At 2:40 pm, a CANWARN spotter observed this brief tornado touchdown which caused minor tree damage in a path that was less than 100 metres long.
Figure 1 depicts a stationary front in southern Ontario at 2:00 pm EDT, which was the focus for thunderstorms and is responsible for spawning this very brief tornado.

According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 2:40 pm EDT near Tilbury, ON. The track of the tornado was 70 metres and width 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 Mon Jul 30 1990. 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/