Figure 1 shows the surface observations at 1:00 pm CDT, which shows a low pressure across Manitoba with a cold front extending south into North Dakota and a warm front extending east across northwestern Ontario. The warm front became the focus for thunderstorms, which ultimately led to this tornado.

According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 2:30 pm CDT near Berens River, 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 18Z Mon Aug 27 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/