A new study of global weather patterns over the past 35 years supports earlier scientific predictions the southwestern United States will become drier as atmospheric conditions that typically bring the most rain and snow to the region continue to become more rare.
The research supported by the National Science Foundation concludes that what's now considered a normal year of precipitation in the Southwest is drier than it used to be.
The scientists emphasize the new data doesn't prove climate change is responsible for increasing frequency and duration of drought.
But they say it's evidence that subtle shifts in large-scale weather patterns over the past three decades have been the driving force behind moisture trends from Southern California to the southern Rockies.
The study was published Thursday in a journal of the American Geophysical Union.