A powerful winter storm system moving across the Great Lakes and Northeast is bringing snow and ice, frigid temperatures and possible whiteout conditions.

After periods of ice and rain overnight, a long-duration lake-effect snow system moved into the state Monday morning. In Western New York, wind gusts reached up to 70 mph, creating dangerous whiteout conditions. Lake-effect snow is expected to persist off Lakes Erie and Ontario for much of the week.

More rain and snow are expected through the weekend in Northern California. The KCRA 3 weather team issued an Alert Day for Saturday because conditions could risk public safety for the Valley and Foothills. It's an Impact Day for the Sierra.

Lake effect snow, intense rain and chilly temperatures dominate the forecasts for different parts of the U.S., before and after the new year arrives.

A storm is expected to bring rain and snow to the Los Angeles area this weekend, with gusty winds and possible flooding possible in burn scar areas, forecasters said.

A bomb cyclone dumped snow on the Midwest and the Northeast over the weekend. Monday afternoon, more than 11 million people were under winter storm warnings or winter weather advisories — and more than 98 million were under high wind advisories from Indiana to Boston, according to the weather service.

In Minnesota, forecasters warned of “potentially life-threatening travel conditions” as whiteout conditions reduced visibility. Heavy snow was expected over the Upper Midwest and Great Lakes.

Wintry precipitation brought an icy slop to roads and sidewalks around the Lehigh Valley on Friday night, just as forecasters had expected.