22-23

Portal Creek small slide

Date
Activity
Snowmobiling

We were snowmobiling up portal creek today near the hidden lakes trailhead and I set off a small slide remotely by riding below a small ridge. The slide was about 3 feet at its crown 30 or 40 feet wide and ran about 40 yards. It just came down to where my track had crossed underneath. Everything was fine and we stayed safe and continued on with our plan and had a nice day.

Region
Northern Gallatin
Location (from list)
Portal Creek

Natural on Cedar Mountain

Date
Activity
Skiing

This natural avalanche was observed in the afternoon around 1500. It was not seen earlier in the day and is thought to occurred at some point after 1200. It was seen from a distance on Pioneer mountain. It occurred on an E facing slope around 9600’. Active wind transport was noted on the ridge line above the avalanche. It looked to be around a R3-D2.

Region
Northern Madison
Location (from list)
Cedar Mtn.
Observer Name
R. Freeman

GNFAC Avalanche Forecast for Fri Mar 31, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>There are two very different sets of avalanche concerns today - avalanches breaking&nbsp; in the upper couple feet of the snowpack and avalanches breaking deep on weak layers buried months ago.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Avalanches in the upper snowpack can be triggered beneath the snow that fell over the last week, particularly where it’s been more recently drifted by the wind. In some places the new snow buried a layer of facets that will keep the snowpack from stabilizing as quickly (</span></span></span></span></span></span><a href="https://youtu.be/8gXkzoEbk6Q"><span><span><span><strong><span><u><span>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Watch out for shooting cracks as a clear sign of instability and dig down around 3 ft to test the upper snowpack before riding any steep slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>A harder to identify, but scarier possibility is triggering a deep slab avalanche. Yesterday, a snowboarder triggered a slide that broke deep in the Lone Lake Cirque, near Big Sky resort, and was carried close to a thousand vertical feet over rocks and huge cliffs (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/lone-lake-cirque-slide"><span><sp…;). Remarkably he wasn’t buried and survived unscathed. Before this incident, the last deep slabs were triggered a week ago in </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28798"><span><span><span><strong><span>…; and near </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28785"><span><span><span><strong><span>… City</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. You’d have to get unlucky to trigger one of these slides today, but if you do, the consequences could be huge. Avalanches in the newer snow could also step down and trigger a deeper slide. Consider the possibility of a huge slide breaking deep in the snowpack before getting into consequential terrain.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is rated MODERATE on all slopes.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).&nbsp;</span></span></span></span></span></span></p>

<p>&nbsp;</p>

<p><span><span><span><span><span><span>In Island Park, avalanches in the upper snowpack can be triggered beneath the snow that fell over the last week, particularly where it’s been more recently drifted by the wind. A harder to identify, but scarier possibility is triggering a deep slab avalanche. You’d have to get unlucky to trigger one of these slides today, but if you do, the consequences could be huge. Avalanches in the newer snow could also step down and trigger a deeper slide. </span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Events and Education Calendar.

**Reporting this from a friend of a friend. Not my photo, nor was I involved.**
 

one skier got caught above large bottom cliff, carried all the way down over cliff to the apron. Said skier walked away completely unharmed. Not buried. 
 

north face of that bowl, near cornrows. 

 

Additional info from BSSP: 

"There was a large, deep slab avalanche snowboard triggered in Lone Lake Cirque this afternoon. The
slide ripped in a secondary start zone below ridgetop, and ran far into the flats, and may have run a

Avalanche Details: Skier triggered Deep Slab in Lone Lake Cirque
Forecast link: GNFAC Avalanche Forecast for Fri Mar 31, 2023GNFAC Avalanche Forecast for Sat Apr 1, 2023GNFAC Avalanche Forecast for Sun Apr 2, 2023
Northern Madison, 2023-03-31
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    • Skier triggered Deep Slab in Lone Lake Cirque

    Lone Lake Cirque
    Northern Madison
    Code
    HS-ARu-R4-D2.5
    Latitude
    45.27710
    Longitude
    -111.46400
    Notes

    There was a large, deep slab avalanche snowboard triggered in Lone Lake Cirque this afternoon (3/30). The
    slide ripped in a secondary start zone below ridgetop, and ran far into the flats, and may have run a bit uphill, where it encountered the rock glacier moraine in the runout. It looks to be a R4, D2.5. Snowboarder walked away unharmed.

    Number of slides
    1
    Number caught
    1
    Number buried
    0
    Avalanche Type
    Hard slab avalanche
    Trigger
    Snowboarder
    Trigger Modifier
    u-An unintentional release
    R size
    4
    D size
    2.5
    Images
    Lone Lake Cirque slide
    Snow Observation Source
    Slide in lone lake cirque off backside of lone mtn
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    22-23

    Slide in lone lake cirque off backside of lone mtn

    Date
    Activity
    Skiing

    **Reporting this from a friend of a friend. Not my photo, nor was I involved.**
     

    one skier got caught above large bottom cliff, carried all the way down over cliff to the apron. Said skier walked away completely unharmed. Not buried. 
     

    north face of that bowl, near cornrows. 

