Northern New Mexico

Dangerous avalanche conditions continue to exist at upper elevations as you can trigger large and destructive avalanches within the recent storm snow.  Strong winds over the last several days, have been drifting snow into stiffer and thicker cohesive slabs.   There is also a possibility that an avalanche triggered near the surface can step down into deeper weak layers creating a very large avalanche.  Avoid slopes that are actively loading or where you notice obvious signs of instability like shooting cracks or loud audible collapses. Sticking to wind-sheltered, lower-angle terrain without steep slopes overhead will provide safer and better riding conditions. 

It's another cold start to the morning, with temperatures below 0 and in the single digits. Today will bring increasing clouds and some light snow showers this afternoon and evening where we could pick up an additional 2 to 4 inches. SW winds are not expected to be as strong as yesterday, but should still be able to transport new snow that falls. This last system will cap a pretty impressive 12-day stretch of weather where we've picked up well over 4 feet of snow and 5 to 7" of snow water equivalent (SWE). Drier weather returns on Monday through the middle of next week with a more zonal flow and warming temperatures. 

Whether you want to call it storm or wind slabs, moderate to strong winds over the last several days and continued light snowfall are what's keeping the avalanche danger elevated at upper elevations. Strong westerly winds have led to a stiffening and thickening of slabs that are easily deeper than 4 feet deep at upper elevations on the leeward sides of ridgelines and cross-loaded terrain features.  With many layers and density changes within the "storm snow" over the last 2 weeks it's difficult to know where within the storm snow you might trigger an avalanche. It could be a foot or potentially four-plus feet deep where we've seen the greatest amount of loading.  Yesterday these slabs were sensitive and reactive in travels on test slopes. With such strong winds over the last several days, you may encounter more loading than you might expect further down the slopes as well as open exposed slopes below treeline.  At upper elevations, these slabs will be harder and may feel supportable on the surface, which can lead to avalanches breaking in unexpected ways, oftentimes well above you.  Most avalanches triggered will take place within the new snow but could create a one-two-punch scenario where a large avalanche within the storm snow, steps down to create a very large avalanche on deeper weak layers. 

The persistent weak layers near the ground that has plagued us much of the season are facing a significant test from the wet heavy snow, and will need time to adjust to this significant loading event. SWE totals over the last week from the two AR events are at 5 - 7" . For context, we had less than 5" of SWE for the water year on January 1st at the Snotel Powderhorn site. This has been a significant amount of loading as the SWE from the last week of storms accounts for about a third of the total water we've received this year.  Many slopes released naturally during the storm, producing very large avalanches running long distances well into the valley bottoms. Even slopes where weak layers were deeply buried and dormant may be more reactive with this added weight.  Near and below treeline terrain is where depth hoar near the ground continues to linger and remain reactive in a relatively shallow snowpack (< 1.5 m) prior to last week's storm.  At upper elevations, there's still a threat of triggering an avalanche near the ground, but most slopes have a deeper snowpack where impacting these layers would be more difficult but may not be impossible with such a significant amount of loading. In the middle of the snowpack, small-grained facets sandwiched between harder slabs and faceted crusts have been observed but are not widespread.  Most of these layers have been found on north and easterly aspects near and above treeline.  These storms over a week period will be the biggest snowfall events of the season and may push us to where we see deep persistent slab avalanches that would be unsurvivable.  Recent very large avalanches during the storm should serve as a good reminder of what the consequences could be if you were to trigger a persistent slab avalanche. 

It's a strange time for the middle to end of March. Very cold temperatures, that are 10 - 20 degrees below average, 10 straight days of snow for us here in the desert southwest, and more snow on the way today, it doesn't feel much like spring except for the typical strong to moderate winds. This is still very much a winter snowpack, and with more snow and cold temperatures in the forecast, it could be into April, before we start to transition to more of a springtime snowpack.   Avalanche conditions will continue to remain elevated through at least the weekend.  Sticking to lower-angle wind-sheltered terrain without steep slopes overhead will help you avoid many of the avalanche problems.