Dec. 6, 2025, 12:18 PM ESTBy Mirna Alsharif and Christine RappAround 19 million people across the West and Midwest are under winter alerts as heavy snow and strong winds sweep through the regions.On Saturday morning, snow showers were scattered over parts of the northern Plains and Rockies, from Montana to the Dakotas. This precipitation is expected to persist through the day, with snow gradually shifting into Iowa and Minnesota by the afternoon.By Saturday night, a burst of snow and wintry mix will shift into Illinois, Missouri and Wisconsin. This quick blast of winter weather will affect the area, including Chicago, through the overnight hours.The snow will extend into parts of Michigan, Indiana and Ohio while lingering over Illinois on Sunday morning. This system will move relatively quickly, reaching the interior Northeast by Sunday night.Snow showers will linger over the region through Sunday night before tapering off Monday morning.The highest snow totals will target the mountains, where parts of Wyoming, Utah, Montana and Colorado could see an additional 5 to 12 inches, with up to 20 inches possible in some areas. The snow combined with 60 mph wind gusts will make mountain travel very difficult through the weekend.Forecasters expect 2 to 5 inches of snow across a swath of the Midwest from the Dakotas through Lake Michigan, including Chicago. Around 6 to 8 inches of snow will be possible over Iowa.Totals across the interior Northeast will be minor, with most seeing a dusting of up to 1 inch. Forecasters expect 2 to 4 inches over western New York.Cold air mass takes holdTemperatures will remain on the cooler side for the Rockies, the Plains, the Northeast and parts of the Southeast on Saturday afternoon, with highs 5 to 20 degrees below average. Daytime highs will range from the single digits in the northern Plains, to the 20s to 50s across the Midwest, Southeast and Northeast.Overnight lows will dip below zero across the northern Plains, and as low as the 10s to 20s across the Midwest, Rockies, Appalachians and Northeast. Despite the chill, no record lows are forecast for Saturday.On Sunday, the bulk of cold air will sit over the Plains, with daytime highs 10 to 25 degrees below average. This will especially affect Minnesota, the Dakotas and Iowa, where highs will stay in the single digits and teens.Active week in the NorthwestA series of strong Pacific storms fueled by an atmospheric river will bring a risk of widespread flooding to parts of Washington and Oregon through the week.Flood alerts will go into effect for the western half of these states, including Seattle and the Oregon cities of Portland and Eugene starting Sunday night and lasting through Friday. Rounds of heavy rain will affect the region over the next week, bringing 2 to 6 inches of rain, with up to 10 inches possible in some areas.Snow levels in this region will climb above 6,000 to 7,500 feet. Prolonged threats include landslides, burn scar flash flooding and coastal flooding.Mirna AlsharifMirna Alsharif is a breaking news reporter for NBC News.Christine RappChristine Rapp is a meteorologist for NBC News.