Greetings from Silverton -
Following an unusually dust-free March, an almost inevitable combination of strong SW'ly and W'ly winds and dry soil conditions finally occurred over the Colorado Plateau and generated our first dust-on-snow event of Water Year 2015 here in the western San Juan Mountains, and in Senator Beck Basin. This event began lateWednesday afternoon and evening, April 1st, at low intensity and was perhaps more intense overnight before fading somewhat to a visible haze at dawn on Thursday morning, April 2nd, under still moderate SW'ly winds. Winds then re-intensified during the day Thursday and began a swing to the WSW, W, and eventually NW by evening, as visibility was restored to 'crystal clear' sky conditions by sunset. Strong winds and dust were observed in the Grand Valley, in Durango, in Gunnison, and elsewhere on the West Slope on both Wednesday and Thursday.
Virtually no precipitation fell with this dust event (1 mm of measured precip in a brief squall here at Swamp Angel Study Plot on Wednesday evening, and 0 mm on Thursday), so we will classify this as an effectively "dry" event. In the end, despite its long duration, this D1-WY2015 dust-on-snow event was at the low end of intensity and mass, here in Senator Beck Basin, but still discernible to the trained eye. We've not had any reports of dust-on-snow from other observers, thus far. Dust samples have been collected at Swamp Angel Study Plot for processing by our USGS collaborators in Denver.
More soon,
Chris