     

    Additional info from BSSP: 

    "There was a large, deep slab avalanche snowboard triggered in Lone Lake Cirque this afternoon. The
    slide ripped in a secondary start zone below ridgetop, and ran far into the flats, and may have run a

    bit uphill, where it encountered the rock glacier moraine in the runout. It looks to be a R4, D2.5."

    Region
    Northern Madison
    Location (from list)
    Lone Lake Cirque

    Poor decision making in small but dangerous terrain.

    Date
    Activity
    Snowmobiling

    After a long day of riding 2 to 3 thousand feet higher in good snow I was getting close to the truck after 10 or so miles on a mostly hard pack trail I decided to climb this hill in a split second decision. My sled was overheating and my plan was to cool it down. As I ascended the hill I hit a pencil hard wind slab about a third of the way up, I knew instantly that I was in trouble as this slope ended up being much steeper than I had initially thought. I made a decision in the moment to continue up the slope as it was not many vertical feet in elevation. My thoughts were that I had lots of speed and momentum built up and that that would carry me up I also thought that if I tried to make an aggressive turn it would put more stress on the snow pack and I also figured the closer to the top of the slab I was when it fractured the better off I would be. I made it about 100 feet from the top of the hill when it first fractured, I was about 20 feet from the fracture and there was a point slightly to my right that was the closest point of the fracture to me. I turned slightly right heading to the closest point of snow above the fracture line. As I turned the slope started sliding. The top of the of the slide rolled over like a large wave and a block hit me in the ribs luckily not nocking me off my sled. I maintained full throttle and kept my momentum traverseing through the rolling blocks. My only thought was to try to stay on top of my machine and keep forward momentum. In the last few moments of the slide I could feel I was loosing control of my machine because it was starting to get sucked into the avalanche. When the slide stopped I was in snow to my knee on my uphill side. I want to end this with a warning of complacency. I had been in big terrain all day and didn't analyze the slope like I should have a simple glance for a moment and I would have recognized the dangers of the wind slab. I got complacent and it almost got me injured or killed. Just because a slope is small doesn't mean it isn't dangerous.

     

    Region
    Dillon Area
    Location (from list)
    Blacktail Mountains

    GNFAC Avalanche Forecast for Thu Mar 30, 2023

    Snowpack and Avalanche Discussion

    <p><span><span><span><span><span><span>There are a few avalanche concerns today, but none are widespread. The snowfall from the weekend was blown into drifts near the ridgetops which could be triggered; cornices grew and could break; a weak layer of facets might be found a couple feet under the surface; and a weak layer 3-5 feet deep could avalanche, although these are rare.&nbsp;</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>The first three items on the list are things we can avoid and navigate around: turn around when wind-drifts crack; on ridges make sure your skis or sled are over solid ground instead of a snow overhang; and dig in the upper 3 feet of the snowpack to test the stability of the new snow. For the fourth item, deep slab avalanches, there’s not much you can do other than avoid avalanche terrain or accept that these rare, big slides, are lurking like sharks with you as chum.</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Over the last few days there have been natural avalanches in the </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28848"><span><span><span><strong><span>… Range</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, up </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28861"><span><span><span><strong><span>…;, on </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28870"><span><span><span><strong><span>… Ridge</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, and a couple deep ones a week ago in </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28798"><span><span><span><strong><span>…; and </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28785"><span><span><span><strong><span>… City</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. Avalanches remain possible. To make your pre-trip homework easier check out our </span></span></span></span></span></span><a href="http://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span>… and Avalanche Log</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> which has a full listing of the natural and human-triggered slides, and watch our field videos where </span></span></span></span></span></span><a href="https://youtu.be/M3hp2s4iQ1o"><span><span><span><strong><span><u><span>… describes the conditions on Buck Ridge</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://youtu.be/8gXkzoEbk6Q"><span><span><span><strong><span><u><span>… talk about digging under the new snow in the Bridger Range</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> and </span></span></span></span></span></span><a href="https://youtu.be/jrjIs789meI"><span><span><span><strong><span><u><span>… gives advice on terrain selection</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>.&nbsp;</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>The avalanche danger is rated MODERATE on all slopes.&nbsp;</span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs). </span></span></span></span></span></span></p>

    <p><span><span><span><span><span><span>There are a few avalanche concerns today, but none are widespread. The snowfall from the weekend was blown into drifts near the ridgetops which could be triggered; cornices grew and could break; a weak layer of facets might be found a couple feet under the surface; and a weak layer 3-5 feet deep could avalanche, although these are rare. Dig, test and turn around if you see any recent avalanches or find instability. </span></span></span></span></span></span></p>

    Upcoming Avalanche Education and Events

    Events and Education Calendar.

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