WMOD00403

• Title: Special Regional Weather Modification Conference Augmentation of Winter Orographic Precipitation in the Western US
• Date: 11/11/1975
• Weather Modification - Doc Type: Report

SAN JUAN PROJECT EVALUATION RESUME

By
Robert D. Elliott
Aerometric Research Inc.

1. INTRODUCTION

The Colorado River Basin pilot project, often called the San Juan Project,
was underway as a randomized orographic seeding test project in the San Juan
Mountains of Colorado from the 1970-71 winter season through the 1974-75 season.
The evaluation of results is completed for 4 of these 5 years, and a pattern
of results has emerged which is unlikely to change significantly with the
inclusion of the fifth year of data.

The map (Figure 1) contains the principle elements of the project. The
recording precipitation gage network is quite extensive and data from this
network has formed the principle basis for the evaluation of results. However,

r;~
to ........... .........
. 0........, s,,,
.. IU"~I.lt_1
A ....... 'ii,
Ow,,.. .U...... Slit
* \N_ s."""", 101'
6 'If",,,~
..r'...._'....oo........
...- ,.......
--
_r....'........."
- 1000 ,.. c-....

,-
,

pAOoIECT '

FIGURE 1. MAP SHOWING TARGET AREA AND
" - INSTRUMENTATION OF THE SAN JUAN PILOT
PROJECT.

..... .... ......... ce.tI
~.:..:.-. -rI"~'_-'~'~ <.._~:.~. .~::-.::..~:

extensive use has also been made of the rawinsondes taken upwind at Durango,
approximately every 3 hours during experimental days. Cloud, air mass, and
wind flow characteristics are embodied in a set of sounding-derived parameters
which have been used as co-variates as well as bases for stratifying the data
in order to sharpen the statistical analysis. Analysis of the effectiveness
of the seeding methodology has also used data based upon ground level nuclei
content, wind, and other physical observations. The observational network was
maintained and the data collected primarily by Western Scientific Services Inc.
(WSSI).

\

10