Quick report
- Red Flags
- Poor Snowpack Structure
- Red Flags Comment
- <p>Where I was traveling, the only red flag is the poor snowpack structure. This exists on shady slopes above 8,500' where the bottom 10-20 cms is weak faceted snow. Despite the poor snowpack structure, no cracking or collapsing, which indicates to me we simply haven't *yet* put enough of a load on top of the buried weak layers.</p>
Overall I was pleased with the depth of snow coverage in Days Fork right out of the Spruces lot, with 30-45 cms at the trailhead. I only got as high as 9,500' but was finding close to a meter. Most of this is from snowfallFriday and overnight into Saturday.
I dug several pits and results were ECTX (no fracture). One pit at 9,500' was ECTP27 (fracture and propagation) that failed at two interfaces:
- down 45 cms in faceted snow at the new/old snow interface;
- down 60 cms in faceted snow that fell in Oct/Nov.
The "storm slab" lacked cohesion and was soft, fist hardness.
But the poor structure is in place and we're only lacking a cohesive slab. With wind and heavy snow in the forecast, we should get our slab and I expect some avalanches will fail down in faceted snow near the ground.
When I was exiting at 2 pm, winds which had been confined to the ridgelines began to work their way down into drainage bottoms, so I expect sensitive wind drifts will be found at both the mid and upper elevations.
With a PWL on mid and upper-elevation aspects facing west-north-east and plenty of low-density snow everywhere, the current snowpack has plenty of weaknesses and I expect the heavy, dense snow and strong winds will create dangerous avalanche conditions overnight and into Sunday.
Snowpack
- Instability Comment
- <p>I was finding the PWL down near the ground as low as 8,500'. There are various crust/facet layers in the bottom 10-30 cms of the snowpack and the weakest snow I found was just below a 1 cm crust 10 cms above the ground.</p> <p> </p> <p>Increasing danger with additional heavy snowfall and strong winds forecast.</p>
The current snowpack consists of layers of faceted snow in the bottom 10-30 cms with recent storm snow totals of 30-45 cms of low-density snow. Where there was any wind-drifting, the shallow drifts were sensitive as they were on top of the weaker, low-density snow.