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Observation: Days Fork

Observation Date
12/2/2023
Observer Name
Gagne
Region
Salt Lake » Big Cottonwood Canyon » Days Fork
Location Name or Route
Days Fork from Spruces
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
West
Wind Speed
Light
Weather Comments
Occasional strong gusts that reached down into drainage bottoms.
Snow Characteristics
New Snow Depth
18"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
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.
Red Flags
Red Flags
Poor Snowpack Structure
Red Flags Comments
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.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
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.
Increasing danger with additional heavy snowfall and strong winds forecast.
Comments
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.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates