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

Utah Water Availability January 2006

Source: USDA Natural Resources Conservation Service and the Colorado Basin River Forecast Center

The current SWE as a percent of normal varies through out
the state of Utah as of January 4,2006 (Figure 9a), but in general
the northern mountains have had more snow than the southern
mountains, like in Colorado. Some southern SNOTEL sites as
well as the western and eastern most sites have 0% - 40% of
normal SWE. On the other hand, parts of the Bear, Weber, Provo
and Uintah River basins, generally have from 100% - 160% of
normal SWE. This snowfall pattern is opposite from most of
last year, when the southwestern part of the state had the highest
SWE numbers and percent of normal.
The Utah Surface Water Supply Index (SWSI) shows a similar
pattern to the SNOTEL sites, with more water available in the
northern part of the state. The southern basins are low with
the Moab, Upper, and Lower Sevier basins below zero and the
Beaver and Virgin basins just slightly above zero. The southern
part of Utah had below average precipitation in about half of the
months between July and December 2005. In addition, these ba-
sins have also had very low snowfall since the start of the winter
season. Lower reservoir levels may also contribute to the lower
SWSI numbers this month. With the exception of the Bear basin,
which has the lowest SWSI at -2.4, the northern basins are above
average. The Weber, Provo, West Uintah, Price, and San Rafael
basins have SWSI numbers of 2 or greater.

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Figure 9a. Currrent snow water equivalent (SWE) as a percent
of normal for SNOTEL sites in Utah as of January 4, 2006.
This is orovisional data. For current SNOTEL data and plots
of specific sites, see http://www.cbrfc.noaa.gov/snow/snow.cgi
or http://www.wcc.nrcs.usda.gov/snow/

Notes
Figure 9a shows the SWE as a percent of normal (average)
for SNOTEL sites in Utah. According to the UT NRCS, "The
Surface Water Supply Index (SWSI) is a predictive indicator of
total surface water availability within a watershed for the spring
and summer water use seasons. The index is calculated by
combining pre-runoff reservoir storage (carryover) with fore-
casts of spring and summer streamflow, which are based on
current snowpack and other hydrologic variables. SWSI values
are scaled from +4.1 (abundant supply) to -4.1 (extremely
dry) with a value of zero (0) indicating median water supply
as compared to historical analysis. SWSl's are calculated in
this fashion to be consistent with other hydroclimatic indicators
such as the Palmer Drought Index and the [Standardized]
Precipitation Index." See page 9 for the SPI.

Figure 9b. Utah Surface Water Supply Index
(released 1/06/06).

On the Web
- For current maps of SWE as a percent of normal like in Figure 9a, go to: http://www.wcc.nrcs.usda.gov/gis/snow.html.
- The Utah SWSI, along with more data about current water supply status for the state, can be found at: http://www.
ut. nrcs. usda. gov /snow/watersupply/.
- The Palmer Drought Index is found on NOAA's drought page: www.drought.noaa.gov
- For current streamflow information from USGS, visit: http://water.usgs.gov/waterwatch/

RECENT CONDITIONS 112