Maple, ON F0 Tornado of June 2, 1999

York - Durham

A CANWARN storm spotter observed a tornado touching down briefly at around 8:00pm, snapping the branches off of trees. This was one of two tornadoes to touch down in Southern Ontario on June 2; the other was an F1 at Purple Valley that snapped trees and destroyed a pole barn.

Figure 1 depicts the surface observations at 8:00 pm, which depicts a low pressure in central Ontario with a cold front extending across southern Ontario. This cold front became the focus of intense thunderstorms, which eventually led to this F0 tornado.

Figure 1. Surface analysis at 00Z on June 3, 1999 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 12:00 pm EDT near Purple Valley, ON. The tornado travelled for 1 km and had a maximum width of 50 metres. The tornado caused no fatalities or injuries, but caused $60 thousand dollars in property damage.


NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 00Z Thu Jun 3 1999. Retrieved from:

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