What is the trajectory and impact of the major winter storm system moving across the United States?

A powerful winter storm system is currently progressing from the western United States toward the Northeast, marking the third major storm of the week. The western regions are experiencing severe conditions with winter storm warnings issued and up to 8 feet of snow expected in mountainous areas, while California faces additional threats of flooding and mudslides. The storm is moving eastward, bringing dangerous weather conditions including severe storms in the south and a combination of snow, ice, and rain to the Northeast by week's end. Major cities including Washington D.C., Philadelphia, and New York City are directly in the storm's path, requiring residents to prepare for hazardous winter weather conditions this weekend.