Potential for ground-based glaciogenic cloud seeding over mountains in the interior Western United States and anticipated changes in a warmer climate

Many seeding programs in this region target cold-season orographic clouds with ground-based silver iodide generators. Here, the "seedability" (defined as the fraction of time that conditions are suitable for ground-based seeding) is evaluated in this region from 10 years of hourly output from a regional climate model with a horizontal resolution of 4 km.

Seedability criteria are based on temperature, presence of supercooled liquid water, and Froude number, which is computed here as a continuous field relative to the local terrain. The model's supercooled liquid water compares reasonably well to microwave radiometer observations. Seedability peaks at 20%-30% for many mountain ranges in the cold season, with the best locations just upwind of crests, over the highest terrain in Colorado and Wyoming, as well as over ranges in the northwest interior.