Observation: NWAC Observer

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Weather Summary

High overcast AM dissipated, becoming clear by mid morning. Strong solar input. Moderate NW winds effectively transported recent snow near alpine ridge crests, in some cases scouring upper elevation windward features down to previous facets and crusts. Windslab deposition observed E thru S along ridge crests with limited extent downslope.

Abundant Wet Loose to sz 2.5 from Jan.20 observed along Hwy 20 corridor. Spire Gully went large enough to ruin the skiing for a while, at least on the exit.
Some favorite E thru SE aspect ski terrain near the pass experienced much solar warming today and some small (sz 1) Wet Loose natural activity. See photo.

Snowpack Observations

We found fast, smooth skiing on N aspects today, between 7500'-6000', with about 8-10cm storm snow from Jan.20, which likely underwent some drying overnight. This new snow has undergone moderate transport, occasionally accumulating into deeper pockets of up to 30cm depth in favored locations. Weak crusts and thinly-buried near-surface facets now underlie the recent snow on colder aspects.
On S aspects, we found well-settled but sun-warmed storm snow overlying a firm and supportable crust. It was edgeable enough to allow for efficient skinning and consistent skiing, with only isolated areas of slickness, where we could easily push the new snow into small, slow-running wet loose sluffs with minimal entrainment. We expect an improving bond with these surfaces, moving forward.

Though we accomplished no formal tests or digging in the field today, I've attached a profile from Jan.19, from a representative N aspect location, albeit further east. The main points to consider are the weakening crusts and persistent grain types in the upper snowpack, which are now shallowly buried in colder locations, above approx. 5500'. This structure is likely to be preserved for some time. The anomalously weak structure captured in the lower snowpack in the profile reflects faceting over the Early December Crust and should be considered an outlier, with unremarkable test results even in a cold, sheltered, rocky easterly location.

Avalanche Problems

Problem	Location	Distribution	Sensitivity	Size	Comments
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	Layer Depth/Date: Jan.21 10-40cm Comments: Likely becoming stubborn into Jan.22
Wet 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: Jan.21 Comments: Expect limited entrainment due to firm surfaces below HST; some Below Treeline terrain may remain locked under melt freeze crust

We avoided steep, loaded features adjacent to alpine ridge crests today, where an unexpected push from a small windslab would have held undesired consequence.