US: Adverse winter weather forecast over the Northwest, West, and Southwest regions through at least Jan. 14 /update 2

Adverse winter weather is forecast across parts of the Northwest, West, and Southwest, US through at least Jan. 14. Unsettled weather is forecast to continue through Jan. 14. Heavy snow and strong winds will result in blizzard conditions in parts of the Northwest through the afternoon of Jan. 11; total snow accumulations may reach several feet in the Cascades and Olympics mountains, especially at higher elevations. Hazardous travel conditions are likely in many mountain passes due to low visibility. Lighter precipitation is forecast in the Northwest through Jan. 11 before another system approaches and brings heavier precipitation Jan. 12-13. Heavy snow and strong winds will also spread south into the Sierra, Great Basin, and Four Corners regions Jan. 11; dangerous travel conditions are likely due to snow squalls with rapidly changing visibility, occasional whiteouts, and possible flash freezes.

As of late Jan. 10, the National Weather Service (NWS) has issued winter storm warnings across parts of far northern and northeastern California, northern and central Idaho, western Montana, western and central Nevada, northeastern Oregon, northeastern Utah, western and far southeastern Washington, and far southern Wyoming. Winter weather advisories, winter storm watches, and avalanches warnings are in place across much of the rest of the affected area. Officials could update and extend the coverage of weather alerts over the coming days.

Snow accumulations are likely across the affected area, especially at higher elevations. Lesser accumulations are possible where sleet and freezing rain mix with the snow, and precipitation is less intense. In addition to the heavy snow, strong wind gusts will likely lead to periods of blowing and drifting snow in some areas. Blizzard conditions are possible. Sporadic power outages could occur throughout the affected area.

The winter weather will likely cause ground and air transport disruptions over the coming days. Traffic and commercial trucking delays are probable along regional highways. Dangerous and challenging driving conditions are likely on secondary and rural roads in the affected states as maintenance crews prioritize clearing major routes. Authorities will probably close stretches of highways if driving conditions become too hazardous. Flight delays and cancellations are likely due to ground stops and deicing operations at regional airports.