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Published May 22, 2013
Southwest Snowpack(updated 5/16/13)
Data Source(s): National Water and Climate Center; Western Regional Climate Center
Snowpacks in the Upper Colorado River Basin continue to decrease as spring temperatures warm. While several spring storms dropped snow in northern Colorado, which helped measuring stations record near-average snowpacks for this time of year, many other regions are recording well below-average totals (Figure 8). This includes the upper Rio Grande headwaters, where snowpacks are measuring, on average, about 24 percent of average.
Precipitation during the 2012–2013 winter was largely below average across the Southwest and Colorado. Since October 1, precipitation in all of New Mexico and most of southern Colorado has been less than 70 percent of average. Arizona has fared only slightly better. This is the third winter in a row in which the water contained in snowpacks, or SWE, averaged across SNOTEL monitoring stations in Arizona has been below average. The consequences of the dry winter are acute on the Rio Grande, where streamflow projections are low and many farmers likely will receive only a small fraction of the water needed to irrigate tree and vegetable crops. Other impacts relate to expanding drought conditions and elevated fire risk.Notes:
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 from 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 1981–2010 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 Dubois, New Mexico State Climatologist
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
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