A winter storm is expected to bring heavy snow and severe weather conditions to parts of the US, with millions of people under winter weather alerts. The storm's impact may be felt across a large portion of the country, with some reports suggesting it could affect over 35 states and potentially cause major disruptions. The number of people affected is unclear, with estimates ranging from 20 million to over 245 million, and the storm's effects are already being felt in some areas, including the Southeast and the East Coast.