I saw several natural avalanches that failed Saturday night or near the end of the storm. I saw several smaller natural avalanches that failed today (Sunday) during the day. While the riding conditions are about as good as they get, the avalanche conditions kept us from riding on any steep slopes and made us cautious when crossing underneath large avalanche paths.
Intermittent flurries, squalls, and sunny periods with no accumulation. Isolated previous wind-loading. There is a lot of snow available for transport at lower and middle elevations.
# | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
---|---|---|---|---|---|---|---|---|---|
3 |
Hiawatha Ditch near Indian Ck W 5800 |
D1.5 | SS | 12 inches? | N-Natural | 3 slabs released during the day today, each around 100' wide and not very thick. The slides were in wind-loaded/wind-affected areas that received a fair amount of direct sunlight this afternoon. There were a couple nearby small wet loose avalanches. | None | ||
1 |
Gimlet W 6400 |
D1.5 | SS | N-Natural | Wind-loaded area. Appeared to be a wind slab above the uppermost crust, and the afternoon sun played a role in triggering it. | None | |||
1 |
Fox Ck E 6600 |
D1.5 | SS | N-Natural | May have been a D2 - visibility was not great. Appeared to have some persistent slab character, but likely failed on the uppermost crust+facet weak layer. | None | |||
3 |
Salmon River Headwaters E 7900-8300 |
D1.5 | SS | N-Natural | E/SE aspects in sheltered terrain. Unknown exactly when they failed. | None |
Visibility was extremely limited. I saw evidence of many D1.5-2 slides in alpine terrain south of Galena Summit (mostly Smoky Mtns) that released during Saturday's storm and were blown in. North of Fox and Eagle Ck's, I only had decent visibility around noon up Murdock Ck and up the N Fork of the Big Wood. Another SAC forecaster (JP) will post photos and details about large recent avalanches in the Boulder Mtns.
HS=180-220cm below 8000'
Surface=new snow (PP/DF) for 25-35cm
uppermost crust=2cm in flats and on solars, thinner on shady slopes but still there...located 25-35cm down...some FC above and below
next crust=thinner, about 35-50cm below surface, in some areas was a crust/FC/crust sandwich
next crust=thin, about 70-110cm below surface, crust was more transient and FC were better developed (likely February crusts responsible for the big March avalanche cycles)
No tests performed (recreation day, avoiding avalanche terrain).
Snowpack was supportable for sleds and only occasionally "punchy" with boot penetration.
We talked to a group that was riding around 9000' in the Salmon headwaters: they reported minimal wind-loading or wind-affected snow with HS=about 250cm and much more new snow.
Below 8000', there wasn't much wind loading. The fairly recent natural persistent slab avalanche on a sheltered E aspect as well as the multiple natural slides that released today on sunnier, wind-loaded slopes are plenty of evidence that the snowpack needs some time without any additional loading to stabilize.
We stayed out of avalanche starting zones and tracks. We cautiously crossed the runouts of large avalanche paths.