WMOD00378

• Title: Physical Investigations of Winter Orographic Clouds in Utah
• Date: 3/1/1984
• State: UT
• Weather Modification - Doc Type: Report

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Utah area. Results of that project were that ice nuclei from ground

generators generally did not reach cloud altitudes in sufficient quantity

for effective seeding of the clouds, but that significant amounts of

supercooled liquid water were present in the clouds and that most trajec-

tories of precipitation particles forming from this water would intersect

the mountain. Thus the clouds appeared to be susceptible to effective

seeding. These results were based on only one field season and must be

judged preliminary.

Following receipt of Hill's (1982) report of the 1981 field investiga-

tions a contract agreement was reached between NOAA and the State of Utah

Department of Natural Resources Division of Water Resources (UDWR) to con-

duct a second year of evaluations of the Utah program. The Utah Division

of Water Resources was to be prime contractor and other groups with

appropriate expertise would provide scientific and technical assistance

through subcontracts.

As part of its contractual obligations UDWR has provided two design

documents to NOAA. The first document (Warburton, 1982) states the objec-

tives of the program of field research conducted from 15 January to 15

March 1983, discusses the randomization procedure, target area, and

response variables, and describes the instrumentation placed in the field

to gather information for a physical evaluation of the operational

program. The second document (Long, 1982) describes the analyses of the

field research data. There is to be a physical analysis and evaluation of

the seeding hypothesis used in the operational program based on data

collected with a variety of instrumentation. There is also to be a