Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
February 7, 2023
Submitted:
February 7, 2023
Observer:
NWAC Forecaster - Matt Primomo
Zone or Region:
Stevens Pass
Location:
Lanham Lake

Signs of Unstable Snow

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

Media/Attachments

N at 4,400ft. Two layers stick out, the uppermost one is the thin near surface facets from 2/3, the next one down is the MLK crust.
Tilt test failing easily and consistently on the Feb 3 interface. N at 4,400ft.
General environment.
Small fracture at the old/new interface around 5,000ft.
Section of storm slab fractured easily to fill in the profile at 5,500ft
Very saturated upper snowpack down at 3,800ft

Advanced Information

Weather Summary

Cloud Cover:
Obscured
Wind:
Light , SW
New/Recent Snowfall:
20-30cm above 4,500ft less below, rain below ~3,500

Today was wet, with snowfall at S1-S2 most of the day that increased to S2+ for a little while.

Snowpack Observations

We found a pronounced gradient with elevation from wet snow to dry snow. Wet snow became moist at about 4,300ft to 4,800ft. Above 5,000ft the snow was dry and fluffy. Being in the tree canopy most of the day, we didn't experience widespread instabilities. Once out on some open areas though we observed fracturing of test slopes and could trigger small sections of storm slab at the old/new interface.

A profile on N aspect at 4,400ft found HS of 162cm. Tilt tests highlighted a consistent weakness with a thin layer of buried and rounding near surface facets (Feb 3) down 27cm. The MLK crust was down 40cm, and ~1cm thick decomposed freezing rain crust. CTM Brk beneath MLK crust on rounding facets.

Another profile higher up, ESE at 5,500ft found 2/3 interface down 38cm as a 1cm opaque sun crust and ~2cm of rounding near surface facets beneath. Tilt tests were consistently and easily failing beneath the sun crust. PST 20/100 (Sfc). When I continued running the saw up the column it propagated to the end at 50/100.
The MLK crust here was very thin and brittle, down 50cm. The snow above and below was strong, with no results of note.

The skiing was good, knee deep snow at times, to heavy sticky snow over refrozen tree drip crust lower down. A short elevation window of rain corn was even enjoyed on the packed access road.