WMOD00465

• Contract/Permit #: 14-06-D-7368
• Title: Twelve Basin Investigation: Analysis of Potential Increases in Precipitation and Streamflow Resulting from Modification of Cold Orographic Clouds in Selected River Basins of the Western United States
• Date: 8/15/1972
• Weather Modification - Doc Type: Report

ABSTRACT

This volume presents the cloud seeding potential for increasing streamflow
from seven major river basins in the Western United States. These major basins
include the following: Upper Colorado; Rio Grande; Truckee, Walker, and Humboldt;
Sacramento; North Platte; Gila; and the Snake. October-April hourly precipitation
data were associated with appropriate rawinsonde data and precipitation-cloud top
temperature curves plott~d. From the curves, critical temperatures (the dividing
line between cloud top temperatures that are susceptable to seeding and those that
are not) were determined for each massif within the major basin.
The area of effect model was employed in determining predicted seeded preci-
pitation cloud top temperature curves and the predicted curves were fitted to the
historical curves based on the predicted not seeded curve in the critical tempera-
ture and colder cloud top temperature range. The seeding potential was then cal-
culated from the difference between the predicted curve and the observed historical
curve, and the frequency of cases. Mean elevations were specified for each massif
where the upwind transition zone begins, where the upwind crest zone boundary lies,
where the downwind crest zone boundary lies, and where the downwind transition zone
ends.

With this input data, potential incremental streamflow was computed for each
major basin for the water years 1951-52 through 1970-71.

LIST OF DESCRIPTORS

Artificial precipitation
Atmosphere
Cloud seeding
Cloud seeding model
Meteorology
Nucleation

River basins
Runoff
Silver iodide

Snow

Snowpack
Storm structure

Orography
Precipitation

Weather modification

i

I

,
I

,\
'I