Professional Observation
Basic Information
Observation Details
Observation Date:
January 7, 2020Submitted:
January 7, 2020Observer:
SAC - Martin Stefan (off duty)Zone or Region:
Galena Summit and Eastern MtnsLocation:
Mushroom ridgeSigns of Unstable Snow
Recent Avalanches?
None ObservedCracking?
IsolatedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
SteadyBottom Line
In addition to our old problems there seem to be a new one to add, a layer of weak faceted snow buried around one foot deep, sometimes on a crust to make things just a little bit worse. I found it today on SW-SE facing terrain above 9000' where the wind has not hammered everything to concrete. If one manages to get this layer to go the potential for stepdown into deeper layers is obvious.
In this area it seems like the early december surface hoar is healing better than what I have seen elsewhere in the zone, for example just across the valley on Prairie Peak it is much more prominent.
Advanced Information
Weather Summary
Cloud Cover:
ClearWind:
Moderate , SWClear skies in the morning with clouds rolling in around noon, and a steady moderate SW wind at ridgetop again moving snow.
Snowpack Observations
I tried to find a "worst case" wind loaded SE slope just below ridge line at 8800' to see how the weak layers liked the load. HS 85 with the bottom 15cm moist DH. Up to 65cm was a mishmash of faceting slabs with more layers of more well developed FC mixed in at 25, 32, 45 and 55cm, where the one at 55cm was most prominent. 12/7 seems to have rotted away into just another layer of FC in this location.
At 65cm there was a clear FCsf layer a few cm thick under the windslab, but it did not produce any results on PST. Nor did I get any clear results on any other of the FC layers, either on PST or ECT.
I also dug a pit at 9100' SSW (so on the other side of the ridge) to see if a more wind-stiffened slab would give results. HS 70cm.
On this location the DH in the bottom was dry, 4f and chained, under a MFcr with a 3cm weak FC layer on top.
At 30cm there was a prominent FC layer that might be 12/7, but I could not see any SH, and it did not produce any results on ECT or PST.
Above this were various P hard wind slabs with softer snow in between, from a wind that cannot make up its mind on what direction to blow. All capped with 20cm soft wind affected "powder". I managed to squeeze out a pst25/100arr down 35cm in the lowest of the hard/soft/hard interfaces of wind snow, but nothing on ECT. No FCsf observed in this pit.
The FCsf under windslab (12/31) seems to be isolated in this area, to ridgetop and leeward slopes above approx 8500' in this area.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
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Layer Depth/Date: 20-30cm, 31/12 Low confidence on distributon and location, and assessment only based on this area so far. |
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Persistent Slab
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Layer Depth/Date: 40-60 cm 12/7, 60-80cm 11/26 These layers were stubborn to unreactive in my tests today, but have shown signs of life elsewhere in the zone in the last few days. |
Terrain Use
I stuck to tightly treed slopes anywhere I was on slopes in the low 30s, but mostly stayed out of avalanche terrain.
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