Avalanches breaking near the ground remain the primary concern. The last slides breaking on these layers were around a week ago. Dig down to look for and assess these layers before committing to steep slopes.
With new snow falling and winds drifting that snow, keep your eye out for fresh wind drifts more than a couple inches deep. If more than a few inches of new snow falls, wind slabs will grow larger and more dangerous.
This problem will be more likely at upper elevations, but the weak layer can still be found at mid elevations and is worth digging down and evaluating it.
A couple inches of new snow might freshen up riding conditions a bit, but they won’t do much to change the avalanche hazard today. Still, if you’re getting onto steep slopes, watch out for anywhere with fresh wind drifts more than a few inches thick that could be easily triggered and might be growing throughout the day. Slopes where you could trigger a Wind Slab avalanche should be pretty easy to identify through the texture of the surface snow and feel beneath your feet. Watch for cracking and steer around these drifts if needed.
Persistent Slab avalanches breaking on the weak snow near the ground remain the primary concern. These are breaking on snow that fell in early fall and didn’t melt off in November, which is more prevalent on high elevation and shadier slopes.
In Cooke City, heavy snowfall over the last couple weeks means that the weak layers are now buried deeply (photo). This means avalanches will be a little harder to trigger and it’ll be hard to assess the weak layers. It also means that any slide that does break will likely be really big. You could definitely still trigger an avalanche if you hit the wrong spot (likely a shallow area) as demonstrated by this slide from Monday.
We’ve seen more recent avalanche activity in the mountains near West Yellowstone and Island Park. Over the last couple days, a big slide was spotted north of Targhee Peak in the Lionhead area and another substantial avalanche broke along Lionhead Ridge. The weak layers aren’t buried quite so deeply here, which means it’d be easier for your weight to effect them and trigger a slide. I’ll still mostly be avoiding steep slopes in these areas. If you are going to get onto steeper slopes, I’d suggest sticking to smaller slopes and those without terrain traps or other obstacles beneath them.
In northern Madison and northern Gallatin Ranges, the likelihood has dropped a bit further and concerns are highest at upper elevations that have stayed cool and had a bit of wind loading. Still, the last Persistent Slab avalanches were less than a week ago (observation), so dig and carefully investigate for weak snow near the ground before committing to steep slopes.
Persistent Slab concerns are less in the Bridger Range. Fewer slopes have the November snow at the base of the snowpack and warm temperatures helped that old snow gain strength where it is present. There have only been two Persistent Slab avalanches in the Bridger Range this season, and the last was almost a month ago.
The avalanche danger is rated MODERATE across most of the advisory area. The exception is the Bridger Range where the danger is LOW.
