Continuing increase in hail-producing storms keeping cloud seeding program busy
Few want to see the end of summer come as much as Dr. Terry Krauss, the Alberta Severe Weather Management Society’s project director.
This year’s hail season has been one of the busiest since the society started its cloud seeding hail suppression program, where the chemical silver iodide is released into clouds to prevent the formation of large pieces of hail, in 1996.
Krauss called this season “above average” in terms of the number of days with hail-producing storms and the number of seeding flights.
As of July 31, the program, which has an annual budget of $3.1 million, had sent up 113 flights to carry out seeding activities for 59 storms on 19 days, with the “busiest week” so far running from July 20 to 25, he said.
The “prime hail season” runs from June 1 to Sept. 15.
Since 2010, the program has experienced its busiest four seasons in 17 years—with 2011 being the busiest on record for number of storms and seeding flights—and the program had to add a fifth plane this year to keep up.
“And we have already seeded with all five aircraft on three days,” Krauss said.
So he said he’s looking forward to late September, when weather patterns shift in the Western Hemisphere to bring high pressure and weather stability to Western Canada.
When asked what’s causing the increase in severe storms, Krauss said the answer is simple.
“The most common and most easiest explanation is climate change and global warming,” he said, pointing to Insurance Bureau of Canada reports stating severe incidents of weather that used to happen every 40 years are now happening every six years.
A report released by the bureau in June of 2012 states a warming climate has led to “an ever-increasing frequency of severe hail events.”
And with more hail, Krauss said, comes more damage to agriculture, infrastructure and private property.
One storm last August in the area the program covers, which stretches from High River in the south to Lacombe in the north and focuses on Calgary and Red Deer, caused $500 million in damage, he said.
In 2011, the Agriculture Financial Servicers Corporation, the province’s crop insurer, paid out $25 million on nearly 1,500 hail claims and the Insurance Bureau of Canada has stated seven of the eight hail events between 1983 and 2005 in Canada that resulted in insurance payouts of $50 million or more happened in Alberta.
Krauss said in the U.S., insurance claims for hail were up 84 per cent from 2010 to 2012.
With the number of hail-producing storms on the rise and the potential for insurance claims to increase, the society, which is privately funded and administered by insurance companies, began offering tours four years ago of the program’s nerve centre at the Olds-Didsbury Airport—where the program’s main radar is housed—for employees of various insurance agencies.
Krauss said the tours offer “everything they wanted to know about cloud seeding but were afraid to ask” and focus on dispelling incorrect information about the program.
“The common misconception is that we’re doing clear-air, broadcast seeding in order to modify the daily weather. In reality, we’re more like the firefighters who go out to put out a fire,” he said, adding storms are only seeded when they threaten towns or cities in the project area and seeding does not take place on clear days.
The tours have become so popular, Krauss said, that a 20-person cap was put in place and the society has limited the number of tours to 12 per year.
Tour participants from various regional insurance firms, he added, receive credit toward professional development and their licence renewals.
Keri Coffey, a Calgary-based intermediate underwriter with the insurance firm Aviva Canada who participated in a tour on July 31, said the tour opened her eyes to the importance of the cloud seeding program.
“It gives you a better idea about why insurers charge what they do in the hail belt. If you can prevent a disaster, you can save a lot of people money and pain,” she said, adding she planned to share what she learned on the tour with other staff at her office. “It’s great knowledge to have behind you because before coming here, I really had no idea about seeder planes.”
During the tour, participants learn about the mechanics of the program, which starts with a daily briefing and conference call where a meteorologist gives a forecast for the day.
“And our forecast success is better than 80 per cent, not only whether storms will occur, but even within one hail size, whether it’s pea-sized, grape, walnut or golf ball,” Krauss said. “Every day that we’ve forecast golf ball-sized hail, somewhere in the area, there’s been golf ball-sized hail.”
Aircrews are put on phone standby or airport standby for urgent notice of a quick launch depending on how likely a storm is to strike the program’s coverage area.
If a storm shows signs it will move into that area, a patrol flight is launched.
And if the storm threatens a town or city, seeding begins.
The program’s planes, which are based in Red Deer and the Springbank Airport near Calgary, are equipped with flares that, when a powder within the flare is electronically ignited, force out a “candle” that smokes for 35 seconds as it drops and releases the silver iodide, which Krauss calls an “ice nucleating agent.”
The chemical creates multiple small pieces of ice using water in the clouds that, if left alone, would form larger hailstones.
“Our goal is to make millions of pea-sized hail, or millions of snowflakes that don’t even make it to hail, and then it will fall and melt and fall as rain,” Krauss said.
He added that despite concerns about using a chemical in the clouds, the seeding program does not pose a risk to human health.
“Silver iodide is not a poison and is not dangerous to the environment in the concentrations that we use.”
This season, the program has so far shot 5,400 flares using a total of 203.8 kilograms of silver iodide over the program’s coverage area that spans 200 kilometres by 100 kilometres.
The heaviest seeding day ever was Aug. 12, 2012, when 26 kilograms of the chemical were used, Krauss said.
“That’s the equivalent of one bag of fertilizer. In comparison with pesticides or fertilizer dispensing, we are applying miniscule amounts of chemical,” he said, adding numerous countries have used silver iodide to fight hail for decades.
“If cloud seeding was damaging to the environment or to health, it wouldn’t be used in 30 countries or across the western United States. There have been numerous environment impact studies done and they all passed.”
As for the results of the program, Krauss said it’s easy to see on the radar when seeding reduces the intensity of a storm.
For example, he said, the storm last August that produced $500 million in damage was much more severe two hours before it entered Calgary than after seeding started.
Had that storm not been seeded, he added, the damage could have been far greater.
“You just shake your head at the thought of what could of it done if Calgary had been located 40 to 50 kilometres to the northwest. It would have been devastating.”
In spite of the program, Krauss said, hail still cost Alberta’s economy more than $1 billion last year.
But since it’s likely the damage would have been greater without seeding, the program is more necessary than ever, he said.
“It’s the economics of the problem that are keeping this program running.”