WMOD00413

• Title: Validation of Precipitation Management by Seeding Winter Orographic Clouds in the Colorado River Basin
• Date: 9/1/1993
• Weather Modification - Doc Type: Report

7-2090 (4-81)
Bureau of Reclamation
1. REPORT NO.
R-93-03

4. TITLE AND SUBTITLE Validation of Precipitation Management
by Seeding Winter Orographic Clouds in the Colorado
River Basin

TFr.HNIr.AI. REPORT STANDARD TITLE PAGE

.111 II. . II I

3. RECIPIENT'S CATALOG NO.

5. REPORT DATE
September 1993
6. PERFORMING ORGANIZATION CODE

D-3720

7. AUTHOR(S)
Arlin B. Super, John C. Lease, Jack T. McPartland

8. PERFORMING ORGANIZATION
REPORT NO.
R-93-03

9. PERFORMING ORGANIZATION NAME AND ADDRESS

10. WORK UNIT NO.

Bureau of Reclamation
Denver Office
Denver CO 80225

11. CONTRACT OR GRANT NO.

13. TYPE OF REPORT AND PERIOD COVERED

12. SPONSORING AGENCY NAME AND ADDRESS

DIBR

Same

14. SPONSORING AGENCY CODE

15. SUPPLEMENTARY NOTES

Microfiche and hard copy available at the Denver Office, Denver, Colorado.

Ed: TH

16. ABSTRACT Reclamation (Bureau of Reclamation), in cooperation with the Colorado River Basin States, developed a
plan for a precipitation management demonstration program titled the CREST (Colorado River Enhanced Snowpack
Test). The program's purpose is to develop scientific evidence that properly conducted seeding of winter orographic
(mountain-induced) clouds can significantly increase high elevation snowfall in the Colorado River Basin. The
multi winter magnitude of the precipitation increase will be quantified at two mountain locations typical of the Upper
Colorado River Basin.
Statistical analyses of some operational and experimental projects in the western United States and elsewhere have
provided strong indications of snowfall enhancement from winter orographic cloud seeding. However, supporting physical
documentation is lacking. The proposed program will build on the strength of past experience and results to prOVIde
convincing physical and statistical evidence that cloud seeding can significantly enhance the mountain snowpack.
The program will begin with environmental compliance activities, and procurement of contracts and equipment. Both
experimental locations will then have a three-winter physical experiment phase, followed by a four-winter statistical/
physical phase.
· The physical phase will be devoted to "direct detection" experiments which will monitor the major links in the chain
of physical events following seeding. The purpose of this phase is to markedly increase physical understanding of the
important cloud and precipitation processes in winter clouds, and how they are affected by seeding. This phase will
validate the physical hypothesis of winter orographic cloud seedin~ and document the range of meteorological conditions
under which it is applicable. This understanding is needed for deSIgn of the second phase.
. The statistical/physical phase will consist of a randomized seeding program with a strong physical monitoring
component. The purpose of this phase is to demonstrate that snowfall can be increased over a tar~et area over a
multi winter period, and to quantify the magnitude of the increase. The statistical experiment will ngorously test a
precisely stated hypothesis, using predetermined seeding and observational criteria, and confirmatory analysis. At the
same time, exploratory analysis will be used to broaden understanding and applicability of the results. Any statistical
results must be physically plausible to be considered convincing.
The combination of confirmatory statistical analysis, and supporting physical observations for a large subset of the
experimental units, is expected to provide the scientific evidence needed to place this developing technology on a much
firmer foundation. The resulting technology is expected to be readily transferrable throughout the Colorado River Basin,
and, to a lesser degree, to other mountain regions of the world. To expedite the transferability of the technology
throughout the Basin, more limited observational programs and numerical modeling investigations will be conducted for
other representative mountain regions during the CREST program.

17. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS-- atmospheric research/ meteorology/ weather modification! orographic

clouds! cloud seeding/ meteorological instruments

b. IDENTIFIERS- American Meteorological Society/ Council on Environmental Quality/
Colorado River Basin Pilot Project! Colorado River Enhanced Snowpack Test! Fish and Wildlife
Coordination Act! High Plains Cooperative Program ExperimentJ National Center for
Atmospheric Research/ Sierra Cooperative Pilot ProjectJ World Meteorological Organization
c. COSATI Field/Group 04B COWRR: 0402.1 SRIM:
18. DISTRIBUTION STATEMENT 19. SECURITY CLASS
(THIS REPORl)
UNCLASSIFIED

21. NO. OF PAGES
160

20. SECURITY CLASS
(THIS PAGE)
UNCLASSIFIED

22. PRICE

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