Bollettino valanghe

San Francisco Peaks / Kachina Peaks Wilderness

Kachina Peaks Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger is considerable above and near treeline. Avoid slopes where drifting snow has created dense slabs over softer snow. Development of large slabs may push deeper persistent weak layers to the point of failure, resulting in larger avalanches. Uncertainty about the snowpack is elevated. 

Coverage has improved, but rock or log strikes will be possible, especially on W, SW, S, and SE aspects. 

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Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Northerly, northeasterly, and easterly slopes will be most susceptible to new wind slab formation, but chutes/gullies may cross-load NW and SE aspects. The force of any wind slab avalanches may "step down", triggering failures in deeper, persistent weak layers above and near treeline. 

    South, southwest, and westerly winds pushed snow around yesterday and last night. Drifting snow will create dense slabs over softer snow.  Expect to find thick windslabs on the leeward side of ridges or in crossloaded gullies. Wind Slabs are often smooth, rounded, and sometimes sound hollow. Blowing snow and cracking or collapsing in drifted snow are warning signs of the problem. Wind Slabs can be avoided by sticking to sheltered or wind-scoured areas. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    KPAC has yet to observe a definitive persistent slab avalanche this season, but persistent weak faceted layers (basal facets and depth hoar) are in the lower ~1/4 of the snowpack. Instability tests have not produced propagating fractures in these layers in nearly two weeks. However, new snow and wind drifted snow are creating larger and more cohesive slabs, possibly pushing the weak layers to the point of failure. 

    On Thursday, March 13, KPAC observed some reactivity in an older (days old) wind slab near treeline, on a northerly slope (see pit below). The wind slab rested on a softer layer containing small near surface facets (NSF). This old wind slab over NSF layer combination was not extensive across the slope, but it may exist in other locations. New and drifting snow may push this combination to the brink of failure. 

Avalanche Discussion

On March 9 and 13, observations indicate a snowpack characterized by poor structure, moderate to high strength, and no tendency to propagate failures. Rapid changes over the last 24 hours are altering these characteristics. With over 2" of snow water equivalent added to the snowpack in under 24 hours,  KPAC expects that new snow and wind slabs are pushing the snowpack to the brink of failure. Uncertainty about the backcountry snowpack is significantly elevated, and KPAC recommends careful snowpack assessment, conservative decision making, and avoiding wind loaded slopes. Today, visibility, blowing snow and -20°F windchill near treeline will complicate good decision making. 

Lack of snow and warm weather for much of the season means plenty of rocks and logs just under the surface of the new snow, especially on W, SW, S, and SE aspects. NW, N, NE and E aspects generally have the best coverage, but log and rock strikes may still occur, especially at lower elevations and previously wind-scoured slopes above treeline. 

If you get out, please submit your observations or email us at [email protected]. 

KPAC has documented evidence of four avalanches this season - Avalanche Database.  

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