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Published February 27, 2013
Southwest Snowpack(data through 2/21/13)
Data Source(s): National Water and Climate Center, Western Regional Climate Center
Precipitation in the last month has been above average for many parts of the higher elevations in Arizona, New Mexico, Colorado, and Utah. While this recent snow helped boost the water contained in snowpack, or snow water equivalent (SWE), in some locations, the overall SWE picture is still grim. This is because precipitation since January 1 in most of the Southwest has been less than 90 percent of average, and less than 70 percent since start of the water year on October 1. Consequently, snow monitoring stations in the Upper Colorado River drainage basins in Colorado are generally reporting only 78 percent of average SWE for this time of year; SWE in the Animas and San Juan basins is about 85 percent of average (Figure 8). The headwaters of the Rio Grande in Colorado, which provides a large fraction of the water to New Mexico’s largest river, is also below average, measuring about 79 percent of average SWE. This low value continues to be a major concern for water managers in this region because reservoirs, like Elephant Butte Reservoir, are low. It seems unlikely that the Rio Grande will experience above-average spring flows, which is also the case for many other rivers in the Southwest.
Snowpack telemetry (SNOTEL) sites are automated stations that measure snowpack depth, temperature, precipitation, soil moisture content, and soil saturation. A parameter called snow water equivalent (SWE) is calculated from this information. SWE refers to the depth of water that would result by melting the snowpack at the SNOTEL site and is important in estimating runoff and streamflow. It depends mainly on the density of the snow. Given two snow samples of the same depth, heavy, wet snow will yield a greater SWE than light, powdery snow.
This figure shows the SWE for selected river basins, based on SNOTEL sites in or near the basins, compared to the 1971–2000 average values. The number of SNOTEL sites varies by basin. Basins with more than one site are represented as an average of the sites. Individual sites do not always report data due to lack of snow or instrument error. CLIMAS generates this figure using daily SWE measurements made by the Natural Resources Conservation Service.
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, Managing Editor, CLIMAS Associate Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Dollin, CLIMAS Publications Assistant
- Dave Dubious, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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