Figure 1 depicts the surface observations at 3:00 pm MDT, which shows a low pressure system across Southern Ontario with a cold front extending southeast across Saskatchewan and Montana.
There were five tornadoes on this day, the others being:
According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 8:00 pm near Edson, AB. The path and width of the tornado was not documented by ECCC.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 21Z Wed Aug 16 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/