Investigating the Potential for Cloud Seeding in the East River Basin of Colorado

Despite significant advances in monitoring and modeling the effects of cloud seeding, some important questions remain unanswered related to quantifying effectiveness and optimization of cloud-seeding technology for specific locations. This is because cloud seeding approaches need to consider local conditions, such as the topography and atmospheric conditions that are suitable for seeding (i.e. seeding opportunities), and appropriate seeding mechanisms. This study focuses on answering the question “What is the potential impact of cloud seeding on precipitation in the East River Basin?”, situated in the headwaters of the Colorado River in Colorado.

To address this overarching question, the first step is to identify the characteristics and frequency of local storms suitable for cloud seeding in the East River Basin with a climatology analysis. To complete this step, a high-resolution (4-km), 40-year Weather Research and Forecasting (WRF) model simulation (hereafter CONUS404) was analyzed to investigate local precipitation patterns, amounts and frequencies of supercooled liquid water occurring at temperatures suitable for silver iodide (AgI) nucleation, and the dominant wind regimes that bring precipitating clouds to the region. The second step uses the WRF-WxMod® model to simulate potential impacts of AgI seeding to design an optimal method to enhance precipitation in the region. This includes simulations that test a variety of potential ground-based generator locations and/or aircraft flight tracks to optimize the precipitation enhancement. The cloud-seeding program designs that are tested by WRF-WxMod are based upon results of the climatology analysis step. This project also engages local representatives, including water districts who operate local cloud-seeding programs and researchers that will provide extensive data from ongoing projects in the region.

The results of the CONUS404 simulation climatology analysis regarding the frequency of atmospheric conditions and their trends over the 40-year period of investigation will be presented, along with preliminary results of WRF-WxMod cloud-seeding program design optimization simulations.