Canada, US: Adverse winter weather conditions forecast across parts of southern Canada and the northern US through at least March 23 /update 1

Adverse winter weather conditions are forecast across parts of southern Canada and the northern US through at least March 23. A series of weather systems across the region over the coming days will bring heavy snowfall across parts of the region. One low-pressure system will continue to bring snowfall to parts of Maine and southeastern Quebec March 21 and another is bringing snowfall to parts of southern Alberta and Montana. This second system will move generally east-southeastward over the northern plains and into the Great Lakes through March 22 before moving into the Northeast US and parts of southeastern Canada late March 22-early March 23. Another system is expected to develop over the northern plains March 23. Widespread snowfall accumulations of 10-40 cm (4-16 inches) are possible across parts of the affected area. with isolated higher totals possible over higher elevations. The combination of heavy snowfall and gusty winds may cause blizzard conditions in places. Hazardous driving conditions are likely across the affected areas due to icy roads and reduced visibility caused by blowing snow.

As of early March 21, Environment Canada has issued red snowfall warnings (the highest level on a three-tier scale) for parts of southern Alberta and southeastern Quebec, red snow squall warnings for parts of southern Ontario, and red winter storm warnings for parts of southeastern Quebec. Weather advisories are in place for parts of southern Ontario.

The US National Weather Service (NWS) has issued winter storm warnings for parts of northern northwestern Montana and central and northern Maine. Winter storm watches have been issued for parts of central, east-central, and northwestern Montana, northeastern New York, central and northern Vermont, central and northern New Hampshire, and southern Maine. Winter weather advisories are in place for parts of northern Montana, North Dakota, northeastern South Dakota, central Minnesota, northeastern Iowa, Wisconsin, far northern Illinois, north-central New York, and eastern, southern, and western Maine.

Officials will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Snow accumulations are likely across the affected area. Lesser snowfall totals are possible where sleet and freezing rain mix with snow. In addition to the heavy snow, strong wind gusts could lead to periods of blowing and drifting snow. Sporadic power outages may occur throughout the affected area.

The inclement weather will likely cause widespread ground and air transport disruptions across the affected areas. Traffic and commercial trucking delays are probable along regional highways. Dangerous and challenging driving conditions are also likely on secondary and rural roads as maintenance crews prioritize clearing major routes. Authorities will likely close stretches of highways if driving conditions become too hazardous. Gusty winds will threaten to topple high-profile vehicles throughout the affected areas. Mountain passes and tunnels will probably be closed as a precautionary measure during periods of intense snowfall. The disruptive weather will likely cause delays and cancellations at airports in the affected regions. Heavy, wet snow and strong winds could bring down power lines and trees with foliage.