Quick report
- Aspect
- Northwest
- Red Flags
- Recent Avalanches, Heavy Snowfall, Cracking, Collapsing, Poor Snowpack Structure
- Elevation
- 3048 m
- Slope Angle
- 38°
- Red Flags Comment
- <p>Widespread cracking and muffled collapsing observed on all shady aspects above 9200 feet with slope angles 33 degrees and greater. See avalanche observation for details on Pioneer Peak area activity. Heavy snowfall rates during the peak hours of the event appeared to help overload a previously poor structured/weak snowpack. The previous event (Oct. 11th) prior to the the event on the 29th has appeared to develop into moderate sized facets. The other two snow events from earlier in Sept. and Oct. have consolidated into 2 to 4 inches of dense/damp m/f crusts. The new snow initially bonded to the previous snow surface due to it's warmth, yet easy to very easy shears were observed in moderate sized facets, 1 to 2 inches down from the previous snow surface. OF NOTE: This layer will be easily detected due to a "Snirt" layer that was formed during the first part of the latest event. These shears were observed 1 to 2 inches below the "Snirt" layer. </p>
Layering was as follows, top down:
Surface, Stellars
12 inches of fist (new snow)
1/2 inch of pencil (consolidated due to the warm snow from the initial phase of the latest event)
Thin "Snirt" layer
Shears 1 to 2 inches below "Snirt" layer: CT11, ECTP13, both exhibiting Q1 and SC Fracture Characteristics
8 inches of fist, moderate sized facets
2 inches of pencil to knife m/f, moderate to large sized damp grains
Ground
Snowpack
- Instability Comment
- <p>Technically the problem is a "Storm Slab" as it is a new slab from the latest event. Yet, due to the nature of the persistent weak layer (as previously described) it may be identified from this point on as a Persistent Slab. Though it did not appear as sensitive as observations indicated it was on the 29th, this problem is not going away, and it may possibly develop into a much thicker faceted layer if we do not get any more new snow within the next couple of weeks. All northerly and or shady aspects with any old snow are suspect. This problem was observed down to at least 9000 feet. Propagation and remote triggering may still be possible on all slopes that had old snow before this latest event on slopes with angles greater than 35 degrees. Of note, it appears that upper elevation slopes with due East and or West aspects may have gotten a significant m/f crust from the latest warm period. In some areas observed, the old snow has consolidated down to a supportable m/f crust with the basal facets not as much of an issue. Each slope should be inspected for the prevalence of these basal facets; and it is very easy to identify the loose basal facets with quick hand pits. </p>
Snow totals for the storm:
13 inches in Silverfork
15 inches at upper elevations
All areas settled out significantly due to the warm ground temperatures and initial warmth of the pre-frontal phase of the storm event.
Total Snowpack Depth:
24 to 33 inches on NNE - NNW aspects above 9800 feet
The bulk of the latest event occurred overnight on the 28th into the early morning hours of the 29th. Another 3 inches fell between 9:00 am and 11:00 am on the 30th. The event came in with moderate winds, and it was quite warm with the initial 3 inches coming in very dense and damp. From this point on the storm was right side up. Then the additional 3 inches that fell on the 30th was a bit more dense and slightly slabby creating a slight density inversion in the upper levels of the snowpack.
Riding conditions above 9800 feet were creamy on NNW - NNE aspects. Obstacles obviously are the main concern in all terrain choices with the limited/thin snowpack.