CODOS UPDATE May 29, 2025: Snow Near gone at Swamp Angel, Still 3’ at senator Beck

Greetings from Silverton,

Snowmelt is always the most interesting time of the season. Here in the southern part of the state streamflow really kicked into action around May 10 and kept climbing for the next four days until a significant storm rolled through starting May 14 and continued until May 19. These 6 days of cooler temperatures accompanied by 1.5” of precipitation arrested snowmelt for a 3-4 days following the event. Beginning around May 21 streamflow steadily climbed for a week to a new peak. On Monday, May 26, a blustery rainy/snowy day slowed down snowmelt (hence streamflow) slightly once again. Today we are seeing streamflow pick back up.

The forecast is calling for a chance of afternoon showers the next seven days. How this will affect snowmelt depends on cloud cover and additional snow/graupel (albedo reset) the high country might receive. The afternoon weather will likely weaken the snowmelt signal a tad, meaning the hydrograph may move sideways for a few days, if there is not a clear stretch of inclement weather or sunny/warm weather. But we are nearing June and there is still sunny/warm conditions forecasted.

All, or the majority of significant dust layers, have been at the surface of the snowpack for at least a month (when not temporarily covered by new snow accumulation). When compared to previous years in our over 20 year record, dust severity is still in the “minimum” category. This means, when compared against itself, dust-on-snow conditions are light. This does not mean there is no impact, because there definitely is, it just is not as severe as a typical season.

Here at our Senator Beck Study Basin at Red Mt Pass, there is about 5.5” of SWE remaining at Swamp Angel (11,060’) as roughly ~1’ snow depth. Snow cover is variable, depending of aspect, exposure, etc. At our Senator Beck Study Plot (12,200’) there is still 3’ of snow depth as 17.5” SWE. So there is still some snow in the high country. Depending on watershed it is this high elevation snowmelt that will constitute the peak in streamflow.

Take care

Below: Swamp Angel on May 28, 2025