Greetings from Silverton,

The forecast last week called for mostly dry/warm conditions with potential storm activity in the mountains. We have seen this play out at Senator Beck with a storm event (defined as 12 mm or more precipitation) late in the evening on June 1, and warm/sunny conditions dominating the last week of May and continuing to the present. With average air temperatures increasing sharply so have minimum air temperatures, staying above freezing since May 29. Consequently streamflows are near their peak snowmelt discharge levels, with recent discharge rates for some rivers being well above median levels (Animas, Rio Grande, Gunnison 1,000-1,500cfs above median. Dolores ~500cfs. Uncompahgre, San Juan, Lake Fork, Snake ~100-300cfs above median).

We recently visited a handful of CODOS sites; Berthoud Pass, Loveland Pass, Hoosier Pass, and Wolf Creek Pass. We documented current state of the snowpack and collected all-layers-merged dust samples for USGS analysis. General observations are that as expected SNOTELS are near melt out, but above the elevation band that SNOTELS are located, the general landscape still has a good amount of snow left to melt. And, looking at SBSP (12,186’) there is still 32” (80 cm) of snow depth and an estimated 17” of SWE. Please see pictures below.

The forecast calls for the ridge of high pressure we have been under to persist through Thursday, with even a slight shift towards keeping it hotter and drier than last few days in the mountains, with less cloud cover. The models are showing a Pacific low heading our direction, with increased southerly hot/dry winds on Friday and the system finally arriving around Monday. Until then, at the least, we can expect it to be sunny, hot, and dry and the snowmelt to continue at a rapid pace.

As of the afternoon on June 6, SWE at SASP is 11.5” (21.6” of snow depth). At SBSP SWE is around 17.7” (32” snow depth). Streamflow at Senator Beck started spiking towards peak discharge May 31. Timing of peak discharge is occurring right at period-of-record mean, and so far is closely tracking WY2016 in magnitude and timing. There is still a good amount of snow at higher elevations and the rate in which that melts will likely be elevated as the forecast calls for more hot and dry weather the next 4-5 days.

Daily average air temperatures since the last week of May, and minimum air temperatures since May 29, have stayed above freezing. This has allowed unhindered snowmelt to ensue and the result is high streamflows. Albedo continues to slowly degrade, but on June 2 after receiving 0.5” of precipitation (we issued possibly our last Storm Report of the season) some portion of which fell as white stuff, we saw a momentary recovery of albedo.