Center for Snow and Avalanche Studies

Swamp Angel Study Site
Swamp Angel Study Plot (subalpine)

Senator Beck Study Site
Senator Beck Study Plot (alpine)

Putney Study Site
Putney Study Plot (summit)

Senator Beck Basin Stream Gauge
Basin Stream Gauge

St Paul Basestation
St. Paul RF Base Station

The Center for Snow & Avalanche Studies serves the mountain science community and regional resource managers by hosting & conducting interdisciplinary research and conducting integrative 24/7/365 monitoring that captures weather, snowpack, radiation, soils, plant community and hydrologic signals of regional climate trends.

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News from CSAS

  • Jan 6: CODOS Update issued Dust Free So Far and Healthy Snowpack
  • Jan 5: Colorado Matters host Ryan Warner speaks with NASA SnowEx project scientist Edward Kim and Center for Snow & Avalanche Studies director Jeff Derry. Learn more at Colorado Public Radio's website
  • Nov 18: Register now for our 2017 Snow School for Water Managers which will be held March 1st-3rd, 2017. Space is limited. Sign up today!
  • Nov 1: CODOS issued Center for Snow Update
  • Oct 31: The Swamp Angel and Senator Beck study plots have been selected as reference sites for the Earth System Model-Snow Model Intercomparison Project (ESM-SnowMIP,). These sites are of great value to ESM-SnowMIP because of the availability of high-quality meteorological and hydrological measurements at different elevations and over multiple years. ESM-SnowMIP will assess the strengths and weaknesses of snow models as a contribution to the World Climate Research Programme's Grand Challenge on "Melting Ice & Global Consequences". The ability of models to predict melt rates for snow with dust loading in the Senator Beck Basin Study Area will be of particular interest.
  • Oct 22: Executive Director, Jeff Derry, presented at American Association of Geographers in Colorado Springs and discussed the new SnowEx campaign at SBSB as well as our unique dust-on-snow monitoring program.
  • Sep 1: NASA is developing a snow-sensing satellite and is using Senator Beck Study Basin to develop the instrumentation and algorithms. The project, called SnowEx, is a multi-year airborne snow campaign. Its goal is to collect multi-sensor observations, including radar, lidar, multispectral imagery, along with ground-truth observations throughout SBSB. The intent is to determine which techniques work best for measuring snow, and to combine these in a design for the development of a snow-sensing satellite. The team began with "snow off" fly-overs of bare ground September 28 - October 4, 2016. "Snow on" fly-overs will take place this February 2017.Since the SnowEx project wants to push current techniques until they break, focusing on challenges presented by forests and extreme topographical relief, SBSB is the perfect venue to collect a unique dataset that will enable snow mission trade studies while also enabling scientific inquiry. In addition, because of SBSB's long history of lidar airborne campaigns, snow science research with over a 10-year meteorological and stream flow dataset, NASA deemed the SBSB the ideal location to conduct the first year campaign. For more information please visit and
  • Aug 1: CODOS Update issued "WY 2016 Season Summary"
  • Feb 19: CODOS Update issued D2 for WY2016 at Senator Beck Basin
  • Feb 10-12: This year's CSAS Snow School for Water Professionals enjoyed hands-on snow observing experience in the field, following morning indoor sessions focusing on snow climatology, snowpack formation, snowmelt energy budgets, and snow data sources and interpretation issues.

    From left to right: Matt Hardesty: Colorado Division of Water Resources, Sarah Baker: Bureau of Reclamation, Lower Colorado Region, William Banks: USGS, Southeast Colorado Office, Jesse Jaminet: Colorado Division of Water Resources, Laurna Kaatz: Denver Water, Planning Division
  • Jan 27-29: Jeff Derry attended the Colorado Water Congress Annual Convention in Denver, attracting over 500 stakeholders in Colorado water policy and management, including many of our CODOS program supporters and users.
  • October 5: CSAS's Summer 2015 data is now available, as Excel workbooks, on our Archived Data webpage. The datasets span June 21, 2015 through September 30, 2015. Our comprehensive workbook contains several worksheets for various time intervals, including 1-hour, 3-hour, and 24-hour summary data. Also presented are updated Metadata for Swamp Angel, Senator Beck, and Putney Study Plots. The complete, integrative Senator Beck Basin dataset revealed compelling details and insight on the highly unusual “Water Year” (October 2014 through 2015) throughout Colorado.

  • September 1: The Arizona Republic recently ran an extended series of articles describing stresses on the Colorado River system and its water users, with a focus on Colorado snow. CSAS's Chris Landry spent a day with the reporting team in April and the article features visits to several of our Colorado Dust-on-Snow program field sites, along with quotes from Landry and extracts from the CODOS Water Year 2015 Season Summary. View the complete Arizona Republic article by clicking here.

