Winter Storms, Snowfall and Freezing Rain
Winter on the prairies is often memorable for the storms or amount of snowfall received. Storms and snowfall are both expected to increase under climate change.
Blowing snow is a main concern with winter storms. Blizzards consist of snow, high winds and often, low temperatures. Blizzards can disrupt travel and power supply and result in injury or death to people and animals.
Figure 1 shows the prairie area that is most prone to blizzards. The area centred on Swift Current, Moose Jaw and Regina receives, on average, over 25 blizzard hours annually. Saskatoon, Kindersley and Estevan fall in the next zone with between 15 and 25 blizzard hours annually.
Figure 2, shows the average number of days per year with blowing snow across the prairies for selected sites. As expected the highest number – between 17 and 24 days are located at Swift Current, Regina and Estevan. Under climate change the number of blizzard hours and days may increase.
According to the Canadian Disaster Database, severe winter storms have occurred in 1941, 1947, and 1964. The 1941 blizzard lasted 7 hours and caused 76 deaths. The 1947 blizzard was prairie-wide and lasted 10 days, burying a train in a 1km long snowdrift. The 1964 “Great Blizzard” had heavy snow, high winds and temperatures below -30°C. Three people died along with thousands of animals.
Freezing rain, a currently infrequent event, may become more common with warmer winter temperatures (Figure 3). A single event can have severe impacts, disrupting highway travel and damaging trees and infrastructure. A prairies-wide freezing rain-storm was experienced on March 6,1983. The Winnipeg airport was closed for two days and TV towers were toppled. In Canada, by far the most damaging freezing rain event was the ice storm experienced in central Canada, January 6 to 10, 1998. Power supplies were cut to cities like Montreal for many days. Twenty-eight people died, 945 were injures and 600,000 people were evacuated.
Snowfall on the prairie is normally relatively low, accounting for a small (but important) portion of total precipitation. For example, Saskatoon receives on average 35 cm of precipitation (measured as rainfall equivalent) a year. Only approximately 1/4 falls as snow, while the remainder is rain. Individual extreme snowfall events can deposit from between 24 cm and 53 cm of snow in a day (Figure 4). Heavy snowfall events such as these can shut down travel in a community or across a region.
- Personal safety is a primary concern with winter storms. Take advantage of weather information (e.g. radar), weather warnings and information on highway conditions before deciding to drive.
- Improve forecasting and highway condition information available via the media and on the internet, where feasible.
- Prepare for power outages.
- Erect snow fences and field shelterbelts where useful.
- Ensure adequate capacity for snow removal and salting/sanding.
- Continue with emergency management for major winter storms.
- Atlas of Canada (n.d.): Snow Cover Maps Natural Resources Canada http://atlas.nrcan.gc.ca/site/english/maps/environment/climate/snowcover/snowdepth[accessed February 6, 2011]
- Environment Canada (n.d): Hazardous Weather http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=15E59C08-1 [accessed December 4, 2010]
- Environment Canada (n.d.): Atmospheric Hazards Northern and Prairie Region http://pnr.hazards.ca/welcome_english.html [accessed December 4, 2010]
- Government of Canada (n.d.): Is Your Family Prepared? Severe Storms in Canada http://www.getprepared.gc.ca/knw/ris/str-eng.aspx#b1 [accessed February 4, 2011]
- Public Safety Canada (2010): Canadian Disaster Database http://www.publicsafety.gc.ca/prg/em/cdd/srch-eng.aspx [accessed Februaray 8, 2011}