This article is the third in a four-part blog series exploring cloud seeding and Utah’s efforts to bolster snowpack. Here, in Part Three, our meteorologist addresses how we ensure safe and best practices. Read Part One to learn about the fundamentals of cloud seeding — what it is, how it works and why it matters. Part Two dives into why cloud seeding works well in Utah, while Part Four clarifies common myths and misconceptions.
SALT LAKE CITY (Feb. 5, 2025) — Cloud seeding in Utah operates under strict legal and safety requirements. Before I cover the licensing process and efficacy, I want explain the history and funding framework of the program.
The division administers Utah’s cloud seeding program under the direction of the state Legislature, which provides funding and policy guidance. Established as a strategic water management tool back in the 1950s, this program enhances snowfall in key watersheds to support water supplies. Our team executes cloud seeding operations with scientific expertise and careful planning, ensuring responsible and effective implementation. This is a targeted effort to maximize water resources in alignment with legislative directives and proven methodologies.
Licensing and experience
Utah state law requires all cloud seeding operators to apply for a permit. This process requires information to be sent to the Division of Water Resources such as an operations plan, map of the target area, proof of high-risk insurance, as well as an affidavit showing that a public notice of intention was run in general circulation news for three consecutive weeks.
Within the operations plan, seeding methods and materials must be highlighted along with suspension criteria. Suspension criteria consider the following: snowpack water equivalent exceeding the 95th percentile (which results in flooding hazards during spring runoff), severe weather warnings, avalanche risks and local sponsor request.
Once the permit is obtained, the operator must then apply for a license. This license shows the day-to-day operating meteorologist’s qualifications. Currently, the cloud seeding rules require a license holder to obtain a four-year or higher degree in meteorology or related physical science or engineering and at least five years of experience in the field of meteorology. Other training and experience may also be acceptable to the division as indicative or sufficient competence in meteorology to engage in cloud seeding activities. Though the rules do not currently require a Weather Modification Association Certification, the current slate of meteorologists contracted to conduct cloud seeding operations in Utah have this certification as well as the American Meteorological Society’s Certified Consulting Meteorologist certificate. The meteorologists operating the programs in Utah are the most qualified in the nation!
Practice makes perfect: ensuring Utah’s cloud seeding is effective
The foundational research for operation plans took place in the 1970s through the early 2000s. In Utah, older studies used radar detection to visualize seeding impacts, but results weren’t always clear. Improvements to radar technology — like the development of high-resolution X-band radar — and new funding opportunities have allowed for further research. One important example was the 2017 field campaign in Idaho, dubbed SNOWIE, which proved physically that cloud seeding does indeed work. Figure 1 shows the zigzag pattern produced by an aircraft releasing silver iodide with enhanced snowfall, which is unnatural in nature. Using the high-resolution radar, it is visibly clear that cloud seeding works. Thus, decades of research built the current conceptual model in which cloud seeding should be conducted. The American Society of Engineers has produced standard practices for running operational cloud seeding programs, and here in Utah, all programs meet that standard in how they operate, report and evaluate.
Speaking of evaluations, this is easily the most challenging aspect of a cloud seeding program. Natural variability can make finding the signal of seeding impact difficult. However, in Utah, a linear regression statistical evaluation has been conducted for the past 20, and in some areas 30, years. These evaluations have shown an increase of snowfall in Utah of 6-11%, which may not sound like a lot. However, cloud seeding should be viewed as a long-term water management strategy. By extending that 6-11% across a decade, an additional 6 months to 1 year of snowfall is produced than what would have otherwise fallen. A 2018 study by the Division of Water Resources looked at correlations between snow water equivalent and streamflow and found that this 6-11% increase produced an additional 186,000 acre-feet of streamflow across the state of Utah.
Other methods of evaluation will be coming to Utah soon. First, a better instrumentation network may allow operators to see a seeding signature using higher resolution radars. Until these are installed, the National Center for Atmospheric Research will be running Weather Research Forecast (WRF) models with a weather modification component that can track the silver iodide and see the reaction it would have with the supercooled liquid water that is present. This model produces a virtual snowpack that will then be ingested into a model that simulates streamflow (WRF-Hydro). An ensemble of these models will provide a range of the impacts cloud seeding has on streamflow runoff, and will (as we hypothesize) validate the statistical evaluations that have been ongoing in Utah since the 1980s.
In addition to evaluating cloud seeding effectiveness, we plan to conduct a comprehensive environmental study within the next 18 months.
About the author
Jonathan Jennings joined the Utah Division of Water Resources in 2024, bringing with him an impressive 13 years of experience in cloud seeding operations. His expertise spans multiple states, including Texas, New Mexico, Arizona and Utah, where he successfully managed operational cloud seeding projects and conducted feasibility studies. Jonathan’s contributions go beyond operations — he has played a pivotal role in developing and manufacturing seeding flares, advancing cloud seeding research and leading impactful educational outreach efforts. He also serves as the President of the Weather Modification Association where he is also certified as an Cloud Seeding Operator and a Manager. A Pennsylvania native, Jonathan earned his Bachelor of Science degree in meteorology from Penn West University in 2008. Now, he’s focused on helping elevate Utah’s cloud seeding program, applying his vast knowledge to ensure continued success and innovation.
