Edmonton Tornado (1987)

Preceding Meteorological Conditions

In the week leading up to the tornado, a low-pressure system over southern British Columbia fed warm and humid air into central Alberta. This increased the dew point to near-record levels. The dew point is the temperature at which air cannot hold any more water vapour, and the higher its measurement, the higher the likelihood of thunderstorms. Daytime temperatures leading up to the tornado were high, and 300 millimetres of rain had fallen in the region, which led to a rise in river water levels by eight metres. At least one storm in the days before the tornado produced tennis-ball-sized hail. In addition, there were at least 14 tornadoes across Alberta in the five days before the tornado, all of which were measured in the F0–F2 range on the Fujita Scale.

Weather forecasters indicated a heightened probability of severe thunderstorms on the day of the tornado.

Sequence of Events

A severe weather watch was issued for central Alberta on the morning of 31 July 1987, noting the potential for thunderstorms. A line of thunderstorms developed along the foothills of Southern Alberta around noon and began moving north. Another severe weather watch, this one specifically for the city of Edmonton, was issued at 1:40 p.m. MT. This was upgraded to a severe weather warning about one hour later. Tom Taylor, a resident of Leduc County, is generally credited as being the first person to report that a tornado was forming. However, he had never seen one in person before. He contacted authorities at 2:48 p.m., describing a “rope-like funnel.” This tornado only lasted about ten seconds.

Eyewitnesses described the dark clouds as having a green colour and appearing very strange, as well as the air feeling “heavy.” Eyewitness Tom Taylor watched the storm from the loft of his home and described the cloud moving toward Beaumont, a community south of Edmonton: “the belly of the cloud slumped down and it spit out a huge funnel, much larger. It was dense. You couldn't see through it.”

The tornado moved from south to north along the eastern edge of Edmonton. The same supercell that had created the rope tornado Taylor observed would touch down several more times, hitting various locations for over an hour. Tom Taylor observed buildings exploding as the tornado hit. The first weather radio tornado warnings were issued at 3:04 p.m. About twenty minutes later, the tornado struck the Mill Woods residential area south of the city, reaching F2–F3 strength. Hailstones up to 10 cm in diameter were reported, and the tornado damaged over 30 homes. The tornado next hit Edmonton’s Strathcona Industrial Park, an area locally known as Refinery Row, where it claimed its first 12 victims. At this point, the tornado was estimated to be at its peak intensity, rating an F4 on the Fujita Scale.

Edward Lozowski, a former professor of earth and atmospheric sciences at the University of Alberta, described the tornado as appearing black and “looked like a monster.” The tornado continued toward the Clareview area northeast of the city, where it struck the Evergreen Mobile Home Park Court. Fifteen people were killed there, with up to 200 homes destroyed. Mayor Laurence Decore declared a state of emergency at 6:15 p.m. after the tornado had dissipated and when the full scale of the destruction had become apparent. The tornado sent cars, trucks and trailers hurtling through the air, derailed freight trains and destroyed heavy equipment. The tornado moved between two operating oil refineries as it passed through the Strathcona Industrial Park. It came very close to hitting a chemical plant, a power plant and another mobile home park, Maple Ridge.

A Unique Tornado

Aside from its overall destructiveness, the Edmonton Tornado of 1987 was unique in several respects. It was a very slow-moving tornado, estimated to have lasted between one and two hours. It produced a considerable amount of hail and a high amount of precipitation, resulting in flash flooding in various locations. The same supercell is estimated to have produced seven tornados on the same day. The disappearance of vortices created by the supercell and the multiple tornados it caused in different areas around Edmonton may have caused confusion about where the tornado was located or whether it was still happening. Five different funnel types were observed during the tornado: rope, cone, columnar, smoke-like and multiple vortices.

The Edmonton Tornado also caused various unique incidents. A 330-metre-long, 4 x 8-metre, oval-shaped, buried, corrugated steel storm sewer was sucked flat. An empty 22-metre-wide oil tank “skipped” 170 meters, jumping over power lines. The overhead cranes inside a steel mill were torn off their rails.

Statistics

The tornado was estimated to have been on the ground for more than an hour and lasted at least two hours in total. Winds were estimated to have reached a top speed of 418 kilometres an hour. The powerful winds were so strong that eyewitnesses described them sounding like a freight train. It travelled 30.8 kilometres and was 1.3 kilometres wide at its widest point. The tornado killed 27 people (though an initial estimate placed the death toll at 36) and is believed to have injured at least 300. More than 300 homes were destroyed, and hundreds more buildings were damaged. The tornado caused an estimated $330 million in damage, more than $771 million adjusted for inflation.

Legacy

The main legacy of the Edmonton Tornado lies in enhancements to Canada’s national weather radar network, as well as improvements to emergency management agencies. The province of Alberta replaced the Emergency Public Warning System as a consequence of the tornado. The Alberta Emergency Alert was designed to break into both public and private radio and television broadcasts to issue an alert rather than waiting for individual stations to report emergencies. Citizens surveyed after the tornado indicated a wide variety of different warnings coming in at different times. The Edmonton Tornado also prompted the government of Alberta to create the Alberta Emergency Management Agency (AEMA) in 1988. AEMA is responsible for coordinating government resources for 57 different kinds of disasters.