This F0, cone tornado touched down near Midland and did not produce any damage. There were several witnesses to the event and it was confirmed based on a video that was taken near the Pillsbury Plant in town.
Figure 1 depicts the surface observations at 5:00 am EDT, which shows an occluding front moving across southwestern Ontario. This front likely became the focus of thunderstorms, which ultimately led to this tornado.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 09Z Sat Aug 11 2012. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php
