Lake Shebandowan, ON F1 Tornado of July 17, 1990

Atikokan - Upsala - Quetico

Witnesses reported observing two tornadoes touching down at around 8:45 pm, however it is likely this was one multiple vortex tornado. Trees were snapped and uprooted as the tornado came ashore from Kabaigon Bay, and several cottages sustained extensive structural damage.

Figure 1 depicts the surface analysis at 4:00 pm CDT, depicting an occluding front into northwest Ontario and a lifting warm front near the Ontario/Minnesota border. The warm-occluding front intersection became the focus for intense thunderstorms later in the evening, leading to this F1 tornado.

Figure 1. Surface analysis at 21Z on July 17, 1990 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017).

According to Environment and Climate Change Canada (2018), an F1 tornado touched down at 8:45 pm CDT near Kabaigon, ON. The track and width of the tornado was not documented by ECCC. The tornado caused no injuries, fatalities or property damage.


NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 21Z Tue Jul 17 1990. Retrieved from:

Environment and Climate Change Canada Data. (2018). Canadian National Tornado Database: Verified Events (1980-2009) – Public. Retrieved from: