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

Precipitation through 12/31/05 Source: NOAA/ESRLlPSD Climate Diagnostics Center, NOAA Climate Prediction Center

Precipitation in the Intermountain West region falls primarily
as snow in December and snowpack and snow water equivalent
(SWE) depend on elevation. Areas experiencing above average
precipitation in December 2005 fell in the north-central moun-
tains of Colorado, the central and western mountains of Wyo-
ming and north central Utah (Figure 3a). These areas received
from 1-3+ inches of precipitation in December, and this amount
was 120% to 200% of average (Figure 3b). The eastern half
of Colorado and southern and eastern Utah remain very dry,
receiving from 0- 0.5 inches of precipitation, or about 40%-60%
of average.
Since the start of the 2006 water year, October, 2005 (Figure
3c) Colorado has received average to above average precipita-
tion in the northern half of the state, with the north central moun-
tains and northeastern plains receiving 120% to 200% of average,
while southern Colorado is average to below average with only
40% to 60% of average in the southeast. Wyoming received
average precipitation for most of the state, with the exception
of the southeast plains and northwest mountains with 120% to
150% of average precipitation. North-central and northwest
Utah received 120% of average precipitation, the middle of the
state received about average, and the southern portion received
40%-80% of average precipitation. The gradient of increasing
precipitation from south to north is similar to a La Nina pattern.
(See page 16 for ENSO outlook.)

Notes
The water year runs from October 1 to September 30 of the fol-
lowing year. As of October 1 , 2005, we are in the 2006 water
year. The water year is more representative of climate and hy-
drological activity than the standard calendar year. It reflects the
natural cycle of accumulation of snow in the winter and runoff and
use of water in the spring and summer.

Average refers to the arithmetic mean of annual data from 1996-
2005. This period of record is only ten years long because it in-
cludes SNOTEL data, which have a continuous record beginning
in 1996. Percent of average precipitation is calculated by taking
the ratio of current to average precipitation and multiplying by 100.

The data in Figs. 3a-c come from NOAA's Climate Prediction
Center. The maps are created by NOAA's Climate Diagnostics
Center, and are updated daily (see website below). These maps
are derived by taking measurements at individual meteorological
stations and interpolating (estimating) values between known data
points to produce continuous categories.

Figure 3a. Total precipitation in inches for the
month of December 2005.

Figure 3b. Percent of average precipitation for the
month of December 2005.

Figure 3c. Percent of average precipitation accumulated
since the start of water year 2006. (Oct. 1 - Dec. 31,2005).

On the Web
- For the most recent versions of these and maps of other climate variables including individual station data, visit:
http://www.hprcc.unl.edu/products/current.html.
- For precipitation maps like these and those in the previous summaries, which are updated daily visit: http://www.cdc.noaa.gov/Drought/.
- For National Climatic Data Center monthly and weekly precipitation and drought reports for Colorado, Utah, Wyoming, and the whole U.S.,
visit: http://lwf.ncdc.noaa.gov/oa/c1imate/research/2002/perspectives.html.
- For a list of weather stations in Colorado, Utah, and Wyoming, visit: htt(2://www.wrcc.dri.edu/summary.

RECENT CONDITIONS I 6

3
2
1.5

0.5
0.25
o

Inches

Wet

200

150

120

80

60

40

Dry

Wet

200

150

120

80

60

40

Dry