This probable tornado was observed by witnesses who reported that it touched down at 4:30 pm. Trees were knocked down and a swath was torn through a corn field. Barn buildings and tobacco kilns were also damaged.
Figure 1 depicts a cold front entering southern Ontario at 5:00 pm EDT with an ongoing squall line ahead of it, which is depicted by the dashed line ahead of the cold front. This line of thunderstorms is responsible for spawning this F1 tornado.
According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 4:30 pm EDT near Aylmer, ON. The track and width of the tornado was not documented by ECCC. The tornado caused no injuries, fatalities or property damage.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Tue Aug 15 1989. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php
Environment and Climate Change Canada Data. (2018). Canadian National Tornado Database: Verified Events (1980-2009) – Public. Retrieved from: http://donnees.ec.gc.ca/data/weather/products/canadian-national-tornado-database-verified-events-1980-2009-public/