WMOD00390

• Title: A Proposed Wintertime Weather Modification Research Program for Colorado
• Date: 1/1/1980
• State: CO
• Weather Modification - Doc Type: Report

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to the surface could be documented and studies. Samples of new
snowfall should be carefully collected at various elevations
within and surrounding the target area throughout the duration of
this program. These samples should then be analyzed to see to
what areal extent the seedinsr material could be detected in the
snowfall. The extent to which the additional instrumentation and
research work is incorporated into the program depends upon the
level of financial support obtained from Federal agencies.

a. Precipitation Network - "aluable information on the type of
surface precipitation observation network necessary to represent
the precipitation over a givEm mountainous region during the winter
season was gained on the Colorado River Basin Pilot project.12 It
was found that recording-type precipitation gages having a 0.01
inch water equivalent resolu1:ion and providing hourly accumulations
were required to evaluate the effects of cloud seeding operations.
Also, the selection of representative sites is critical for the
collection of precipitation. Sites should be selected at various
elevations within each sub-basin of the target area. An ideal
setting would be to locate the gate in a small park about 50 yards
across which is surrounded by trees and where the gage opening to.
tree top angle is approximately 30 degrees. The method of reaching
the precipitation sites must be considered. On the Pilot Project
the utilization of a helicop1:er for servicing remote sites proved
to be efficient and very useful.12
There are presently a fE~w recording precipitation gage sites
within and surrounding the proposed program area which are operated
by the National Weather Service or some other State or Federal
agency. Most of these sites are located in the mountain valleys
at elevations below 9,000 feet MSL. The collection of data records
from these sites is importani: and necessary. However, these data
will not provide answers regarding seeding effects within the
target area (the mountainous terrain above 9,000 feet MSL). In
addition to collecting hourl:{ precipitation data from existing
sites, cumulative snow data should be collected from all Soil
Conservation Service snow courses within the area, and subsequent
runoff data should be collec.ted for stream gages operated by the

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