Northern New Mexico

It's possible to trigger a large and dangerous persistent slab avalanche. Near and above treeline on previously wind-loaded slopes pose the greatest concern. You're more likely to impact weak layers in likely trigger points where you find a shallower snowpack. These will be areas near rock outcroppings or on the margins of the slab.  Although the likelihood is lower, the consequences remain high if you were to trigger an avalanche as it could break 3 to 5 feet deep. Below treeline, wind-sheltered terrain on northerly aspects will provide safer and better riding today.  

A winter storm impacts our area tonight into Tuesday.  Expect changing and increasing avalanche danger as heavy wet snowfall and strong winds build slabs that will be dangerous on their own as well as stress deeper buried weak layers. 

Today will be a transition day as we wait for snowfall to ramp up later tonight into Tuesday. Spring-like weather continues for us here in northern NM as we end the month of February.  Overnight lows below 11,000' were above or just barely dipping below freezing.  W/SW winds have been in the 20's with gusts in the 50 mph range.  Today will bring mostly cloudy skies and a chance of rain/snow with not much accumulation expected during the day.  Things change overnight into Tuesday as we've been placed under a Winter Storm Warning with upwards of a foot of snow and strong winds forecasted for our mountains.  We've kept the avalanche danger status quo as to what it's been for today as less than an inch of snowfall is expected, but if the storm arrives sooner than forecasted it won't take much new snow to easily drift into wind slabs at upper elevations with the strong winds today. Expect dangerous and changing avalanche conditions to develop overnight into Tuesday as snow starts to stack up. 

Unfortunately, skiing and riding conditions have become highly variable, with most of our solar aspects forming crusts, while upper elevation terrain has been pressed into stiff wind board and breakable crusts from the strong winds on Wednesday.  Thankfully northerly wind-sheltered slopes continue to ski well due to large diurnal temperature swings with warm sunny days and cold clear nights creating a layer of near-surface facets.  These surfaces will become the first interface slabs will form on either making for a great sliding surface or providing a very easy-to-collapse weak layer depending on what aspect and elevation you're on. 

It's now been close to two weeks since our last snowfall and triggering a persistent slab avalanche has become increasingly stubborn as we push further away from the last loading event.  With that said, weak layers continue to remain reactive in PSTs and have been slow to heal where the snowpack remains shallow <1.5 m.  These weak layers exist near the ground from depth hoar or the early January drought layer or are found in the middle of the pack around crusts.   It will most likely take you to find the right slab and weak layer combination in steep terrain where the snowpack is relatively shallow and you can impact these weak layers.  If you were to trigger an avalanche, these avalanches would be large potentially breaking 3 to 5 deep, and come with significant consequences.  It sounds like a broken record at this point, but we're living in a world of lower likelihood, but high consequences.  With heavy snow and strong winds these weak layers that have been lying dormant may become more reactive with an added load and reactive slab on top, as well as potentially provide the classic step-down scenario where an avalanche in the new snow steps down into deeper weak layers creating a larger and more destructive avalanche.  

We'll finally see a return to winter, but with that will come an increase in avalanche danger. Slopes that we've felt comfortable stepping out onto over the last week will once again become suspect. With each significant storm this year, we've seen avalanches fail naturally on our persistent weak layers.  It's hard to tell if we've turned the corner and are insulated or bridged enough, but I suspect we haven't fully put these weak layers to bed just yet.  Many of our avalanche paths have slid at least once this year either during the mid-January cycle or during the February storms.  These slopes have a shallower and faceted snowpack and will be more susceptible to the added stress of loading.