Surface weather features associated with freezing precipitation and severe in-flight aircraft icing

Surface observations of freezing precipitation and pilot reports of severe in-flight aircraft icing for the continental United States are compared to the location of surface weather features, including airmasses of different origin and position relative to fronts, low-pressure centers and troughs. Statistics are calculated to determine where freezing precipitation and severe aircraft icing occur most often, and are produced most efficiently (number of occurrences per unit area). Airmasses found along the east and west coasts of the US are the most efficient producers of freezing precipitation and pilot reports of severe icing, respectively, while the areas ahead of surface warm fronts are the most efficient producers of both of these phenomena. The weather conditions typically found in these locations, and others that are of interest for freezing precipitation and aircraft icing, are discussed.