Figure 1 depicts the surface observations at 1:00 pm CDT, which shows a low pressure system in central Manitoba with a warm front extending east across northwestern Ontario and a cold front extending south across southern Manitoba. The warm front became the focus for intense supercells in the afternoon hours of August 5th, which ultimately led to this long-track tornado.
Several tornadoes occurred on this day:

According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 4:50 pm CDT near Petersfield, MB. The path of the tornado was not documented by ECCC, but its maximum width was 50 metres. The tornado caused no fatalities, injuries or documented property damage.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Sat Aug 5 2006. 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/