Canada: Severe weather forecast across eastern and southeastern regions through at least Dec. 13 /update 1

Severe weather is forecast over parts of eastern and southeastern Canada through at least Dec. 13. An intense low-pressure system is expected to bring a mix of heavy rainfall, freezing rain, heavy snowfall, and strong winds across the region. Rainfall totals of 2.5-6 cm (1-2.4 inches), ice accumulations of up to 0.5 cm (0.2 inches), snowfall accumulations of 15-25 cm (6-10 inches), and winds gusting up to 110 kph (68 mph) are possible across parts of the affected area. 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. Strong winds may cause property damage and power outages.

As of early Dec. 11, Environment Canada has issued the following warnings:

• Red freezing rain warnings (the highest level on a three-tier scale): Parts of eastern, south-central, and southeastern Labrador, central and western New Brunswick, and eastern and southeastern Quebec.

• Red heavy rainfall warnings: Parts of southern and western New Brunswick and southern and southeastern Quebec.

• Red winter storm and snowfall warnings: Parts of central Quebec.

• Red strong wind warnings: Parts of northeastern and southern New Brunswick, southwestern Newfoundland, northeastern and western Nova Scotia, and southeastern Quebec.

• Yellow snow squall warnings: Parts of southeastern Ontario.

• Grey special weather statements for strong winds, heavy rainfall, and snowfall: Parts of eastern, south-central, and southeastern Labrador, central and eastern New Brunswick, and western Quebec.

• Grey fog advisories: parts of southeastern Ontario and far southwestern Quebec.

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.