Northern New Mexico

You can trigger a persistent slab avalanche up to several feet deep today.  Cohesive slabs rest on top of extremely fragile persistent weak layers, and this recipe for avalanches is widespread across much of the North and East facing terrain in our range.  Ongoing widespread cracking and collapsing shows that conditions remain ripe for human-triggered avalanches.  If you trigger a slab that breaks closer to the surface, there's a good chance it will step down into deeper weak layers creating a larger, more destructive avalanche.

Potential avalanches will grow in size as you move up in elevation.  Avoid being on or connected to slopes steep than 35 degrees.  These conditions lend themselves to remotely triggering avalanches from the flats below or adjacent slopes.

The snowpack in Northern New Mexico is currently well set up for human-triggered persistent slab avalanches, even with a week having passed since the last significant storm on Valentine's Day.  In fact, our persistent weak layers are obviously still stuggling with the weight of new snow from that storm, which laid down cohesive slabs on the surface at all elevations.  Some additional light snowfall on Tuesday and sustained moderate SW winds throughout the week have continued to build out these slabs in terrain near and above treeline, incrementally loading our weak layers and helping propel incidences of human-triggered avalanches throughout the week.  Today will be a calmer day in the mountains with the winds easing off, but the persistent slab problem remains alive and well, so please give it some real respect if you're heading out there.

The persistent weak layers we're most concerned about are the ones we've been talking about all season: very well developed depth hoar as well as faceted crusts that formed over the November to January period dominated by drought and overall shallow snow depths.  Between our northerly and easterly terrain, these weak layers are simply widespread and are additionally present on some West-facing terrain near treeline.  Buried near surface facets can also be found just beneath the surface-level slabs in more sheltered northerly terrain and could pose a further issue, but the persistent slab problem is the same.  Below treeline, slabs averaging 6 inches to a foot deep now sit on top of the weak snow, and have settled and stiffened a bit over the last several days.  Moving up in elevation to places where the winds have continually loaded slopes this week, larger slabs up to several feet deep overlie the weakest snow.  This strong-over-weak setup has been giving us tremendous evidence that it's primed to react throughout the week, and this pattern will continue today.

We easily triggered this avalanche 2 days ago while walking along the nearby ridgeline.  The slope is an East aspect near treeline at around 11,500 feet, and the avalanche clearly failed on depth hoar. 

It's been an active week for avalanches in the region.  Natural avalanches (D Size 1 - 2) during the Valentine's Day storm - when we issued an avalanche warning - were mainly confined to below treeline terrain on northerly aspects above 35 degrees, where the fragile depth hoar below couldn't handle the added load.  On east and west aspects that had connected snow on them prior to the storm, melt-freeze crusts from the record-breaking warm temperatures to begin February fared a bit better at handling the added weight for natural activity. The same can be said at upper elevations, where strong winds for almost a week prior to the storm pressed the snow into hard slabs that new snow was loaded onto.  However, over the last few days we've seen and heard of multiple human-triggered avalanches, some of which occurred higher in elevation on slopes that didn't slide naturally during the storm.  The largest avalanche reported was triggered in above treeline terrain and was bordering on a destructive size 3 (thankfully, no one was caught).  These events help paint an overall picture for today: all it could take is you as a rider to get a persistent weak layer to collapse and lead to a dangerous avalanche, and the size of avalanches triggered will be larger as you move up in elevation.  I'm positive that if we had a larger user base in this area, we would be seeing and hearing many additional reports of human-triggered avalanches this week.

If you've stepped off the skin track or well-packed in trails, it should be readily obvious that a strong-over-weak structure is everywhere.  Widespread collapsing and cracking remains utterly constant on most slopes that face North and East.  Take the time to dig a quick pit and see if the slope you're planning to travel on has this strong over weak snowpack structure -- I'll be surprised if you can't find it.  A ski pole or probe pole is another great way to feel for weak layers deeper down in the snowpack.  We have an intense warmup forecasted for the next few days and it might feel tempting to go ride something big and exciting before the melting commences, but you need to fight that urge and treat our snowpack with significant caution.  We're sticking to slopes below 35 degrees and giving large steep slopes a wide berth, as these conditions can also cause remotely-triggered avalanches.  We strongly suggest that you do the same.