Lower elevations have recovered from last week’s atmospheric river, as cooler temperatures have refrozen the rain-soaked snowpack. This is not the case at upper elevations, where we continue to see evidence of a reactive snowpack producing large avalanches.
Winds continue to transport last week’s storm snow, loading lee terrain in the alpine and at treeline. Many of the avalanches failing on this problem have been stepping down to the persistent weak layer.
A reactive facet/crust interface is buried 50–150 cm deep. This problem will be more reactive in areas where a surface crust hasn't formed.
A widespread avalanche cycle has occurred over the past week, with avalanches reaching up to size 4. Explosive control work on Sunday along Highway 93S produced large avalanches up to size 3.
The widespread results from avalanche control indicate that the alpine remains highly reactive and continues to produce consistent large avalanches. This reactivity tapers with elevations.
60-150 mm of precipitation has fell over the last week, which translates into roughly 100-160 cm of storm snow at higher elevations, and significant amounts of rain at lower elevations which is forming a crust treeline and below. Strong south and west winds have loaded lee aspects.
A few flurries are expected on Monday, with a mix of sun and cloud throughout the day. By Monday night, the next system will move into the region, bringing 20 to 40 cm of snow along with moderate to strong south and west winds. Freezing levels will climb to 1800 m.
This system is expected to move through by Thursday, followed by a ridge of high pressure building in its wake.
