WMOD00299 ‎(2)‎

• Title: Scientific Weather Modification Experimentation in the United States
• Date: 8/25/1984
• Weather Modification - Doc Type: Report

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ment of ice particles by a Hallet-Mossop type secondary ice crystal process
effectively removes the available condensate on the barrier. The primary fac-
tors influencing successful seeding of the convective clouds are cloud lifetime.
Although well documented seeding signatures have been observed both by aircraft
and conventional radar for these convective cloud types, loss of liquid water by
entrainment is substantially greater than that used up in growing ice particles
added by seeding.

Given the above scenario, SCPP tends to concentrate on the warm, shallow
orographic cloud as the most treatable and most productive cloud type for pro-
ducing additional precipitation on the ground. Targeting of the seeding effects
will be at a fixed site high on the barrier equipped with a dual channel
radiometer, Ka band radar, ground microphysics observations, a rawinsonde unit
and other meteorological sensors to help measure the magnitude of the seeding
effect and with the help of aircraft in-situ cloud physics observations, docu-
ment the physical links in the chain of events leading to additional precipita-
tion on the ground.

5. CREST

The Bureau of Reclamation has proposed, but not received, funding for CREST (the
Colorado River Enhanced Snowpack Test) which is designed to demonstrate an
operational capability for increasing the flow of the Colorado River through
cloud seeding. Current cloud seeding technology has the potential to increase
winter snowpack by 10 to 15 percent in many mountainous areas of the Colorado
River Basin, and could produce approximately 2.3 million acre-feet of additional
water in the Colorado and surrounding river basins. The increase would produce
economic benefits of $140 million annually from increased power production,
salinity reduction and additional water supplies.

CREST is designed to address all aspects of precipitation management through
cloud seeding and provide the basis for establishing a fully operational program
for snowpack augmentation. The objectives of CREST are: 1) production of water
to the maximum extent possible during the demonstration period, 2) demonstration
of cloud seeding technology to establish procedures for an operational program,
3) quantification of increases as a result of cloud seeding, 4) assessment of
impacts to ensure there will be no adverse effects on the environment resulting
from cloud seeding, and 5) minimization of risks through the application of
established suspension criteria to safeguard against potential flood or ava-
lanche conditions.

Pending approval and funding of CREST, the Bureau of Reclamation is conducting a
wintertime research program, CRADP (the Colorado River Augmentation
Demonstration Program), on the Grand Mesa of west central Colorado. The program
is designed to develop an improved winter cloud seeding technology, improve the
already favorable benefit-to-cost ratio in the Colorado River Basin and refine
seeding suspension criteria. This will be accomplished by conducting studies
which will develop: 1) a more accurate climatology of winter cloud seeding
opportunities, 2) improved methods of recognizing and treating seedable con-
ditions, and 3) a reliable and consistent method of delivering seeding material.

Field activities began in the winter of 1982-83. Since that time efforts have

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