Snowpack & Drought–Climate Impacts CIRC 1.0 Final Report

Mountain snow, or snowpack, acts as a natural water reservoir. By slowly melting over the summer months, snowpack provides water during what is typically the Pacific Northwest’s warmest and driest time of year. As with much of the American West, rising temperatures in the Pacific Northwest are making it far more likely that precipitation will fall more as rain and less as snow. This trend is expected to continue as temperatures continue to rise under human-caused climate change. Climate change-induced alterations of the Pacific Northwest’s hydrology have already led to water scarcities in our region.

Probably the best example of this happened in 2015 when abnormally warm winter temperatures and near-normal precipitation resulted in record low snowpack across Oregon and Washington. A good deal of CIRC research has revolved around tracking how the loss of snowpack has affected our region’s hydrology in the near term as well as how the loss of snowpack is likely to affect our region in the future.

OSU_icon_bulb_Black Key Findings:

  • Watersheds in the Pacific Northwest that receive a mix of rain and snow and derive a substantial portion of streamflow from spring snowmelt are most sensitive to future warming expected during the winter months (Vano et al. 2015).
  • The Cascade Mountains in Oregon and Washington are expected to be particularly hard hit by declines in snowpack with a projected decrease of 65%—or 37.5 km3—in April 1st snow water equivalent (SWE) storage—by the 2080s under the high emissions scenario (RCP 8.5) (Gergel et al. 2017).
  • By the mid-21st century (2040–2069) under the high emissions scenario (RCP 8.5), every SNOTEL site in the West is likely to see less snowfall and that snowfall is more likely to come in extreme snowfall events (Lute et al. 2015). (SNOTEL sites are automated snow-observing stations.)
  • Sites that currently experience average winter temperatures that hover just above freezing are projected to see the largest decreases in the amount of snow that falls during extreme snowfall events, declining 20–50% from historical records. These include most of the SNOTEL sites in Oregon and Washington (Lute et al. 2015).
  • In the Cascade Mountains are some of the hardest hit SNOTEL sites, which are projected to experience a 35–70% reduction in snowfall from historical levels (Lute et al. 2015).
  • Low snowfall years will become common in the Cascades by the mid-21st century, whereas high snowfall years will become exceedingly rare (Lute et al. 2015).
  • The water year 2014–2015 was dubbed a “snow drought” because precipitation was near-normal while abnormally warm temperatures led to record low snowpack. Record low spring snowpack measurements were set at 80% of mountain recording sites (or SNOTEL sites) in the Western United States (Mote et al. 2016).
  • Spring snowpack in 2015 was the lowest on record for Oregon—89% below normal—and tied for lowest on record for Washington (Mote et al., 2016).
  • Anthropogenic forcing added about 1° C (1.8° F) of extra warming to the water year 2014–2015 exacerbating the “snow drought” (Mote et al. 2016).

    OSU_icon_arrowleft_01Main Article

OSU_icon_gears_Black  Resources:

OSU_icon_pencil_Black Rotated Key Publications:

  • Gergel, Diana R., Bart Nijssen, John T. Abatzoglou, Dennis P. Lettenmaier, and Matt R. Stumbaugh. “Effects of Climate Change on Snowpack and Fire Potential in the Western USA.” Climatic Change 141, no. 2 (2017): 287-299.
  • Lute, A. C., John T. Abatzoglou, and Katherine C. Hegewisch. “Projected Changes in Snowfall Extremes and Interannual Variability of Snowfall in the Western United States.” Water Resources Research 51, no. 2 (2015): 960-972.
  • Mote, Philip W., David E. Rupp, Sihan Li, Darrin J. Sharp, Friederike Otto, Peter F. Uhe, Mu Xiao, Dennis P. Lettenmaier, Heidi Cullen, and Myles R. Allen. “Perspectives on the Causes of Exceptionally Low 2015 Snowpack in the Western United States.” Geophysical Research Letters 43, no. 20 (2016).
  • Vano, Julie A., Bart Nijssen, and Dennis P. Lettenmaier. “Seasonal Hydrologic Responses to Climate Change in the Pacific Northwest.” Water Resources Research 51, no. 4 (2015): 1959-1976.

OSU_icon_pencil_Black RotatedFull Report:

Screen Shot 2018-04-10 at 10.13.14 AM
Gilles, Nathan G., Josh Foster, Meghan M. Dalton, Philip W. Mote, David E. Rupp, John Stevenson, Katherine A. Serafin, Janan Evans-Wilent, Peter Ruggiero, John T. Abatzoglou, Timothy J. Sheehan, Katherine C. Hegewisch, Denise H. Lach, Jessica Andrepont, and Kathie D. Dello. Responding to Climate Variability and Change in the Pacific Northwest United States: the Pacific Northwest Climate Impacts Research Consortium, September 2010–August 2017 Phase 1 Final Report. the Pacific Northwest Climate Impacts Research Consortium (CIRC), a NOAA RISA team. Corvallis, Oregon: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 2017.

OSU_icon_arrowleft_01Main Article

Photo Caption: Mount Rainier and the Nisqually Glacier as seen from Nisqually Vista in the winter. (Photo Credit: Mount Rainier National Park, some rights reserved.)

Nathan Gilles is the managing editor of The Climate Circulator, and oversees CIRC’s social media accounts and website. When he’s not writing for CIRC, Nathan works as a freelance science writer. Other Posts by this Author. 

Screen Shot 2017-08-07 at 2.41.20 PM

Stay up to date on the latest climate science news for the Northwest, subscribe to the CIRCulator.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s