Editor's Note– The December issue of the Southwest Climate Outlook is abbreviated due to the Christmas and New Year’s holiday.
December Climate Summary
Drought: Drought conditions remain largely unchanged from one month ago. Moderate or a more severe drought classification covers more than 97 percent of both Arizona and New Mexico.
Temperature: Temperatures have been more than 2 degrees Fahrenheit above average in most of Arizona and New Mexico during the past month, with temperature anomalies exceeding 6 degrees F in many parts of eastern New Mexico.
Precipitation: Above-average rain and snow have fallen in many parts of Arizona in the last month as a result of several early winter storms. Despite the recent storms, below-average precipitation has defined conditions in most of New Mexico.
ENSO: ENSO-neutral conditions prevail and have more than an 80 percent probability of continuing through the March–May period.
Climate Forecasts: Precipitation outlooks call for increased chances for drier-than-average conditions in January through March, while temperature outlooks suggest warmer-than-average conditions.
The Bottom Line: Drought conditions across the Southwest remain widespread, with about 97 percent of Arizona and New Mexico experiencing at least moderate drought. Several recent early winter storms have delivered copious rain and snow to many parts of the Southwest, which should help short-term drought conditions. These storms boosted early winter snowpack conditions, which measure more than 200 percent of average in many parts of Arizona’s higher elevations. The storms also dropped snow in the high country of the Upper Colorado River and Rio Grande basins, although water contained in the snowpacks of most measuring stations in these regions remains below average. With water storage in many of the region’s reservoirs much below average, a heavy dosing of snow is needed to mollify concerns of water shortages, especially on the Rio Grande and Pecos River in New Mexico. Even if winter rain and snow is above average, however, drought conditions likely will persist. They may also worsen if precipitation forecasts, which call for below-average rain and snow, play out. Drier-than-average conditions in the Southwest are forecasted in part because ENSO-neutral conditions and cooler-than-average sea surface temperatures in the western North Pacific Ocean, both of which exist now, have historically favored dry conditions in the region. Forecasts in the Upper Colorado and Rio Grande basins also call for slightly increased chances for below-average rain and snow. Temperature forecasts continue to favor warmer-than-average conditions. In recent months, temperatures have been in the top 10 warmest in the historical record, which dates back to 1895, and 2012 will likely go in the record books as the warmest year on record for the Four Corners States. Warmer-than-average spring temperatures could hasten spring snowmelt, potentially increasing the risk of wildland fires because the landscape would have a longer period to dry out before summer rains arrive.