Lake-Effect Snowstorms over Southern Ontario, Canada, and Their Associated Synoptic-Scale Environment

摘要

Lake-effect snowstorms are an important source of severe winter weather over the Great Lakes region and are often triggered by the passage of synoptic-scale low pressure systems. In this paper, a climatology of lake-effect snowstorms over southern Ontario, Canada, for the period 1992-99 is developed. The distinguishing characteristics of the synoptic-scale environment associated with intense lake-effect snowstorms in the region are identified through the study of individual events and through composite analysis. In particular, it is found that a low pressure and a cold-temperature anomaly situated over Hudson Bay, north of the Great Lakes, is a favorable environment for the development of intense lake-effect snowstorms over southern Ontario. It is also found that the track of the low pressure system can have a significant impact on the development or lack thereof of lake-effect snowstorms over southern Ontario. It is found that the low pressure systems that trigger intense lake-effect snowstorms tend to have an anomalous northeastward track as compared to the eastward track of most low pressure systems that transit the region.