Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
January 29, 2023
Submitted:
January 29, 2023
Observer:
NWAC Forecaster - Irene Henninger
Zone or Region:
Stevens Pass
Location:
Skyline Ridge (4000-6000ft, all aspects)

Signs of Unstable Snow

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

Media/Attachments

Yesterday's skin track had drifted in late in the day or overnight before winds calmed by Sunday morning.
A pit just beneath Skyline Ridge. The MLK crust was just under a foot down, and round 1mm facets were visible above the crust. We got a CT26 SP above the crust on that layer, but also an ECTX. Surface hoar was noticeable on the surface everywhere we traveled- it hadn't been destroyed by wind anywhere. Subtle amounts of near surface faceting are beginning to form near the surface.
Thin wind skins up to a few cms thick were present on east facing terrain at sparsely treed ridgeline at 5200' and it was noticeable through moderately treed areas down to about about 4600ft. Small-table-sized 2" pockets of wind slab released on very steep, small features.
The east face of Tye Peak, with subtle wind-effect from overnight visible in sparsely treed areas.
Overnight easterly wind-effect visible on the ridge in the Stevens Pass backcountry.
2mm surface hoar crystals and a few near surface facets (.5, hard to see in this photo) in a surface sampling from 5000ft, south around 9am Sunday.
Sparkly snow surfaces averaging 2-3mm surface hoar was present everywhere we travelled on Sunday. Surprisingly it hadn't been destroyed by wind anywhere we travelled.

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
9°F
Wind:
Calm

Overnight/late Saturday easterly winds gusting moderate/strong, but while we were out wind was mainly calm with occasional light gusts. No snow visibly transporting on any of the nearby peaks. It was cold! The day started off with single digits F and reaching into double digits midday. With the subtle breeze at the ridge, it was remarkably colder.

Snowpack Observations

We traveled up Skyline/Moonlight vicinity. Surface hoar was visible on the surface everywhere we travelled, so we suspect it developed after the wind event.

Recently formed thin hard and soft slabs were present along ridgelines and around features on sparsely treed slopes. Sheltered north-facing slopes still had around a foot of right-side-up snow over the MLK crust, but southerly aspects only had about 2" of low density snow over a crust. The only thing that slightly resembled avalanches was mid-slope ~3 foot wide, 2 inch deep soft slab pockets which likely developed in the recent wind. They were triggered on steep rollovers during our descent in a few spots.

In a NW facing pit just below the ridge we saw rounding 1mm 4F facets above the MLK crust which produced a CT26 SP, but ECT's yielded no results. Near surface faceting was present everywhere we traveled, although it was mainly very subtle, .5-1mm grains mixed in with decomposing forms.

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