US: Adverse weather forecast over parts of East North Central, Northwest, Southwest, West North Central, and West regions through April 14

Event

A late-season winter storm is forecast to bring strong winds and mixed precipitation across portions of the East North Central, Northwest, Southwest, West North Central, and West regions through at least April 14. As of April 11, the storm system is located over the Pacific Northwest and will bring rainfall to coastal ranges of the western US and heavy mountain snow to the Cascades. The storm and cold air mass behind it will track eastwards across the Rockies and into the northern plains April 11-12, bringing snowfall, sleet, and rainfall to the country's northern parts. The weather system will then move into the Upper Midwest April 13-14.

As of April 11, the US National Weather Service (NWS) has issued winter storm warnings for parts of southern Washington, western and northeastern Oregon, far northern California, central Idaho, northern Utah, and western Montana. Winter storm watches have been issued for parts of northwestern and northeastern Wyoming, western Colorado, eastern Montana, North Dakota, northern South Dakota, and northwestern Minnesota. Winter weather advisories have been issued for parts of northern and eastern California, Oregon, Washington, northern Nevada, southern and central Idaho, central and northeastern Utah, far southwestern Wyoming, northern and western Montana, and northeastern Minnesota.

The NWS's Weather Prediction Center has warned of widespread precipitation across much of the Pacific Northwest, northern Rockies, and northern plains through April 14. The heaviest snow accumulations are expected over mountain ranges, with accumulations of more than 30 cm (12 inches) likely in the Oregon Cascades and over 20 cm (8 inches) possible in the Washington Cascades to the Klamath Mountains in California and the northern and central Sierra Nevada April 11. Further snowfall is expected in the northwest through April 14, with daily snowfall accumulations of over 20 cm (8 inches) likely to continue in the Oregon Cascades. Heavy snowfall accumulations of 20-30 cm (8-12 inches) are expected across southeastern Montana, northwestern South Dakota, and southwestern to central North Dakota April 13, with heavier accumulations possible in western North Dakota. Heavy snowfall is likely to continue in North Dakota and Minnesota April 13-14.

In addition to the precipitation, strong wind gusts could lead to periods of blowing and drifting snow. Sporadic power outages are likely throughout the affected area.

Transport
The winter weather will likely cause ground and air transport disruptions across much of the affected areas over the coming days. Traffic and commercial trucking delays are possible along regional highways. Dangerous and challenging driving conditions are also likely on secondary and rural roads in the affected states as maintenance crews prioritize clearing major routes. Authorities could close stretches of highways if driving conditions become too hazardous. Gusty winds may threaten to topple high-profile vehicles throughout the affected area. Flight delays and cancellations are likely due to ground stops and deicing operations at airports in the region.

Advice

Monitor local media for updated weather information. Verify road conditions before driving in areas where heavy snowfall is forecast. Allow extra time to reach destinations in these areas and carry an emergency kit and warm clothes if driving is necessary, especially on secondary or rural routes that could become impassable. If routing shipments by truck through the affected area, plan accordingly for delivery delays. Confirm flights. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

US National Weather Service
US Road Conditions
Weather Prediction Center