Climatology of Lake-Effect Precipitation Systems over the Great Salt Lake, UT and Lake Tahoe, CA/NV

Lake-effect snowstorms in the Great Salt Lake (GSL) and Lake Tahoe (LT) regions have been observed for decades. Lake-effect events, regardless of their association with small or large lakes, can produce localized precipitation resulting in noteworthy societal impacts and present a considerable forecasting challenge. Several previous studies found GSL and LT events have several similarities to lake-effect snowstorms which occur in the Great Lakes region. To improve forecasting, previous studies have identified atmospheric conditions that typically result in the development of lake-effect snows over the GSL; however, climatological investigation has been insufficient concerning the seasonal and interannual frequency of GSL and LT events.

The current investigation seeks to enhance the climatological understanding of GSL and LT lake-effect events. WSR-88D Level II data for the Salt Lake City, UT (KMTX) and Reno, NV (KRGX) radar sites were used to identify lake-effect events which occurred during the winters (October-March) of 1997/98 through 2008/09. An important indicator of lake-effect precipitation was the spatial and temporal association of precipitation with the geography of the GSL and LT, specifically the quasi-stationary positioning of precipitation over the lakes or near the downstream shorelines. The frequency of and environmental conditions during lake-effect events for the GSL and LT will be compared to results found for small lakes in the northeastern United States, specifically Lake Champlain and New York State Finger Lakes. The event frequency for these small lakes is significantly lower than that observed for Great Lakes events suggesting the variability of environmental conditions is smaller than exists for Great Lakes events and the frequency of small-lake lake-effect events may be more sensitive to changes in the regional climate.