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. Cracking and collapsing indicate that you've found this poor snowpack structure of strong over weak. Avoid being on or connected to slopes steeper than 35 degrees. It's possible to remotely trigger avalanches from the flats below or adjacent slopes. 

Watch for small wet loose snow avalanches on solar aspects at lower elevations as the day warms up. Pinwheels and roller balls are indications that the snow surface is getting wet, and it's time to head to shadier aspect. 

If you like spring-like weather for the end of the February, you'll be in luck for most of the next week. Today starts the real warm-up with temperatures climbing into the mid 40's and 30's under sunny skies and light NW winds. The real beach like weather begins tomorrow, where record-breaking high temperatures will be challenged on Monday and Tuesday. After a brief cool down on Wednesday, temperatures ramp back up again for the rest of the week. It'll be the type of weather where you can ski, bike, climb and raft all in one day. Unfortunately, from a mountain snowpack prospective, a week of very warm temperatures at the end of February, is the last thing we needed as we look towards the spring and fire season.  There is hope on the horizon with moisture looking to move into our area around the beginning of March, but it's too far out for details at this time.  

Most of our solar aspects at lower elevations, don't have much snow on them right now, but as the day warms, watch for signs of wet snow and head to a shadier aspect if you notice the top 6 inches of snow is becoming wet. This problem will move in elevation starting tomorrow as temperatures climb well above freezing at all elevations. Don't let the talk of the warm temperatures and wet snow concerns have you forget about our very real persistent slab avalanche problem that continues to plague our snowpack.  

The snowpack in Northern New Mexico remains well set up for human-triggered persistent slab avalanches, even with a week having passed since the last significant storm on Valentine's Day.  Our persistent weak layers continues to remain weak and fragile resting underneath cohesive slabs that formed from the Valentine's Day storm and wind events. Cracking and collapsing continues to be present in travels, and stability tests are failing with easy force on our persistent weak layers.  The 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 drought period.  Between our northerly and easterly terrain, these weak layers are simply widespread and can also be found on some West-facing terrain near treeline.  In sheltered northerly terrain, buried near surface facets lie beneath the upper-level slabs and could pose a further issue, but the persistent slab problem remains the same.  Below treeline, slabs arond 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 continually loaded slopes over the last week, larger slabs up to several feet deep overlie the weak snow. 

We easily triggered this avalanche (size D2) several days ago while walking along the nearby ridgeline.  The slope is an East aspect near treeline at around 11,500 feet, and the slab 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 East-facing above treeline terrain and was bordering on a size 3.  These events support an overall message that 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.  If we had a larger user base here in our backcountry, we would be seeing and hearing many additional reports of human-triggered avalanches.

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 or probe down into the snow 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.  The imminent warmup might make it tempting to go ride something big and exciting this morning before the melting commences, but you need to fight that urge and treat our snowpack with significant caution.  Please stick to terrain below 35 degrees and give large steep slopes a wide berth, as these conditions can also cause remotely-triggered avalanches.  Stay safe out there and break out those shorts and sandals if you haven't already!