Droughts getting longer with increasingly erratic rainfall in the western US
Updated Apr 12, 2021 1:06 PM EDT
Over the past 50 years, annual rainfall across large portions of the western United States has become more erratic in nature, while dry periods have become longer, according to a new report from the United States Department of Agriculture.
Average annual rainfall for the western U.S. has decreased 0.4 of an inch over the past 50 years. This may not seem like much, but keep in mind many parts of the West average less than 10 inches of rainfall through the year.
On average, the duration of the longest dry period in the western U.S. during a given year has increased from 20 to 32 days over the past 50 years. More specifically, in the Desert Southwest that same figure has increased from 30 to 45 days. As a result, droughts are becoming more extreme in the southwestern U.S.
The erratic nature of rainfall events has seen the greatest change over the half century, according to the EurekAlert report.
"Consistency of rainfall, or the lack of it, is often more important than the total amount of rain when it comes to forage continuing to grow for livestock and wildlife, for dry land farmers to produce crops, and for the mitigation of wildfire risks," said co-senior author Joel Biederman, a research hydrologist with the ARS Southwest Watershed Research Center in Tucson, Arizona.
These changes have been much less pronounced from the Pacific Northwest to the northern High Plains compared to the Southwest.
A predicted northward shift of the Pacific jet stream due to climate change is likely the main culprit to these significant, long-term shifts in precipitation in the West.
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Weather Blogs / Global climate change
Droughts getting longer with increasingly erratic rainfall in the western US
Updated Apr 12, 2021 1:06 PM EDT
Over the past 50 years, annual rainfall across large portions of the western United States has become more erratic in nature, while dry periods have become longer, according to a new report from the United States Department of Agriculture.
Average annual rainfall for the western U.S. has decreased 0.4 of an inch over the past 50 years. This may not seem like much, but keep in mind many parts of the West average less than 10 inches of rainfall through the year.
On average, the duration of the longest dry period in the western U.S. during a given year has increased from 20 to 32 days over the past 50 years. More specifically, in the Desert Southwest that same figure has increased from 30 to 45 days. As a result, droughts are becoming more extreme in the southwestern U.S.
The erratic nature of rainfall events has seen the greatest change over the half century, according to the EurekAlert report.
"Consistency of rainfall, or the lack of it, is often more important than the total amount of rain when it comes to forage continuing to grow for livestock and wildlife, for dry land farmers to produce crops, and for the mitigation of wildfire risks," said co-senior author Joel Biederman, a research hydrologist with the ARS Southwest Watershed Research Center in Tucson, Arizona.
These changes have been much less pronounced from the Pacific Northwest to the northern High Plains compared to the Southwest.
A predicted northward shift of the Pacific jet stream due to climate change is likely the main culprit to these significant, long-term shifts in precipitation in the West.
Report a Typo