Center for Snow and Avalanche Studies

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Colorado Dust-on-Snow (CODOS)
With direct funding support from stakeholders, CODOS monitors the presence/absence of dust layers at 11 mountain pass locations throughout Colorado.

With those data, data from nearby Snotel sites, and weather forecasts, CODOS provides its funders with a series of “Update” analyses of how dust-on-snow is likely to influence snowmelt timing and rates during the snowmelt runoff season.

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     CODOS Updates > March 25, 2013 CODOS Tour Summary

CODOS TOUR SUMMARY - First CODOS Circuit of WY2013 Completed

Greetings from sunny Silverton -

As of Saturday evening, March 23, we finished our first complete circuit of Colorado dust-on-snow (CODOS) monitoring sites.  Our objective was to roughly match the timing of our first CODOS circuit of last season, for comparative purposes with that unusually dry spring.  Our itinerary was unusual, in this first trip, working around mid-week weather and other logistics.  We also happened to travel concurrent to two fresh dust events, D4 on March 17/18, and D5 on March 21/22.  Updates are now posted for all eleven sites (including Swamp Angel Study Plot) and our Dust Log has all events, and their wind roses, updated.

In summary, these site visits found the expected sub-par snowpack conditions shown by Snotel data, statewide.  More to the purpose of CODOS, we also confirmed the presence/absence of dust-on-snow at our CODOS snow pit sites, and in those locales, as of the date of our visit.  First visited on Monday, March 18, was the Park Cone site, where event D4 was close on my heels (significant dust in the air lower in the Gunnison Valley) and dust layer D2 was faintly present.  Next, four of our Front Range sites revealed no discernible dust in or on the snowpack as of Monday evening and Tuesday, March 18 and 19 - Hoosier Pass, Grizzly Peak, Berthoud Summit, and Willow Creek Pass.  Those sites may have received the subsequent D5 dust event, of Thursday afternoon and Friday, March 21 and 22.

Farther west, event D4 was clearly present on Wednesday, March 20 at Rabbit Ears Pass and McClure Pass.  Layer D2, the strongest event to-date at our Senator Beck Basin study area, was not apparent at Rabbit Ears but was clearly evident at McClure Pass.  The McClure Pass site snowpack also had the distinction of being the only isothermal snowcover (at 0° C throughout) among the eleven sites.  Those sites may also have received the subsequent D5 dust event, of Thursday afternoon and Friday, March 21 and 22. 

After an interlude on Thursday, we resumed the CODOS circuit on Friday morning at Swamp Angel Study Plot in Senator Beck Basin.  There we found a fresh and significant D5 layer at the surface and that deposition likely continued throughout that day, based on our observation of dust in the air in the Uncompahgre valley as we traveled to Grand Mesa.  D5 dust was also depositing there, and layer D2 was clearly evident as well.  Finally, we finished the southern part of the circuit on Saturday, in unusually cold weather, finding layer D5 at both the Spring Creek and Wolf Creek Pass sites, as well as D2 and other layers.

Aside from McClure Pass, the snowpack at all other CODOS sites retains some or significant cold content and will require further warming before "ripening" and discharging snowmelt runoff.  Dust-enhanced absorption of solar radiation will accelerate that process at those sites where dust was already observed at/near the surface (as that dust emerges) and perhaps at other sites where D5 was the first dust event of the season.

Our next full CODOS site tour is tentatively planned for the week of April 8-12, contingent on weather and dust events. As always, we welcome any first-hand observations you may have of dust activity in your area ... this dust season is clearly becoming more active and those observations are very helpful.

Updates by Site:

Berthoud Summit (March 19)  |  Grand Mesa (March 22)  |   Grizzly Peak (March 19)  |  Hoosier Pass (March 18)
McClure Pass (March 20)  |  Park Cone (March 18)  |  Rabbit Ears Pass (March 20) |  Senator Beck Basin (March 22)
Spring Creek Pass (March 23)  |  Willow Creek Pass (March 19)  |  Wolf Creek Pass (March 23)

More soon,
Chris

Chris Landry, Executive Director
clandry@snowstudies.org
Center for Snow and Avalanche Studies
PO Box 190, Silverton, CO 81433 USA
(970) 387-5080
www.snowstudies.org