by Jim Farrell
EDMONTON – Weather forecasters use all manner of technological gimmicks so they can tell the public when a tornado is heading our way. But the best device is still a human eyeball connected to an objective brain.
“We usually require a reliable report of a tornado on the ground and even then we won’t take someone’s word,” says Dan Kulak, extreme weather specialist with Environment Canada’s Edmonton office. “We ask questions.”
Last year, Environment Canada enlisted the help of amateur radio operators around the province to keep an eye on the sky. Fifty ham radio operators from the Edmonton area took a five-hour course on the basics of meteorology and what to look for in cloud formations.
Another 50 from central and southern Alberta took the same training, all of it intended to avoid false reporting of would-be major storms.
Now, whenever Environment Canada issues a severe weather watch, it alerts the network of amateur radio volunteers, usually through a text message or phone call to a co-ordinator. Volunteers then contact other members of the ham radio network, asking them to report signs of approaching severe weather, including lightning, hail, cumulonimbus or funnel clouds.
That eyeball-to-radio system represents a final stage of Alberta’s tornado-warning system. Weather analysis done the day before possible storm conditions is the first stage.
“Our numerical weather models will flag the forecast for the next day as having the potential for severe weather,” says Steve Ricketts, acting regional director for Environment Canada’s meteorological service. “A forecaster will issue a severe thunderstorm watch and can narrow it down to two or three or maybe five counties.”
In the morning, Environment Canada will issue the severe thunderstorm watch and warn people in the forecast area to stay tuned to their radios or TVs throughout the day.
If the clouds begin to brew up, Environment Canada will issue a severe thunderstorm warning. If the agency’s Doppler radar installations detect circular motion within a towering storm cloud, it will raise the thunderstorm warning to a tornado warning.
The circular motion of water droplets, or even clouds of dust or other particles within a storm cloud, indicates that cloud may be spawning a tornado or may have already given birth to one. At that point local radio and TV stations will interrupt their broadcasts with a single, high-pitched tone to get people’s attention. A recorded message with a tornado warning will come on the air.
Alberta is the only province with this type of alert system. It was created by the Alberta government shortly after the Edmonton tornado. It can stand some improvement, however, since it only uses local TV and radio. If people are tuned into satellite television or an American cable station, for example, they will miss the warning.
“We are working with Public Safety Canada and the CRTC to issue the message at the cablehead, through all the cable TV channels,” Ricketts says. “That project has been in the works for a couple of years through Public Service Canada. I don’t know why it hasn’t happened yet.”
Doppler radar was first used to analyze the inner workings of a tornado when a twister swept through Union City, Okla., on May 24, 1973. That discovery led to dramatic improvements in accuracy and lead time in forecasting severe storms in the United States and a resulting ability to save lives and prevent serious storm-related injuries.
Between 1990 and 1997, the U.S. government acquired and installed a network of 158 Doppler radars, most of them operated by the U.S. National Weather Service.
Alberta got its first Environment Canada Doppler radar installation shortly after the 1987 tornado. Five units now cover the province.
In the U.S., Doppler radar increased the lead time of tornado warnings from five minutes to 13 minutes — just long enough for most people to take cover if they’ve heard the alert on radio or television.
Those eight extra minutes can save hundreds of lives. That’s especially true in the heart of the United States’ tornado alley, where residents know enough to take cover. In 1999 an F5 tornado with winds of 418 to 509 km/h (the highest magnitude possible) slammed into Oklahoma City. Despite that city’s high population density, only 12 people died.
In Canada, the chances of dying in a tornado are likewise small. There have been the occasional large clusters of fatalities — 27 in Edmonton in 1987, 13 in the 2000 Pine Lake tornado, 12 in Barrie, Ont., in 1965 and 28 in Regina in 1912 — but most fatalities come in ones and twos.
Overall, Canadians stand a one-in-12-million chance of dying in a tornado. Every year as many as 150 of Canada’s 33 million people are injured by lightning strikes. Eight to 12 are killed.