At 6:39, a thunderstorm capable of producing a tornado is located 14 nautical miles northwest of Tiverton (north of Sarnia), moving east at 20 knots.
The Sarnia Police Service has activated the emergency sirens in Sarnia for this reason.
Per the Emergency Alert issued by the Ontario Alert Ready, the recommendations are to take immediate cover in a basement or interior room if weather threat approaches. Shelter from flying debris if outside.
Please check with Enviroment Canada for any further developments.