Avalanche forecast

Avalanche forecast

Payette Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

10-20" of light, soft snow could create dry loose avalanches (sluffs) on the northern half of the compass today, especially on slopes steeper than 35 degrees. Another clear day with abundant sunshine will increase the likelihood of wet loose avalanches on solar aspects. South-facing slopes have multiple melt-freeze crusts with weak snow above and below these crusts. These weak layers were failing very easily yesterday from the weight of a person.

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Recent storm totals Tuesday through Thursday ranged from 8-20" around our advisory area. The West Mountain zone was at the higher end with 16-20". Temperatures were very cold Wednesday and Thursday while snow was falling. This produced very low density snow. This soft, light snow is lacking any slab-like characteristics and has the ability to move easily on terrain steeper than 35 degrees. Dry loose avalanches (a.k.a sluffs) are typically small and fairly manageable. However, 16-20" of snow could produce an avalanche that would be large enough to bury a person. Dry loose snow also has the ability to knock you off your feet or steer your machine off course, especially if you find yourself in consequential terrain.

    If you are entering steeper terrain on the northern half of the compass, be sure to have a plan with your travel partners for how to manage this dry loose snow problem.

    (2/24/2023)

    Looking south into Poison Bowl. Evidence of small, dry loose snow (sluff) avalanches from recent storm.

    Photo: Studley

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    All of this new snow saw a full day of solar radiation yesterday. Today, slightly warmer temperatures and clear skies will provide another day of strong solar radiation on south-facing slopes. As we near the end of February, we need to remember that longer days mean a higher sun angle. Which translates to longer and more direct sunshine on the snow. You can expect to see this new snow shedding off rocks, cliffs, and trees today. As temperatures warm and the upper snow becomes moist, wet loose avalanches could start small and grab more soft snow farther down the slope to create larger avalanches.

    Additional Discussion: South-facing slopes are haboring at least a couple of melt-freeze crusts from weather events in recent weeks. Above and below these crusts are weak layers (facets and buried surface hoar). Crust and facet combinations are very poor snowpack structure. Yesterday, while traveling on a south-facing slope south of Tamarack Resort, we experienced a large collapse (whumpf). A weak layer of large-grained surface hoar and facets beneath a melt-freeze crust was responsible for this collapse. This weak layer failed in isolation on a CT and ECT. Although the snow above these weak layers is lacking a slab, you should be alerted by these red flags (poor structure, collapsing or whumpfing, columns failing on isolation). 

     

Avalanche Discussion

Today's avalanche forecast is sponsored by Mile High Powersports of McCall. Thanks for supporting the Payette Avalanche Center.

Wind slab activity has been minimal this week. Yesterday, we did not observe any evidence of wind slabs in terrain above 7500. However, with 10-20" of very light snow, there is lots of snow available for transport. Southwest winds today could begin forming wind slabs by this afternoon. Pay attention to north and east-facing slopes to see if winds are forming slabs on this leeward slopes.