WMOD00277

• Contract/Permit #: 14-06-D-6467
• Title: An Operational Adaptation Program for the Colorado River Basin
• Prepared By: Lewis O. Grant, Chappell, Crow, Mielke Jr., Rasmussen, Shobe, Stockwell, Wykstra
• Date: 10/1/1969
• State: CO
• Country: United States
• Weather Modification - Doc Type: Report

'Department of Commerce, Environmental
Science Services Administration, '>,
Weather Bureau

(b) Climatological Data, Wyoming. U. S.
Department of Commerce, Environmental
Science Services Administration,
Weather Bureau

(8) Ski areas
Sources for the location of the ski areas
have been:

(a) Colorado Skiing, publication of the
Colorado Visitors Bureau, 225 West
Colfax, Denver, Colorado

(b) Forest Service maps

(0) State highway maps

(9) Power lines
Major electrical power line transmissions
have been added to the Basin map of the
Upper Colorado River ~ollection area and
the San Juan collection basins. This informa-
tion has been supplied by the local electric
associations. In Colorado most of the
associations serve a small area. Therefore,
a number of offices have been contacted.
The following associations have supplied
information:

(a) Em pi r e Electric Association, Inc.,
Cortez, Colorado

(b) LaPlata Electric Assoclation, Inc.,
Durango, Colorado

(0) Mountain Parks Electric, Inc., Granby,
Colorado

(d) The San Miguel Power Association, Inc.,
Nucla, Colorado

(e) The Western Colorado Power Company,
Montrose, Colorado

Additional power transmission lines are
being added to the base map for other sub-
areas as information is received.

(10) Communication lines
Major telephone transmission lines are not
yet added to the maps. MountainStates
Telephone Company has indicated that they
will supply maps of their lines that serve
specific areas when they receive a list of
specific sites where communications are
desired. The location of their major lines
over large areas are not readily available.

(11) Permanent look-out stations
The locations of permanent look-out
stations have been transferred from Forest
Service maps to the sub-basin map.

(12) Forested areas
Overlays of the forested portions 01 the
major areas of interest are being constructed.
The non-forest areas as may be used for
instrumentation or possibly landing sites
are being emphasized. U. S. G. S. Survey
maps are the source of this information.

(13) Overlays of proposed instrumentation
Overlays of propos~d sites for
precipitation gages, !streamgages, and
seeding generators tiave been prepared
for the Upper Color~do River and the
San Juan collection ~asins. The major
portion of this map >York has been
completed. Up-dating and revision of
the information will continue as
I
necessary.

I
D. Weather Modification Climatology
The mate.rlal presented in this section
describes certain natural climatic characteristics of
the Basin. The specific items included serve as
backgramd in formulating the program design. They
include a description of certain characteristics of
the precipitation, snowfall accumulations,- tempera-
ture regimes, and of the upper 'air conditions control-
ling the formation of both natural md artificial
precipitation. Much of the material is presented for
the Climax area due to the ready availability of
background data. This material should apply, at
least in a general way, to most of the important
subareas of the Basin in central and northern
Colorado. Climatic conditions in;the San Juan
Mountains are substantially differeht in many aspects
and are, . consequently, presented separately.

1. Surface Climatology

a. Hourly precipitation
(1) Hourly precipitation rates
The substantial :accumulation of
snowcover over1the Colorado Rockies
during the wint~r season results
from many hours of snow falling at
a very low rate.' Figure 24 shows
the distribution ;of hourly precipita-
tion intensities (a) and of total
snowfall (b) at Climax for the period
November through May 1964-67.
Snowfall occurs' at a water equivalent
rate of .02 inch!, per hour or less
71 % of the time 'and at .04 inch per
hour or less 89% of the time. Rates
in 'excess of . 20 inch per hour do
not occur. The' high frequency of
snowfall at the lower intensities is
so marked that these lower inten-
sities also account for most of the
snowfall. 42% Of the total snowfall
occurs at the rate of .02 inch per
hour or less, 68% at the rate of
.04inch or less, and 910/0 of the
total snowfall occurs at the rate of
.08 inch per hour or less.
It can be seen from Figure 25
that there are also many hours of
low intensity snowfall in the San
Juan area of the southern part of
the Colorado River Basin. Six
hour ly reporting stations are
available for this general area.
although only two are above 9,000 ft
msl and none are located in the
highest precipitation areas. The

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