Southwest Snowpack

Snowpack levels continued to drop over the past month as very little precipitation fell across most of Arizona and New Mexico. The current La Niña event drew winter storms northward into the Upper Colorado River Basin states of Utah, Colorado, and Wyoming. As of March 17, nearly all Snow Telemetry (SNOTEL) stations in Arizona and New Mexico measured below-average to well below-average snow water equivalent (SWE) (Figure 8). SWE in the central Mogollon Rim area was the lowest in Arizona, measuring only 15 percent of average. The Verde River Basin measured the highest SWE in the state, with only 53 percent of average. In New Mexico, the San Miguel, Dolores, Animas, and San Juan river basins in the northern part of the state had near-average levels measuring 92 percent of average SWE. The snowpack in the southern portion of the state fared worse, with the Mimbres, San Francisco, and Gila river basins containing only 8, 23, and 28 percent of average SWE, respectively. While many river basins in the region measured near-record levels of snowpack during the winter months of 2010, this winter was almost completely opposite.

Forecasts show a weakening La Niña pattern but still call for elevated chances of below-average precipitation for the spring months. As a result, streamflow forecasts anticipate below-average to well 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.