Figure 1 shows the surface observations at 7:00 am CDT, which shows a low pressure near the Ontario/Manitoba border and a stationary front across central Manitoba. The stationary front likely became the focus for thunderstorms in the afternoon/evening hours of August 8th, which ultimately led to three tornadoes across Manitoba.
According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 6:00 pm CDT near Winnipeg Beach, MB. The tornado travelled for 100 metres, but the width of the tornado was not documented by ECCC. The tornado caused no fatalities, no injuries and no property damage.
Sources
NOAA Central Library. (2020). U.S. Daily Weather Maps. Wednesday August 8, 1984 [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/
