November 2011 Climate Summary
Editor's Note– The November issue of the Southwest Climate Outlook is abbreviated due to the Thanksgiving holiday. The publication of complete issues will resume in December.
Drought– Drought conditions intensified from moderate to extreme in central Arizona in the last 30 days. Nearly half the state is classified with moderate or a more severe drought category. In New Mexico, drought conditions remained virtually unchanged from one month ago. Currently, about 91 percent of the state is classified with at least moderate drought.
Temperature– Temperatures generally have been within 2 degrees F of average across the Southwest. While parts of southern Arizona deserts have been warmer than average, higher elevations in Arizona and New Mexico have experienced cooler-than-average temperatures.
Precipitation– In the past 30 days, several early winter storms moved across the region from southwest Arizona to northeast New Mexico, delivering above-average precipitation to those regions. Meanwhile, southeast Arizona and the southern two-thirds of New Mexico experienced less than 75 percent of average precipitation.
ENSO– Weak La Niña conditions persisted in the past month. Most models project that La Niña will continue through the winter; models and historical observations suggest that the intensity of the event will fall in the weak to moderate range.
Climate Forecasts– Temperature outlooks for the December–February period call for increased chances for above-average temperatures in most of New Mexico and below-average precipitation in most of both states. The odds for drier-than-average conditions are highest in the southern tier of Arizona and New Mexico where La Niña impacts are strongest.
The Bottom Line– Drought conditions remain entrenched in nearly all of Arizona and New Mexico, the residual effect of the dry 2010–2011 winter and a so-so monsoon. The expectation is that dry conditions will continue in part because La Niña has returned. Although forecasts suggest the La Niña will reach at most a moderate strength, this does mean precipitation deficits will also likely be moderate. In the past, weak La Niña events have produced both high and low precipitation anomalies in the Southwest. Although storms tend to be pushed north during La Niña events, the jet stream often meanders more than during El Niño events, and it occasionally bows enough to waft frigid Arctic air into the region, like it did last winter when record cold air froze many parts of Arizona and New Mexico in early February.