Climatology of lake-effect precipitation events over the Lake Tahoe, CA/NV region

Numerous studies have examined lake-effect precipitation on the Great Lakes, but much less research has been undertaken to investigate lake-effect events associated with smaller bodies of water. The current study uses WSR-88D radar data from Reno, NV (KRGX) for the thirteen winters (October through March) of 1996 through 2008 to conduct a climatological study of lake-effect precipitation events in the vicinity of Lake Tahoe and Pyramid Lake. Lake-effect events were found to develop as (a) well-defined, isolated bands with extension over the lake [BAND], (b) isolated convection that remained persistent over the lake with little or no downwind extension [OLC], (c) quasi-stationary lake-effect bands embedded within widespread synoptic precipitation [SYNOP], or (d) a transition between two different types [TRANS]. The radar analysis identified 57 lake-effect events during the 13-winter time period, 32 associated with Pyramid Lake and 23 connected to Lake Tahoe. In addition to determining the frequency of events, a preliminary examination of the meteorological conditions during events was conducted using surface observations, regional reanalysis, and soundings. Analyses showed that events occurred most frequently during October, a result much different from the typical occurrence time period of Great Lakes lake-effect events and events that have been examined for other small lakes in the eastern and western United States. In addition, Lake Tahoe and Pyramid Lake events had an average duration of 6.5 hours, a much shorter duration compared to Great Lakes lake-effect storms which often last more than 24 hours. Lastly, a remarkable event which resulted in the development of multiple lake-effect vortices on 27 October 2004 over Lake Tahoe will be discussed.