What causes Environment Canada to issue a Tornado Warning?

On Tuesday night, residents of the Moose Jaw area were greeted with a severe thunderstorm, that featured the elements to trigger a Tornado Warning by Environment Canada.  

Areas of Chaplin, Mortlach, Shamrock, Old Wives Lake, Caronport, and Caron all were under a tornado warning for over an hour, as a strong storm cell was moving east through the area.  

Meteorologist, Natalie Hasell says that the warning was based on what their weather radar was showing prior to it being issued.  

“We don’t have eyeballs in our systems on the ground,’ says Hasell. “We can tell that something could be coming out of the storm, but we don’t know until we get a report.” 

At this time Hasell does not have enough information to confirm whether a tornado did occur near Moose Jaw but did say that hail, strong winds, and torrential rainfall were seen.  

Though there wasn’t a confirmed tornado around Moose Jaw, Hasell did say that they did receive a report about a funnel cloud that emerged around Regina.  

The question remains what are the parameters around issuing a Tornado Warning by Environment Canada? 

Hasell says that a number of factors have to come together for a severe thunderstorm, which could lead to a tornado warning.  

“We need moisture at low levels, this could be local or from quite a distance like the Gulf of Mexico. We need an unstable atmosphere, so that’s an atmosphere that will allow vertical motion since thunderstorms are vertically developed clouds. We need a trigger or something to start the upward motion so a lifting mechanism. The fourth element is wind shear or the vertical profile of the wind in the atmosphere. Certain profiles lead to the formation of storms that are more likely to produce tornadoes.” 

If all these come together, they can identify an area where severe thunderstorms or possibly tornadoes will occur.  

Then Environment Canada will continue to track the speed of the storm’s development through satellite and radar signatures. 

Environment Canada relies on the public to submit videos and pictures of storms, allowing them to investigate further and confirm whether a tornado has formed or touched down.  

In addition, they have to investigate the amount of damage that has been done using their EF scale. In Canada, tornadoes are rated from EF0 with winds of 40-72 mph and light damage, all the way up to EF5 which has wind speeds ranging from 261-318 mph and creates catastrophic damage. 

“We look for reports of damage. The type of damage, the extent of damage, the severity of the damage, and the pattern of the damage. This would help identify if a tornado occurred in a particular area.” 

Hasell concludes by saying that tornadoes are pretty rare, as people will see torrential rainfall, strong winds, and hail more often than a tornado.  

So far this season, only one tornado has been confirmed, which was back in May near Regina.  

Last year, 15 tornadoes were confirmed to touch down in Saskatchewan, which is around the average for the province.    

Between 1991 and 2021 the average number of tornado sightings each year in Saskatchewan is 13.