Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

You can trigger avalanches at middle and upper elevations, especially where the easterly winds drift fresh slabs of snow. Watch for plumes of blowing snow and steer around steep slopes where the wind is depositing them. You may be able to trigger dangerously large avalanches in this terrain on a shallowly buried weak layer.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    After a couple das of intermitent winds, east winds will increase on Friday. Watch for clues like blowing snow, cornices, and stiff or textured snow surfaces to identify wind-loaded slopes. You can also use small, inconsequential test slopes to observe how the snow reacts. Cracking or mini avalanches on test slopes are a sign you should avoid steep wind-loaded terrain. 

    It's critical to consider the potential for more widely propagating avalanches where wind-drifted snow overlaps with the distribution of more dangerous persistent slab conditions. See below.

    (2/9/2025)

    A small skier-triggered wind slab in the Cutthroat Drainage caught and carried a skier without injuries. 

    SE, 7100ft, SS-AS-R1-D1

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    We expect the most likely place to trigger a large persistent slab will be on northerly aspects at the base of cliffs or in steep rocky terrain where the snowpack is shallow and variable.  Signs of instability, like avalanches, whumpfing collapses, or shooting cracks, are bullseye signs to avoid steep slopes and keep more significant safety margins between you and large avalanche paths.

    You can find facets from the January Drought Layer 1-2ft below the snow surface. You may consider staying off of slopes over 35 degrees where you you find slabs of 4-finger hardness, or harder, over surgery, weak facets. 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, they've been the culprits in two close calls since February 1st. 

    (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

With another day of very cold temperatures, make sure to pack extra warm layers and be proactive to prevent cold-weather injuries. Consider how a simple issue, like equipment failure, could become dangerous if you have to spend an unplanned night in the mountains.

On Feb. 9th, an observer triggered a small wind slab and was caught and carried on a southeast aspect. The avalanche ran on a melt-freeze crust and no one was injured. Over the last 3 days, 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. As backcountry users venture out into more remote areas of the zone, there are also growing reports of large and very large avalanches that occurred during the storm at the beginning of February. We suspect these avalanche failed on the weak, faceted January Drought Layer (JDL). 

NWAC forecasters, observers, and other professionals in the Highway 20, Washington Pass area have found substantial evidence of weak snowpack structure throughout the zone. The early February storm brought 1-2 feet of snow to the zone that fell on either the JDL persistent weak layer or wind-stiffened snow over the JDL. The JDL exists at lower elevations. However, it doesn't seem to be a current issue for triggering persistent slab avalanches since the overlying snow lacks cohesion or "slab" characteristics in many places. 

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 where the mid-December facets were 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. 

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

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