Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
March 16, 2023
Submitted:
March 16, 2023
Observer:
NWAC Forecaster - Katie Warren
Zone or Region:
East Central
Location:
Middle Icicle Creek (2200-7100ft; All aspects)

Signs of Unstable Snow

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

Media/Attachments

Wind drifting in the upper ATL around 8000ft in Icicle Creek.
Small, feathery surface hoar was observed in sheltered areas in Icicle Creek.
Some more recent dry loose avalanches triggered by the warm sun today.
Cornices were large along the ridge, but were not very overhung.
Snow profile from 6000ft on a ENE aspect on Cashmere.
Just left of center, you can see an older crown of a wind slab that likely ran during the stormy weather last week.
Older loose avalanches that ran from the steep cliffs above.
West face of Cashmere
Old debris from a cornice fall.
If you look closely, you can see numerous older dry loose avalanche that ran in very steep terrain near ridgeline.

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
<30°F
Wind:
Calm , E
New/Recent Snowfall:
15cm over the crust formed between 3/12 and 3/13.

We experienced clear skies and calm winds throughout the day. However, blowing snow was visible in the upper ATL terrain off Cashmere Mountain. The temperature felt warm in the sun, and snow surfaces were becoming moist by midday. In the shade, it was still chilly, with soft snow surfaces.

Snowpack Observations

It sure felt like spring out today, with the strong March sun moistening snow surfaces in the sun and cold, dry snow in the shade.

We saw evidence of last week's storm cycle with one older D2 wind slab at the base of cliffs, a cornice fall, and numerous old dry loose avalanches that ran in very steep terrain.

In the morning, we found refrozen surfaces with a 3-4cm thick melt-freeze crust on the surface that was not supportable to boots. There was soft snow below this crust. In shady areas above 3000ft and a few cm of new snow rests over the crust formed on 3/12-3/13. This recent crust disappeared by 4000ft on northerly aspects.

We parked the snowmobiles around 4500ft on a north aspect and observed 15cm of recent snow overlaid a slightly denser layer of snow around 10cm thick, likely from the same warm-up that created the melt-freeze crust at lower elevations. However, even this density change quickly disappeared by 5000ft.

In a snow profile on an ENE aspect at 6000ft, we observed an HS of approximately 300cm with 120cm of right-side-up storm snow overlaying the Valentine's Crust. Weaker snow around the Valentine's Crust is rounded and 1F-P hard. The Valentine's Crust complex was limited to elevations below 7000ft. Compression tests and Tilt Tests identified a storm interface down 15cm, failing on buried stellar (precipitation particles), but this instability did not produce results on test slopes. The MLK crust is around 150cm deep, and the Christmas Crust is down 200-220cm.

Corniced ridgelines showed evidence of the shifting winds and are more vertical in many places than in a typical winter. Wind slabs on lee aspects were unreactive to ski tests and small cornice drops. We observed a slightly shallower snowpack between 230-250cm on easterly aspects near ridges.

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