Bridger Range

Ripping winds yesterday and more this morning from the southwest have formed wind slabs up to 18 inches deep. Look for and avoid slopes with fresh drifting, and do not underestimate the danger of these types of avalanches. Seek out slopes sheltered from the wind (hard to do) with no recent drifting.

WINDS ripped across the entire forecast area yesterday forming many fresh wind slabs. They will continue blowing this morning from the southwest making wind slabs likely to be triggered.

• At Bridger Bowl some chairlifts were unable to run yesterday due to high winds, and the ski patrol triggered fresh wind slabs at the ridge 4-18” deep.
• A skier near Bridger Bowl intentionally triggered fresh wind slabs 6-12” deep
• Guides near Cooke City found drifts all over the place and wind slabs that would easily release on small test slopes.
• A skier in Hyalite near Mt Blackmore observed active wind loading all day and watched another skier trigger a fresh wind slab.

Sadly a rider in California near Lake Tahoe died in a wind slab avalanche 2 days ago, and I mention this so that we don’t take this problem lightly. Use visual clues to identify fresh wind slabs or likely locations and avoid them. They will remain sensitive today with more snow falling and winds continuing to drift snow.

Persistent slab avalanches remain a problem to varying degrees across the forecast area. These types of avalanches are much tricker than wind slabs and they persist as a problem for a long time. Slopes with fresh wind slabs can also be prime locations to trigger a much larger persistent slab avalanche.

This persistent problem is a significant issue in the Southern Madison and Gallatin Ranges and the Lionhead area. Ian spotted these avalanches “everywhere” near Lionhead at the end of last week, and observed the weak layer responsible for this problem yesterday in Bacon Rind. Dave and I returned to Lionhead on Monday and triggered a repeater avalanche which is where new snow had partially refilled the slope, and it avalanched again. 

In the Northern Madison and Gallatin Ranges, the persistent slab avalanche problem is unlikely because these areas haven’t received much snow over the last 7+ days. The exception is on wind loaded slopes with the extra weight and stress of wind slabs could wake up this problem in some places.

Near Cooke City and in the Centennial Range near Island Park, the weak layer causing the persistent slab avalanche problem is buried so deeply that it barely registers as a problem. Yesterday near Sawtell Peak, Dave and I and our riding partners had to get above 9000 feet and dig a snowpit over 6 feet deep to find the weak layer. While unlikely, relatively thin snow near rocks and cliff bands at upper elevations would be the place where one of these avalanches might be triggered.

In the Bridger Range, the last persistent slab avalanche was one month ago and not a current problem.

Throughout all the forecast zones, the avalanche danger is CONSIDERABLE due to fresh wind slabs that will be sensitive today. The Lionhead area and Southern Madison and Gallatin Ranges have the added threat of big persistent slab avalanches remaining likely.