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

Winds will continue to build stiff, textured drifts where you could trigger an avalanche. On northern aspects, these avalanches may run on deeper weak layers and be much larger. Stick to lower-angle slopes in wind-affected terrain, below cliff bands, and confined chutes where avalanches are more likely. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Snowfall will taper off on Monday, but moderate winds will continue to build wind slabs on lee aspects. Avoid steep slopes below corniced ridgelines, the base of cliffs, and confined rocky features where triggering a wind slab is most likely. On northerly aspects, wind slabs rest over weak, faceted snow from the January Drought, so avalanches may be much larger and more dangerous.  Shooting cracks, collapsing, or fresh avalanches are all red flags that the snow is unstable.

    Wind slabs and fresh snow fell on inconsistent and variable surfaces, including slick crusts, wind-stiffened snow, and weak, faceted snow. The variability in both deeper weak layers and surfaces makes the distribution of triggering avalanches tricky to forecast. So, while you can make observations using test slopes and hand pits to observe how the new snow reacts, don't try to extrapolate your results to nearby slopes. Give these wind slabs some extra space and time to heal. 

    (1/31/2025)

    A natural wind slab from earlier this season at the base of cliffs, where stiffer snow settles. This is terrain where you could trigger a wind slab on Monday. 

    SS-N-R2-D1-I

    Photo: Katie Warren

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Continue practicing patience and conservative decision-making regarding this frustrating and tricky avalanche problem. This is a low-likelihood, high-consequence situation. So, while you'd be unlucky to find just the right spot for triggering one of these avalanches, the subsequent avalanche could take you for a nasty ride and/or fully bury you. With persistent slab problems, you may or may not observe signs of instability before triggering an avalanche. The safest travel choice is simply to avoid steep terrain on wind-loaded slopes below ridgelines or the base of cliffs on northerly aspects where this problem is most likely.

    Over the last few days, there have been multiple reports of wind slab avalanches on the weak, faceted snow of the January Drought Layer (JDL). You can find facets from the January Drought Layer 1-2ft below the snow surface. Facets from early January and December, buried 2-3 feet deep under old stiff wind slabs, are more isolated. While these layers are less likely to be problematic, consider the consequences of triggering a much deeper avalanche. The distribution and reactivity of this problem are still uncertain. However, with the recent snow,  give these layers additional time to adjust before considering stepping out into steeper or more complex terrain. 

    (2/7/2025)

    A natural avalanche that likely ran on the 4-5th. The wide propagation suggests that it could have ran on the January Drought Layer. 

    Photo: Katie Warren

Avalanche Discussion

Well, our forecasted precipitation amounts fell a bit short on Sunday, and we don't expect much more throughout the day on Monday. But you can expect slightly warming temperatures and continued moderate winds. We don't think this light dose of a few inches of snow moved the needle much on our avalanche problems at lower elevations. However, in wind-exposed terrain, the impact of this storm could be more consequential. Temperatures probably won't get warm enough for significant wet loose avalanches, but you could see a few rollerballs or smaller wet avalanches in the valleys, particularly further west in the zone. Warming temperatures may also help form more of a cohesive slab at lower elevations, so heed any warning signs of instability like collapsing. 

Lower elevations have a very weak, faceted snowpack because they stayed in the deep freeze below the inversion even as upper elevations warmed in January. On Saturday, an NWAC Forecaster found a thick layer of very weak, faceted snow below last week's storm slab. We are slowly adding incremental loads to this weak layer at slightly warmer temperatures. We'll reach the tipping point sometime, but we don't think we're quite there yet. 

On Friday, NWAC Observers in the Twisp River area noted increasing westerly winds and significant blowing snow along ridgelines. The snowpack in this area of the zone was shallow and faceted, but where they traveled at mid and lower elevations, the lack of an overlaying slab limited avalanche concerns. Further north, near Washington Pass, observers reported a large (size D2) natural avalanche resulting from a cornice fall on Feb.13th. They also reported a skier-triggered hard wind slab avalanche. Both were at upper elevations on northerly aspects and may have involved the January Drought Layer.  Since then, multiple human-triggered and natural wind slabs have been reported. While most of these avalanches have been relatively small, one was reported to have surprisingly wide propagation, indicative of a persistent slab. There are also reports of isolated, large, and very large avalanches that occurred during the storm at the beginning of February. We suspect these avalanches failed on the weak, faceted January Drought Layer (JDL).

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 is an example of the problematic mid-December facets. 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. 

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

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