As winter nears its end and Colorado’s mountains get hit with the latest March snowstorm, climatologists and forecasters are predicting that the spring will bring drier weather and, in turn, lead to drought developing or deepening across much of the state. 

The Feb. 28 seasonal drought outlook from the National Weather Service predicted that most of Colorado would develop drought conditions heading into May, as La Nina weather patterns predict drier — and in some areas warmer — conditions than normal. 

“That spring outlook shows a pretty high confidence of drier-than-average conditions across Colorado in the spring,” said Russ Schumacher, Colorado’s state climatologist and director of the Colorado Climate Center. “The spring tends to be pretty wet across Colorado as a whole, and so if we do have a dry spring, then things can go south pretty quickly in terms of drought — and the outlook is tilted toward those drier-than-average conditions.” 

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While the likelihood of drought increases the further south and west you go, the picture in northwest Colorado and the northern Rockies is a little less clear.

National Weather Service Forecaster Adam Allgood wrote that the outlook is based on the expected continuation of La Nina, but that a wetter pattern is favored in the northern Rockies and “should be sufficient to alleviate drought conditions that have recently developed.” 

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“There’s a lot of places that are across Colorado that are not exceedingly wet but not especially dry at the moment,” Schumacher said. “A dry spring would take them into drought pretty quickly, but a wetter spring could keep things at the status quo of where it is right now.”

The National Weather Service will release its next seasonal outlook on March 20. 

Snowpack and drought conditions 

While drought conditions can be swayed by many climate factors, snowpack plays an important role. 

Across the Colorado River basin, “winter snowpack in the Colorado Rockies usually sets the tone for drought conditions from year to year,” according to the National Oceanic and Atmospheric Administration. 

Snowpack from the Upper Basin constitutes the majority of the Colorado River’s water supply, acting as a reservoir, said John Berggren, the regional policy manager for Western Resource Advocates.

Each month, NOAA issues a report detailing snow drought conditions across the Colorado River basin. Snow drought refers to a period of abnormally low snowpack for that season. 

The latest report from March 6 details a worsening picture for the Lower Basin and the Colorado River as a whole. 

“Extremely dry conditions across the West in January transitioned to a more active precipitation pattern in February improving the snowpack for much of the West, particularly in the Sierra Nevada, northern Great Basin, and northern Rocky Mountains,” according to the report.  

“In contrast, much of the southern Rocky Mountains, Arizona, and New Mexico saw very little snowfall over the past month. The worst snow drought conditions continue to be in the Southwest,” it adds. 

While snowpack varies from year to year and place to place, the report follows an overall trend in the region, Berggren said. 

“More and more, we’re seeing you can get an average snowpack throughout the Upper Basin, but it’s not translating into an average supply or average flows in the river anymore because of the impacts of climate change on things like soil moisture,” he said. “We really need to get well above average snowpack to land somewhere more average for the actual flow in the river itself.”

One example, he said, is that even with around normal snowpack in the Upper Colorado River Basin this year, the inflow into Lake Powell is predicted to be much lower than normal.

The U.S. Bureau of Reclamation weekly water supply report from March 10 predicts unregulated inflows into Lake Powell will be 70% of normal between April and July, despite 92% of normal snow water equivalent in the Upper Colorado Basin. The NOAA snow drought report indicates that this is due to below-normal precipitation and persistent low soil moisture as you head south and west in the basin.

“Spring storms could help boost snowpack, but erasing the deep seasonal deficits across these basins is unlikely,” the report adds. 

If these forecasts hold, this will bring concerns about ecological health, infrastructure, legal agreements and water supply across the basin, according to Berggren. 

Colorado’s snowpack — much like the entire river basin — is experiencing a north-south divide. 

Snowpack in the southern San Juan, Sangre de Cristos and Grand Mesa regions is in “pretty bad shape” despite recent storms, Schumacher said. 

According to the March 13 NOAA Colorado drought monitor, most of southwestern Colorado — with the exception of the majority of Gunnison County — is experiencing moderate to severe drought. 

“They’re still lagging way behind in terms of snowpack, and the time’s kind of running out to get a big boost,” he added. 

