Toward improved aviation forecasts for icing

Progress toward improved in-flight aircraft icing forecasts is being made as part of the Federal Aviation Administration's (FAA) Aviation Weather Development Program (AWDP). The forecasting methods are scientifically based and are rigorously verified using pilot reports of icing and/or measurements from research aircraft. Algorithms which use temperature and relative humidity fields from operational weather forecast model outputs have been shown to be quite reliable and, throughout their development, have continued to reduce the area and volume of icing hazard warnings while maintaining a high probability of detection. The incorporation of explicit cloud liquid water fields into new operational or research weather forecast models shows promise for icing forecasts. Studies of the relationship between synoptic weather features and icing encounters have shed light on the processes which govern production of supercooled liquid water, and have provided insight on the success or failure of the temperature/relative humidity algorithms. The use of data from satellites is beginning to show encouraging results for screening clear regions from automated icing forecasts, and for estimating droplet size near cloud top.