Figure 1 shows the surface observations at 7:00 am CDT, which shows no true forcing mechanism. It is possible that a storm developed as a result of lake-breeze interactions or a trough of low pressure nearby in the morning hours of June 15th.
According to Environment and Climate Change Canada (2018), an F0 tornado touched down at 9:00 am CDT near Traverse Bay, MB. The track and width of the tornado was not documented by ECCC. The tornado caused no fatalities, injuries or property damage.
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 12Z Wed Jun 15 1988. 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/