  • June 25: CSAS Executive Director Chris Landry presented a review of "what has the science taught us ..." about dust-on-snow at the 40th annual Colorado Water Workshop in Gunnison on June 24. The workshop has a long and storied history of presenting new science and "all responsible positions" on water issues, and this panel discussion included a review of climate change science as well. Neither dust-on-snow nor climate change were on the agenda at the first Water Workshop, 40 years ago. Landry's first presentation about dust-on-snow at the Water Workshop was in summer 2006.

  • June 24: CSAS's Winter 2014/2015 Senator Beck Basin data have been QC'd and are now posted, as Excel workbooks, on our Archived Data webpage. Winter 2014/2015 data began October 1, 2014 and run through June 20, 2015. Each Excel workbook - for the Swamp Angel, Senator Beck, and Putney Study Plots - contains several worksheets for various time intervals, including 1-hour, 3-hour, and 24-hour summary data. Also presented are updated Metadata for each study plot, a "Sensor Status" workbook showing instrument height above the snow surface and other data, a compilation of all of the Winter 2014/2015 snow profiles performed in Senator Beck Basin, and a snow profile metadata document describing our methods. This was a highly unusual winter throughout Colorado and the complete, integrative Senator Beck Basin dataset captured the details, perhaps as well as any location in Colorado.

  • June 9: See our report on the recent rain event and streamflow effects

  • May 31: May 2015 precipitation was exceptional at Senator Beck Basin, and in the Red Mountain Pass locale. Our Noah II precipitation gauge at the Swamp Angel Study Plot recorded 201 mm (7.91") of water equivalent, almost all in the form of snow (only 8 mm as rain). That exceeded the May 2011 total of 190 mm as well as the 1995 total of 7.60" (193 mm) at the nearby Red Mountain Pass Snotel, the largest May in that Snotel site's 30-year period of record. We recorded at least 1 mm of precipitation on 27 of the 31 days in May 2015. See our precipitation data graphs. More details to follow ...

  • April 6: CODOS Update issued title "WY 2015 Unfolding"

  • April 3: CODOS Update issued title “CODOS Dust Alert-Event D1-WY 2015

  • April 2: CODOS was featured in the High Country News recent blog post “Colorado’s snow is dust-free for the first time in a decade” on Colorado's dust-on-snow "dust free" March. To view the article, visit High Country News website. As it happened, CSAS and our Colorado Dust-on-Snow monitoring program logged it's first dust-on-snow event at Senator Beck Basin just a couple days into April, and other locales also reported dust from that storm.  See our CODOS Program website at

  • April 2: A snow hydrology research team led by Karl Lapo, at the University of Washington, have recently presented a new peer reviewed paper in the prestigious journal Water Resources Research titled "Impact of errors in the downwelling irradiances on simulations of snow water equivalent, snow surface temperature, and the snow energy balance".  They utilized radiation measurements and other data from the Senator Beck Basin Swamp Angel Study Plot for this analysis.  The abstract for the paper is available here

  • March 23: CODOS Update issued title "Dust-free Snowmelt Underway"

  • March 1: CODOS Update issued title "March 1 SWE Conditions"

  • Feb 16: CODOS Update issued title "Dry Spell, Early Snowpack Warming "

  • Feb 11-13: This year's CSAS Snow School for Water Professionals benefited from warm, dry, and sunny days here in the San Juan Mountains.  Participants Rob Phillips from the Rio Grande Water Conservation District, Nathan Elder from Denver Water, Brenna Mefford from the Wyoming State Engineer's office, and Marta Nelson from Radiometrics Corporation in Boulder came to the session with four quite different job duties and perspectives. 


    From left to right, Nathan (back to camera), Rob, Brenna, and Marta got hands-on snow observing experience in the field each day, following morning indoor sessions focusing on snow climatology, snowpack formation, snowmelt energy budgets, and snow data sources and interpretation issues.

  • Jan 29-30: Chris Landry attended the Colorado Water Congress Annual Convention in Denver, attended by some 500 stakeholders in Colorado water policy and management.  Highlights included panel discussions regarding climate change impacts on Colorado water supplies (where the impacts of dust-on-snow were also mentioned) and 'worst case' drought planning activities among the Upper Colorado River Basin states.  All of our CODOS program supporters and users were present at the meeting, and our former director Eric Kuhn participated, as always, in several of the panels and plenary sessions.

