Northern New Mexico

Triggering a persisent slab avalanche remains the concern today. You are most likely to trigger one of these avalanches on North through East and West aspects near and above tree line. Stiffening slabs over weak faceted snow can still produce an avalanche large enough to bury, injure, or kill a person. Avoid terrain steeper than 35 degrees in areas where this problem exists. 

There have been a total of 4 avalanche fatalities reported across the West over the previous week.  Our deepest condolences go out to all the family and friends effected by these accidents. 

• Solo skier fatality near Crested Butte, CO on Dec 18
• Snowmobile fatality in the Salt River Range, WY on Dec 18
• Two skiers caught, buried and killed near Silverton, CO on Dec 19

You can read more about these accidents on avalanche.org/avalanche-accidents

Strong winds continue to be the big story for us. Last night we experienced another round of strong to extreme winds with a max gust of 84mph recorded at 3am this morning. Although there isn't much left in the way of transportable snow, these winds continue to build hard slabs in the alpine and further stiffen slabs in wind exposed terrain near treeline. These slabs sit over weak faceted layers that  aren't gaining strength faster than the slabs are forming keeping a concern for a large persistent slab avalanche on the forecast. Although hard slabs can make it more difficult to effect weak layers buried beneath them - when they are effected the strength of those slabs does a great job of communicating propogation. We seem to be entering that uncomfortable world of low liklihood, high consequence avalanche conditions. 

The need to address each peice of terrain individually is crucial as we have an incredible amount of spacial variability in our snowpack right now. The take away here is you are looking to identify two weak layers of concern. Buried facets that you'll find 1 to 2 feet deep just under the Dec 11-13 storm snow and depth hoar that you'll find living just above the ground. Is there a cohesive slab sitting on top of those layers? If "Yes", then the persistent slab avalanche problem exists on that piece of terrain. You will most likely find this structure on West through North and East aspects near and above tree line. 

Below tree line and in wind sheltered areas near tree line we are faceting our snowpack. Sound familiar? We talked a lot about this prior to our last big storm. We have lost a significant amount of strength in our slabs in those areas. Even though you can find basal facets and depth hoar in these areas the slabs on top of them lack the appropriate cohesion needed to communicate energy. As we move forward a small concern for Dry Loose snow avalanches may arise in steep terrain. Strong solar has also been doing some work on our South and West aspects and we were able to find a melt freeze crust over much of this terrain. We had a very small period of instability on the afternoon of Dec 21 and we saw a few Loose Wet avalanches that started from rock bands on solar aspects. One such point release that managed to produce on a West aspect below treeline was able to entrain shallow weak faceted snow to the ground. This just further points to the fact that we are moving towards a cohesion-less snowpack below tree line.