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Professional Observation

       

Basic Information

Observation Details

Observation Date:
December 4, 2022
Submitted:
December 5, 2022
Observer:
Everett Phillips | ESAC Forecaster
Zone or Region:
Convict Creek
Location:
Aggie McGee Col - Blowing Snow and Widespread Collapses

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
Widespread

Collapsing was widespread, but a large clearing on a N slope at 10400′ produced an exceptional whumpf when we stepped out of our skis to dig a snowpit.

Key Points

The goal of today’s tour was to get a feel for the snowpack post-storm outside the Mammoth Lakes Basin. Takeaways:

  • Poor structure and signs of instability that have been seen in other areas are present in the Tobacco Flat area where there is enough snow to cover anchors.
  • ATL start zones were loading throughout the day with SW Winds, intense blowing snow, and light snowfall.
  • No crown lines observed despite a good view of start zones on a variety of aspects and elevations. Evidence of avalanche activity may have been covered by wind loading over the last 12 hours.

Media

Wind loading on Mt. Aggie
10400' N. Aspect near Mt. Aggie
Wind loading on Mt. Morrison

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
16 F
Wind:
Strong , SW

Skies clearing throughout the day. Scattered snow showers. Strong SW winds and intense blowing snow ATL. Cold.

Snowpack Observations

HS: 0-130

Wind-packed snow over facets.

Good ski quality in wind sheltered pockets above 9700′

Below 9700′ breakable wind crust and thin coverage require creative route finding.

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