Figure 1 shows the surface observations at 7:00 am CDT, which shows a low pressure developing in southern Saskatchewan and a low pressure in northern Manitoba. Southern Manitoba is observed as being in the warm sector in the morning hours of August 4th. A cold front would later develop and move through Saskatchewan and western Manitoba, which triggered thunderstorms and ultimately this tornado in the evening hours of August 4th.
According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 7:00 pm CDT near MacGregor, MB. The track and width of this tornado was not documented by ECCC. The tornado caused no injuries, fatalities or property damage.
Sources
NOAA Central Library. (2020). U.S. Daily Weather Maps. Thursday August 4, 1983 [PDF]. Retrieved from https://library.noaa.gov/Collections/Digital-Collections/US-Daily-Weather-Maps
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/