Flathead Range & Glacier NP

Weak layers of snow lurk 1 to 4 feet below the surface and are still proving reactive to the weight of a machine or human. Signs are most common on northwest, north, and east facing slopes, but don’t let your guard down on south aspects where thundering collapses have recently occurred. If triggered, one of these avalanches would be difficult to survive. Look for and steer around areas of wind drifted snow on typically windward aspects.

You will notice that we have broadened the distribution of persistent slabs to all aspects again. This is a result of increasing signs of instability on south and southwest aspects. On the 10th, Clancy was able to trigger a small avalanche on a southwest aspect at about 5800 feet. Another observation came in yesterday (Saturday the 14th) where a rider collapsed a slope on a southerly facing aspect at a similar elevation. Though we expect slabs to still be more dangerous on the shadier part of the compass where surface hoar exists, we cannot rule out the possibility given these recent signs. 

A noteworthy theme recently is the lack of feedback prior to triggered avalanches. Weak layers have been showing little to no warning signs until they are collapsed, sending a wall of snow down the mountain. Don’t be duped into stepping out into bigger terrain by appearances, or because your "stash" has gotten tracked out. Manage slope angles and use an inclinometer to rule out guessing. There is plenty of good riding to be had on slopes 35 degrees or less. This is going to continue to be the case and we need to learn to live with this problem.

Surface hoar sitting on top of a hard surface is an unusually dangerous structure. Here is an analogy that explains this setup well. Imagine yourself with a carrot in your hand. Now push that carrot into a bowl of oatmeal. It sinks in right? Now take that same carrot and push it into a sidewalk. Not going anywhere. You continue to apply force and the carrot either collapses and tips over, or you don't have the force to snap it yet and it stays standing straight up and down. We are left to wait until more load crushes these carrots or they rot away. That's what we have and patience is key. 

Be extra conscious of windblown snow onto what you typically view as “safe” or “sheltered” terrain. Easterly winds Saturday and overnight transported snow onto west, south, and north-facing aspects. Though I expect them to be less reactive today, I would still steer around wind textured surfaces and pillows to find higher quality snow in sheltered terrain.

Surface snow is continuing to weaken and facet with prolonged cold temperatures and clear nights. This is doing a few things. The most immediate is that it is making the surface snow cohesionless, which is causing it to sluff easily. Expect to find small natural point releases, and be able to trigger loose dry avalanches in steep terrain. I wouldn’t expect any of them to be large enough to bury and injure a person, but they could be dangerous if they knock you into a terrain trap. The second thing this is doing is making another weak layer for new snow to land on. We are set up for another round of snow starting tomorrow and new snow will bond poorly to the current surface condition. Observations from you all of the surface conditions and especially where surface hoar is located significantly improves the accuracy of upcoming forecasts.

Since January 30th, there have been nine different accidents in the U.S resulting in 16 fatalities. Of these nine accidents, seven involved multiple people caught in the same avalanche. This is a shocking number of multi-burials. This type of scenario makes successful recovery very challenging, if not impossible. One major takeaway from these tragic accidents is to space out and only expose one person at a time. Ridgelines and open meadows far from runouts are great places for spotters to be located. Here is a report of the tragic accident and heroic rescue of the avalanche that resulted in 4 fatalities in Utah. Sharing of accidents is by no means an avenue to point fingers. We can learn critical lessons by reviewing accidents and putting ourselves in the situations with the victims. 

Need an update on the week? Watch the video below. Mark also did a great writeup summarizing the snowpack and avalanche conditions from the last month, found here.