Decoding the Canadian weather forecast

This story was originally titled "The Weather Report" in the December 2008 issue. Subscribe to Canadian Living today and never miss an issue!

"This is the true north strong and free, and cold and wet and icy and dark – sometimes all at once. It's why God invented long johns. This is Canada. We have winter. Life sucks. Get a toque. And embrace it." – Rick Mercer

While we don't always laugh about winter, we certainly are fascinated by it. Here's how to understand our coolest season and get through it safely.

You say it's bitter, I say it's better
The first thing we've got to realize is that there's no such thing as a "Canadian winter." There are huge climate variations in this country, says Geoff Coulson, a warning preparedness meteorologist at Environment Canada. In Regina, for example, winter is characterized by blizzards and bitter windchill, while in Windsor, Ont., heavy rain is as much a part of winter as snow. In recognition of this fact, Environment Canada uses similar terminology across the country to describe a weather event (see "Winter weather words," pages 5 and 6), but allows flexibility in the criteria each region uses. For instance, since the west coast of B.C. doesn't see a lot of snow, an accumulation of about 10 centimetres in 24 hours or less may trigger a snowfall warning, whereas southern Ontarians don't get a warning until a total of 15 centimetres of snow falls within 12 hours.

The brr factors
Typically, winter weather systems in Canada originate in the west and southwest and move east, dragging with them bitterly cold arctic air. These low-pressure systems (see "Winter weather wystems," page 6) are steered across the continent from the U.S. by the jet stream, a river of air high in the atmosphere. The greater the temperature differences between the sultry air to the south and the cold to the north, the stronger and faster the jet stream flows. Not surprisingly, the jet stream is most intense in winter.

Other factors that help determine the climate of a region include the amount of sunshine an area receives, its altitude and the presence of large bodies of open water. "Very cold air that passes over the open waters of the Great Lakes will be warmed, which has a moderating effect on the winter climate of southern Ontario," says Coulson.

In Winnipeg, on the other hand, "the nearby lakes [lakes Winnipeg and Manitoba] freeze up relatively quickly, so they have no mitigating effect on the polar express of air that comes down from Nunavut."

Be prepared
Here's what you can do to prevent becoming a winter weather casualty.
• Check the weather forecast. If a blizzard or other storm is predicted, stay somewhere safe and wait it out.

• Keep a supply of ready-to-eat, high energy food on hand, enough to last at least 72 hours, as well as a windup or battery-powered flashlight and radio. If you live in a remote area, you might want to prepare for a longer period of self-sufficiency.

• Ensure that you are able to heat at least one room of your home to 20 C. This may mean using a portable generator or an emergency heating unit such as a kerosene heater. Follow all operating instructions and be aware of the danger of carbon monoxide poisoning. Never use barbecues or camping stoves indoors.

Page 1 of 6 - on page 2, find out the best ways to brave the winter weather