Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

You could trigger an avalanche on steep, wind drifted slopes on Saturday. A few inches of snow overnight and a couple more inches during the day, with wind, will redistribute snow into drifts. Search for these thicker snow pockets on leeward slopes, around rocky outcroppings and in gullies, and avoid them on steep slopes.

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs that could react to a human trigger are expected to form on Saturday. About 4 inches of snow is forecasted to fall overnight, and another couple inches should fall during the day Saturday. Moderate to strong winds will help redistribute the snow into drifts along ridgelines, around rocky outcroppings and in gullies.

    The new snow layer will stay relatively shallow, so you can quickly dig down with your hand to check the interface between the new and old layer and determine how well the new snow sticks to the older layer. In most areas, the old snow layer got wet on Thursday and has probably frozen since then. Fresh snow could stick better to the old layer if it was damp as snowfall began. If the old layer froze first, newly fallen snow may easily slide on the underlying crust.  Search for indicators like cracking, and avoid slopes greater than 35 degrees if you encounter cracking, or find thicker drifts, as they could avalanche with a human trigger. 

    (12/29/2021)

    Small skier triggered wind slab in Canyon Creek. Wind deposited snow drifting onto a leeward slope, like in this photo, is where you are most likely to trigger an avalanche on Saturday. 

    Photo: Greyson Herdman

Avalanche Discussion

We received four to five feet of snow in the West North Zone Sunday through Tuesday, making Tuesday and Wednesday some of the best powder days of the year for many backcountry users. Freezing levels quickly shot up to 9000 feet on Thursday, and rollerballs and wet loose avalanches ran on nearly all steep slopes. Temperatures cooled Friday, but not enough for a half-inch to an inch of precipitation to fall mainly as rain below 5000 feet. Residual wet loose avalanches were reported on Friday in the near treeline elevation band. Freezing levels will drop lower by Saturday, and the 2000 foot freezing level is expected to finally freeze most surfaces. Continued unsettled weather with cooler temperatures is forecasted for the next week. Expect challenging snow travel in the coming days, with hard underlying bumpy surfaces but hopefully enough new soft dry snow on top to lessen the chatteriness of the old snow surface. 

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