Canada: Severe weather forecast across southern regions through at least Dec. 9

Severe weather is forecast over parts of southern Canada through at least Dec. 9. A winter storm is forecast to bring a wintery mix of snow, freezing rain, and rain to the region. Freezing rain of 1-6 hours, snowfall totals of 5-20 cm (2-8 inches), and maximum wind speeds of 50-60 kph (31-37 mph) are forecast. Flooding is possible in areas where heavy rainfall occurs and hazardous travel conditions are likely in areas where more wintry precipitation falls due to slippery roads and reduced visibility caused by blowing snow.

As of late Dec. 7, Environment Canada has issued the following warnings:

• Red freezing rain warnings (the highest level on a three-tier scale): east-central Alberta through Dec. 7 and far southeastern Saskatchewan and far southwestern Manitoba through early Dec. 8.

• Red winter storm warnings: Trans-Canada Highway from Eagle Pass to Rogers Pass in British Columbia through Dec. 7, west-central Alberta, central Saskatchewan, and the rest of southwestern Manitoba through early Dec. 8, far southeastern Alberta through the evening of Dec. 8, and far southwestern Saskatchewan through Dec. 8.

• Red snowfall warnings: Highway 3 from Paulson Summit to Kootenay Pass and West Columbia region through Dec. 7, Coquihalla Highway from Hope to Merritt and from Pontiac to the Laurentians in Quebec through early Dec. 8, and southeastern Manitoba through Dec. 8.

• Yellow winter storm watches: Arrow Lake, City of Thunder Bay, Cloud Bay, Dorion, Kakabeka Falls, and Whitefish Lake in Ontario through the evening of Dec. 9.

• Grey weather advisories: southern Ontario through the evening of Dec. 9.

Officials could update and extend the coverage of weather alerts over the coming hours.

The storm system could produce rounds of heavy precipitation, including rain and snow, and strong winds across 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, as well as 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. Precipitation could fall as snow in parts of the affected area over the coming days. Wind gusts could cause blowing and drifting snow; decreased visibility is likely in these areas.

Floodwaters and related debris may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas could also result in significant traffic congestion. Heavy snow will likely make driving hazardous in some areas; authorities could implement temporary road closures or detours in such locations.

The disruptive weather will likely cause some delays and cancellations at airports in the region. Flooding or snow could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding or strong winds, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.