December 2011 Climate Summary
Drought-Drought conditions in Arizona and New Mexico have improved slightly as a result of several early winter storms. Drought conditions remain widespread, however, due to significant precipitation deficits that have accumulated since the start of last winter.
Temperature-Temperatures have been colder than average in the last 30 days, but near average since the water year began on October 1.
Precipitation-Several winter storms tapped subtropical moisture and moved across Southern California and into Arizona and New Mexico in the past 30 days. As a result, many areas have received more than 150 percent of average rain and snow.
ENSO-Weak to moderate La Niña conditions persist in the tropical Pacific Ocean. Forecasts suggest the event will peak in January or February, with half of the models suggesting it will increase to moderate intensity.
Climate Forecasts-Seasonal precipitation outlooks call for drier-than-average conditions through April in New Mexico and Arizona, with southern regions drier than northern areas. Temperature outlooks call for increased odds of warmer-than-average conditions in New Mexico in the next three months.
The Bottom Line-A weak to moderate La Niña event remains entrenched in the tropical Pacific Ocean and continues to influence below-average precipitation outlooks for the winter. However, several wet and cold early winter storms moved through the region, dumping rain and snow in the Southwest that improved drought conditions in some areas. These storms tapped tropical moisture and chilly polar air, creating ripe conditions for snow to fall at mid-elevations. However, these storms missed the southeast corner of New Mexico, where precipitation in the last month has been below 75 percent of average. Exceptional and extreme drought continue to grip this region. The atmospheric circulation that ferried several early winter storms into the Southwest is somewhat abnormal for a La Niña, which often pushes storms north of the region this time of year. However, weak La Niña events tend to be wetter than moderate or strong events. There is uncertainty about how long and how strong this La Niña will be, but forecasts suggest at least a weak event will persist through the winter.