24-25

Avalanche on Saddle Peak, Bridgers

Date
Activity
Skiing

No wind today, but recent loading 

Note from BB ski patrol - skiers triggered a medium sized cornice fall that triggered a dry loose (sluff) avalanche that created large powder cloud.

Region
Bridger Range
Location (from list)
Saddle Peak
Observer Name
Steve White

Cold powder and little else of note

Date
Activity
Skiing

Skied up the southern of the two typical Bacon Rind skintracks (through the more heavily burned area to the upper meadows). Saw no signs of instability (no cracking, collapsing, or recent avalanches).

Dug a pit on an E aspect at 8800 ft in one of the upper meadows. 128 cm snow depth. No propagation in an Extended Column Test. There is weak snow at the ground, but it isn't super well developed or very weak (4 Finger minus hardness).

No wind affect where we traveled today. 

Region
Southern Madison
Location (from list)
Bacon Rind
Observer Name
Ian Hoyer

Deep in the Crazies

Date
Activity
Snowmobiling

Deep snowpack in the Crazy Mountains and seemingly strong. It seems that the snowpack in the Crazies is typically weak, shallow, and sketchy. This year the snowpack is quite deep - crazy! 

We saw one soft, storm slab and a few sluffs. We didn't get onto slopes steeper than 30 degrees, but we felt ok traveling in runout zones which says a lot. 

Winds were drifting some snow in the alpine but otherwise mostly calm. Tons of snow available for the wind when it finally picks up

Region
Out of Advisory Area
Observer Name
Staples

GNFAC Avalanche Forecast for Wed Feb 19, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>There is simply a lot of snow and riding conditions are as good as it gets; however, remember that most avalanches happen within 24-48 hours after snowfall or wind.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Wind slabs</span></span></strong></span></span></span><span><span><span><span><span><span> - In all areas, the primary avalanche problem is wind slabs as Dave found </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34254"><span><span><span><span><span><… Island Park </span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>and a skier found on </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34251"><span><span><span><span><span><… Peak</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> yesterday where a wind slab broke 18 inches deep, 50 feet wide and ran a significant distance. Winds yesterday from the NW did most of the drifting, and winds shifting to the SW today may find a little snow to move. Fortunately there are many slopes unaffected by winds.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Storm slabs</span></span></strong></span></span></span><span><span><span><span><span><span> - The new snow should be bonding to itself and stabilizing quickly, but there is just a lot of powder out there creating some uncertainty. Because there’s still a possibility of storm slabs, I’d select terrain with a clean runout today free of terrain traps, rocks, and trees if getting onto steeper slopes.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Persistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> - A problem in the Lionhead area, southern Madison Range (Taylor Fork, Teepee, Carrot, etc.) and southern Gallatin Range. The problem layer is small facets that formed in late January, now buried 2-3 feet deep. The Cooke City area may still have this problem, but it is buried deeper and seems to be less of an issue.&nbsp; A snowmobiler was caught in a </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34154"><span><span><span><span><span><… persistent slab avalanche on Lionhead</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> on Thursday BEFORE all this snow fell. The most likely places to trigger one of these slides is on a slope with extra loading from yesterday’s winds, but I think there will still be slides on this layer on non-wind loaded slopes that will surprise you..</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Travel advice today</span></span></strong></span></span></span><span><span><span><span><span><span> -&nbsp; Stay off slopes or portions of slopes with fresh wind drifting. Consider the consequences of triggering a soft storm slab avalanches even though the likelihood of these slides is going down. If traveling in areas with a persistent slab avalanche problem, I’d simply avoid avalanche terrain for now and give the faceted layer time to stabilize.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger in all areas is CONSIDERABLE in places with fresh wind loading where you will trigger a slide.. The danger is MODERATE on all other slopes not loaded by recent winds</span></span></span></span></span></span></p>

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Wind Slab Instability

Date
Activity
Snowmobiling

We got lucky in the Centennials with great snow and good visibility. There was about 20" of new snow from this weekend's storm. We covered 35 miles of backcountry riding and got eyes on a lot of avalanche terrain from lower elevation slopes, to Jefferson Bowl, the terrain in and above Hellroaring Creek, and East Hotel Creek. We didn't see any avalanche activity. However, we observed shooting cracks in drifts and triggered small wind-loaded slopes and cornices. So, human-triggered avalanches on wind-loaded slopes are likely. 

We dug three quick pits but prioritized getting eyes on terrain over in-depth snowpack analysis: 

Low-elevation slope on Sawtelle - NE @ 7600' on a slope with no wind effect: ECTX in a 160 cm deep pit

Above Hellroaring - S @ 8400' on a wind loaded slope: ECTP1 6" deep (wind slab) and ECTP21 20" deep (wind slab)

Arange - SW @ 8700' non-wind-loaded slope: ECTP21 20" deep on facets below a melt-freeze crust 

Travel Advice: 

  1. Avoid wind-loaded slopes
  2. While stability on non-wind-loaded slopes seemed good, it snowed a lot. So, I would either carefully assess for instability in the upper 3 feet of the snowpack with an ECT , or I would give it a few days to settle out before getting on steeper, non-wind-loaded slopes.

The danger was CONSIDERABLE on wind-loaded slopes (human-triggered avalanches likely) and MODERATE in non-wind-loaded terrain (human-triggered avalanches possible).

Region
Island Park
Location (from list)
CENTENNIAL RANGE
Observer Name
Dave Zinn
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