At about the same time the Lion's Head tornado dissipated, two very severe thunderstorms had developed (that probably owe their inception, at least partially, to lake breeze convergence): one to the east of Clinton and another further to the north, in the Walkerton area.
These two developing supercells would grow into a pair of incredibly devastating, monster storms within the next hour - likely the most prolific tornado producers in Canadian history to date.

The second tornado of the day touched down south of Hopeville around 3:45pm, causing some localized F3 damage along its track.
This tornado lifted after a 17-kilometre (11 mi) path, but another tornado quickly formed just north of Corbetton, in northern Dufferin County at about 4:15pm.
It stayed over rural areas for most of its 40-kilometre (25 mi) path, however a few homes (especially in the Terra Nova and Mansfield area) sustained F3 damage (it has been somewhat disputed whether this path was of two separate tornadoes, rather than just one).
In any case, shortly after this tornado had clearly dissipated, there were hints of another brief touchdown near Angus in the Blackdown Park training area of Canadian Forces Base Borden (north of Alliston).
This northern storm, clearly a cyclic supercell, was far from finished.
The next tornado was the last of this storm, but was the most infamous one.
It formed in southern Simcoe County (Essa Township), less than 10 kilometres (6.2 mi) southwest of Highway 400 and the Barrie city limits.

At approximately 4:00pm, all electrical power in Barrie went out, as the Grand Valley/Tottenham tornado took out the main hydro transformers, southwest of the city (LeGrand, 1990).
Few residents had any idea of what was looming over the horizon, but many people were let off work 30–45 minutes before the storm hit due to these power outages.
Had this not happened, the death toll would have undoubtedly been much higher.
The intensifying tornado first obliterated a pine tree forest plantation.
Some 10-metre (33 ft) high trees were snapped at the 2-metre (6 ft 7 in) level.
At this point the damage path was about 600 metres (2,000 ft) wide, moving steadily towards the east-northeast.
It then entered the southern part of Barrie shortly before 5:00pm.
Visibility was very low as the tornado was cloaked in heavy rain and dust, thus making it very difficult to see.
Extensive F3 (although some localized F4) damage occurred to an entire square block of homes in the Crawford Street and Patterson Road subdivision.
Five people were killed in the area as some homes there were not well-built, and thus collapsed after being pushed off their foundations.
Two of these five deaths included a mother and son, killed when their Crawford Street home was completely levelled (Bruineman, 2010).
Most of the fatalities occurred in homes with no basements, where head and chest trauma resulted from an increased exposure to flying debris.

Next, the tornado hit an industrial complex (known then as Molson Park).
One person died at a tire retreading facility while at least fifteen other businesses were damaged or destroyed (Bruineman, 2010).
Steel I-beams were twisted horribly out of shape, and splinters of wood were found embedded into nearby concrete walls.
The tornado then proceeded to cross Highway 400 at Essa Road (former Highway 27) interchange, just missing the Barrie Racetrack to the south.
The grandstand was heavily damaged and several barns nearby were destroyed.
A man was killed after he was sucked out of his parked car in an adjacent lot (Bruineman, 2010).
Several vehicles traveling on Highway 400 were tossed into the ditch, their drivers escaping with only minor injuries.
Highway guard rails were found wrapped around telephone poles nearby.
Many cars were also found with puncture holes in their frames, owing to the flying debris.
As it crossed the highway, it moved into the Allandale subdivision.

Many homes sustained severe damage there, with much of their upper floors missing.
By this time the tornado's path had narrowed to about 300 metres (980 ft).
The track mov
At about the same time the Lion's Head tornado dissipated, two very severe thunderstorms had developed (that probably owe their inception, at least partially, to lake breeze convergence): one to the east of Clinton and another further to the north, in the Walkerton area. These two developing supercells would grow into a pair of incredibly devastating, monster storms within the next hour - likely the most prolific tornado producers in Canadian history to date.
The second tornado of the day touched down south of Hopeville around 3:45pm, causing some localized F3 damage along its track. This tornado lifted after a 17-kilometre (11 mi) path, but another tornado quickly formed just north of Corbetton, in northern Dufferin County at about 4:15pm. It stayed over rural areas for most of its 40-kilometre (25 mi) path, however a few homes (especially in the Terra Nova and Mansfield area) sustained F3 damage (it has been somewhat disputed whether this path was of two separate tornadoes, rather than just one). In any case, shortly after this tornado had clearly dissipated, there were hints of another brief touchdown near Angus in the Blackdown Park training area of Canadian Forces Base Borden (north of Alliston). This northern storm, clearly a cyclic supercell, was far from finished. The next tornado was the last of this storm, but was the most infamous one. It formed in southern Simcoe County (Essa Township), less than 10 kilometres (6.2 mi) southwest of Highway 400 and the Barrie city limits.
At approximately 4:00pm, all electrical power in Barrie went out, as the Grand Valley/Tottenham tornado took out the main hydro transformers, southwest of the city (LeGrand, 1990). Few residents had any idea of what was looming over the horizon, but many people were let off work 30–45 minutes before the storm hit due to these power outages. Had this not happened, the death toll would have undoubtedly been much higher. The intensifying tornado first obliterated a pine tree forest plantation. Some 10-metre (33 ft) high trees were snapped at the 2-metre (6 ft 7 in) level. At this point the damage path was about 600 metres (2,000 ft) wide, moving steadily towards the east-northeast. It then entered the southern part of Barrie shortly before 5:00pm. Visibility was very low as the tornado was cloaked in heavy rain and dust, thus making it very difficult to see. Extensive F3 (although some localized F4) damage occurred to an entire square block of homes in the Crawford Street and Patterson Road subdivision. Five people were killed in the area as some homes there were not well-built, and thus collapsed after being pushed off their foundations. Two of these five deaths included a mother and son, killed when their Crawford Street home was completely levelled (Bruineman, 2010). Most of the fatalities occurred in homes with no basements, where head and chest trauma resulted from an increased exposure to flying debris.
Next, the tornado hit an industrial complex (known then as Molson Park). One person died at a tire retreading facility while at least fifteen other businesses were damaged or destroyed (Bruineman, 2010). Steel I-beams were twisted horribly out of shape, and splinters of wood were found embedded into nearby concrete walls. The tornado then proceeded to cross Highway 400 at Essa Road (former Highway 27) interchange, just missing the Barrie Racetrack to the south. The grandstand was heavily damaged and several barns nearby were destroyed. A man was killed after he was sucked out of his parked car in an adjacent lot (Bruineman, 2010). Several vehicles traveling on Highway 400 were tossed into the ditch, their drivers escaping with only minor injuries. Highway guard rails were found wrapped around telephone poles nearby. Many cars were also found with puncture holes in their frames, owing to the flying debris. As it crossed the highway, it moved into the Allandale subdivision.
Many homes sustained severe damage there, with much of their upper floors missing. By this time the tornado's path had narrowed to about 300 metres (980 ft). The track mov
1985 United States–Canada tornado outbreak