April 16, 2019: Dust Event #3 Observed
Greetings from Silverton,
Witnessing the high winds and dusty conditions in the Four Corners region last Tuesday night thru Wednesday (April 9-10) we were fully expecting to see some of that dust in the Colorado snowpack. So we weren't surprised that yesterday we observed and sampled this new dust event at Swamp Angel. D3 was a dry event, meaning it came in just prior to precipitation on the incoming storm front and settled on the existing surface crust. We would characterize it as moderate severity and at Swamp Angel it is ~10" (25 cm) below the surface. However it has started to emerge around other parts of the landscape where less snow accumulated or redistribution took place. Being deposited as a dry event naturally leads to variable distribution on the mountain landscape by being whipped around by the whim of the wind. Once it is exposed, or where it is exposed, it is severe enough to have a significant impact on albedo and hence snowmelt. D3 marks the second dust event documented at Swamp Angel so far this season. D1 was an extremely light event that was more noticeable near Lizard Head Pass the first week of February but not visible in profiles at Senator Beck, only faintly on certain terrain features. D2 was a light event that occurred on March 6 that traveled as far as parts of Central Colorado near Crested Butte but reduced even fainter still in that environ.
A few inches are expected over the next couple days then we get a warm up Thursday and Friday before chances of precipitation return to the forecast.
Winds that deposited D3 were out of the S-SW and peaked at 73 mph.
Sampling D3 at Swamp Angel for USGS analysis
A slough reveals D3 on a hillside