Canada: Adverse weather forecast across eastern Ontario and southern Quebec through at least March 11

Severe weather is forecast across parts of eastern Ontario and southern Quebec through at least March 11. A storm system is expected to bring rainfall over parts of southeastern Ontario and southwestern Quebec March 8 through early March 9 before precipitation gradually transitions to a mix of freezing rain and snow as the system moves eastward across the region through March 11. The heaviest snowfall is expected in northern and eastern parts of the affected area, with the heaviest rainfall likely in southwestern parts. Snowfall accumulations of 15-25 cm (6-10 inches) and rainfall totals of 2-4 cm (0.8-1.6 inches) are expected across parts of the affected area, with localized heavier amounts of precipitation possible. Strong winds may generate high tides and rough seas in areas of southeastern Quebec around the Gulf of St Lawrence. 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 early March 8, Environment Canada has issued red rainfall, snowfall, and freezing rain warnings (the highest level on a three-tier scale) for parts of southwestern Quebec around Val d'Or. Grey special weather statements for mixed wintry precipitation are in place across the rest of the affected area. Officials may 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 or snowfall due to potential track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding or snowfall accumulations, 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.