Figure 1 shows the surface observations at 4:00 pm CDT, which shows a trough of low pressure on the Saskatchewan/Manitoba border. This trough likely triggered storms in western Manitoba, which ultimately led to this tornado.

According to Environment and Climate Change Canada (2018), an F1 tornado touched down at 4:00 pm CDT near Mink Creek, MB. The track and width of the tornado was not documented by ECCC. The tornado caused no fatalities, injuries or property damage.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 21Z Fri Jun 29 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/