Northern New Mexico

New snow and wind will create dangerous avalanches conditions today near and above treeline. You are likely to trigger a persistent slab or wind slab avalanche where you find 8" or more of wind drifted snow.  Below treeline, we have a mostly faceted snowpack, but in open wind-exposed areas, you may find enough of a cohesive slab on the surface to create an avalanche. Cautious route-finding and conservative decision-making are essential today.

It's day 1 of a four-day weather event and snow totals as of 5 AM are only 2 - 3 inches with .2" of snow water equivalent (SWE) but snow is coming down as I'm writing this.  An additional 3 to 6 inches of snow is forecasted throughout the day with strong SW winds in the 20 - 30 mph range gusting into 40's.  Over the next four days, we'll be loading our slopes with a series of smaller storms and moderate to strong winds that in their totality will add up to a significant loading event.  

It's starting to become a complex and challenging snowpack near and above treeline where there are a series of very fragile weak faceted layers, sandwiched between harder slabs that formed from prior wind events. These faceted weak layers are also found in the top 30 to 70 cm of the snowpack and still very much still able to be impacted by the weight of a human. Complicating things are hard slabs buried in the snowpack from previous wind events are spatially variable in thicknesses (5 - 20 cm) across slopes.  Areas where these slabs are thinnest are where we have been able to impact and collapse weak layers either triggering an avalanche or getting the slope to collapse.   

Last Tuesday's storm with 6- 8 inches and .6" SWE and wind were not enough to "tip the scales" with natural avalanches, but we have had several human-triggered avalanches over the last couple of days.  The common theme with these persistent slab avalanches are where wind drifted snow from Tuesday's storm has deposited close to a foot slab on top of the old existing surface. With more snow and wind it's going to get increasingly difficult to decipher what slopes have been loaded.  At some point in the next four days, we will likely hit a tipping point and start to see natural persistent slab avalanches.  

Below treeline, we have a mostly homogeneous snowpack of faceted snow. In open slopes exposed to the wind, you may find a small pocket of wind drifted snow capable of producing a small avalanche. The more likely hazard would be producing a loose dry avalanche from steep terrain. Be mindful of terrain traps and the consequences of being swept off your feet. Ground hazards, unfortunately, continue to be a real threat at these elevations.  Below treeline terrain will probably become more of a problem here in the coming days as we start to introduce a more uniform cohesive slab on top of a faceted snowpack.

We are just starting a fairly active 4 days of unstable weather. None of the systems appear to be large producers but rather, we can expect to slowly accumulate snow over the course of several days. With weaknesses in our snowpack structure and the addition of new snow with strong wind, we can expect the avalanche danger to increase. It can be tricky when we slowly accumulate snow to conclude exactly when we might be hitting our tipping point for instability. If you find yourself out skiing or riding during these events you'll have to pay close attention to the conditions. You might find generally stable conditions in the AM but that extra 2 or 3 inches by the PM was all it took to increase avalanche hazard dramatically. Something like that might go unnoticed if you aren't looking for it. Pay attention to what the weather and the snow are telling you. A collapse or whumpf, shooting cracks, precip rates of 1" or more an hour, wind loading, etc. These are the "Bulls-Eye" clues to pay attention to if you find yourself out there today.