Bollettino valanghe

Northern New Mexico

Taos Avalanche Center
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Pericolo valanghe

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

Near and above treeline have the most dangerous slopes where you'll find new snow that has fallen on a variety of different surfaces. Below the new snow are a variety of persistent weak layers that you could impact and trigger a persistent slab avalanche. The most likely weak layers are in the top 1 to 2 feet of the snowpack, consisting of facets or faceted crusts. Deeper down in the snowpack, depth hoar and faceted weak layers continue to linger in shallower snowpacks. Avoid the margins of the slab or rock outcroppings as these are areas where you're more likely to impact weak layers.

With rapid warming and our intense sun during this time of year, natural wet loose avalanches will also be likely throughout the advisory area today on solar aspects at all elevations. These avalanches will be occurring in the top 4 to 6 inches of new snow that was received during Friday's storm.

Problemi valanghivi

  • Persistent Slabs

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

    The persistent slab problem is most active in the upper meter of our snowpack. Faceted crusts on solar aspects, and buried near surface facets on shadier or wind-loaded aspects that formed during our recent dry periods are now buried beneath 1 to 2 feet of snow. These layers have been producing easy to moderate results in column tests, and in many cases they sit underneath a significant hard slab of snow, most notably in spots that see frequent wind-loading. This setup is now widespread in our snowpack, and it's where you're most likely to trigger an avalanche as a backcountry traveler. A persistent slab avalanche on this layer may break well above you and propagate widely across a slope. Watch for obvious signs of instability like shooting cracks and loud audible collapses in your travels.

    Deeper down in the snowpack, depth hoar and the early January drought facet layer are still at play and continue to produce moderate to hard results in extended column tests where the snowpack is generally 1.5 m deep or less. These layers will be more difficult to impact and trigger but if you did find the right slab/weak layer combination they can produce a large avalanche failing on or near the ground.  Avoid likely trigger points on the margins of the slab and near rock outcroppings as these will be the areas where you're more likely to impact these deeper buried weak layers.  A probe pole can be a useful tool to identify snowpack depths on the slope you plan to play on. 

    (3/9/2024)

    Near surface facets from the February dry spell sit under a decent-sized slab (50cm+), such as this wind-loaded pit on an East aspect near treeline.

    Photo: Charlie Harrison

  • Loose Wet

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

    With temperatures pushing into the upper 30's above 10'000 feet today with plenty of sunshine, we expect to see a wider wet loose cycle. Some East-facing terrain slid naturally yesterday morning before the clouds moved in, but there are still plenty of slopes out there where the new snow didn't pick up the same amount of heat that it will today. Watch which slopes are getting direct sunlight today if you head out, and pay attention to obvious signs of instability for this problem like roller balls or pinwheeling on the surface. Most of these wet loose snow avalanches will be confined to to top 4 to 6 inches and they will run on crusts or harder slabs. These avalanches typically start small in steep terrain near rock bands and fan outward as they travel downslope. With our persistent slab problem active in the upper meter of snowpack in many places, its possible that a smaller wet loose avalanche could step down into deeper weak layers, creating a larger and more destrucive avalanche.

    (3/9/2024)

    Wet loose avalanches on steep, East-facing terrain.

    Photo: Charlie Harrison

Avalanche Discussion

The shift to Daylight Savings Time always seems to cause a shift in my mentality towards spring, and sure enough we are looking at a spring-like warming trend over the next few days. If you head out into the backcountry, you'll want to time your skiing and riding really well, and in a lot of cases that means leaving early and getting back to the trailhead before the snow really starts to heat up. The recent storm snow will get sticky rapidly today, so it's a good idea to bring glob-stopper for your skins and bases, even if you're on the early program.

Friday's storm didn't add enough weight or slab development to increase the avalanche danger over the weekend, but it has added complexity with the potential for more wet loose avalanches today. Winds were predominantly light during the storm and have remained that way through this morning, so the fresh snow hasn't been blown around very much and most of it is just sitting and waiting to pick up heat from our intense sun. The wet loose cycle will start on East aspects this morning and move clockwise around the compass throughout the day. Pay close attention to the obvious signs of this problem on slopes where you plan to recreate today, as the new snow typically has a really good bed surface to slide on. For these reasons, we expect it to be easy to kick off small wet slides on steeper slopes today, and even a small wet loose avalanche is capable of throwing you off your feet or carrying you downslope. A wet loose avalanche also provides an easy trigger for a larger persistent slab avalanche, which I'll dive into next.

Our snowpack is currently harboring a variety of concerning weak layers, all of which are currently capable of producing a large and destructive avalanche. The most problematic layers are buried near surface facets on North and East aspects, and faceted crusts on solars. After the last storm, these layers are approximately 1-2 feet from the surface, and we are finding them all over the place. The near surface facets give me a lot of hesitation, as I've been getting them to fail with easy to moderate force in my snowpits, and they've also been causing a very clean, planar break when they propagate. In some places, I've even found them 60+ cm below the surface and seen similar test results, yet I haven't been getting that much feedback from this layer as I've traveled around and broke trail. The main reason I can surmise for what's going on is that we've got hard slabs in the upper snowpack in a lot of places throughout our backcountry, and this makes for more infrequent collapses in your travels. However, it also means that if you do manage to collapse the weak layer, it could propagate really widely. If this happens on a steep slope, it could spell disaster and there's no telling how far above and away from you the slide could break.

The faceted crusts are also a point of concern for me, but perhaps less so than the near surface facets due to the bridging effect of additional crusts atop the faceted crusts. You can find a faceted crust on any aspect that gets a lot of sun, so if the terrain you plan to ski has a crust underneath the new snow, treat it as a suspect slope for a deeper faceted crust. I can't tell you exactly what to think about this weak layer, but know that it is more than capable of causing a significant persistent slab avalanche much like the near surface facets are. Do your due diligence and dig for these layers to see if they are present before committing to a slope.

Deeper down in the snowpack, the weak layers that have plagued us throughout the season continue to be present in the shallower snowpack  (<1.5m prior to Friday's storm).  These layers have been failing with moderate to hard force in extended column tests and continue to produce short results in long PSTs. This latest storm wasn't enough to stress these weak layers, but if you found the right "sweet spot" where the snowpack is shallower you could release a large avalanche that would take most of the season's snowpack with it.  

Skiing and riding conditions will be solid, at least through this morning, and it will be tempting to go and chase powder in steep terrain as we haven't had good skiing conditions for quite some time. Try to fight that temptation and evaluate snow and terrain carefully, thinking about the consequences if you were to trigger an avalanche.

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