Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Periods of moderate wind are forecast for the early morning and late afternoon. Lingering instability can be found in select areas where there is a weaker layer under the new snow. Evaluate the bond of new snow layers in low-angle terrain before moving onto anything bigger. Avoid slopes where you observe active or recent wind transport.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    There are a couple of variations on wind slab that you could find tomorrow. One would be older slabs that formed during the last storm. The other kind would be fresher slabs that form early Tuesday morning or again in the afternoon. These would trend toward being shallower but more sensitive to triggering. 

    If it’s windy, blowing and drifting snow will show which slopes are loading up. These are also the ones you would want to avoid. If not so windy, track changes in snow depth, texture, and stiffness as you gain elevation and change aspects. Hand shears and stomping on test slopes or wind lips can provide information about the reactivity of fresh slabs.

    (2/21/2023)

    Wind slabs usually have crowns of varying thicknesses. This photo shows where the wind created thicker sections of slab compared to shallower areas that saw less loading.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    It might be a bit early or an overstatement to say we have a real persistent slab avalanche problem, but a number of human-triggered avalanches in Canyon Creek point toward a slightly different type of avalanche that should be on our collective radars. Surface hoar that was widespread prior to the last storm looks to have survived and was buried in that subzone. Other subzones like the Baker BC  and Schriebers/Mt. Baker NRA saw plenty of traffic with none like these reported as of Monday evening. None were especially large, but some propagated widely or were triggered from the side or below. 

    You might find this layer 1-2'  below the surface by doing simple slope cuts or maybe in a hand pit. Look for an easy and clean shear and feathery surface hoar. Other than digging, the best strategy would be to approach steep slopes with extra caution and default toward lower-angled terrain to reduce the risk of triggering one.

     

    (3/10/2025)

    A snowmobile triggered avalanche on a northerly, upper elevation slope in Canyon Creek. Note the crown wrapping around the convex feature. This is suspected as having failed in a layer of surface hoar buried on Saturday.

    (SS-D1.5-AM-I)

     

Avalanche Discussion

It was an exciting and varied day across the forecast zone on Monday.  The most interesting observations were the previously mentioned slab avalanches in Canyon Creek. Some occurred on wind-loaded slopes at upper elevations while others were in much more wind protected terrain. All were on northerly aspects. 

A mix of avalanche activity was reported from around the Baker BC. Lots of steep lines saw traffic and only produced sluffing - albeit sluffs large enough to carry you down slope if you got caught up in one. One human-triggered slab, estimated D1.5 in size, was reported from a very steep northwest aspect at about 4800'.  The person who triggered it was caught and carried over cliffy terrain but was reported as uninjured.

Natural loose snow avalanches and slab avalanches on southerly aspects were also reported.  One very large natural that likely released overnight Sunday was observed to have run from high on Shuksan Arm near the White Salmon Glacier down to valley bottom.

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