Huntsville, ON EF1 Tornado of August 4, 2017


This tornado touched down at 3:52 pm and tracked to the northeast, narrowly missing downtown Huntsville as it moved toward Fairy Lake. Through the south end of town it struck several homes, sending trees crashing through roofs and smashing down onto vehicles. One house had its roof surface peeled away and a shed blown apart. Large tracts of trees were snapped leaving behind shattered stumps and twisted limbs, and the damage path was measured to be up to 150 metres wide. After passing for one kilometre over land, it moved out over Fairy Lake, striking cottages on the shoreline. Again, collateral tree damage was extensive as they toppled down. The tornado was caught on video by cottagers as it passed across the lake, a rain-wrapped column of spray that rose in a tube from the water surface. The tornado travelled an additional 1.5 kilometres over the lake before it dissipated.

More photos of the damage left behind as a tornado touched down in Huntsville yesterday afternoon. It cut a swath…

Posted by Hunters Bay Radio on Saturday, August 5, 2017

This was the second of three tornadoes that ripped through the Muskoka Region on August 4. The first tornado to touch down was an EF1 at Utterson; the final tornado was an EF2 that struck Rebecca Lake and Bella Lake causing devastating destruction of forest and damage to cottages.

Figure 1. Surface analysis at 18Z on August 4, 2017 showing mean sea-level pressure (MSLP) contours, surface observations, fronts and pressure centres (WPC, 2017)

Figure 1 depicts the surface observations at 2:00 pm EDT, which shows an occluding low pressure system over Sault Ste. Marie, a warm front in northern Ontario/Quebec and a strong cold front moving across southwestern Ontario and Georgian Bay. The cold front became the focus for intense thunderstorms in the afternoon and evening hours of August 4th, which resulted in three tornadoes across Ontario.


NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 18Z Fri Aug 4 2017. Retrieved from: