A flurry of research illuminates snow’s foes

New studies detail how hotter temperatures, humid air and wind-blown dust can pummel the Western snowpack.

 

Depending on where in the West you are, this winter was either a winner or a big bust: Montana, for example, is swathed in snow while parts of the Southwest are dismally bare. As of late March, the Upper Colorado River Basin snowpack was well below average.

But the longterm trend is clear: Years of research show that the region’s snowpack is declining as the climate warms. About two-thirds of the West’s water comes from snow, and “we’re losing that natural reservoir,” says Sarah Kapnick, a hydroclimate scientist with the National Oceanic and Atmospheric Administration.

Forecasting the coming winter’s bounty months in advance could help Westerners prepare for surplus or scarcity, Kapnick says. Better predictions would allow officials time to implement flood control or water conservation measures, for example, and help farmers decide whether to plant thirsty crops or hardier ones.

The first step is understanding what can diminish a snowpack, like hotter temperatures, humid air and wind-blown dust. Here are three recent studies that dive into the snowpack and its foes:

Frank Gehrke, chief of the California Cooperative Snow Surveys Program, right, plunges a snow survey tube into the snowpack to check its depth on March 5, 2018, near Echo Summit, California. By late March, the statewide snowpack was about 60 percent of normal.
Rich Pedroncelli/AP Photo
THE STUDY:Exploring the origins of snow drought in the Northern Sierra Nevada, California,” Earth Interactions, December 2017.

THE TAKEAWAY: Not all droughts are dry. A “snow drought” can occur even when there’s plenty of precipitation if it’s so warm that it falls as rain instead of snow.

WHAT IT MEANS: To understand what causes snow droughts, scientists from the Desert Research Institute in Reno, Nevada analyzed decades of monthly snow measurements from the northern Sierra Nevada, near Lake Tahoe. They identified several snow droughts caused by a variety of factors, including dry periods, warm weather and rain falling on snow and melting it.

The researchers found that some weather patterns have inconsistent impacts: For example, atmospheric river storms, bands of water-soaked air that can drench the West Coast, might initiate a snow drought if they bring mostly rain, or end one if they deliver snow.

While snow droughts aren’t a new phenomenon — the scientists found evidence for one in 1951, the earliest year they studied — it does appear that they are becoming more common. “We’re seeing them stack up a little bit more now,” says Benjamin Hatchett, one of the study’s co-authors. That trend will likely continue as the climate warms, stressing both ecosystems and economies that depend on snow and the water it holds.


Fog rolls in below snow-dusted peaks on Washington’s Olympic Peninsula. In relatively humid places like the Pacific Northwest, more water melts from the snowpack during the wintertime than in more arid regions.
Brooke Warren/High Country News

THE STUDY:Humidity determines snowpack ablation under a warming climate,” Proceedings of the National Academy of Sciences, January 2018.

THE TAKEAWAY: The amount of moisture in the air drives wintertime dips in the snowpack. There’s more midwinter snowmelt in humid corners of the West than arid ones.

WHAT IT MEANS: Scientists from the University of Nevada Reno and the University of Utah scrutinized decades of weather and snow records from 462 sites across the West to understand why water in the snowpack sometimes dwindles during the wintertime.

They found that relatively wet places experienced more wintertime melting. During humid weather — a stretch of foggy days, for example — water vapor in the air condenses on the snowpack, releasing energy and heating the snow. Clouds and moist air also prevent nighttime cooling, pushing the snowpack closer toward thawing, sometimes well before spring. “If (snow) is melting and not sticking around to the times later in the year when we need and expect that water, that’s a real problem,” says Adrian Harpold, a hydrologist at the University of Nevada Reno and co-author of the study.

Harpold says parts of the Western snowpack could be hit hard by amplified humidity in the future. Because a warmer atmosphere can hold more moisture, places near the ocean or other large bodies of water will likely experience more humidity — and more melting.


Layers of dust stripe the sides of a pit dug into the snow in Colorado. Dust deposited or exposed on the surface of the snowpack contributes to faster warming and melting.
Center for Snow and Avalanche Studies

THE STUDY:Variation in rising limb of Colorado River snowmelt runoff hydrograph controlled by dust radiative forcing in snow,” Geophysical Research Letters, December 2017.

THE TAKEAWAY: Snow covered in dust melts faster than clean snow, because it absorbs more energy from the sun. In some areas, dust influences the speed of spring snowmelt more than air temperature.

WHAT IT MEANS: Dust blown in from the Great Basin and the Colorado Plateau periodically darkens alpine slopes in southwest Colorado’s San Juan Mountains. A team of scientists examined air temperature, dust deposition and how quickly a handful of rivers in the area rose in the spring between 2005 and 2014. Dust was the dominant factor: Spring runoff happened more quickly in years with more dust, regardless of whether the air was warm or cool.

