Sowing seeds on the edge of the storm to reduce hail damage

Taking to the sky to minimize hail damage Kevin Fleming reports on a team in Didsbury who cloud seed to reduce the likelihood of a devastating storm

There has been a lot of hail this summer and a team north of Calgary is working to minimize the damage to property through cloud seeding.

At an airport between Olds and Didsbury meteorologists keep track of thunderstorms in the province and send up planes to release silver-iodide flares when things heat up.

“This is our radar site and we have our own sophisticated radar software programs that measure the intensity of the storms and we know when a storm is going to have hail or not and it’s only severe storms with the danger of hail falling at the surface that we seed. If it’s just a rain shower or a rain event, we don’t seed that, we watch it and we only seed severe hail storms and when they pop, we go directly to them and seed them specifically,” said Terry Krauss, Project Director for the Alberta Severe Weather Management Society.  “There’s been a lot of research over the past 20 to 30 years in many countries to identify the storm conditions that produce hail at the ground. So when a certain intensity on the radar is returned and it’s above the freezing level and it’s up around minus five or minus ten and growing then we know that there’s a high probability of hail falling at the surface.”

The smoke particles work to attract water within the cloud and reduce the hail stones to rain.

“Continental clouds are not efficient rain producers and there’s been a lot of research to show that the largest hail forms from clouds that have a low-rain efficiency. If the rain process is efficient, then large hail particle won’t form so that’s why we seed and we use silver-iodide smoke particles that initiate ice crystals at warm temperatures, minus four, so we’re trying to make a thousand more times ice crystals and then that competes for the liquid water within the cloud and so we get much smaller particles that form and they can fall as rain instead of large, damaging hail stones,” said Krauss.

“We are sitting right in hail alley because of where we are in proximity to the mountains and where the moisture comes from and the temperature here and we are right in a hotspot for hail,” said Dan Gilbert, Chief Meteorologist. “That’s why the project exists here.”

Krauss says crews have had a very busy summer so far.

“We have had a very busy June and July. We have already seeded 81 storms on 28 days and the summer average is 90 storms on 30 days so we’re almost there two months into the program,” he said.

Jody Fischer is the chief pilot for Weather Modification and has been flying into thunderstorms for over 16 years now.

“When you learn to fly you’re supposed to stay 20 miles away and there’s a good reason for that, but when you learn this job, you learn the safe place to go around thunderstorms and we do two types of seeding so when people ask me what’s it like to fly there two different types of flying really and totally different so we have bottom seeding and at bottom we’re out in front of the thunderstorm, kind of underneath it, so as the thunderstorm moves west to east, it’s like a big vacuum sucking lots of air in, so we get into that area of in-flow and that’s where we release our seeding agent and typically it’s very smooth and quiet but really dark and ominous looking just like when it comes over your house,” said Fischer.  “When we’re doing our top seeding, top seeding meaning we’re going up to an altitude where minus ten is because that’s the altitude that works for us for seeding, and that’s typically here somewhere around 14 to 18, 19 thousand feet and there we’re going in the feeder cloud of the thunderstorm so we’re right on the edge of the thunderstorm, we’re not going in the middle of it but that is bright, white clouds, boiling clouds and it’s bumpy, up, down, left, right, totally different types of flying.”

Insurance companies are also learning about weather modification and about 200 people from the industry tour the facility north of Calgary each year.

Participants are given a lecture about the science of seeding and can even take a look at the latest big hail event to understand the seeding process.

“In the last five years insurance companies have paid more than $2 billion in property damage claims and we have had several storms that have caused $500 million damage,” said Krauss. “The insurance people are very happy to learn more about the program, about what goes on and the complexities behind it because then they can help answer the questions and they know what we do and we’re happy about that.”

The program is 100 percent funded by the private insurance companies of Alberta and 92 percent of the insurance businesses in the province participate in the project.