US, Canada: Adverse weather likely in West, Southwest, Northwest, Northern Rockies and Plains regions, US, and western Canada through at least Jan. 5 /update 39

Event

Adverse weather, including heavy snow, rain, and flooding, are likely in parts of the West, Southwest, Northwest, Northern Rockies and Plains regions, US, and western Canada through at least Jan. 5. Lingering disruptions are ongoing in British Columbia, Canada, following severe flooding.

Authorities in British Columbia have extended the provincewide state of emergency through Jan. 11 following severe flooding in November. Additional rainfall could result in flooding or flash flooding on already saturated soil and exacerbate current disruptions.

Government Advisories
A "High Risk" for heavy snow of more than 10 cm (4 inches) is in place across portions of the Pacific Northwest to the Central Rockies through Jan. 5. Widespread snowfall is likely.

As of early Jan. 3, the US National Weather Service has issued winter storm warnings for northern California, central Oregon, and most of Washington. Winter weather advisories are in place for much of the rest of the affected area. Avalanche warnings are also in place for the mountains in central and southwestern Utah as well as the mountains in central Colorado.

The Meteorological Service of Canada has issued red (the highest level on a three-tier scale) snowfall, winter storm, arctic outflow, and extreme cold warnings for northern Alberta, much of British Columbia, northern Manitoba, and northern Saskatchewan provinces as well as southern Yukon Territory. Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.

Hazardous Conditions
Snow accumulations are likely across the affected area. Lesser accumulations are possible where sleet and freezing rain mix with the snow, and precipitation are less intense. In addition to the heavy snow, strong wind gusts will likely lead to periods of blowing and drifting snow. Blizzard conditions are possible. Sporadic power outages are possible throughout the affected area.

Where precipitation falls as rain, flash and areal flooding is possible. Such flooding is possible in low-lying communities near watercourses and other large bodies of water and in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs may be subject to flash flooding after relatively short periods of intense rainfall.

Transport
Sections of highways 1 and 8 and many other roads in British Columbia remain closed due to heavy rain, landslides, and damage. Road reconstruction is underway, and authorities have estimated that Highway 1 will reopen in mid-January. Authorities have not provided an estimation for the reopening of Highway 8. Authorities are restricting the types of vehicles permitted to travel on sections of highways 5 and 99. Additional 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. Flight delays and cancellations are likely due to ground stops and deicing operations at regional airports.

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
Meteorological Service of Canada
DriveBC