This talk will focus on a few heavy precipitation events associated with atmospheric rivers (ARs) during 12-13 November and 8-9 December, along with a moderate precipitation associated with a strong baroclinic system on 3 December 2015. We evaluate the impact of ice microphysical processes (deposition, riming, and melting) on cloud water accretional growth and precipitation characteristics during these events using surface gauges, ground radars (NPOL and DOW), in situ aircraft (Citation), and satellite sensor measurements (GMI and SSMIS). The WRF was nested down to 1-km grid spacing using the Global Forecast System (GFS) analyses for initial and boundary conditions for a relatively short 36-h simulation. Four unique bulk microphysical schemes were evaluated, including the predicted particle properties (P3) scheme, Thompson, YLin-Stony Brook, and Morrison schemes. We also conduct WRF simulations using the Hebrew University spectral bin microphysical (HUJI) scheme to help identify issues in the bulk parameterization schemes. The P3 scheme predicted a layer of light to moderate rimed ice particles with faster fallout speeds that led to the development of a well-defined melting layer, which generally agreed with radar and aircraft measurements. As a result, P3 produced higher precipitation rates and accumulations that were in overall closer agreement than the other schemes. Conversely, the MORR scheme overpredicted snow mass while underpredicting graupel/rime mass, which led to a weak melting layer and a general underprediction in precipitation along the windward slopes. The HUJI scheme encountered similar issues as MORR, which limited its use for improving the bulk microphysical schemes. Our model results highlight the importance of both the cold and warm rain processes on simulating the orographic precipitation for these events.