  • Jan 21: CODOS Update issued title "No Dust-on-Snow So Far, Looking Ahead Using CODOS Experience"

  • Dec 23: We’re very pleased that Senator Beck Basin data are supporting an expanding group of mountain researchers.  Our downwelling longwave radiation and other data were analyzed by Yonghua Chen (Columbia University) and her colleagues in a recent peer-reviewed journal article in Environmental Research Letters.  Mark Raleigh and his colleagues also utilized our data, along with data from comparable study areas, to test snow model sensitivities to errors in “forcing data”.  Still other papers now in review also utilize Senator Beck Basin data … stay tuned.  Also, several presentations at the just-concluded American Geophysical Union Fall Meeting utilized Senator Beck Basin data including two about snowcover modeling, by Mark Raleigh (National Center for Atmospheric Research) and Michael Follum (Army Corps of Engineers).

  • Oct 23: Jay Welz, a graduate student just wrapping up his snow hydrology MSc at Montana State University, came on board as the CSAS field operations manager-in-training.  Jay brings an extensive background in managing field science programs with the US Forest Service and a wealth of snow experience.  More about Jay later this season …

  • September 29 – October 3: CSAS attended the International Snow Science Workshop in Banff, Alberta, and Chris Landry presented a poster and paper on “Desert Dust and Snow Stability”.

    Japanese ISSW participants and others found the CSAS “Desert Dust and Snow Stability” of interest, vis-à-vis there own experiences with dust-on-snow.

  • August 19: CSAS conducted a field tour to the Swamp Angel Study Plot and Senator Beck Stream Gauge for a class of 24 Colorado State University undergraduate and graduate students during their Watershed Practicum in the San Juan Mountains.  Their faculty advisor Dr. Steven Fassnacht is at the far left, pointing toward the tower.  Chris Landry gave the class a talk on dust-on-snow later that day.

  • July 25:  CODOS WY 2014 Summary

  • July 19-27: Third survey of Senator Beck Basin vascular plant community completed: in a marathon effort from July 19-27, botanists Peggy Lyon, Sara Simonson, and Renee Rondeau (left to right in the July 20, 2014 photo to the right) completed our third comprehensive inventory of the Senator Beck Basin plant community.  Gordon Rodda also assisted.   Species and coverage were documented in a total of 230 plots of 0.1 m2 along 23 established transects at three different elevation bands, in the sub-alpine, at treeline, and across alpine tundra.  This dataset complements the original July 2004 baseline data and the July 2009 first repeat study. Comparative analyses will follow.

  • July 17: Senator Beck Basin data presented at the international Global Fair and Workshop on Mountain Observatories, Reno, NV: on behalf of the authors of our recent Water Resources Research article, co-author Dr. Mark Raleigh, from NCAR, presented the 7-year Senator Beck Basin dataset to the “Observing the Mountain Water Cycle” session on July 17, 2014.  Some 180 mountain scientists, from several continents, attended the conference.  Mark's talk was titled: "High elevation headwaters hydrology and snow monitoring at Senator Beck Basin, San Juan Mountains, Colorado, USA: a 7 year dataset".

  • June 19: CODOS Alert - Long duration dust event D10
  • June 15: CODOS Dust Alert - Event D9-WY2014
  • June 10: CODOS Update - Dust forcing high snowmelt rates statewide
  • May 29: CODOS Alert for imminent, dust-enhanced surging in snowmelt runoff
  • May 27: CODOS Update - Upper Gunnison River and North Fork of the Gunnison
  • May 25: Memorial Weekend Winter Storm #25 of the season
  • May 22: CODOS Update – Senator Beck Basin and Western San Juan Mountains
  • May 19: CODOS Update - Rio Grande Watershed Conditions
  • May 11: CODOS Dust Alert for Dust-on-Snow event #D8
  • May 11: Mother's Day Storm (Storm #24 of the season)
  • May 11: Durango Herald story on CSAS, Senator Beck Basin and dust
  • April 29: Storm #23 was the biggest of the season (so far)
  • April 28: CODOS Alert for D6 and D7; CODOS Update - Tour Summary from April 23-26
  • April 27: Denver Post article on dust on snow and runoff by Scott Willoughby
  • April 23Dust event averted
  • April 18Dust event D6-WY2014 is increasingly likely next Tues/Weds
  • April 15-17: At the Western Snow Conference in Durango, Chris Landry presented "Dust on Snow Impacts on Colorado Hydrographs" and hosted a field tour to Molas Pass and the CSAS office in Silverton.
  • April 16CODOS Update - Streamflow Surging and Decline, D4 (Re)Emergence
  • April 14, 2014: Winter Storm #22 brought us another inch of water
  • April 3, 2014: CODOS Site-Specific Updates posted from ten sites around Colorado
  • April 2-3, 2014: Winter Storm #20
  • April 1, 2014: CODOS Dust Alert for Event D5
  • March 31, 2014: CODOS Dust Alert for Event D4
  • March 27, 2013: CODOS Dust Alert for Event D3
  • March 18, 2014: CODOS Dust Alert for Event D2
  • March 17, 2014CODOS Update on Large Snowpacks, Lack of Dust, Runoff Patterns
  • March 11, 2014: We've issued a Press Release (pdf) about our recent Mountain System Monitoring publication in Water Resources Research.

