Avalanche forecast

San Francisco Peaks / Kachina Peaks Wilderness

Kachina Peaks Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Three to four feet of snow has fallen in the last three days, loading existing weak layers.  Backcountry travelers are very likely to trigger small to large avalanches on steep slopes near and above treeline that could have significant consequences.   Avoid steep slopes, pockets of wind loaded terrain near ridgelines, and areas of widespread wind deposition, such as cross-loaded gullies and starting zones.

Catchment zones at the top of big avalanche paths could produce large and maybe very large avalanches.  

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Two primary persistent weak layers are now buried deeper within the snow but could release a large avalanche if triggered by a skier or rider.  The most widespread weak layer is at the bottom of the snowpack and another is at what was once the mid-level layer.  In areas where slopes are sufficiently loaded, human-triggered avalanches are very likely, and natural avalanches are likely. As the weather momentarily improves, backcountry travelers should continue to avoid steep terrain near and above treeline.  

    It is possible that some avalanches have already occurred and that others may happen today.  Visibility has been obscured and storm conditions have made travel difficult.  Anyone entering the backcountry, especially above and near treeline, should navigate cautiously and avoid slopes greater than 30 degrees, particularly steeper slopes more prone to avalanches.  These avalanches can release without warning, and scour zones holding thinner snowpacks could act as trigger points.  

    (2/4/2024)

  • Wind Slabs

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

    Winds near treeline have stayed in the moderate zone, while ridgetop gusts have been strong or extreme.  There has been widespread snow transportation, and many leeward slopes and ridgelines have experienced significant loading.  Avoid loaded starting zones, wind drifts, mounds of snow, pillowed areas, and cornices.  These wind slab avalanches may be difficult to trigger but could bury a skier or rider.  If large enough, a wind slab avalanche could step-down and release a persistent slab avalanche buried deeper in the snowpack. 

Avalanche Discussion

Storm totals over just 3 days range between 39" and 55" of snow.  Over 5" of SWE has been recorded at the Snowslide Canyon  Snotel site since the storm's beginning.  Due to limited visibility, avalanches have been difficult to see, but it is probable that natural avalanches have occurred on north facing slopes and within the general Inner Basin zone of the San Francisco Peaks.

As mentioned previously, two primary persistent weak layers are the focus of concern, and these are the likely failure points of today and tomorrow, as another pulse of moisture is forecast to enter the region.  The first and most prominent of these layers is a set of basal facets and depth hoar buried at the bottom of the snowpack. This layer has been found most commonly on North, East, and West aspects above and near treeline.  Its presence seems widespread except in some south facing areas where snow has melted off between storms and other high terrain aspects where snow has been significantly stripped by wind.  The second and more variable is a set of persistent weak layers, facets, and near-surface facets located above and below various melt-free crusts.  The continuity of these layers has been harder to assess, but if present continuously in the snowpack, these layers could also result in large avalanches.  They have been observed mostly on east facing slopes.

Yesterday, an assessment of West facing slopes, including loaded ridgelines and cross-loaded gullies, showed the windslab to be stubborn to non-reactive.  An ECTP24 was recorded that failed on 2-4 mm of chained depth hoar at the bottom of a shallower (110cm) NNW slope.  

Winds have been variable and intermittent during different phases of the storm.  It's likely that on Tuesday through Thursday some areas were stripped and others were loaded, and similar winds could happen today.  In areas that become significantly loaded by wind, the basal facets may fail, making for large to very large avalanches with 4'-7' crowns.  Wind loading will also stress other persistent weak layers in the snowpack.

Wind slabs are expected to build again today.  Use appropriate spacing when traveling and avoid wind drifted locations.  Retreat or find a different route if cracking or shearing is observed.  

Cold temperatures and severe wind chills are expected today, but visibility may improve.  Observe for natural avalanches, this is the most obvious sign of instability.  Travel above treeline is not recommended due to high avalanche danger.

Note that the snowpack depth and layers were quite variable pre-storm.   For those seeking more information, please view the observations page.  https://kachinapeaks.org/Observations/#/view/observations.   You can also check out the snowpits published this week at snowpilot.org.

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