Strong East Wind Events in the Tahoe Basin and the High Sierra

While most are familiar with strong west to southwest wind events in the Sierra ahead of and during winter storms, east wind events can be just as severe and pose similar hazards. Strong east wind events in the Sierra can last up to 3 days and typically occur between October and March as low pressure systems pass through southern California and southern Nevada. This synoptic pattern often spawns other well-known offshore wind events in California, such as the Santa Ana and Diablo winds. Impacts in the Sierra include downed trees, damage to power infrastructure and potential for wildfire ignitions, diminished ski lift operations, lake shore damage due to large waves on Lake Tahoe, and strong turbulence and low level wind shear for air travel. Since unusually strong east wind events occur less frequently, the lack of familiarity poses a challenge to meteorologists when communicating the strength and duration of these events. In the more extreme cases, peak winds are determined by forced flows in the complex terrain of the Tahoe Basin and High Sierra which are not well resolved by the coarse resolution of forecast models. Fortunately upgrades to the GOES-West satellite and denser surface observation networks have improved real time analysis to help mitigate messaging and forecast challenges. This presentation will tell the story of two extreme east wind events, where wind gusts exceeded 150 mph, in the Sierra from December 1st, 2011 and February 9th, 2020.