  • March 8, 2014: Winter Storm #18 for Senator Beck Basin blew out this morning. A glance at our 10-year period of record shows the number of storms we've experienced so far this winter to be "normal."

  • February 26, 2014: We are excited to have just published our Senator Beck Basin at Red Mountain Pass data in Water Resources Research! Our SUPER ESSENTIAL co-authors were Martyn Clark and Mark Raleigh of National Center for Atmospheric Research.

  • February 24, 2014: Dust Alert for event D1-WY2014

  • February 20, 2014: Storm #14 for the season was a short and windy storm in which the barometer dropped an impressive .18 inches (from 29.98 to 29.80 in Hg) in just 8 hours. 

  • February 12-14, 2014: Field School for Avalanche Professionals held at CSAS

    Approaching the Swamp Angel Study Plot in Senator Beck Basin for a field session on snowpack energy budget measurements, at Red Mountain Pass. Photo by Matt Hoobler, from Wyoming State Engineer's Office.

  • February 6, 2014: Windy January without Dust

  • January 7, 2014: CSAS Director, Chris Landry, quoted in Wall Street Journal article "Dust on Rockies Snow Quickens Melting, Disrupts Water Supplies."
    Wall Street Journal

  • Jan 2, 2014Clean snowcover so far, interesting early winter hydrology

  • November 24, 2013: Winter Storm #4 has wrapped up with no recorded precip for 12 consecutive hours. The National Weather Service is calling for an additional snow accumulation possible this afternoon and overnight. If we get another 1/2" of SWE (12mm), we will count that as winter storm #5.

  • November 21, 2013: After the positive response to the 'snow school' session at last summer's Colorado Water Congress in Steamboat Springs, CSAS is offering a 2 1/2 day Snow Field School in Silverton on February 12-14, 2013.  This small workshop will be limited to ten students and is intended for water professionals.

  • November 18, 2013: We now have 200 entries into our drawing (our max). Thank you to all who donated towards this successful fundraiser! The Silverton Standard will do the actual drawing and will announce the winner no later than December 1st!

  • November 14, 2013: New study utilizing Senator Beck Basin Study Area: Dust, warming portend dry future for the Colorado River. Land management efforts could help protect snowpacks, water from a warmer future - See more at:

  • November 6, 2013: Chris Landry presented "Dust-on-Snow: Adapting to the New Normal" at the Upper Colorado River Basin Water Conference, Colorado Mesa University.

  • October 30, 2013: Data from Winter Storm #2 for the season has been posted

  • October 2013: A new paper uses Senator Beck Basin data to explore how downward surface radiation is affected by cloud changes. Naud et al. (2013), Sensitivity of downward longwave surface radiation to moisture and cloud changes in a high-elevation region, J. Geophys. Res. Atmos., 118,10,072–10,081, doi:10.1002/jgrd.50644.

  • October 4, 2013: Summer data and complete 2013 Water Year graphs are now available.

  • September 23, 2013: First snow on the ground in Silverton (earlier in the morning), and 7 inches (.18m) of snow on the ground at Swamp Angel Study Plot.

  • September 20-21, 2013: David Scott, a CSU PhD student, conducts a forest health study, coring Spruce trees in Senator Beck Basin.

  • August 26, 2013: Ethan Gutmann from the National Center for Atmospheric Research Hydrometeorological Applications Program, and Warren Young, USFS soil scientist, visit Senator Beck Basin to do soil sampling for hydrologic properties testing.

  • August 10, 2013: First dusting of snow on peaks surrounding Silverton.


  • July 12, 2013: Several presentations at the Davos Atmosphere and Cryosphere Assembly (DACA-13, July 8-12) utilized data from or fieldwork at Senator Beck Study Area. In the Abstract Proceedings, see Deems et al. (page 10), Raleigh et al. (page 322), and Painter et al. (page 326).

  • June 24, 2013: We've published this past winter's datasets for Swamp Angel, Senator Beck and Putney Study Plots. We've also updated our metadata and period of record datasets:

  • June 17, 2013:
    Final Report for Water Year 2013
    Colorado Dust-on-Snow Program WY 2013 Summary

  • May 15, 2013: Snowmelt has really accelerated over the past couple of days. We're updating graphs for Senator Beck Basin snowpack, precipitation and streamflow daily through SAG (Snow All Gone).

Graph of Height of Snow for 7 Winters at Swamp Angel Study Plot Graph of Height of Snow at Senator Beck Basin Study Plot Graph of Senator Beck Stream Gauge Cumulative Discharge in acre feet