Archived

Avalanche Forecast

Feb 1st, 2023–Feb 2nd, 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

1: Low

The avalanche danger rating below treeline will be low

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

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

Regions: Glacier.

Strong SW winds and rising temperatures will elevate danger levels in the Alpine, and potentially Treeline as well if wind values exceed the forecast.

Confidence

Moderate

Avalanche Summary

No new avalanche activity observed in the hwy corridor Wed.

Several human-triggered sz 1-1.5 avalanches were reported over the weekend on Avalanche Crest, Hermit Slide path, and Swiss Couloir.

A natural cornice failure triggered a size 3 deep persistent slab on the SE slope of Grizzly Peak on Saturday.

Snowpack Summary

25-30cm of low-density storm snow sits atop old wind-affected surfaces in the alpine and treeline.

The early Jan surface hoar is buried 50-80cm and is most prevalent at treeline. The November 17th facet weakness can still be found near the base of the snowpack in many areas.

Weather Summary

Strong SW winds and warming on Thurs/Fri will elevate the danger levels in the short term.

Thurs: mix of sun and cloud, Alp high -6*C, 1100m FZL, mod/strong SW winds

Fri: mainly cloudy, scattered flurries, 5cm, Alp high -5*C, 1400m FZL, moderate/strong gusty SW winds

Terrain and Travel Advice

Storm slab size and sensitivity to triggering will likely increase through the day.
Loose avalanches may start small but they can grow and push you into dangerous terrain.
Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

Avalanche Problems

Storm Slabs

Low density storm snow, moderate/strong ridge-top winds, and rising freezing levels will form soft slabs on variable wind-affected surfaces. Sensitivity to triggering will increase as the day progresses.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

This layer has been most reactive around treeline, particularly in areas that have not seen significant skier traffic.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 3

Deep Persistent Slabs

Recently, a large cornice-triggered natural avalanche stepped down to this basal layer near Grizzly Peak. Watch for steep, thin rocky areas where this layer could be activated.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2.5 - 4