Differentiating freezing drizzle and freezing rain in HRRR model forecasts

Significance Statement Aircraft icing is a hazardous condition that can lead to aviation accidents. We are working to improve forecasts of when aircraft icing conditions occur, especially with respect to a special type of icing condition that occurs from larger supercooled liquid drops that can more detrimentally impact some aircraft than icing from small drops. We investigated a method to distinguish two types of large drop icing in operational forecast models: freezing drizzle and freezing rain. These findings suggest that forecast models are capable of distinguishing these two types of icing, which can provide valuable information to aviation weather forecasters. However, there are improvements that still need to be made to improve how often models accurately predict supercooled large drop icing.