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Greetings from Silverton,

We visited Willow Creek, Berthoud Pass, and Loveland Pass CODOS sample sites yesterday to assess the presence of the hard hitting D5 event we documented on April 12.  Not surprisingly, D5 was indeed a statewide dust event.  It is very evident in the snow profiles and surrounding landscapes across Colorado.  We updated the Update we posted on April 18 to include observations and pictures from this trip:


Like we noted in the April 18 Update, on April 17 we received dust event #6 (D6).  At Swamp Angel it was a dry event that came in with very high winds.  It is of light severity, we observed it on the surface of the snow on April 18, about 4" above D3-D5.  Yesterday, and into the evening, we received dust event #7 (D7).  During the day yesterday the cameras in the Southwest showed very hazy/dusty conditions and starting around 2 pm in the Red Mt Pass area came high winds and very suspicious looking, slightly tinted wispy clouds.  D7 was primarily a wet event, arriving with rain and then wet snow falling in the San Juans, allowing it to fall on top of D6, and currently rapidly merging with D6 with this wet snow.  So, D6/D7 are essentially merged at the snow surface and a couple inches above D3-D5 at Swamp Angel.

Across other parts of Southern Colorado - and possibly Central/Northern Colorado - where D6/D7 fell on already exposed dust layers, it might be difficult to discern the addition of D6/D7, depending on the severity.  Where D6/D7 was deposited on clean snow that had buried D3-D5, will exacerbate the melting of snow down to these dust layers where they will all merge, drastically effecting snowmelt rates.  The current weather system is expected to stick around until Saturday and deposit a few inches of snow across the Colorado high country, providing a temporary albedo reset.  We will post more updates soon as conditions unfold.

Please see windrose plots for D6 and D7 below.

More Soon.