Bollettino valanghe

San Francisco Peaks / Kachina Peaks Wilderness

Kachina Peaks Avalanche Center
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Pericolo valanghe

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

Avalanche hazard has decreased now that we are over 48 hours since significant accumulation; however, human-triggered avalanches are still possible on the steepest slopes near and above treeline. Persistent weak layers in the snowpack may not give any warning before failing.

Avoid areas with cohesive slabs of new wind-packed hard snow over soft snow, especially if the weight of a skier/rider produces cracking or shearing in the snow. 

By Tuesday afternoon, expect increasing hazard as significant weather moves into the region. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    In general, dangerous wind slabs were not observed over the weekend. Some small, thin, and soft to hard wind slabs did develop, and some produced shooting cracks under skis, but overall, they have been stubborn to propagate. Snow remains available for transport and moderate to strong south winds are forecast today. Watch for newly formed wind slabs and avoid areas with cohesive slabs of wind-packed hard snow over soft snow, especially if cracking or shearing is observed. 

  • Persistent Slabs

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

    Weak basal facets and depth hoar overlayed by stronger snow remains a problem on slopes near and above treeline. This is a challenging problem to negotiate as it presents a low probability but high consequence scenario. These weak basal layers will likely be triggered in a shallow area near rocks or cliffs, often without warning. Additionally, easterly aspects have a weak layer under a melt/freeze crust at 40-60cm below the snow surface. This layer produced failure/crack propagation in many instability tests performed by KPAC on Sunday, February 4, in Humphreys Cirque. This m/f crust can be found on more southerly slopes as well. The m/f crust has been found on northeasterly slopes but is very thin. 

    (2/4/2024)

Avalanche Discussion

In general, the snowpack above/near treeline has poor structure and moderate to strong strength. The snowpack depth and layers can be quite variable in short distances. Instability tests tend to produce propagating failures in basal facets on many aspects. Instability tests on approximately easterly slopes produced propagating failures in facets (under a m/f crust) about 40-60cm below the snow surface. See the Feb. 4 observations to learn about facets under the m/f crust.   https://kachinapeaks.org/Observations/#/view/observations. 

Thus far, no avalanches have been reported this season. This may change with significant snow forecast this week. Near treeline, 20-40" of snow will accumulate by Thursday, and persistent weak layers in the snowpack will have trouble supporting this new large load. 

Several snowpits were published this week at snowpilot.org.

Coverage has improved, but the backcountry still has thin and bare spots. Rock and log hazards may be just under the surface. 

 

Regioni coperte