Boletín de aludes

Boletín de aludes

Payette Avalanche Center
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Peligro de aludes

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

Lo esencial

1-2 feet of recent snow with strong winds have created unstable conditions. Another 10-20" is forecasted today through tomorrow with more strong SW winds. Wind slab avalanches will be become very likely this afternoon. Our weak snowpack is reaching the tipping point where large avalanches (size D2) may become widespread.

Problemas de aludes

  • Wind Slabs

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

    1-2 feet of very light snow is at the surface just waiting for strong winds to pick it up and form it into a slab. Strong southwest winds are forecasted to be gusting between 40-50 MPH at upper elevations. Lower elevations are expected to see gusts 20-30MPH. Dense wind slabs may form quickly today. Localized terrain features can alter the prevailing wind direction and load snow onto slopes of all aspects. Slabs will be deepest and most reactive above 7000' on north and east-facing slopes. Instabilities within the recent storm snow will become increasingly reactive as more snow stacks up. Signs of instability will not be hard to come by today. 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. Pay attention to the slopes you are adjacent to and underneath. Avalanches will be increasing in size and sensitivity as the day progresses.

    ADDITIONAL DISCUSSION

    New snow continues to fall on a variety of weak snow. There is very light snow that was buried on Monday (01/08). On solar aspects, there are crust/facet combinations buried 1-2' down. On shaded aspects, there may be a layer of surface hoar buried 1-2' deep. The new storm snow today will likely not bond well to these existing surfaces and instabilities. In wind-protected areas , you can expect dry loose snow to be unstable. This dry loose snow (or sluff) will create small avalanches that will be growing in size throughout the day.

  • 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. As new snow adds weight and stress to the existing snowpack, this older, weak snow will undergo more strain. When will this weak snow near the ground beome overloaded and fail? This is the question to ask yourself if you're out in the mountains this week. As more weight is added, the likelihood of triggering a deeper avalanche on weak snow near the ground increases. 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 is actively loading slopes.

Avalanche Discussion

Today's danger rating captures the higher danger associated with the rising instability throughout the day. This morning, instability will likely be lower than this afternoon and evening.

A series of significant winter storms are impacting our forecast zone all week. Recent storm totals from Monday have been in the 1-2 feet range. This storm came in with significant wind in some areas. Instability from this storm has varied and began to trend down yesterday. Another significant winter storm will impact our region today through Saturday, bringing an additional 15-30" of snow with strong SW winds. We are doubling 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 will tip the scales and create 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 is becoming overloaded. Recent observations highlighted this trend yesterday. It's not quite a matter of IF but WHEN our weak snowpack will say, "Enough is enough".

Avalanche danger will be on the rise again today. Winter weather will make mountain travel extremely difficult this afternoon and evening. Avalanche conditions will make that travel dangerous. Be alert to changing conditions and remain aware of terrain above you and adjacent to you.

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.