The variability of regional climate conditions associated with Lake Champlain lake-effect snow systems
A number of studies have recently indicated that lake-effect snows can occur in connection with lakes of significantly smaller size than the Great Lakes. As an example, Lake Champlain lake-effect storms can generate snowfalls over localized regions which are comparable to large-scale winter storms and on rare occasions produce snow squalls with visibilities less than ¼-mile and up to 33-cm (13 inches) of snow in a 12-hour period. Recent investigations have suggested that lake-effect systems which develop in association with small lakes require a selective subset of mesoscale forcing conditions, and therefore may be more sensitive to changes in climatic conditions. To establish a better understanding of the lake-effect snow systems in the vicinity of Lake Champlain, an investigation was undertaken to determine the intra-seasonal and inter-annual variability of events and the changes in climatic and mesoscale conditions related to these variations.
The current study used Burlington, VT Weather Surveillance Radar 88 Doppler (WSR-88D) radar data to identify lake-effect events for the winters (October – March) of 1997 through 2005. Lake Champlain lake-effect events were found to develop as (a) well-defined, isolated snow bands over and downwind of the lake, independent of larger-scale weather systems, or (b) a quasi-stationary mesoscale snow band over the lake embedded within widespread regional snowfall from a synoptic weather system. Over the nine winters examined, 67 events were identified and the largest frequency of lake-effect events were found to occur during the months of December and January; however there were several winters when events did not occur in either month. Environmental parameters for each event, atmosphere and lake climatic conditions for the Lake Champlain region, and intra-seasonal and inter-annual lake-effect system frequency were used to better understand the potential influence of changing climatic conditions on the development of mesoscale systems.