THIS AVALANCHE ADVISORY EXPIRED ON January 29, 2018 @ 6:03 am
Avalanche Advisory published on January 28, 2018 @ 6:03 am
Issued by Hannah McGowan - Taos Avalanche Center

Avalanche danger is MODERATE above treeline.  Human triggered persistent slab avalanches are possible on NW through E aspects where very poor snowpack structure exists.  Avalanches are unlikely near treeline, through pockets of unstable snow may exist on isolated terrain features.  Generally safe avalanche conditions exist below treeline, due to lack of snow. Pay attention to signs of instability and evaluate snow and terrain on a slope by slope basis to identify areas of concern.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
  • 1. Low
  • 2. Moderate
  • 3. Considerable
  • 4. High
  • 5. Extreme
Avalanche Problem 1: Persistent Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Human triggered persistent slab avalanches remain POSSIBLE today on northwest through east aspects above treeline.  In these zones the 1/21 snow capped weak, uncohesive facets (See photo 1 in the forecast discussion) or added an additional burden to the persistent slabs that already existed (See photo 2 in the forecast discussion).  Persistent slab instability is incredibly variable right now, so evaluate terrain slope by slope.  Places where the most recent snow fell on much deeper snow, with older slab/facet combinations, are the most suspect.  However, anywhere with a strong-over-weak structure is worth your awareness.  It is tricky to tell which slopes have a deeper, more suspect snowpack, so let the terrain inform your travel plans.  You can avoid most of the avalanche danger today by sticking to slopes less than 35 degrees that are not connected to steeper slopes.  It is possible in these conditions for avalanches to break above you.  Pay attention to obvious signs of instability like shooting cracks, whumpfing, and collapsing, which were all observed in the field yesterday.  Most avalanches today would be small, though in places with deeper snow they could be larger.  Any avalanche right now would cause serious injury or death, with so many ground hazards still present.  

 

advisory discussion

We basically have two different kinds of persistent slab instability right now.  The first (See photo 1) is shallower, less complex, and perhaps less consequential than the next- though with the overwhelming amount of ground hazards present right now, any avalanche coud be tragic.  This set up is where the 1/21 snow created a slab that capped a snowpack made of facets to the ground. This is a very weak structure and can be found near and above treeline on all aspects except S and SW.  The other set up (See photo 2) exists on specific slopes above treeline, on NW-E aspects.  This is the deeper snowpack, where snow has stuck around since November.  Now what we have is very well developed depth hoar with a layer cake of slabs and facets sitting on top of it.  In some places the snowpack is even about 4 feet deep.  Its easy to be caught off guard by how much snow is in these places!  These are the slopes we're most concerned with, since the structure is incredibly weak and the amount of snow that would be put in motion if you did trigger an avalanche here could easily be fatal.  In either form, its important to know that persistent slab instability exists out there.  Collapsing, whumphing and shooting cracks about 100 feet above a trigger point were all observed yesterday.  Check out our video from yesterday, and Andy will give you the break down.

There's another important factor in play today, and that's wind slab.  Strong winds Friday- including gusts into the 70's- moved even more of the 1/21 snow around.  Though much of this most recent snow has begun to settle out, a bit of fluff was still available for transport before this wind event, and it now exists as 10-20 cm of hard wind slab in certain areas.  To identify these places, look for smooth, wind drifted snow with firm, maybe supportable, surfaces.  Hard slab can be tricky to deal with, since it distributes your weight much farther across the snowpack.  This means avalanches are harder to trigger but that they tend to break farther above you if you do manage to trigger one.  In combination with deeper instabilities this is even more concerning, as there is always the potential for an avalanche to step down.  A small, superficial avalanche in these new wind slabs is not out of the question today, but the main concern remains with the possibility of deeper persistent slab istability.  

Backcountry travel with skis on is possible today, but its certainly not for the faint of heart. If you were looking for an easy way to trash your new touring setup, look no further.  That being said, I think we're all grateful for the improvement in travel that came with the most recent snow!  Stay safe out there-- pay attention to obvious signs of instability like shooting cracks, whumpfing, and collapsing and evaluate terrain slope by slope basis since the snowpack is highly variable.  Staying away from slopes that are steeper than 35 degrees is the simplest way to stay safe today.  Any avalanche could be tragic with the amount of ground hazards present. 

Photo 1

Photo 2

 

recent observations

Strong WSW winds yesterday (Gusting 70 MPH) have left a hard pencil hard slab above treeline that is capping our snow from Sunday (1/21) . In other places the strong winds have scoured back to bare ground and further in others has left breakable wind crust.  Not great conditions to make a turn!  We are still experiencing loud collapsing whumpfing on north aspects above treeline.  Pretty much every slope we touched on a north aspect collapsed with shooting cracks well above us.  This is where we have a variable but poor snowpack structure with fragile depth hoar near the ground that is capped by some form of slabs.  We continue to see evidence of a natural avalanche cycle that occurred during the storm on Sunday 1/21.   We have two types of persistent slab problems that can be seen in the first two photos.  Both are a result of depth hoar near the ground but one is more obvious than the other.  Areas that had a deeper snowpack before last Sunday's storm holds the potential for a larger deeper avalanche where snow from November has lingered and is capped by several slab weak layer combinations.  This is harder to identify as the persistent weak layers are further down from the surface.  The other persistent slab problem is where last Sundays snow fell on faceted depth hoar on the ground.  Although triggering an avalanche is getting harder and harder, there's a very real spooky feeling when traveling on north aspects above treeline. Either way you slice it, all the ingredients are there for an avalanche breaking on or near the ground.

Other aspects are not as worrisome, and we are getting sun crusts on solar aspects and are quickly seeing our snowpack settle at lower elevations.  The extant of the wind loading and producing a wind slab seems to be limited to above treeline and areas near treeline that are open and prone to wind loading.  

 

 

Weather and CURRENT CONDITIONS
weather summary

More sunny weather is on tap for today and the coming work week.  Temps will be in the lower 40's, and winds will stay light.  Our next hope for snow looks like a backdoor cold front next Sunday night and Monday, though so far models are in disagreement about the timing and amount of moisture that it will bring.  We'll have to just keep an eye on it throughout the week. 

Weather observations from the Wheeler Peak Wilderness between 9000 ft. and 13000 ft.
0600 temperature: 17 deg. F.
Max. temperature in the last 24 hours: 29.2 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 17 mph
Maximum wind gust in the last 24 hours: 22.4 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 16 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Albuquerque NWS
For 9000 ft. to 10000 ft.
Sunday Sunday Night Monday
Weather: Mostly Sunny Mostly Clear Sunny
Temperatures: 38-43 deg. F. 15-20 deg. F. 42-47 deg. F.
Wind Direction: NW NW W
Wind Speed: Up to 15 Up to 10 Up to 10
Expected snowfall: 0 in. 0 in. 0 in.
For 11000 ft. to 13000 ft.
Sunday Sunday Night Monday
Weather: Mostly Sunny Mostly Clear Sunny
Temperatures: 27-34 deg. F. 17 deg. F. 32-38 deg. F.
Wind Direction: NW NW W
Wind Speed: 5-15 5-10 5-10
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This advisory applies only to backcountry areas outside established ski area boundaries, Click here for a map of the area. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the Taos Avalanche Center who is solely responsible for its content.