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Is the Western drought finally ending? That depends on where you look

Dan McEvoy, Associate Research Professor in Climatology, Desert Research Institute, The Conversation on

Published in Science & Technology News

Similar to the Sierra Nevada, the Upper Colorado River Basin – Wyoming, Colorado, Utah and northwestern New Mexico – has a healthy snowpack this year, and it’s looking like a very good water year there.

But one single good water year is not going to fill Lake Mead and Lake Powell. Most of the region relies on those two reservoirs, which have declined to worrying levels over the past two decades. NOAA’s seasonal drought outlook released on March 16 noted that both remained low.

Two good water years won’t do it either. Over the next decade, most years will have to be above average to begin to fill those giant reservoirs. Rising temperatures and drying will make that even harder.

So, that system is still going to be dealing with a lot of the same long-term drought impacts that it has been seeing. The reservoirs will likely rise some, but nowhere close to capacity.

The Pacific Northwest isn’t having as much rain and snow, and it’s a little drier there. But it’s close to average, so there’s not a huge concern there, at least not right now.

Drought can also have longer-term impacts on ecosystems, particularly forest health.

 

The Sierra Nevada range has seen large-scale tree die-offs with the drought in recent years, including in northern areas around Lake Tahoe and Reno that weren’t as affected by the previous drought. Whether the recent die-offs there are due to the severity of the current drought or lingering effects from the past droughts is an open question.

Even with a wet winter, it’s not clear how soon the forests will recover.

Rangelands, since they are mostly grasses, can recover in a few months. The soil moisture is really high in a lot of these areas, so range conditions should be good across the West – at least going into summer.

If the West has another really hot, dry summer, however, the drought could ramp up again, particularly in the Northwest and California. And then communities will have to think about fire risk.

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