WMOD00104

• Applicant: North American Weather Consultants, Inc.
• Sponsor Name: Denver Water
• Project Name: Cloud Seeding Evaluation
• Title: Development of Traget/Control Evaluation Procedures For the Denver Board of Water Commissioners Winter Snowpack Enhancement Project
• Prepared For: Denver Water
• Prepared By: NAWC
• Date: 12/31/2002
• County: Summit
• County: Clear Creek
• Weather Modification - Doc Type: Report

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3. Regression Trials

With information regarding a) prior seeding projects, including their periods of
operation, b) current seeding project target areas and c) the storm airflow indications,
the laborious process of assessing the statistical relationships during the base period
began. The first step involved identification of all prospective data sites for use in the
analyses. Fortunately. many such sites exist. Of sites still in operation, a list of
candidate sites, following a first cut for apparent data quality, was developed. That list
appears in Appendix 8.

Selectinq Tarqet Area and Control Area Sites

Given knowledge of previous seeding areas and periods, the list of candidate
data sites was subjected to further scrutiny, with the following factors in mind.

Meteorological representativeness relative to the target area (controls)
Geographic bracketing of the target area (controls)
Elevation relationships
Period of record (target and control)
Data quality (target and control)
Potential contamination by this and other project seeding operations (controls)
Statistical Correlation

Table 2 lists the data sites with adequate periods of record. All twenty-three
target area sites are shown. It also includes prospective control sites located in totally
not-seeded regions and some sites in areas which had experienced some seeding, but
for which sufficiently long not-seeded periods exist. The data types for each are
shown. For the prospective valley control sites, only those with high data quality (A or B
on a scale ranging to A-F) are listed.

TABLE 2
Target Sites and Prospective Control Sites for the Denver Water Project

Target Area Sites
Site Name Elev Lat Lon Snowcourse Snowpillow PreciD
Antera 9300 38.55' 105.58' 1949-present
Arrow 9680 39.55' 105.45' 1938-1989 1938-present 1979-present
Berthoud Falls 10500 39.47' 105.47' 1951-present
Berthoud Pass 9700 3950' 105.45' 1936-present
Berthoud Summit 11300 39.48' 105.47' 1951.present 1961-present 1979.present
Blue River 10500 39.23' 106,03' 1957 -present
Como 10370 39.21' 105.55' 1967.present

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