Further Exploratory Analysis of the Bridger Range Winter Cloud Seeding Experiment

Abstract

Further exploratory analysis of the Bridger Range Experiment was carried out with 6 h data blocks partitioned from the original 24 h experimental units. The analysis was limited to 6 h periods having a rawinsonde observation, Main Ridge temperature ≤?9°C and westerly flow. The results suggest that silver iodide seeding was particularly effective in increasing precipitation in a small fraction of the cases, but had little or no effect most of the time. Seeding appeared to be especially effective when cloud top temperatures were warmer than about ?25°C and the wind had a Wong cross-barrier component. Marked decreases in precipitation were not apparent during seeded periods.