Seeking the perfect storm

Seeking the perfect storm

John Hanesiak chases extreme weather in the name of atmospheric science
June 30, 2009
Graduate student Justin Hobson looks on as the
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Graduate student Justin Hobson looks on as the tornado approaches the town of Elie.
Justin Hobson

Mother Nature always has the upper hand — and sometimes the last laugh.  John Hanesiak knows this well. When asked about the most memorable weather he’s tracked, the University of Manitoba atmospheric scientist and storm chaser points out that he’s witnessed several tornadoes, but the event that stands out most in his mind is the storm that wasn’t.

Hanesiak was in northwestern Iowa on a field trip with students from his storm-chasing course — the only one of its kind in Canada — when the brewing severe-weather conditions promised the perfect storm.

“The energy was enormous,” says Hanesiak. “Almost every chaser in the States was there. We sat around waiting for things to go, and nothing happened. That’s the difficulty in forecasting these storms — you either get an extreme event or you get nothing.”

June 22, 2007 - 7:00 p.m.: The F5 tornado touches
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June 22, 2007 - 7:00 p.m.: The F5 tornado touches down.
Justin Hobson

Hanesiak studies atmospheric convection, or how the atmosphere interacts with the Earth’s surface. For example, he looks at how crops and other surface features affect the moisture supply that fuels storms. Focusing his research on the Prairies and the Arctic, Hanesiak has tracked thunderstorms in Alberta and has flown through large winter storms off Baffin Island to better understand weather and climate processes. His ultimate goal is to contribute to improved weather prediction.

Severe-storm forecasting has advanced dramatically over the past decade, mainly due to Doppler radar and other technologies as well as a better overall understanding of convective systems, says Hanesiak, but computer models are not yet able to predict exactly when and where a storm will form. And some storms are simply not clear-cut, as was the case when a tornado struck the town of Elie, Man., about 30 kilometres west of Winnipeg, on June 22, 2007. It was the first F5 tornado in Canada, the highest level on the Fujita scale, which measures tornado strength based on damage indicators.

Humidity in the lower atmosphere was high for southern Manitoba that day, and the low level wind shear was strong, while winds in the middle to upper atmosphere were not as strong as one would expect for an F5 tornado. Breezes off Lake Manitoba helped trigger the storm, adds Hanesiak.

John Hanesiak and his team wait for an
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John Hanesiak and his team wait for an approaching storm.
Justin Hobson

What’s more, the Elie tornado didn’t act like an F5 storm. Instead of moving rapidly along a single track, it proceeded relatively slowly, drawing a few loops along its five-kilometre path. It levelled four homes and severely damaged a flour mill on the edge of town. Miraculously, no one was injured.

Although Hanesiak was out of town and missed the storm, one of his graduate students, avid storm chaser Justin Hobson, videotaped the tornado’s 40-minute spectacle from a country road about 1.5 kilometres south of town. It hit Elie on its downward spiral, says Hobson, whose master’s thesis focuses on the tornado. He heard it tearing through buildings, but what struck him most was its unusually slow dance. “Tornadoes are not supposed to pose for you,” he says.

As a result, the Elie tornado was a well-witnessed and recorded event. “It was almost like a trapped animal,” says Hobson. “It was covered on all angles. It formed near the radar site, so we were able to get good data on it.” In the end, the not-so-perfect storm turned out to be a perfect case study.