15th Conference on Planned and Inadvertent Weather Modification


The feasibility of cloud seeding in the North Platte river basin headwaters to increase mountain snowfall

Jonnie G. Medina, U. S. Bureau of Reclamation, Denver, CO

The United States Bureau of Reclamation is considering several options for increasing streamflow in the North Platte River Basin of northern Colorado and southern Wyoming to improve habitats for endangered and other wildlife species. Options include alternative reservoir management, vegetation management at high-elevation areas of snowpack accumulation, and winter cloud seeding. Under consideration is the feasibility of the application of cloud seeding to winter orographic clouds in the Headwaters Region of the North Platte Basin to increase snowfall. Orographic winter cloud seeding information and technology have significantly improved in the past 20 years. When properly conducted, this type of cloud seeding provides a viable option to enhance fresh water resources in some mountain watersheds of the western United States. Physical evidence exists that seeding increases mountain snowfall when supercooled liquid water (SLW) exists in excess to that naturally converted to snowfall, and seeding created ice particles have adequate growth time in a favorable environment. Previous studies in the Headwaters Region indicate excess SLW exists in winter storms, and the meteorology and terrain characteristics support that seeding can lead to additional snowfall at high-elevations. It is proposed to use an automated system of data collection, high-altitude propane dispensers, and possibly silver iodide generators to seed winter clouds over the Park Range/Sierra Madre and Medicine Bow Mountains. The proposed program consists of conducting cloud seeding design and operational seeding phases. The design phase is aimed at determining the proper seeding approaches, and equipment numbers and locations for the conditions of the Headwaters Region. Estimates of additional water volume suggest that seeding has the potential to cost-effectively add 60,000 acre-feet or more of water at locations above 9000-feet elevation. The issue of augmented water yield well downstream of the Headwaters Region under current water allocation regulation will be discussed.

Session 3, Cloud Seeding Technology for Precipitation Enhancement
Wednesday, 17 January 2001, 1:30 PM-3:15 PM

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