Nairn, ON F1 Tornado of August 24, 2011

London - Middlesex

Numerous trees were snapped and a large farm shed was totally demolished as this F1 tornado tracked through the Nairn area. It touched down about 6 km west of that community at about 7:50 pm, was on the ground for 10 km and had a width of 300 metres.

This was one of three tornadoes that touched down on August 24, 2011. The others occurred at Kirkwall (F1) and Neustadt (F0). In addition, this event occurred just a few days after the deadly and destructive tornado that ravaged Goderich (F3) on August 21, leaving tornado-weary Ontarians with frayed nerves.

Figure 1. Surface analysis at 00Z on August 25, 2011 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017)

Figure 1 depicts the surface observations at 8:00 pm EDT, which shows a cold front across Michigan and a warm front extending from north to south across southern Ontario. A squall line is also depicted across southwestern Ontario at this time. This line of thunderstorms was responsible for several tornadoes across southern Ontario in the evening hours of August 24th.


NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 00Z Thu Aug 25 2011. Retrieved from: