Boletín de aludes

West Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

 When you notice the sun breaking down a preexisting crust or moistening the snow and resulting in rollerballs or small slides, steer around steep nearby slopes and the lower angle terrain beneath steep slopes. All but steep, direct north-facing slopes will likely get moist and could slide, possibly up to large in size. Wind-drifted deposits may still react to a human trigger above treeline, so consider steering around steep slopes with thicker pillows of snow. 

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Higher freezing levels and a little more sun means we can expect wet loose avalanche activity to increase a bit from Tuesday. I drove the Highway 2 corridor midday Tuesday and saw some steep, sunny slopes in the West Central zone had copious amounts of rollerball activity on them. Many surfaces will probably start with a crust but when the sun shines on these slopes the crust will probably break down quickly. When this happens, steep slopes will likely begin showing signs of a weak snow surface by rollerballing. Wet loose avalanches could follow.

    When you notice surfaces getting wet, or you start sinking down past your ankles in wet snow, steer around steep slopes and the lower-angle terrain beneath these slopes. We expect avalanches to run in the top few inches or top foot of snow, but depending on how wet the snow gets they may run all the way down to the old crust, which, depending on elevation and aspect, could range anywhere from several inches to 2 feet deep. Plan your day so you won't be needing to travel on or beneath steep, sun-affected slopes once they heat up, which could be different from when you began your trip earlier in the day. 

    (4/4/2023)

    Wet loose dribbles or rollerballs, not yet avalanches, on the Highway 2 corridor, NE, 3500ft.  These were seen on Tuesday midday. Expect them to transition from rollerballs to avalanches, possibly up to large in size, on Wednesday. 

    Photo: Irene Henninger

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Upper elevation ridgelines and other wind-drifted locations may still harbor reactive wind slabs. Identify wind slabs in areas below cornices and on other thicker, featured drifts of snow, and steer around these deposits on above treeline slopes steeper than 35°. Resulting avalanches will probably be small, and around a foot or so in depth, however some thicker drifts may still have the capacity to produce a large avalanche. Even if just a small avalanche occurs, if you're near a terrain trap such as above a cliff, rocks, trees, or a gully the outcome could still be very bad. 

    Pockets of wind drifted snow along ridgelines are where you're most likely to still be able to trigger an avalanche in a wind slab. Photo: Dallas Glass

Avalanche Discussion

Unsettled spring weather is in full swing. One moment we've got dark clouds and graupel, the next moment we're getting hot in the intense sun. No meteorologist can give us a perfect weather forecast for Wednesday, which in turn directly affects the avalanche forecast and specifically the wet loose avalanche problem. Expect a mixed bag of conditions, and probably a bit more activity than Tuesday, but we're not quite sure exactly how much more the wet loose avalanche problem is going to turn on. Increasing afternoon clouds and wind could stymy the full extent of avalanche activity in the afternoon.

The last week or more was mostly cool and cloudy and we received 1-2ft of snow near and above treeline mostly over the weekend. Before this last storm we only had a few days of sunny skies and wind to cap off our previous dump of snow . A lot of surfaces, especially north-facing, have several feet of cold, dry snow. Many steep slopes, especially northerly, saw dry loose avalanches in the last few days. You may still be able to trigger dry loose avalanches on steep northerly slopes. A bit more warming may cause wet loose avalanches on surfaces that are still low-density and dry snow, closer to north-facing terrain.

Freezing levels are going to increase even more on Thursday, and we're in for some precipitation just to make the latter half of the week more exciting with avalanches. Start thinking about cornice failures and glide avalanches as temperatures warm and snow gets moist. 

 

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