{
  "abstract": "Operational winter cloud seeding programs claim precipitation increases of 3-15%, but the evaluations supporting these claims are produced by program operators using target/control methods that cannot separate seeding effects from operator storm selection: storms are seeded precisely when atmospheric conditions favor the target areas. This study performs, to the author's knowledge, the first independent storm-level evaluation of an operational program built entirely from public records. We assemble a machine-readable record of Utah's operations across seven winters (2016-17 and 2019-20 through 2024-25): 181 generator sites and 525 seeded storm periods totaling 37,773 generator-hours, transcribed from the operator's seasonal reports (the 2024-25 set published online, six earlier seasons provided by the Division of Water Resources), together with per-storm 700 hPa winds from the HRRR archive and daily precipitation from 546 SNOTEL stations in seven states. Three research designs of increasing selection-robustness are applied. A naive seeded-versus-unseeded storm comparison yields an implausible +335% for the largest program, quantifying the selection artifact. Same-sector near-miss controls reduce the pooled estimate to +24% [+4, +50]. The most robust design, a wind-rotation test in which plume exposure is recomputed from each storm's own wind field per generator, yields, pooled over seven seasons (937 program-events, 143 seeded), +5.8% [-0.0, +12.1] in-plume during seeded storms against a placebo of +3.0% [+0.1, +6.2] in-plume during unseeded storms. The placebo is now resolvably positive, revealing a wind-aligned orographic gradient that the smooth control does not fully absorb; the placebo-corrected seeding effect is +2.7% [-2.1, +8.8] per seeded storm. Seven seasons therefore remain consistent with a small positive operational effect and with zero, and exclude per-storm effects above ~9%, ruling out the upper half of the 3-15% claims. Carried through to water at the State's own baseline, the estimate implies an expected ~95,000 acre-feet per year (38% of the 249,600 claimed) at ~$52 per acre-foot, with a 17% probability that the program removes water from its target areas. All data and code are released.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "name": "Bryce Judy"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/17pwdf5xb9kqv.bib",
  "cited_by": 0,
  "doi": "10.31223/x5d23z",
  "fulltext_url": null,
  "id": "17pwdf5xb9kqv",
  "issns": [],
  "landing_url": "https://eartharxiv.org/repository/view/15605/",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/legalcode",
  "metadata_licence": null,
  "native_subjects": [
    [
      "bepress",
      "Atmospheric Sciences"
    ],
    [
      "bepress",
      "Fresh Water Studies"
    ],
    [
      "bepress",
      "HRRR"
    ],
    [
      "bepress",
      "Meteorology"
    ],
    [
      "bepress",
      "SNOTEL"
    ],
    [
      "bepress",
      "Utah"
    ],
    [
      "bepress",
      "causal inference"
    ],
    [
      "bepress",
      "cloud seeding"
    ],
    [
      "bepress",
      "program evaluation"
    ],
    [
      "bepress",
      "weather modification"
    ],
    [
      "openalex",
      "2306|Atmospheric aerosols and clouds"
    ]
  ],
  "openalex": "W7222938499",
  "pdf_url": "https://eartharxiv.org/repository/object/15605/download/27040/",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/17pwdf5xb9kqv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:46Z",
      "native_id": "15605",
      "source": "eartharxiv",
      "url": "https://eartharxiv.org/repository/view/15605/"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "bepress:Atmospheric Sciences",
      "subfield": "atmospheric"
    }
  ],
  "title": "Storm-Level Independent Verification of Operational Cloud Seeding: Seven Seasons of Utah's Program, 2016-2025",
  "title_text": "Storm-Level Independent Verification of Operational Cloud Seeding: Seven Seasons of Utah's Program, 2016-2025",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:46Z",
  "url": "https://research.draconitic.com/paper/17pwdf5xb9kqv",
  "venue": "EarthArXiv",
  "versions": []
}