On the evening of Tuesday, August 7, 1979, at least three tornadoes touched down in southwestern Ontario, devastating scores of farms and homes in the Woodstock area. The southern end of that city suffered some of the most intense destruction along with several other nearby towns in Oxford County. Two people died, 142 were injured, and hundreds of homes suffered significant damage. Overall monetary losses totaled an approximate $100 million in 1979 Canadian dollars.
Meteorological synopsis
A relatively cool and dry air mass was being pushed in from the north by means of a cold front, into warm and unstable air from the southern United States. Severe weather had already affected northeastern Ontario the evening before with this same cold front. During the late morning of the 7th the front had stalled across the Bruce Peninsula, where newer convection produced a couple of weak F1 tornadoes near the towns of Wiarton and Tara. It has been speculated that a large outflow boundary associated with these particular storms may have interacted with the lake breeze fronts, thus resulting in the Woodstock and Stratford tornadic supercells later that day.
The Ontario Storm Prediction Centre in Toronto issued a severe thunderstorm watch for southwestern Ontario at 3:40 pm. The first thunderstorms of the afternoon began forming over Lake Huron before coming ashore in southern Bruce County (Toll, 1980). Storm motion was primarily to the southeast, and as these storms quickly began to intensify, reports of large hail began to pour in. A severe thunderstorm warning was issued at 6:15pm for Oxford, Perth County and Waterloo Region (Toll, 1980). A broken line of intense thunderstorms propagated toward Highway 401 with the two most intense storms located near Stratford and Embro. At this point, a tornado touchdown was mere minutes away as they began to morph into the powerful supercell variety, possibly a result of convergence along the Lake Erie and Lake Huron breeze fronts.
Stratford and Woodstock tornadoes
At 6:18pm, the supercell thunderstorm located near Stratford spawned a tornado a couple of kilometres south of that town. Moving to the southeast at approximately 60 km/h, it quickly became stronger and as it passed north of Hickson some twenty minutes later, its path had widened to 1 kilometre as the tornado attained F4 intensity. Farm homes and outbuildings along the path were leveled by the tornado. The path began to curve towards the east-northeast thereafter as the tornado began to weaken (Newark, 1979). It dissipated approximately four kilometres east of Bright at 6:56pm, after some 30 kilometres on the ground.
At around 6:52 pm, a separate supercell thunderstorm northeast of Embro dropped a tornado near the village of Golspie. As it approached the city of Woodstock within the next ten minutes, the tornado quickly widened to over half a kilometre and took on the appearance as a dark stovepipe or wedge tornado, not unlike those witnessed in the Midwestern United States (Grazulis, 1991). As many as 300 structures sustained damage in a four-kilometre track from Ingersoll Road through Sixth Avenue to Parkinson Road and approaching Highway 401. A church and a school near the intersection of Highway 401 and Norwich Avenue were both destroyed (Toll, 1980). Trees that remained standing were partially debarked and, in a few instances, straw and other small objects were found embedded into the trunks. Among some of the other oddities were a pond in Southside Park that was reportedly sucked dry by the tornado, and a fourteen-foot aluminum boat carried for almost a kilometre. Crossing Highway 401 it blew a tractor-trailer rig into the centre median, badly injuring the driver (Toll, 1980).