A climatography of freezing rain, freezing drizzle, and ice pellets across North America

Using surface weather observations from 1976 to 1990, we produced a climatography of freezing rain, freezing drizzle, and ice pellets across the United States and Canada. These types of precipitation have been shown by previous studies to have a potentially serious impact on airport operations and aircraft. Our preliminary results indicate that the most frequent type of precipitation is freezing drizzle, followed by freezing rain and ice pellets. Although these types of precipitation have been observed during summer at high northern latitudes, they occur primarily from December through March. Freezing rain and freezing drizzle occur most frequently near sunrise, whereas ice pellets occur most frequently in the afternoon. The largest percentage of these events last for one hour or less.

The spatial distribution of freezing rain and ice pellets shows that these precipitation types have been observed across a large portion of the United States and Canada. Freezing rain and ice pellets are reported most often in the eastern United States and eastern Canada, with few reports in Alaska. Freezing drizzle events are most frequent in the central part of the United States and Canada, and the northern coasts of Canada and Alaska.

This presentation will also discuss some of the meteorological aspects of these events.