WMOD00286 ‎(3)‎

• Project Name: Colorado River Basin Pilot Project
• Title: Comprehensive Atmospheric Data Report 1974-75 Season - Volume I
• Date: 8/31/1975
• Weather Modification - Doc Type: Report

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using a seed rate based on the Climax m<Xlel. Effective seeding rates
to be used are determined by the forecast and monitored 500 mb temp-
erature as follows:

1) For 500 mb temperatures -140C or warmer, use a
generator solution burning rate up to 140 grams of Ag I per hour.
This rate should produce up to 1016 effective nuclei per hour per
generator site at -150C.

2) For 500 mb temperatures of -15 to -230C, use a
generator solution burning rate up to 20 grams of Ag I per hour.
This should produce up to 1016 effective nuclei per hour per gener-
ator site at -20oC.

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Appropriate generators, located upwind of the target area,
were started one hour prior to the beginning of an experimental "seed"
day (or suitable portion therElof) and were stopped two hours prior to the
end of the suitable seeding period.

The normal operating season for 1974-75 was set by the
Bureau of Reclamation in a letter to EG&G, INC., dated August 20,
1974, to begin at 1100 MST on November 6, 1974.

Suspension criteria were examined daily and prior to the
declaration of an experimental period, and they were monitored
throughout each seeding period. Suspension of seeding operations
was asked for on five occasions and granted on three occassions.

-

1) 1100 MST January 8, 1975 - 1100 MST January 9, 1975
Operations were suspended on the basis of a 24- hour forecast
of a foot or more of new snow accompanied by strong winds upon a very
unstable snowpack. A major episode of avalanches occurred during
this storm and the highway aeross Wolf Creek Pass was closed for sev-
eral hours by several avalan<=hes.

2) On January 30, 1975 the Durango staff of EG&G, INC.
recommended to the BuRec that seeding operations be suspended for a
24-hour period starting at 1100 MST on the basis of a 24-hour forecast
of heavy snow and strong winds upon a potentially unstable snowpack.
This request was denied.

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