US: Adverse winter weather forecast across northwestern regions through at least Nov. 19

Adverse winter weather is forecast across parts of the northwestern US through at least Nov. 19. A front will create coastal rain over parts of the Pacific Northwest into Northern Central California through early Nov. 18. The system will produce heavy snow over the Olympic Peninsula and Cascades through the afternoon of Nov. 18, followed by moderate to heavy snow Nov. 19. As the front moves eastward, moderate to heavy snow will develop over parts of the Northern Intermountain Region and Northern Rockies late Nov. 17-18, then moderate snow over the region Nov. 19. Rain is likely over parts of coastal Northwest and Northern California Nov. 18-19. Hazardous travel conditions are likely due to reduced visibility.

As of late Nov. 17, the National Weather Service (NWS) has issued winter storm warnings across northern California, central Oregon, central Washington, and west central Wyoming. Winter weather advisories are in place across parts of northern and central Idaho, western Montana, and the rest of western Wyoming. Officials could update and extend the coverage of the weather alerts over the coming days.

Snow accumulations are likely across the affected region, 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. Sporadic power outages could occur throughout the affected region.

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.