Pro Field Report
Basic Information
Observation Details
Observation Date:
December 27, 2022Submitted:
December 27, 2022Observer:
SAC - Jon Preuss (off duty)Zone or Region:
Galena Summit and Eastern MtnsLocation:
Johnstone Creek (N-E-S, 6570-8000')Signs of Unstable Snow
Recent Avalanches?
YesCracking?
None ExperiencedCollapsing?
IsolatedSnow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
WorseningBottom Line
Quick afternoon tour to see what the rain was doing to the snowpack. The winds were strong enough to knock you off balance and transport the wet and heavy new snow. Rain line looked to be at around 7300' (based on snow in trees), although I bet it climbed higher than that for a hot second. The rain didn't percolate down as much as I would imagine, but was enough to weaken the snow. There are plenty of weak layers out there to pick from and avoid today.
Media/Attachments
Advanced Information
Weather Summary
Cloud Cover:
ObscuredWind:
Strong , SWNew/Recent Snowfall:
HN: 15-20cm (very challenging to get a good read with wind effect)It was sprinkling rain at the trailhead (1320hrs) and switched to snow at some point. The winds picked up and were consistently blowing from the SW at Strong speeds. New snow was being transported and scouring down to the new/old melt freeze crust. It snowed S2-3 for the few hours I was in the field with white out conditions. When I got back to the trailhead, it was snowing down to Triumph before changing back to rain.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Mine Bender NW 7,600' |
D2 | WS | N-Natural | The light was too flat in the start zone for me to have any certainty where this broke and to verify it was a slab avalanche. I'm guessing by the texture of the chocolate milk debris that this was wet in release. Debris was visible up to 7300'. |
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| 2 |
Mine Bender NW 6100' |
D1 | WS | I-New/Old Interface | 1-2' | N-Natural | These small slab avalanches looked may have been sympathetically released from wet loose coming down from above. |
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| 7 |
Carbonate (east face) E 5800' |
D1.5 | WL | N-Natural | A couple of these loose avalanches had some nasty debris piles heading towards the river. |
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Snowpack Observations
I dug in a similar pit location to last week (12/23 obs). I was curious to see how the 12/19 was interacting with the new load. Within the 20cm of new snow, the top 5cm was fairly dense (4F-) and moist and moved into F at the bottom. The slab was reactive with CT1 (SC) and ECTP5x3 down 26cm.
In the lower elevation where it was raining. The melt water was only making it down the first 10cm on a North aspect in the valley floor. I could feel a thin melt freeze that formed in the last two days of above-freezing temperatures and must have been impeding the rain's progress into the snowpack.
The south aspects had a firm 3-4cm crust under the new "slush." The previous facet/crust sandwiches going down to the ground were moist.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
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Layer Depth/Date: 25-70cm Comments: Lumping the 12/19 and 12/8 into this problem. Both are a concern and one could lead to the other stepping down. |
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Wind Slab
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Layer Depth/Date: 20-30cm Comments: Based on the amount of new snow that was being transported even though some of it was like glue. |
The two small slab avalanches near the drainage bottom where likely on 12/8 based on their depth. I'm guessing they releases by rainfall triggering the loose slides next door. Wet Loose was a concern today for anyone braving the rain in the lower elevations.
Terrain Use
I didn't stop my car under runouts while driving and avoided avalanche terrain while touring.