https://journalofweathermodification.org/index.php/JWM <p>The Journal of Weather Modification publishes articles related to weather modification research, operations, and instrumentation, with a historical emphasis on operations. Articles on cloud physics and aerosol-cloud interactions of relevance to weather modification operations may also be published. The scope covered by the articles are subdivided into; 'Scientific Papers' or Technical Notes and Correspondence'. Articles published in the 'Scientific Papers' section are put through the industry standard scientific peer-review by experts. The reviewers provide a recommendation to the Journal Editor who then makes the decision that the article is acceptable for publication. The 'Technical Notes and Correspondence' section is for papers of general interest to the weather modification community. They are put through an industry standard science and technical peer-review. The Correspondence section may contain information about the Journal, messages from the Weather Modification Association, and 'In Memory' notes about people in the weather modification community. </p> The Weather Modification Association en-US The Journal of Weather Modification 0739-1781 <div>Authors that submit papers for publication agree to the Journal’s copyright and publication terms. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the manuscript’s authorship and initial publication in Journal of Weather Modification. 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After the author approves the gallery formatted version for publication, the Weather Modification Association’s Secretary will invoice the corresponding author for the page charges and payment is due within 30 days.</div> https://journalofweathermodification.org/index.php/JWM/article/view/730 <p>North American Weather Consultants, Inc. (NAWC) has conducted operational winter cloud seeding programs in the mountainous areas of Central and Southern Utah since 1974. Beginning in 1988, seeding has also been conducted in three additional mountainous target areas within the State. The goal of these programs has been to enhance winter snowpack accumulation in the target areas, which now include most of the mountainous areas of the State. Studies have demonstrated that a large majority of the annual runoff in Utah streams and rivers is derived from melting snowpack, which explains the focus on wintertime seeding (within the November – April period). Augmented water supplies are typically used for irrigated agriculture or municipal water supplies. Programs are typically funded at the county level with cost sharing grants from the Utah Division of Water Resources (UDWR) and the three Lower Colorado River Basin States of Arizona, California, and Nevada, since 2007. An earlier WMA paper (Griffith et al. 2009) provided a summary of seeding operations for the water years of 1974 through 2007 for the four target areas. This paper is focused on the Central and Southern Utah program which is both the largest target area and the longest running program in the state. It covers all but three water years from 1974 through 2021 and is one of the three or four longest operational winter cloud seeding programs that have been conducted in the United States.</p> <p>The target area encompasses several mountain ranges in Central and Southern Utah. NAWC has defined the target area boundaries as those locations that are above 7,000 feet MSL. This is a large area of approximately10,000 square miles.</p> <p>Cloud seeding is accomplished using networks of ground-based, manually operated silver iodide nuclei generators located in valley or foothill locations upwind of the intended target mountain barriers. As such, these programs are classified as orographic winter cloud seeding programs. Orographic winter cloud seeding programs are typically categorized as those with the highest level of scientific support based upon capability statements of such organizations as the American Meteorological Society and the Weather Modification Association.</p> <p>NAWC historical target/control evaluations of this program indicate an average increase in December-March target area precipitation of 12% or an average increase in precipitation of 1.3”. These results were significant at the 0.06 level from a one-tailed Student’s t-test. The UDWR has conducted periodic studies to estimate the increases in annual streamflow resulting from the estimated increases in April 1^st snow water content produced by this seeding program. The most recent study (UDWR 2018) indicated an estimated average annual streamflow increase of about 84,000 acre-feet for the Central and Southern Utah target area. Factoring in the cost of conducting this program resulted in an estimate of the average cost of the augmented runoff to be $2.02 per acre-foot.</p> Don Griffith David Yorty Garrett Cammans Jake Serago Copyright (c) 2022 The Journal of Weather Modification 2022-07-11 2022-07-11 54 1 10.54782/jwm.v54i1.730