October 2010 Climate Summary

Drought– Some welcome October precipitation has kept drought at bay across much of Arizona and New Mexico and has helped improve some areas of northern Arizona. Abnormally dry conditions still continue to linger across much of western and northern Arizona and parts of northwest New Mexico.

Temperature– Temperatures in the past 30 days have been 2–6 degrees Fahrenheit warmer than average for the entire Southwest.

Precipitation– Two rain storm events in the last month have dropped large amounts of precipitation across the Southwest. Northwest Arizona and north-central New Mexico have been the principal beneficiaries of these storms. Southern portions of both states have been relatively dry.

ENSO– A La Niña Advisory remains in effect. Moderate to strong La Niña conditions are expected to persist through next spring.

Climate Forecasts– The seasonal temperature forecasts call for increased chances for temperatures to be warmer than average through the winter; the precipitation outlooks suggest drier-than-average conditions for most of the fall and winter in all of Arizona and western New Mexico.

The Bottom Line– Several unseasonably wet storms drifted into the Southwest during late September and early October, adding valuable moisture that could become increasingly scarce as the winter progresses. The La Niña event that currently is classified as moderate to strong is the driving force behind expected dry conditions. During La Niña events since 1950, winters in the southwestern U.S. have been dry between 60 and 80 percent of the time. Temperatures have been as much as 6 degrees F above average in the last month. Forecasts suggest these warmer-than-average conditions will continue in part because of the historical warming trend and the La Niña event.