Heavy rain and significant snowfall are set to impact California and parts of Oregon in the coming days, with multiple winter storm warnings already issued. Regions such as the Sierra are bracing for up to 8 feet of snow, while areas like Reno may experience a mix of rain and snow. Caltrans is urging travelers to reconsider their plans due to anticipated major travel disruptions along vital routes like I-5. Forecasts indicate the arrival of cold systems starting this weekend, bringing additional rain and snow that could help alleviate current snowpack deficits in the region. With warnings in effect until midweek, residents and visitors are advised to prepare for potentially hazardous travel conditions.