Boletín de aludes

Boletín de aludes

Payette Avalanche Center
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Peligro de aludes

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

Lo esencial

2-4 feet of snowfall this week along with strong winds have created dangerous avalanche conditions. Triggering a wind slab several feet thick is likely in terrain above 7000' that faces east. These wind slabs are overlying weak that was buried earlier this month. Triggering a larger avalanche on older weak snow near the ground remains possible.

Problemas de aludes

  • Wind Slabs

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

    Several feet of very light snow has been picked up and moved around by recent westerly winds. Strong southwest winds occurred earlier this week and most recently, winds were blowing out of the NW.  Wind slabs will be thickest and most reactive above 7000' on east-facing slopes. You're most likely to encounter a wind slab near and just below ridgelines. Look for clues like pillows or drifts of dense snow and wind sculpted snow. Localized terrain features can alter the prevailing wind direction and load snow onto slopes of all aspects. Look for shooting cracks from your skis or sled. Listen to the snowpack "talking" to you with sounds like whumpfing or collapsing of weak layers.

    ADDITIONAL DISCUSSION

    New snow fell on a variety of weak snow. There is very light snow that was buried on Monday (01/08). Several feet down there are crust/facet combinations on solar aspects and buried surface hoar on shaded slopes. These weak layers have been the primary layers of failure during this week's event.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Triggering a persistent slab on weak facets from November has been unlikely up until this week. New snow this week has added weight and stress to this older, weak snow near the ground. As more weight was added this week, the likelihood of triggering a deeper avalanche on weak snow near the ground has increased. In areas where the snowpack is shallow, wind slab avalanches could step down to the November facets. Avalanches this size would be large and destructive. Where are you most likely to trigger a persistent slab avalanche?  Steep, north-facing terrain above 7000', especially where wind has recently loaded slopes.

Avalanche Discussion

Another storm system will impact the region this afternoon and evening. Storm totals are expected to less than what we've seen this week, with 4-8" in southern areas around West Mountain and 3-5" in zones north and east of McCall. There remains a little bit of uncertainty with this storm. If we receive lighter snow totals with very cold temperatures and light winds, the avalanche danger is not expected to rise. However, if the storm tracks further north and we receive more snow and wind than forecasted, the avalanche danger could increase during the afternoon today.

A series of significant winter storms have brought 2-4 feet of snow, strong winds, and very cold temperatures to our region this week. We have doubled our entire season's snowpack in less than 7 days. Adding this amount of snow (weight) to a weak snowpack in a short period of time has created very unstable conditions. If you've been reading the forecast or watching our videos (fingers crossed!), then you should be well aware of the poor snowpack structure we've been talking about for weeks now. This weak snowpack has undergone severe stress this week. Just like sleep-deprived avalanche forecasters, weak snowpacks don't respond kindly when stress continues to pile on. Recent observations have highlighted this week's trend of instability.

Although several feet of very light snow can make you think you're invincible, myself and several snowmobilers can attest that you and your sled are not invincible. Broken A-arms abounded yesterday and the local shops are stocked up with replacement parts. Lots of obstacles are still lurking underneath all of this very light snow. 

The best way for us to know what's happening as more people are out in the mountains is to submit an observation. Submitting an observation improves your skills, informs other users, and benefits avalanche forecasts. Simple photos highlighting conditions are very helpful.

Did you know there several avalanche classes this month specifically for motorized users? Check out our classes and events page to learn more.