State Climatologist Jan Curtis indicated that all signs are pointing towards another year of drought due to below average levels of snowpack again this winter. However, some areas have relied on something other than Mother Nature to help increase snow pack.

 Cloud seeding, or weather modification, is the deliberate treatment of certain clouds or cloud systems with the intent of affecting the precipitation process within those clouds.

According to Don Griffin of North American Weather Consultants, Inc., there are two types of cloud seeding, warm and cold. Cold cloud seeding is obtained by using a ground-based generator attached to a propane tank. The generators are placed on the upwind side of mountains. Silver iodide is dissolved in acetone and the uplift wind carries the silver iodide up into the clouds. When the clouds are colder than freezing the silver iodide crystallizes and freezes the water droplets inside the cloud. As the moisture in the cloud increases and gets heavier it will fall out, or in other terms will produce a snowstorm.

Warm cloud seeding is the more expensive of the two and produces rainfall from clouds that are warmer than freezing.  Cloud seeding of this type of cloud involves introduction of additional condensation, which can cause additional water droplets to condense within the cloud. Ground based generators are not used, instead the additional condensations is placed in the cloud manually by flying a plane through the cloud.

Municipalities, agricultural interests, hydroelectric companies and others that would benefit from additional snow pack help cover the costs. Jeri Trebelcock with the Popo Agie Conservation District said the cost of cloud seeding equates to $1 per acre foot. “Primarily municipalities and ag can benefit, [from cloud seeding] but more water benefits everyone,” she said.

 North American Weather Consultants set up the ground based generators and train personnel to operate the machines. Griffin said his company also tracks storm systems and when conditions are right they will have the personnel turn on the generators and then turn them off when conditions have passed. “We customize the facilities for the particular area and monitor storms through the target area. Once the season is over we will also put together a report detailing the snow pack in the target area,” Griffin said.

   Cloud seeding has been used for over 50 years across the world. In the U.S. cloud seeding has been used extensively in California, Nevada and Utah as well as in the Eden Valley Irrigation District in Wyoming. Griffin said on average cloud seeding can increase winter snow pack 10-15 percent.

 Others however question the use of cloud seeding and it’s benefits. During the Governor’s Drought Management Task Force meeting University of Wyoming Professor Gabor Vali stated there isn’t enough science and research supporting cloud seeding. Others feel the 10-15 percent increase in snow pack isn’t significant enough to justify its use. Trebelcock said others see a downside as it is messing with what Mother Nature intended.

“There are just a million different factors to consider,” said Grant Stumbough, chairman of the agriculture and natural resources subcommittee. “We don’t know if the success Utah has seen will transfer to success in Wyoming.”

Stumbough added that climate, temperature, wind and weather patterns will all affect the outcome of cloud seeding. “We need to learn more about it and become more knowledgeable,” he said of the task forces position on cloud seeding.

 The Eden Valley Irrigation District on the other hand does seem to think the additional snow pack is beneficial. The district has been cloud seeding since the 1960s and has seen an 11 percent increase in snow pack through their efforts.

 The next Governor’s Drought Management Task Force meeting has tentatively been scheduled in Lander April 22. Stumbough said the state task force will meet with the Fremont County Drought Management Task Force to increase the interaction between the county and state levels. He also said he hopes to have additional conversion on the possibility of cloud seeding and the possibility of a pilot project elsewhere in the state.