This area tends to be a bit drier than the central and northern Sawtooths, but it was clearly hammered by the January 10th storm. At upper elevations, the problem has become a deep persistent; weak layers are buried 3-5+ feet deep. Middle and lower elevations are not as straightforward. There are weak layers as shallow as 2.5 feet, but these were unreactive in tests and there's hasn't been recent activity on them. In any case, the primary weak layers have become deeply buried and will be difficult to trigger, but with potentially catastrophic results.
By late morning, clouds were clearing. Clouds increase again in mid-afternoon and there were a few flurries. Winds were generally light, but occasionally gusted moderate. Not much snow was moving today.
# | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
---|---|---|---|---|---|---|---|---|---|
2 |
Imogene East Bowl E 9900 |
D3 | SS | O-Old Snow | N-Natural | Smaller, separate avalanche on smaller terrain feature below main bowl. |
Didn't list all of the large slides in the Sawtooths that have been previously discussed. Included the one above because I had a good photo and the lower slide was interesting.
Snowpack obs were from 7700' to 9800', SE-E-NE.
Mid elevations had somewhat defined weak layers, but the layering was the only red flag. Tests were generally unreactive, we haven't seen much, if any, activity on them, and we felt no collapsing and cracking.
@7700' where we parked (flattish), the HS was 100cm (up to 1F hardness) with the lower 20cm consisting of F facets.
@8200', ENE, 24*: HS 125cm. May have identified 12/31 80cm down but not a prominent layer. 12/7 SH and FC was down 105cm. ECTX, one ECTP with very hard hits. 11/26 was a thin layer of DH on a crust on the ground, down 120cm. Also got an ECTP with very hard hits.
At upper elevations, weak layers are deeply buried and have transitioned to a deep slab problem. Weak layers are less deep on solars, but also seem less remarkable.
@9100', SE, 28*: HS 150cm. Most prominent weak layer was 4F FC below a 1F slab. ECTX
@9500', ENE: HS 200cm. 12/7 was still visible 165cm down. 11/26 presented 185cm down as a 1cm layer of FC over a P crust atop "welded" DH. The facets on the crust may have been responsible for much of the Sawtooth deep slab cycle. There was a thin, subtle layer of 1F- FC 120cm down - 12/31?
We walked along a wind-affected ridge with lots of depth variation connected to steep, rocky terrain with no significant collapses or remote triggers.
Problem | Location | Distribution | Sensitivity | Size | Comments |
---|---|---|---|---|---|
Deep Persistent Slab |
|
Unknown |
Layer Depth/Date: 12/7, 11/26: >150cm Comments: No tests performed to assess sensitivity. |
||
Persistent Slab |
|
Layer Depth/Date: 80-120cm, various FC layers Comments: Basically calling out areas where there is the problem is less clearly a deep slab. |
Didn't see any wind slabs of consequence. Less wind affect than expected based on how Galena Summit looked yesterday.
Avoided consequential avalanche terrain