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Published January 25, 2011
Southwest Snowpack(updated 1/20/11)
Data Source(s): National Water and Climate Center, Western Regional Climate Center
The water contained in snowpack has been variable across Arizona and New Mexico (Figure 8). As of January 20, snow water equivalent (SWE) measured by snow telemetry (SNOTEL) stations ranged from 41 percent in the Gila River Basin to as much as 124 percent in the headwaters of the San Juan River. In Arizona, SWE ranged from 118 percent in the Verde River Basin to 74 percent in the Salt River Basin. Statewide, average snow levels were slightly above average. New Mexico, on the other hand, is experiencing a drier-than-average season so far, with scant precipitation falling across the state between October and December. Most basins recorded snowpack levels of less than 65 percent of average, except for the high elevation areas that include the Animas and San Juan river basins in southern Colorado and the Upper Rio Grande Basin in northern New Mexico.
The current moderate to strong La Niña event has played a large role in the dry winter in the Southwest. La Niña events typically steer storms north of the region and deliver warmer temperatures and less precipitation to the Southwest, especially in the southern areas. Current forecasts issued by the NOAA-Climate Prediction Center indicate a high chance that La Niña conditions will persist throughout the spring, likely delivering below-average rain and snow totals to the region.
States to the north of Arizona and New Mexico, which supply most of the water to the Colorado River and Rio Grande, are experiencing a wet winter. Currently the majority of snow monitoring stations in Colorado, Wyoming, and Utah measure more than 125 percent of average SWE.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 content (SWC) or snow water equivalent (SWE) is calculated from this information. SWC 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 SWC than light, powdery snow.
This figure shows the SWC 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 SWC measurements made by the Natural Resource Conservation Service.
Southwest Climate Outlook Staff
- Michael Crimmins, UA Extension Specialist
- Stephanie Doster, Institute of the Environment Editor
- Dan Ferguson, CLIMAS Program Director
- Gregg Garfin, Founding Editor, Institute of the Environment
- Zack Guido, CLIMAS Associate Staff Scientist
- Gigi Owen, CLIMAS Assistant Staff Scientist
- Nancy J. Selover, Arizona State Climatologist
- Jessica Swetish, CLIMAS Publications Assistant
Please direct your Southwest Climate Outlook comments and suggestions to Zack Guido.
The CLIMAS Web site contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials.... Read full disclaimer