What are the current severe weather conditions and their impacts across the western United States?

The western United States is experiencing the third major winter storm of the week, creating dangerous and life-threatening conditions across multiple states. On Interstate 84 near Portland, Oregon, whiteout conditions have caused a massive vehicle pileup involving dozens of cars, resulting in multiple injuries and forcing authorities to shut down parts of the interstate while emergency services respond to the chaos. The storm system is bringing winter storm warnings across the West, with Northern California facing additional threats of mudslides as rain falls on areas previously damaged by wildfires. As this unpredictable weather system moves eastward, it's expected to bring tornado threats to southern regions and heavy snowfall to northeastern areas, prompting officials to urge families and communities to prepare for worsening conditions and prioritize safety.