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Published February 23, 2011
Southwest Snowpack(updated 2/17/11)
Data Source(s): National Water and Climate Center, Western Regional Climate Center
The current La Niña event has continued to push winter storms to the north of the Southwest, leaving Arizona and New Mexico relatively dry. January was the driest January on record in New Mexico, and most areas in Arizona also experienced no rain or snow. Snowpack levels have significantly declined since last month, and most Snow Telemetry (SNOTEL) stations measure below-average snow water equivalent (SWE) in Arizona and New Mexico (Figure 8). As of February 17, SWE in the Upper Gila River Basin in Arizona was the lowest in the state, measuring only 26 percent of average. SWE in the central Mogollon Rim area and the Verde River Basin were only slightly better, tallying 40 and 61 percent of average, respectively. SWE was more variable in New Mexico. River basins in the northern part of the state had near-average levels, including the Zuni/Bluewater River Basin, where SWE is about 98 percent of average. On the other hand, river basins in southern regions have extremely low SWE, including the Mimbres, where SWE stood at 19 percent of average on February 17.
Forecasts call for the continued presence of the La Niña pattern and elevated chances for below-average precipitation for the next several months. As a result, streamflow forecasts anticipate below-average runoff from most basins in the Southwest, except those with headwaters in the Rocky Mountains to the north of Arizona and New Mexico where precipitation has been higher this winter.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
- 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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