A video of a thunderstorm in Kitchener, ON, is circulating online and has sparked concerns over a possible tornado. However, Environment Canada says the phenomenon is a natural occurrence that commonly accompanies severe thunderstorms. Despite the cloud’s menacing appearance, Environment Canada says the swirling formation does not appear to be a tornado, but rather a shelf cloud, which typically occurs alongside severe thunderstorms and strong wind gusts. According to Alexopoulos, shelf clouds occur regularly throughout the year, and are most notable in Southern Ontario during the summer months, when thunderstorms and windy conditions are present. AdvertisementThough the cloud may resemble a tornado, Alexopoulos says a shelf cloud tends to appear more linear and typically forms under unidirectional winds.