WMOD00427

• Title: Design of Physical Cloud Seeding Experiment for the Arizona Atmospheric Modification Research Program - Final Report
• Date: 2/1/1991
• Weather Modification - Doc Type: Report

Experiments frequently have attempted to meet too many goals for the resources and number of
storms available with the result that none were well met. Side issues have a way of evolving into
key issues to the detriment of those few questions that are critically important to answer. The goal
of the physical experiments discussed in this report is to develop a demonstrated ability to seed some
Arizona winter orographic clouds in a manner leading to enhanced snowfall on the Mogollon Rim.
It is not to improve weather forecasting, develop some new type of instrument (unless critical to the
experiments), pursue some interesting but nonessential basic research or to provide topics for
theses, Some past experimental projects have allowed such "hidden agendas" to compete for limited
resources. The end result has been progress at a much slower rate than possible, so that policy
makers have grown weary of waiting for clear indications of an authenticated, useful technology.

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The history of scientific weather modification has clearly shown that they are no quick answers and
no easy way to success. However, persistence in pursuing the critical uncertainties will lead to
significant improvements in the emerging technology. Both scientists and policy makers need to be
continually reminded that scientific progress, while rarely rapid, will be extremely slow if attention
does not remain focused on the key uncertainties.

1.4 Optimum Area for Arizona Physical Seeding Experiments

1.4.1 Search for the Optimum Area. - Topography, air traffic restrictions, surface access, and
prior Reclamation field experience were all considered for the entire Mogollon Rim higher than
1830 m1 from the San Francisco Peaks just north of Flagstaff to the White Mountains bordering
New Mexico. It is considered impractical to use separate research areas for ground-based and
airborne seeding, as similar extensive ground instrumentation is required in either case, Moreover,
it is desirable to be able to shift from one seeding mode to the other as storm conditions change.

The search for the best area for physical experiments soon focused on the region south of Flagstaff
(fig. 1.1). The high elevation region from about Mormon Lake to the intersection of state
highway No. 87 and the road that passes southward from Mormon Lake (Forest Service Road
No.3, also called Lake Mary Road) appeared to have particular advantages for experimentation,
The portion of the Mogollon Rim from Mormon Lake to about 45 km south-southeast, referred to
as the Happy Jack area, was chosen as most feasible, largely by a process of elimination as will be
described.

In-cloud aircraft seeding and sampling over the high country north of Mormon Lake would
experience conflicts with air traffic control for the Flagstaff Airport, and would have to stay above
the very high San Francisco Peaks when north of Flagstaff. The portion of the Mogollon Rim
immediately north through east from Payson would be impractical because it is under a major air
traffic route for the Phoenix airport and airspace conflicts would be common above 3350 m,
Further, high elevation surface access would be difficult in that region because of the absence of
all-weather roads. The White Mountains, which extend into New Mexico (not shown on fig. 1.1),
have limited all-weather surface access and none to the higher elevations west of the town of
Alpine, Moreover, air traffic conflicts would often exist because of MOAs (military operating
areas). The Williams 3 MOA is immediately west of the White Mountains and the Reserve MOA
is over the southeast quadrant of these mountains. Elevations in the vicinity of Pinedale and Show
Low are lower than the rest of the rim so uplift, condensate production and, hence, seeding

1 All elevations are above sea level.

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