This F1 tornado’s path of damage was 1.5 km long and 60 metres wide through the west end of Ganonoque, along Oak and Victoria Streets. Trees were snapped or uprooted and some had their tops shorn off, a shed was damaged and several houses lost shingles and siding. This was one of two tornadoes to touch down on August 21, 2011. The other occurred later in the day at Goderich (F3), and devastated the town, leaving one dead, 37 injured and over $150 million in damage.
Figure 1 depicts the surface observations at 2:00 pm EDT, which shows a cold front moving through southern Ontario. This front triggered thunderstorms throughout the early afternoon hours of August 21st in eastern Ontario, which ultimately led to this tornado.
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Sun Aug 21 2011. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php