Avalanche forecast

San Francisco Peaks / Kachina Peaks Wilderness

Kachina Peaks Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

A skier or rider could trigger a large persistent slab avalanche above treeline, particularly on north-facing terrain.   Smaller wind slab avalanches are also possible on mostly east and south faces.  Avoid steep wind-loaded starting zones and isolated pockets of wind drifted snow in cross-loaded gullies.  

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    The December facets are still present in most areas under the snowpack, as is a weak layer associated with a single or multi-layered melt-freeze crust. In some locations, such as catchment zones and areas undisturbed by wind, this problem behaves as a deep persistent slab and has not been reactive to standard stability tests.  However, in other locations, such as wind-effected chutes and gullies, this layer is buried a mere 50 cm or less in the snowpack and could be triggered by a single rider or skier.  Although unlikely, If triggered, these avalanches could be large and easily result in a complete burial.  Work around the top of avalanche paths guarded by large deposition zones and loaded starting zones.  These loaded starting zones and the adjacent thinner terrain, are the most likely spots to trigger a large and dangerous avalanche.  

    West facing aspect, with HS over 150.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Winds Thursday gusted from the west as high as 50 mph on the Agassiz/Humphrey's ridge.  This transported significant amounts of snow in the form of spindrift, and also layered snow behind ridgelines, and cross-loaded numerous gullies.  Yesterday, winds were calm but shifted to the northwest.  Overnight wind speeds increased, and today, backcountry travelers may find some small wind slabs in isolated pockets.  The exception to small avalanches is in wind loaded starting zones where wind slabs have loaded the underlying weak layers.  A wind release in these locations could step-down and impact the underlying weak layers. These conditions could produce large to very large avalanches, (D2-D2.5 in size), and have destructive consequences.  Avoid heavily wind loaded areas and be observant of any signs of instability, such as cracking or shearing.  

Avalanche Discussion

It has been a week since the last snowfall, which resulted in our first and only avalanche cycle of the season. To view some of the aftermath and learn more about the size and type of these avalanches, click here.  Since then, the snowpack has become more stable, and the avalanche hazard has decreased.  Nonetheless, persistent slab avalanches remain a potential problem.  Stability tests are less reliable with this type of avalanche, especially when buried deeper in the snowpack.  This problem might be dormant, but rising temperatures and the weight of a skier or rider may resurrect it.  

In most locations on the Peaks the persistent weak layers, some of which were failure points during the last storm cycle, were buried by over a meter of snow.  In areas that haven't slid, these weak layers are supporting the additional load, but this is in the absence of a skier or rider. In locations of shallow snowpack, the weight of a skier or rider will more highly affect the underlying layers, and could trigger a large avalanche.  In problematic locations, such as steep starting zones, we're still facing a low probability but high consequences scenario.  Avoid steep entries to avalanche paths, especially those that have been loaded or are actively being loaded by wind. 

In a few sampled locations, the temperature profile and crystal type, (rounding facets), suggest that this problem is starting to heal.  However, it may take a couple more weeks of warmer weather and possibly more snow before it completely abates.

Wind slabs are the second concern and are limited to isolated pockets above and near treeline.  Winds last night were in the moderate category and out of the north. This may have produced some small, slightly more sensitive wind loaded areas, most notably in cross-loaded gullies near treeline where more snow has been available for transport.  The more northerly wind direction tends to produce more common wind slab avalanches, especially at the top of west and south facing slide paths.  Today, expect calm to moderate winds still out of the northwest and possibly shifting back to the west this afternoon.  More recent snow transport could make for more easily triggered wind slabs.  Beware of underlying hazards if crossing any newly formed wind drifts, mounds, or pillows.

Conditions on the Peaks are highly variable, and numerous aspects and elevations have been affected by both sun and wind.  Most mid-level elevations at nearly all, but south-facing aspects still contain soft snow.  Some south and west facing slopes are going through melt-freeze cycles, and as this warm weather trend continues, some slopes may start to corn up in the afternoon.  Much of the above treeline zone has been impacted by high winds and can boast a seriously slippery or grabby wind crust. The growing distribution of wind and sun crusts may be the future weak layers in the snowpack.

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