Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A widely variable snowpack with inconsistent weak layers creates a tricky avalanche problem. You could trigger large avalanches on the northern side of the compass, but adjacent slopes could react very differently. Make frequent snowpack assessments as you travel, build in larger safety margins, and consider the consequences of triggering a large, surprising avalanche. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    The snowpack structure is weak, variable, and complex. We expect the most likely place to trigger a large persistent slab will be in wind-drifted locations below ridgelines or the base of cliffs and steep terrain with exposed rocks where the snowpack tends to be shallower. The uppermost weak layer, the January Drought Layer, exists 1-2ft below the snow surface. Dig down and feel for stiffer, 4-finger, snow over surgery, weak facets. This could be especially problematic if you find a melt-freeze crust under the facets. If you see signs of instability, like avalanches, whumpfing collapses, or shooting cracks, avoid steep slopes and put a large margin around complex terrain and large avalanche paths.

    Winds on Feb. 8-9 may have formed slabs over these weak layers, and most reported avalanches occurred at the base of cliffs where snow accumulates as it sifts down the rocks. More isolated and unlikely are facets from December, buried 2-3ft deep under old stiff wind slabs. We expect this issue to be problematic in shallow, wind-affected terrain above 6500ft.

    (2/2/2025)

    A skier triggered avalanche (D2) that ran on an old weak layer of facets from mid-December. 

    Snagtooth Ridge, NE, 6,600ft

    Photo: Adam Butterfield

Avalanche Discussion

Easterly winds will bump up slightly on Monday, especially pass-level winds, with continued cold temperatures and sunshine. We don't expect the winds to be that impactful, but plenty of light snow is available to drift over our weak snowpack structure.

There's a lot of variability and complexity in layers that formed in the mid and upper snowpack since early December. Over the past 10 days, 1-2ft of snow accumulated over this complex snowpack. However, both storm snow totals and total snow depths vary significantly throughout the zone. With increased uncertainty, your best management strategy is to choose more conservative terrain. Consider avoiding steep wind-drifted slopes or steep, shallow, rocky terrain. Consider the potential and consequences of triggering a large avalanche at middle and upper elevations, especially where facets formed and were preserved on northerly aspects. You can dig snowpits and use sudden or propagating tests to identify the problematic structure.

On Friday, observers investigated several slopes at middle and upper elevations. Near Cutthroat Lake (NNW, 6,780ft), they found small and large column test results (CTM(SC), PST 38/100 END) about 1.5 feet (50cm) below the surface, consistent with impressive shooting cracks reported by a party the day before. They also reported a couple of large natural slab avalanches at the base of cliffs and some small point releases in the surface snow.

Substantial evidence of the weak snowpack structure throughout the zone exists. Unfortunately, identifying a likely pattern of this current avalanche problem remains elusive. Over the past few days, a few avalanches have occurred, including natural wind slabs, skier-triggered avalanches, and cornice-triggered avalanches. These avalanches all occurred on northerly aspects, many at the base of cliffs. The JDL weak layer is widespread and present at most elevations. But at lower elevations, we don't have evidence showing that it's a current issue for triggering persistent slab avalanches. The overlying snow lacks cohesion or "slab" characteristics in many places. This structure may become more problematic with future storms or as the recent snow gains cohesion.

Less likely, but still a concern, are deeper layers of facets buried by older wind-drifted slabs during mid-December through mid-January. The distribution of this layering is more cryptic and complex but has been observed between 6,500-7,500ft in moderately wind-exposed terrain. An avalanche triggered on 2/1 near Cedar Creek/ Snagtooth Ridge shows an isolated area where this layer of mid-December facets was problematic. There are also slopes where you won't find the facets as they were melted or capped by a crust (high elevation rain event on Dec 7th) or blown away. See more below. 

 On February 2nd, NWAC observers investigated an avalanche near the Snagtooth Ridge triggered in an old, weak layer up to 3ft deep. The incident occurred at 6,600ft on a northeast aspect from a shallow spot in very steep, rocky terrain. The weak layer was into the lower half of the snowpack and was 1-2mm faceted grains. It's believed that these facets were buried on December 17th. 

You can help us gather more data by submitting an observation HERE or via the Avy App. 

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