Canada: Adverse weather forecast in central and eastern regions through at least Dec. 1

Event

A low-pressure system is forecast to bring a combination of heavy rainfall, snowfall, and strong winds across parts of central and eastern Canada through at least Dec. 1. Precipitation is more likely to fall as snowfall in more northern parts of the affected area, whereas closer to the US border precipitation is mostly expected to fall as rain before turning to snowfall late Nov. 30 as temperatures across the region begin to drop. Rainfall totals of up to 5 cm (2 inches) and snowfall accumulations of up to 20 cm (8 inches) are possible in parts of the affected area, as well as winds gusting up to 100 kph (62 mph). Heavy downpours could trigger flooding in low-lying areas, as well as flash floods and ponding on road surfaces. The combination of strong winds and heavy snowfall could lead to hazardous driving conditions due to slippery roads and reduced visibility.

As of early Nov. 30, Environment Canada has issued the following weather warnings across the affected area:

• Red rainfall warnings: Parts of southern New Brunswick, southwestern Newfoundland and Labrador, Nova Scotia, and southern Quebec.

• Red snowfall warnings: Parts of central and southern Quebec.

• Red winter storm warnings: Parts of central Ontario.

• Red blizzard warnings: Parts of northern Quebec.

• Red strong wind warnings: Parts of northeastern and far southern New Brunswick, southwestern Newfoundland and Labrador, across Nova Scotia, far southern Ontario, across Prince Edward Island, northwestern, eastern, and far southern Quebec.

• Yellow snow squall watches: Parts of south-central Ontario.

• Special weather statements for strong winds, rainfall, and/or snowfall: Across most of New Brunswick, Nova Scotia, much of southern Ontario, and parts of eastern and far southern Quebec.

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

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.

Precipitation could fall as snow in many parts of the affected area over the coming days. Wind gusts could cause blowing and drifting snow, which is likely to decrease visibility. Rain-induced landslides cannot be discounted in areas of elevated terrain; there is also the possibility of avalanches in mountainous areas where the snowpack has become unstable due to heavy snowfall. Power outages could occur throughout the affected area.

Transport
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. Mountain passes and tunnels could be closed as a precautionary measure during periods of intense snowfall.

The disruptive weather will likely cause delays and cancellations at regional airports. 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, 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.

Advice

Monitor local media for weather-related updates and advisories. Confirm all transport reservations and business arrangements before traveling in the affected area. Seek updated information on road conditions before driving or routing shipments through areas where severe weather is forecast; plan for possible supply chain disruptions throughout the affected areas. Stay away from elevated streams, creeks, and other watercourses that are prone to flash flooding. Do not attempt to navigate flooded roadways. Exercise caution in elevated terrain due to the threat of landslides, as well as mountainous regions where avalanches pose a threat. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

Environment Canada