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Archived

Avalanche Forecast

Jan 17th, 2023–Jan 18th, 2023
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Rogers Pass and the surrounding Columbia Mtns have a weak basal snowpack this season, which is making all snow professionals work hard to identify hazards not normally seen in these areas.

Drop your desires a notch; ski/ride to the conditions we have this year.

Confidence

Moderate

Avalanche Summary

The weekend's natural avalanche cycle has passed, and in its wake we have observed isolated sz 1.5 to 2.5 soft slabs along the highway corridor, mostly from steep S'ly aspects.

Snowpack Summary

Two surface hoar (SH) layers, present in the upper 40cm, are potential failure planes in areas where the surface snow has become slabby (ridgecrests, immediate lee features). The mid-pack facets are slowly rounding and gaining strength, while the basal facets and Nov 17 facet/SH/crust weakness are still reactive when isolated in snowpack tests.

Weather Summary

Continuing mix of sun, cloud, and isolated flurries, with light winds at ridgetop.

Wed: mainly cloudy, trace to 4cm, Alp high -6*C, 1200m FZL, light SW wind

Thurs: mix of cloud and sun, trace snow, Alp high -8*C, 1000m FZL, light W wind

Terrain and Travel Advice

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Use caution when approaching steep and rocky terrian.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Avalanche Problems

Persistent Slabs

The Jan 3 surface hoar (5-10mm) is buried ~40cm and is more reactive at ridgeline or in immediate lee features, where wind has stiffened the surface. If triggered, this slab has the potential to step down to the deeper persistent slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 2.5

Deep Persistent Slabs

The Nov 17 layer, which consists of a faceted crust and decomposing surface hoar, highlights a weak basal snowpack.

Be particularly cautious in steep, rocky areas with thin snow coverage, where the majority of the snowpack is weak and faceted.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4