WMOD00581

• Title: Targeting of AgI in a Utah Winter Orographic Storm
• Date: 8/2/1992
• State: UT
• Country: United States
• Weather Modification - Doc Type: Report

558

IRRIGATION AND DRAINAGE

the IN concentrations estimated from the tracer gas observations. Direct observations
of ice particle concentrations associated with the AgI need to be examined. Such
measurements were made but have yet to be analyzed. 2'..:,. ~

Summary and Conclusions

s,*, 1$ (!}-tl.
:r-~

Although both AgI and tracer gas were observed on and well above the Plateau,
measured and estimated IN concentrations were probably too low for effective cloud
seeding with the possible exception of the highest, coldest cloud turrets. The
observations from this case study support that assertion. While the SL W amounts and
temperatures were typical of many Utah winter storm periods, Plateau snowfall was
very light and intermittent in spite of the AgI being well-mixed though the clouds.
It is recommended that seeding rates be significantly increased in the Utah
operational program and an AgI complex with greater warm temperature effectiveness
be used. Also recommended are further investigations of targeting under a wide range
of storm conditions to include observations of ice crystal concentrations caused by
seeding.

Acknowledgments

This research was primarily supported by the National Oceanic and Atmospheric
Administration with additional support from the Bureau of Reclamation and the Utah
Division of Water Resources.

References

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