRR forecast. Rankings are calculated using the Model Evaluation Tools Method For Object-Based Diagnostic Evaluation package. Case studies are performed for the top and bottom rankings. Synoptic and Mesoscale features are analyzed for each case in order to identify common features associated with both a good and bad forecast. By analyzing how features are similar and different, banded snowfall forecasting can be improved upon recognition of each environment.