24-25

Skier-triggered small soft slab, northern Bridger Range

Date
Activity
Skiing

Today (Saturday, 4/19), I triggered a small soft-slab avalanche at about 7,700' on a E-NE aspect on the headwall between Frazier Lake and Angier Lake in the northern Bridgers. The slide was maybe 6" deep, 20' wide and ran 100-200 feet and involved only the new storm snow over the icy, thick crust underneath. No one was caught or injured, though I had a bit of a scare because my dog was right in the path (luckily she outran it). We had gone up with the intention of skiing the Ainger "Love Chutes", but bailed partway up when that whole aspect turned out to be breakable crust. However, we had beta from another party that conditions on the Frazier-Angier headwall were good, so decided to check that out. We skinned up without incident, following a well-set skin track that followed the line of least resistance; snow surface was variable but seemed stable. Coming down, we mostly followed the ascent route, but towards the end I was tempted onto a fun-looking, untracked stash a bit to skier's left, that seemed only a tad steeper than the ascent line. A few turns into this line is when I triggered the slide, right at the steepest part (mid-high 30s). It definitely took me by surprise given that we'd been skiing great, stable powder in the Bridgers the past couple days. No harm done but definitely a good wake-up call! 

Region
Bridger Range
Location (from list)
Northern Bridgers
Observer Name
Alexey

Wet loose in northern bridgers

Date
Activity
Skiing

Meant to submit this yesterday (4/18), saw this one wet loose slide that naturally started off some rocks. Decent size by the bottom. Other than that, just some spiff. Surprisingly didn’t see any big wind slabs trigger, despite the widespread wind effect in the northern Bridger’s. Lots of wind scour on southerly aspects. Northern aspects had wind loading. 

Region
Bridger Range
Location (from list)
Fairy Lake
Observer Name
William Landrey

"yesterday (4/18), saw this one wet loose slide that naturally started off some rocks. Decent size by the bottom. Other than that, just some spiff. Surprisingly didn’t see any big wind slabs trigger, despite the widespread wind effect in the northern Bridger’s. Lots of wind scour on southerly aspects. Northern aspects had wind loading." Photo: W. Landry

Avalanche Details: Wet loose in northern bridgers
Forecast link: GNFAC Avalanche Forecast for Mon Apr 21, 2025GNFAC Avalanche Forecast for Fri Apr 25, 2025
Bridger Range, 2025-04-19
Access other image sizes:
  • Very Large 1200px
  • Large 480px
  • Medium 220px
  • Small 150px
  • Original

    • GNFAC Avalanche Forecast for Sat Apr 19, 2025

    Snowpack and Avalanche Discussion

    <p><span><span><span><span><span><span>This morning, the snowpack is mostly stable and avalanches are unlikely. Wind drifts of recent snow will mostly have bonded and be unreactive. Stay alert in case you find one that is still unstable. With temperatures well below freezing overnight, wet snow concerns are minimal first thing this morning.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>As the day heats up, warm temperatures and intense sunshine will destabilize the recent snow, particularly on slopes facing towards the sun. Expect to trigger </span></span></span></span></span></span><span><span><span><strong><span><span>Wet Loose avalanches </span></span></strong></span></span></span><span><span><span><span><span><span>if you get onto a steep slope that has been baking in the sun for more than a couple hours. These slides will also release naturally from around exposed rocks on steep slopes. These wet loose slides will mostly be confined to the recent snow, so they won’t be huge, but still plenty big enough to knock you off your feet or push you into rocks or off a cliff. With firm crusts underneath the recent snow, they could run long distances. Be most wary in areas where there is more recent snow or in very steep, consequential terrain where a small slide would have big consequences.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Clouds moving in this afternoon could stop the melt and keep the danger from rising, but it looks like they’re going to develop too late to make a huge difference today.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>The avalanche danger will start out at LOW this morning, rising to MODERATE for wet snow as the day heats up.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>With firm surface crusts and without recent snow to destabilize, avalanches are unlikely and the avalanche danger is LOW.</span></span></span></span></span></span></p>

    Good Stability at Lionhead

    Date
    Activity
    Snowmobiling

    We rode up to the old weather station and then to the current weather station, down Airplane Bowl, along the base of the LH Ridge to the head of Targhee Creek and back. There is a 4-5" Thick refrozen crust below 3-5 inches of new snow at upper elevations. At lower elevations, there was less snow, and I suspect more rain, and east winds stripped many of the upper starting zones back down to the melt-freeze crust. 

