April WY2016 CODOS Tour Update:
Summary
The majority of the April CODOS tour was accomplished just prior to the very significant closed low pressure system that set up over the four corners region and deposited at least 1” of precipitation at most CODOS sites across the state. The bulk of this storm occurred Friday, April 15 through Sunday, April 17. This spring storm brought high winds ahead of, and with, the precipitation, but as of this writing it appears dust did not accompany the storm. The Hoosier Pass site was visited late in the day on Friday, April 15 and the intense snowfall, snow packed roads, and chaotic traffic conditions prevented us from continuing on and visiting the last two locations on our April CODOS tour, Grizzly Peak (Loveland Pass) and Berthoud Pass. Following the posting of this trip summary, these two sites will be visited and a separate report issued.
During the CODOS tour April 13-15, dust events D2 (occurring Feb. 19) and D3 (March 22), and D4 (March 28), were at and/or near the surface of the snowpack at central and southern sites. Locations that so far have escaped dust altogether are Rabbit Ears Pass, Willow Creek Pass, and possibly Berthoud Pass and Grizzly Peak. Hoosier Pass, which was dust free last month, received D3 as a minor event. Some CODOS sites are rapidly approaching “snow all gone” (McClure, Spring Creek, Park Cone) but others have just now reached isothermal conditions (Rabbit Ears, Hoosier). During, and following the storm event April 15-17, streamflow surging has lost momentum and even reversed in most watersheds due to the stormy weather and restoration of high albedo to most snow cover.
In addition to this information being provided below, we have posted the snow profiles just performed and new photos on each CODOS site’s webpage, as well as hydrographs and SWE graphs. Below you will also find a discussion for each location visited. Using the Dust Enhanced Runoff Classification (DERC) approach, links to hydrographs of the CODOS sites from WY2006-2015 are collated and presented to help with ascertaining what this Spring runoff scenario might look like. We anticipate at least one additional circuit of our ten CODOS sites this season as well as intensive monitoring at Senator Beck Basin (SBB).
Multivariable Plots
It is my ongoing goal to present data in a clear and informative manner so that users can quickly and easily view, interpret, and digest data for their intended purpose. One approach to help accomplish this is to provide comprehensive plots of data that summarize a particular CODOS site. The intention is to continually improve, build upon, and expand these plots over time.
When viewing plots, please consider:
- SWE from the CSAS snow profiles are provided to show a possible range of values at a site. It is important to keep in mind SNOTEL stations, with few exceptions such as Berthoud Pass, are in heavily forested areas. CODOS data are collected in open clearings in the vicinity of the SNOTEL stations.
- The date designating an isothermal snowpack is based on direct CODOS snow profile observations. The snowpack could likely have reached isothermal conditions before the date specified.
- At SASP, a mass loading of each dust event is provided. At other locations a qualitative descriptor is provided based on field observations.
- When a dust event occurs, detected primarily at our Senator Beck Study Basin, the date is marked on the SNOTEL SWE plot, indicating what SWE may accumulate on top of this dust layer or if it is exposed and remains exposed. On-site observations from CODOS snow profiles and surrounding landscape are used to modify the plots.