Assessing the Cloud Seeding Potential over the Laramie Mountains in Wyoming

Assessing the feasibility of a mountain range’s winter cloud seeding potential requires knowledge of the frequency of clouds containing supercooled water, as well as the clouds heights, associated winds, temperatures, and atmospheric stability. The State of Wyoming funded a winter cloud seeding feasibility study for the Laramie Mountains, located in the south-central part of the state. As part of this study a fine-resolution regional climate model (RCM) based on the Weather Research and Forecast (WRF) model was developed to produce climatological fields to assess the cloud seeding potential of the Laramie Mountains. The simulation covered 11 winter seasons from 2005-2015, and generated nested hourly output at 9-km, 3-km, and 1-km. In addition to the WRF model climatology, a matching observed storm climatology was also constructed. The observed climatology assembled observations from snow gauges, surface observations, satellite imagery, icing pilot reports, upper air synoptic maps, and nexrad radar.

In this study we summarize the cloud seeding climatology using the WRF model output and the observed climatology. Several case studies when cloud seeding conditions were present are reviewed using the observed climatology. These cases are compared the time-matched WRF runs. Finally, the microphysical differences between the fine-resolution model output (1-km), are compared to the more course-resolution (9-km) model output.