Five Questions About Frankenstorms

U of A weather expert Gerhard Reuter answers questions about the recent flooding in southern Alberta, Frankenstorms and how to change the weather.

If it falls from the sky, Gerhard Reuter probably knows all about it. The earth and atmospheric sciences professor is the university's precipitation specialist and the City of Edmonton's go-to guy when it comes to developing weather-predicting models and flood forecasts.

Why was the flooding in southern Alberta so bad this year? It was a mixture of heavy rainfall and saturated soil. The thing is that in southern Alberta, when you're close to the mountains, the water moves a lot faster.

Is climate change to blame?
I think there's something in common. Our understanding isn't totally complete, though. As a researcher, you're very skeptical. I think the main thing is that the mid-latitude wind belt or jet stream - where Edmonton, Calgary and all of southern Canada lies - is between the cold Arctic and the warm subtropics, and the temperature contrast is decreasing. The Arctic warms up, and there is less ice, less snow and the ice caps melt, so it's getting a bit warmer. The implications are that the temperature contrast is less and the wind speed is less. And that means that systems don't move as fast, and they stay over one space longer. But I wouldn't go as far as to say that we humans are completely responsible for all the climate change. Climate has always changed. Climate is the average of weather and the weather changes from day to day.

Are you more concerned about floods now?
No. I think I'm maybe more nervous that people, as a whole, don't organize ourselves to deal with disasters very well. I don't think we're the best stewards of our resources and energy. In this case, people had very little notice, and the impact of that could be weakened if people had better advance notice. I think science is in the stage that a better forecast is possible. You could go, "OK, it seems the weather patterns line up. Several models say it's very likely that it rains. We are not 100 per cent sure about that, but make some preparations." [In southern Alberta] I think these flooding cases are predictable within a week before, knowing the conditions of that area.

What's a Frankenstorm?
When you look at the rainstorms where there's more than 100 millimetres at one point, some people have called them giant storms. [Fifty millimetres of rainfall within 24 hours is enough for Environment Canada to issue a rainfall warning.] You don't have them every year, these "monster storms." Over 10 years, you might have five. Or, in some years you might have two or three of them within one month - always between May and August, but mostly in June. It's not something completely new, but I think the atmosphere conditions might make these more common.

I heard you know how to change the weather. Is that true?
I don't think it really works. There's a whole scientific hypothesis of weather modification, or cloud seeding, where you put materials into the clouds to increase precipitation. If you can make ice crystals in liquid clouds, you could turn the liquid phase into the ice phase, and I think it's a really good way to clear up fog. If you put ice crystals there, the droplets will form drizzle and rain out and clear up. In Alberta, they use it for hail seeding, where they increase the amount of precipitation and decrease the size of the hail. I don't think it works, but it's probably worthwhile to do some research about it. Of course, we have inadvertent weather modification all the time. If you make a dam or drive a car or if you put pollution in the atmosphere, you change it.