    There was little, if any danger of avalanches today. You may have been able to find an isolated wind slab from the east wind-loading, but it would have been small in area and depth. We rode out at 2 PM and the crust had not started breaking down in any meaningful way. 

    Tomorrow is supposed to be 8-10 degrees F warmer, but cold temperatures tonight should refreeze the crust, and it is pretty robust. There may be a few very small, wet snow avalanches in the recent snow with warming temperatures, but I would not be particularly worried about slides. There is more snow and colder temps forecast for Sunday and Monday. Fingers crossed for a bit more powder riding. 

    The road from the Buttermilk TH was reasonable but is melting out quickly. There were a few dirt patches that will grow tomorrow. 

    Beautiful day to spend in the mountains and the riding through the upper bowls was quite nice. 

    Region
    Lionhead Range
    Location (from list)
    Lionhead Ridge
    Observer Name
    Dave Zinn

    GNFAC Avalanche Forecast for Fri Apr 18, 2025

    Snowpack and Avalanche Discussion

    <p><span><span><span><span><span><span>Today’s avalanche concerns are all going to within the 5-9” of new snow that fell since Wednesday morning.&nbsp;</span></span></span></span></span></span></p>

    <p><span><span><span><strong><span><span>Wind Slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are the primary concern. The new snow has been drifted into cohesive slabs by north and east winds since snowfall began. With an easterly component to the winds, be on the lookout for drifts in unusual locations. Some of these drifts will be easily triggered today and some will have already started to bond. Steering around the deepest wind drifts is an easy way to avoid much of the avalanche hazard today. You can also quickly dig down to check how well they’ve bonded to the old snow surface. Cracks shooting out in front of your skis or sled are clear signs you’ve found an unstable drift.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>With clear skies today, the new snow will get wet on sunny slopes and you’ll be able to trigger </span></span></span></span></span></span><span><span><span><strong><span><span>Wet Loose avalanches</span></span></strong></span></span></span><span><span><span><span><span><span>. These slides will run on top of the hard crusts underneath the recent snow. Feel for the snow surface getting wet and sticky and look for rollerballs and pinwheels as clear signs that Wet Loose avalanches are imminent. Most of these slides probably won’t have enough volume to bury you, but they can still be surprisingly powerful, plenty strong enough to push you off a cliff or into rocks. Plan to move off steep sunny slopes later in the day, as the snow gets wet.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>With both wet and dry avalanches possible, the avalanche danger is MODERATE today.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>With little new snow and a firm, solidly refrozen crust underneath, avalanches are unlikely and the avalanche danger is LOW. </span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Look out if you find more than a skiff of new snow, in which case you might be able to trigger small Wind Slab or Wet Loose avalanches.&nbsp;</span></span></span></span></span></span></p>

    GNFAC Avalanche Forecast for Thu Apr 17, 2025

    Snowpack and Avalanche Discussion

    <p><span><span><span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> will be the most likely slides to trigger today. With gusty east winds this morning and stronger north-northeast winds expected today, wind slabs will grow larger and easier to trigger as the day progresses. HEADS UP - easterly winds will create abnormal loading patterns.</span></span></span></span></span></span></p>

    <p><span><span><span><strong><span><span>Storm slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> will be something to consider especially as more snow accumulates. The storm is</span></span></span></span></span></span><a href="https://avalanche.org/avalanche-encyclopedia/#right-side-up-storm"><spa…; right-side-up</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> this morning which is good thing. Today, brief periods of higher snowfall rates or a little bit of warming could create a slightly cohesive slab in the new snow. Look for signs of instability in the new snow by looking for cracking, jumping on small test slopes, and stepping above your partner’s tracks. At a minimum expect sluffing of the new snow.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Today the avalanche danger is CONSIDERABLE on wind loaded slopes. Seek out soft powder on slopes untouched by the wind where the danger is MODERATE. Assess stability in the new snow before getting into steeper terrain.</span></span></span></span></span></span></p>

    <p><span><span><span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> will also be a concern in the Gallatin and Madison Ranges but with less new snow they will be shallower. Otherwise, riding slopes untouched by winds may be “dust on crust” and there will only be minor sluffing of the new snow on the hard icy surface underneath.&nbsp;</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Today the avalanche danger is MODERATE.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>With the snowpack refrozen and no new snow this morning, skiing and riding conditions will be a bit rugged. Avalanches are unlikely and the avalanche danger is LOW.</span></span></span></span></span></span></p>

    Subscribe to 24-25