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Professional Observation

Basic Information

Observation Details

Observation Date:
March 16, 2022
Submitted:
March 16, 2022
Observer:
WCMAC - Jeff Carty
Zone or Region:
Seeley Swan
Location:
Morrell Mountain

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Isolated

Snow Stability

Stability Rating: 
Good
Confidence in Rating: 
High
Stability Trend: 
Worsening

Bottom Line

It was possible to trigger an avalanche at Morrell Mountain today, in just the right terrain. On convexities over 38º between about 6600' and 7600' you could trigger an avalanche in facets sitting on top of the March 1st rain crust.
At upper elevations, wind slab is building, wind lips are touchy. Windloaded start zones over 35º are most suspect for reactive wind slab.
Cornices are getting huge, and growing bigger. Lots of evidence of recent cornice fall. Stay back from the top, and avoid being below.

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Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
25º F (-4ºC) to 32ºf (0ºC)
Wind:
Moderate , W

Rain extended up to about 5500' yesterday, upper elevations received up to 6" new snow.
Intermittent snow showers dropped about 3" of new snow today.
Moderate west winds with strong gusts are loading east slopes at ridge top. Lower elevations had both south and north winds, due to local terrain effects, that that were transporting snow and cross loading ridges.

Snowpack Observations

We found whumphing, cracking and slabs shifting between switchbacks around 7000' on south aspects. Near surface facets sitting on top of the March 1st crust are the culprit. They are buried up to 14" deep in this location. The slab lacks the stiffness to transmit the propagation in the extended column test, hense a ECTN 11. However, the propagation saw test (PST) propagated at 30% cut, PSTend 30/100, indicating likelihood of propagation.
At elevations above the rain crust, 7200'-7400', this problem is much less reactive and lacks the stiff bed surface to slide on. Below about 6600' the snowpack has been thoroughly warmed and consolidated, the likelihood of an avalanche decreases quickly.

Terrain Use

We stuck to plannar slopes under 35º today to mitigate problems with buried facets and windslab.

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