In the northern mountains, conditions are looking slightly better with snowpack close or slightly above average, Schumacher said. 

In Northwest Colorado, the latest drought monitor shows the western portion of Eagle County heading into Garfield and Pitkin counties, as well as portions of Rio Blanco and Moffat counties, as abnormally dry. 

Further west toward the state border, conditions worsen. The north-central mountain region touching eastern Eagle County as well as Routt, Grand, Summit and Jackson counties shows no current drought conditions. 

The forecasts for water supply and runoff don’t give a particularly optimistic outlook for drought conditions, Berggren said. 

“Water managers should be keeping a close eye on their region, looking at — as the snow melts, as it runs off, and as we see what actually flows in the rivers — what are those drought conditions?” he said. “As we’ve seen in the past, they can turn pretty quickly and you can go from being in moderate drought to extreme drought in just a matter of weeks. That’s going to be important to keep an eye on this spring.”

Could March and April storms shift the tide? 

While March and April can deliver significant snow in Colorado’s mountains, it is difficult for spring precipitation to turn the tide of the entire season from good to bad or vice versa, according to Schumacher. 

“By that point in the winter, you’ve already accumulated a large fraction of the snow that is going to happen,” Schumacher said. “If those winter months are very snowy or not snowy, that dictates a lot of how the season as a whole is going to end up looking. March and April can turn it around, but the average in March is still quite a lot of snow. So by the end of February, you have a pretty good sense of what the season’s going to look like.” 

The National Weather Service Climate Prediction Center predicts a colder and wetter pattern over the next month in the West, reporting that this could be favorable for snow accumulation. 

Over the weekend of March 14, snow is expected to accumulate across most of western Colorado, with another storm likely early next week, Schumacher said. However, neither storm is expected to be what he would consider a “drought buster.” 

“It’ll be welcome snowfall, but it doesn’t look like the amount of snow that would turn things around in a big way,” Schumacher said. 

However, as with all things weather and climate-related, the “atmosphere can always throw us curveballs” as it did in May 2015 when Colorado experienced a “Miracle May” bringing extreme moisture after lower-than-normal snowpack, according to Schumacher. Historically, however, it’s uncommon that a super dry winter is saved by spring storms, he added. 

So, while a wetter spring is not out of the picture, La Nina conditions predict the opposite. Past the next 30 days, the weather service is predicting hotter and drier conditions in April and May. 

“Springs tend to be drier on average during La Nina,” Schumacher said, adding that it means a “hotter than average summer is a pretty safe bet this year.”

“The summer and fall is when we’ve seen the biggest warming trend over the last several decades,” Schumacher said. “Hot summers put more stress on everything in terms of water because the warmer air is thirstier for water — it’s trying to pull more water out of the soils and the forests and the reservoirs and the croplands and everything else.” 

Bergerren said that in addition to water supply concerns during serious drought conditions, the western United States will also see an increased risk for wildfire. 

What could earlier snowmelt mean for drought conditions? 

According to Schumacher, one of the most confident predictions surrounding climate change is how it will impact the timing of snowmelt and spring runoff — which in turn could impact drought conditions. 

“In climate models or future climate scenarios, there’s a lot of uncertainty still about how precipitation will change precisely in the mountains here,” he said. “But basically, every climate model shows the meltout happening earlier in the spring and thus the runoff happening earlier in the spring.”

This earlier snowmelt and runoff is driven by warming temperatures in the spring and summer. This could impact drought conditions as it affects the summer water supply. 

With Upper Basin snowpack serving as a “reservoir” for the Colorado Basin, “the longer you can keep water in that reservoir, the more likely there’s going to be water there when you need it the most, which is in the late summer for irrigation, for agriculture, for water supply” Berggren said. 

However, the impacts of an earlier snowmelt and runoff are not set in stone. 

“Just because the melt starts early doesn’t necessarily mean that you won’t build some of it back up later on in the spring,” Schumacher said. “The monsoon (rain season) can also help with that, but the amount of water you get from monsoon thunderstorms is just so much smaller than the amount of water you get from these big snowstorms that get stored in the snowpack.”