WMOD00034

• Contract/Permit #: #94-6
• Applicant: North American Weather
• Project Name: Willow Creek Basin
• Date: 11/1/1994
• Weather Modification - Doc Type: Report

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4.0 OPERATIONS

The program was operational from November 1, 1994 through April 30, 1995.
There were a total of 31 stonn periods that were seeded during this period on portions
of 52 days. Overall, this was an above-nonnal period of frequent stonn systems.
Precipitation amounts however were below nonnal for most of the project period, with
some sites reaching above nonnal by the end of April 1995.

4.1 Onerational Procedures

A NA WC meteorologist monitored the local weather on a day to day basis, using
NWS infonnation. A short-tenn forecast was developed and updated by the
meteorologist with emphasis on weather systems that would be favorable for cloud
seeding opportunities. Wind directions and speeds, temperature structure of the
atmosphere and precipitation possibilities were the crucial factors forecast on the
program. A daily logbook was maintained which briefly described weather conditions
and program activities.

When a potentially seedable weather situation was identified by the meteorologist,
the monitoring of weather conditions would intensify. As the weather system approached
the target area, a seeding schedule was developed by the meteorologist, indicating which
CNGs to activate and at what time. If a detennination on when to end the CNG operation
could be made at the beginning of the stonn period, then the CNG operator was given
this infonnation along with the times that the CNGs were to be activated. However, a
detennination of when to end the seeding operations usually was not made until later in
the stonn episode.

The CNG operators were contacted no more than 12 to 18 hours before the CNG
needed to be activated. Frequently, the activation time was within an hour of the
operator being contacted. The length of CNG operation varied greatly from stonn to

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