Microphysical and Dynamic Drivers of Precipitation Distribution within the Russian River Watershed

Landfalling winter storms frequently produce high precipitation rates and flooding within the mountainous Russian River watershed of coastal Northern California. Studies have shown that periods of southerly to southwesterly flow with high integrated water vapor transport (IVT), frequently observed during Atmospheric River events, can generate the highest precipitation accumulations over the Russian River watershed as a whole. However, varied environmental conditions including stability, IVT, and wind speed and direction during these periods can produce sub-basin-scale variations in the spatial distribution of precipitation in addition to contributing to basin-wide precipitation totals. These variations have not yet been characterized, and the physical processes driving them remain poorly understood. This study uses multi-year precipitation gauge and profiling radar observations, coupled with soundings collected during the Forecast Informed Reservoir Operations (FIRO) field campaigns, to determine the mesoscale processes that impact sub-basin-scale precipitation distribution and streamflow within the Russian River watershed.