Southwest Snowpack

Several wet and cold early winter storms have helped boost the amount of water contained in snowpack, or snow water equivalent (SWE), across the Southwest (Figure 8). SWE measured by snow telemetry (SNOTEL) stations in Arizona was all above 210 percent of average, with as much as 284 percent measured in the Central Mogollon Rim as of December 15. Snowpack in New Mexico has been slightly more variable, with southern mountains having more SWE than northern basins. SWE measured 331 percent of average in the Mimbres River Basin in southwest New Mexico and 88 percent in the Zuni-Bluewater River Basin in west-central New Mexico.

States to the north of Arizona and New Mexico, which supply most of the water to the Colorado River and Rio Grande, experienced a drier-than-average fall. The majority of SNOTEL stations in Colorado, Wyoming, and Utah measured less than 90 percent SWE as of December 15.

La Niña events usually deliver below-average rain and snow to the Southwest but do not as strongly influence precipitation totals in the Upper Colorado River Basin. Current forecasts issued by the NOAA-Climate Prediction Center (CPC) indicate a weak La Niña event will persist through the winter, increasing the odds of below-average rain and snow in Arizona, New Mexico, and southern Colorado. There are equal chances of above-, below-, or near-average precipitation for most of Utah, Wyoming, and parts of Colorado for the December–February and January–March periods (see page 14).