IntermtnClimateSummaryJan2006

• Title: Intermountain West Climate Summary
• Date: 1/17/2006
• Description: Water Availability Task Force Meeting Presentation
• Basin: Statewide
• Drought Mitigation - Doc Type: Presentation

INTERMOUNTAIN WEST CLIMATE SUMMARY, JANUARY 2006

Water Supply Outlook for the 2006 runoff Season

Source: Wyoming Water Resources Data System and USDA Natural Resources Conservation Service

The first water supply outlooks for the season
are issued in January, and are a cooperative effort
of NOAA River Forecast Centers (RFCs) and the
NRCS. The Colorado Basin RFC Water Supply
Outlook for the Upper Colorado, for January 1st,
forecasts April-July runoff volume for major basins
in the Upper Colorado. This product also provides
specific site forecasts for some stations, and ba-
sin conditions compared to average for December
precipitation, water year precipitation, snow water
equivalent, December streamflow, and reservoir
contents. The outlook reflects the dichotomy of pre-
cipitation levels throughout the Colorado River Basin
(See Recent Precipitation on page 6 and Snowpack
on page 8.), projecting slightly above average "most
probable" April-July 2006 inflows for all the major
reservoirs in the upper basin (106-108 % compared to
the 1971-2000 average) except for Navajo Reservoir
on the San Juan River in Colorado (65%). Note
that these are probabilistic, not deterministic fore-
casts. You can find the product on the web, including
minimum probable and maximum probable runoff, at
http://www.cbrfc.noaa.gov/wsup/wsup.cgi.
The NOAA West Gulf RFC water supply forecast
for the Rio Grande River basin summarizes condi-
tions and projects runoff volume for April-September
and March-July 2006 periods (See http://www.srh.
noaa.gov /wgrfc/watersupply /html/ default.html). The
most probable runoff for Rio Grande forecast points
in Colorado is 45-77% of the 1971-2000 average.
The Arkansas RFC will issue its volume forecasts
on April 1 st.
The NRCS summarizes forecasts across the region
in a map (Figure 14). In addition to streamflow fore-
casts for the Upper Colorado and Rio Grande River
basins, this map shows streamflo\:v forecasts by cat-
egory for the other river basins in the Intermountain
West Region. In Wyoming, the Missouri River basin
streamflow forecasts range from around average to
70% of average, while the North Platte River basin
is up to 150% above average in some areas. The
rest of the state is around average. In Colorado, the
South Platte and upper Arkansas River basins are up
to 150% of average. Finally, the streamflo\:v fore-
casts for the Great Basin in \:vestern Utah range from
50%- 69% of average in the south to near average in
the north.

Figure 14. NRCS map showing the expected natural streamflows
for spring and summer in the Intermountain West region as a
percent of average streamflows. (Dated January 1, 2006.)

Notes
The map on this page does not display the official NOAA
streamflow forecast, official forecasts are developed by
individual river basin forecast centers. (See 'On the Web'
box below for links to the official forecasts.) We present the
NRCS water supply forecasts because they show the entire
Intermountain West region together.
Figure 14 shows the forecasts of natural runoff, based
principally on measurements of precipitation, snow water
equivalent, and antecedent runoff (influenced by precipita-
tion in the fall before it started snowing). Forecasts become
more accurate as more of the data affecting runoff are
measured (i.e. accuracy increases from January to May).
In addition, these forecasts assume that climatic factors
during the remainder of the snow accumulation and melt
season will have an average affect on runoff. Early season
forecasts are, therefore, subject to a greater change than
those made on later dates

On the Web
For more information about NRCS water supply forecasts based on snow accumulation and access to the graph on this page, visit:
http://www.wcc.nrcs.usda.gov/wsf/.

The official NOAA streamflow forecasts are available through the following websites of individual River Forecast Centers:
- Colorado Basin (includes Great Basin): http://www.cbrfc.noaa.gov/
- Missouri Basin (includes South Platte and North Plate: http://www.crh.noaa.gov/mbrfc/
- West Gulf (includes Rio Grande): http://www.srh.noaa.gov/wgrfc/
- Arkansas Basin: http://www.srh.noaa.gov/abrfc/

FORECASTS 11 7

>150%

130 - 150

110 - 129

90 - 109

70 - 89

50 - 69

<50

No
Forecast