The snowpack has not refrozen in a meaningful way for 48 hours. Some areas will be entirely unsupportable, and the risk of wet snow avalanches is increasing. Loose snow avalanches that start at a point can gouge deeply into the season’s snowpack and entrain a dangerous amount of snow, and larger avalanches breaking as a wet slab are possible. Head home, get off and out from under slopes steeper than 30 degrees, or transition to cooler locales (north-facing and upper-elevations) if you sink more than a few inches into wet snow.
Read the full forecast for more details about the complexities of today’s avalanche conditions.
Surface crusts will be superficial at best. When these crusts break down, and the snowpack transitions to unsupportable, get your avalanche hackles up. The most likely instability will be wet loose avalanches. Wet slabs are less likely, but are more destructive and can run farther.
I usually maintain a pretty good attitude toward snow conditions, but other than our highest-elevation areas (around Big Sky and Cooke City), I can’t say today is my first choice for a winter backcountry adventure.
The danger increases today because liquid water weakens the snowpack. SNOTEL sites in our area lost 0.2-0.4” of snow water equivalent in the last 24 hours. Temperatures, except for the summit of Big Sky and the upper elevations near Cooke City, have remained above freezing for 48 hours. Today, temperatures will spike to near 50 degrees under mostly sunny skies before light rain begins falling this afternoon.
This morning, surface crusts will be flimsy, if they exist at all, and the snowpack will quickly become unsupportable. Wet loose avalanches will gouge deeply through the snowpack and entrain a dangerous volume, and we may see a few destructive wet slab avalanches today. Check out photos and details from some of the many wet snow avalanches within the last week to better understand the hazard (Emigrant Peak observation, Cedar Mt. 1, Cedar Mtn. 2, Woody Ridge, Town Hill, North Bridger Range).
Where wet snow avalanches are not a concern, in higher-elevation, north-facing terrain, it is still possible to trigger large persistent slab avalanches that break 2-3 feet deep on weak layers that formed in January and February. On Monday, I had the opportunity to travel outside our normal forecast area to look at a persistent slab avalanche on Emigrant Peak that caught one skier and narrowly missed two others (video). Another backcountry enthusiast noted persistent slab avalanches on north-facing slopes in the Bridger Range (observation).
The last avalanche-related hazard to note is cornice fall, as warm temperatures open wide cracks far back from the edge, and these huge overhanging drifts unpredictably break off and cascade downhill.
What to do:
The avalanche danger is CONSIDERABLE.
