Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

December 19, 2022

Submitted:

December 20, 2022

Observer:

NWAC Forecaster - Josh Hirshberg

Zone or Region:

Stevens Pass

Location:

Lanham Lake (3,000-5,560ft, E, N)

Recent Avalanches?

Yes

Cracking?

None Experienced

Collapsing?

None Experienced

The Dec 18th interface shears sudden and planar on buried surface hoar (3.0mm). Lanham Creek, E, 5,560ft.

Large (3.0mm) surface hoar, buried on 12/18, was found resting on older drifted slabs. E, 5,560ft, Lanham creek

Very low-density new snow. Lanham creek.

Deep pillows of snow cover a boulder field. Lanham creek.

https://youtu.be/jB_esfkRM7M

Advanced Information

Cloud Cover:

Obscured

Temperature:

15°F

Wind:

Light , W

New/Recent Snowfall:

28cm

Very cold with light snowfall. Previous blowing snow overnight subsided to only light gusts.

Avalanche Observation Comments:

We triggered a few small loose avalanches in the new snow.

New snow that fell in the past 24hrs was very light and uncohesive.
Wind features at 5,500ft ridge were easy to trigger.
12/18 surface hoar was most pronounced where in rested on older wind-drifted slabs. Elsewhere it sank into the very soft layers above and below. Profiles in wind-sheltered locations found very soft snow above and below the 12/18 interface made it difficult to discern potential buried weak layers, including SH.

Profile, E, 5,560ft
HS 121cm, HST, 27cm
Boot pen- 40cm
94-93cm: F hard, SH, 3.0mm, fast and clean tilt test, CT4 (PC), ECTN 4, 12/18 interface
25-33cm: 4F+ hard, MF(FCxr), 1.0-1.5mm, CTH 24(SC), ECTX, 11/22 interface (mid-Nov Facets)
Tests produced either no results, breaks, or resistant planar results on both 12/9 and 12/8 interfaces

Problem	Location	Distribution	Sensitivity	Size	Comments
Dry Loose	N E S W	Isolated Specific Widespread	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Layer Depth/Date: 28cm Weak Layer(s): Dec 18, 2022 (SH)
Wind Slab	N E S W	Isolated Specific Widespread	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Weak Layer(s): Dec 18, 2022 (SH)