Understanding how dust affects snowmelt and spring runoff is crucial for water management, says Tom Painter, an author of the study and a snow hydrologist at NASA’s Jet Propulsion Laboratory. A bigger, faster pulse of water could stress infrastructure and increase the risk of flooding.

That doesn’t mean air temperature is completely irrelevant. After all, that’s what determines how much precipitation falls as snow rather than rain. “That is an enormous impact on the water resources as well,” Painter says.

Emily Benson is an assistant editor at High Country News. 

High Country News Classifieds
  • DEPUTY DIRECTOR
    The Methow Valley Citizens Council has a distinguished history of advocating for progressive land use and environmental values in the Methow Valley and Okanogan County...
  • ACTING INDIGENOUS AFFAIRS DESK EDITOR
    High Country News is seeking an Acting Indigenous Affairs Editor to oversee the work of our award-winning Indigenous Affairs Desk while our editor is on...
  • GRANTS PROGRAM DIRECTOR
    The Cinnabar Foundation seeks an enthusiastic, team-oriented and knowledgeable Grants Program Director to work from their home in Montana. Established in 1983, the Cinnabar Foundation...
  • ARTEMIS PROGRAM MANAGER
    The Artemis Program Manager will work with National Wildlife Federation sporting and public lands staff to change this dynamic, continue to build upon our successful...
  • ALASKA SEA KAYAK BUSINESS FOR SALE
    Well-known and successful sea kayak, raft, hike, camp guiding & water taxi service. Sale includes everything needed to run the business, including office & gear...
  • MEMBERSHIP AND EVENTS PROGRAM COORDINATOR
    Great Old Broads for Wilderness seeks a detail-oriented and enthusiastic Membership and Events Coordinator to join our small, but mighty-fun team to oversee our membership...
  • PROGRAM DEVELOPMENT FACILITATOR
    ABOUT THE HIGH DESERT MUSEUM Since opening in 1982, HIGH DESERT MUSEUM has brought together wildlife, culture, art and natural resources to promote an understanding...
  • LAND STEWARD, ARAVAIPA
    Steward will live on-site in housing provided by TNC and maintains preserve areas frequented by the visiting public and performs land management activities. The Land...
  • DEVELOPMENT WRITER
    Who We Are: The Nature Conservancy's mission is to protect the lands and waters upon which all life depends. As a science-based organization, we create...
  • CONNECTIVITY SCIENCE COORDINATOR
    Position type: Full time, exempt Location: Bozeman preferred; remote negotiable Compensation: $48,000 - $52,000 Benefits: Major medical insurance, up to 5% match on a 401k,...
  • EXECUTIVE ASSISTANT
    ArenaLife is looking for an Executive Assistant who wants to work in a fast-paced, exciting, and growing organization. We are looking for someone to support...
  • EXECUTIVE DIRECTOR
    The Mountain Lion Foundation is seeking an Executive Director. Please see our website for further information - mountainlion.org/job-openings
  • WASHINGTON DC REPRESENTATIVE
    Position Status: Full-time, exempt Location: Washington, DC Position Reports to: Program Director The Western Organization of Resource Councils (WORC) is seeking a Washington, DC Representative...
  • REGIONAL CAMPAIGN ORGANIZER
    Position Title: Regional Campaign Organizers (2 positions) Position Status: Full-time, exempt Location: Preferred Billings, MT; remote location within WORC's region (in or near Grand Junction...
  • STAFF ATTORNEY
    Western Watersheds Project seeks a Tenth Circuit Staff Attorney to bring litigation in the interests of protecting and restoring western watersheds and wildlife, particularly focused...
  • DEVELOPMENT DIRECTOR
    Driggs, ID based non-profit. Full time. Full job description available at tvtap.org. Submit cover letter and resume to [email protected]
  • ENVIRONMENTAL AND CONSTRUCTION GEOPHYSICS
    - We find groundwater, buried debris and assist with new construction projects for a fraction of drilling costs.
  • SPRING MOUNTAINS SOLAR OFF GRID MOUNTAIN HOME
    Located 50 miles northwest of Las Vegas, Nevada in the pine forest of Lee Canyon at 8000 feet elevation. One of a kind property surrounded...
  • MAJOR GIFTS MANAGER - MOUNTAIN WEST, THE CONSERVATION FUND
    Cultivate, solicit and steward a portfolio of 75-125 donors.
  • NATURE'S BEST IN ARAVAIPA CANYON
    10 acre private oasis in one of Arizona's beautiful canyons. Fully furnished, 2123 sq ft architectural custom-built contemporary home with spectacular views and many extras....