Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
February 16, 2023
Submitted:
February 16, 2023
Observer:
NWAC Forecaster - Katie Warren
Zone or Region:
East Central
Location:
Lower Salmon La Sac (2500-5000ft Primarily N and E aspects)

Signs of Unstable Snow

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

Media/Attachments

Quick hand pits showed around 20-30cm of recent snow with a favorable bond to the underlaying crust.
Textured surfaces indicated previous wind transport, but even these surfaces remained soft without a surface wind crust.
These sparkly surfaces are surface hoar crystals that are still intact, but have been knocked over by the wind.
A compression test produced sudden results on a layer of weak faceted snow beneath the recent crust.
There was good skiing in low angle sheltered glades.
A profile dug at around 4800ft on a NNE aspect showed a relatively strong rightside up snowpack. The most recent crust had some weaker snow surrounding it.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Calm
New/Recent Snowfall:
The recent snow totals from the storm on 2/13 were at 5cm at the trailhead and quickly increased with elevation to approximately 30cm at 5000ft.

It was a benign weather day with mild temperatures, overcast skies, and calm winds. Previous winds have left textured surfaces and some drifts, but even in these areas the surface was soft (F) and lacked any stiff wind crust.

Snowpack Observations

At the trailhead, there was around 5cm of new snow. On some steep southerly road cutbanks, there was a thin melt-freeze crust on the surface. But most areas had soft surface snow. The recent storm snow totals increased quickly, and above 4500ft, I found 15-30cm of recent snow, with the greater depths existing in forest openings and meadows. Travel below the tree canopy was challenging at times, with a slippery crust beneath the new snow. If I had been on steeper terrain, I would have needed ski crampons.

Quick hand pits showed an overall favorable bond to this underlying crust. However, a snow profile dug at 4800ft did show some weak faceted snow beneath the crust with sudden failures on compression tests, although shear quality was low with a rough uneven surface. This layer did not show a propensity for propagation in an extended column test. This crust was fragile and not supportable to boots at these elevations in open areas.

I observed drain channels in the snowpack, and water seems to be pooling on the Christmas crust, buried around 100cm deep. The snow above this crust was P hard, moist melt forms. The other notable crust is the MLK crust which is buried 70cm deep in this location and produced no notable snowpack test results.

There was a layer of surface hoar at upper elevations in gladed areas that had recently been blown over by the winds but was still intact, just laid over.

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