This tornado touched down at 5:40 pm and struck farms on the east side of Leamington. Residents captured photos and videos of the twister, an elongated, classic cone tornado that was briefly condensed all the way to the ground. It struck several properties, flattening crops, snapping trees, destroying a solar panel and seriously damaging a large greenhouse. On that property, the tornado narrowly missed the farmhouse but blew out most of the glass from the greenhouse, leaving shards spread through nearby fields.
This was the first of two tornadoes that touched down in Southern Ontario on August 11; the second was an EF2 tornado at Hawkesville.
Figure 1 depicts the surface observations at 8:00 pm EDT, which shows a low pressure system over Owen Sound with a cold front extending south into southwestern Ontario and a warm front extending east into central Ontario/Quebec. A thunderstorm (marked as a red ‘R’) was also observed over London.
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 00Z Sat Aug 12 2017. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php