21-22

Loose Wet Avalanches at Bridger Bowl

Bridger Bowl
Bridger Range
Code
WL-N-R2-D2-I
Elevation
8000
Aspect
E
Latitude
45.81560
Longitude
-110.92300
Notes

From 4/30/22: "...there were several wet loose avalanches at Bridger today. Some with ~5cm of snow on top, maybe from yesterday or earlier in the week, and some new this morning. We watched a relatively slow moving natural size 2 come down Colter's area around 10:30. We also ski cut a size 1.5 from the skiers right of the Lower Nose (NE asp) around 9:45 which ran on the melt freeze crust from earlier this week. It moved slowly but I was surprised by how much mass it entrained. A couple other ski cuts just above had produced smaller size 1s. The debris stopped on top of an older debris pile which was significantly larger and had run significantly further. (You can kind of see the difference in the photo). There was also widespread roller balling and pinwheeling on all aspects and elevations. Note - sizes are D sizes..."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Images
Loose Wet Avalanches at Bridger Bowl
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
21-22

From 4/30/22: "...there were several wet loose avalanches at Bridger today. Some with ~5cm of snow on top, maybe from yesterday or earlier in the week, and some new this morning. We watched a relatively slow moving natural size 2 come down Colter's area around 10:30. We also ski cut a size 1.5 from the skiers right of the Lower Nose (NE asp) around 9:45 which ran on the melt freeze crust from earlier this week. It moved slowly but I was surprised by how much mass it entrained. A couple other ski cuts just above had produced smaller size 1s.

Avalanche Details: Loose Wet Avalanches at Bridger Bowl
Bridger Range, 2022-05-02
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    • Wet new snow slide in Beehive

    Bear Basin
    Northern Madison
    Code
    SS-AS-R1-D1.5-I
    Elevation
    8900
    Aspect
    E
    Latitude
    45.34530
    Longitude
    -111.37500
    Notes

    A meadow descending into bear basin. Sun affected, new snow sliding.

    Number of slides
    1
    Number caught
    0
    Number buried
    0
    Avalanche Type
    Soft slab avalanche
    Trigger
    Skier
    R size
    1
    D size
    1.5
    Bed Surface
    I - Interface between new and old snow
    Problem Type
    New Snow
    Images
    Wet new snow slide in Beehive
    Slab Thickness units
    centimeters
    Single / Multiple / Red Flag
    Single Avalanche
    Advisory Year
    21-22

    Flathead Pass

    Date
    Activity
    Skiing

    This morning we toured south of Flathead Pass to check out the conditions. We noticed on our way up that the freezing line was ~7500 ft. The punchy and wet surface crust became quite supportive and icy at this altitude. We dug a pit at ~7900ft on a NE aspect. At this location, the overnight snow totaled only 2cm but we observed more significant wind deposition in and around the trees of about 10cm. Our shovel shear tests resulted in an easy shear at 120cm and hard shear (Q1) at 90cm. We saw no results from the ECT but, upon shearing the ECT block, we were able to pop off the block at 90cm with a surprising amount of energy (see photo). This block was quite consolidated, so much so that it remained intact as we pushed it out of the pit. With this observation, we stayed off steeper terrain today and will be looking for increased instability at this interface as temperatures warm. 

    Region
    Bridger Range
    Location (from list)
    Flathead Pass
    Observer Name
    Erich Schreier

    Loose Wet Avalanches at Bridger Bowl

    Date
    Activity
    Skiing

    I'm sure this is not unexpected, but there were several wet loose avalanches at Bridger today. Some with ~5cm of snow on top, maybe from yesterday or earlier in the week, and some new this morning. We watched a relatively slow moving natural size 2 come down Colter's area around 10:30. We also ski cut a size 1.5 from the skiers right of the Lower Nose (NE asp) around 9:45 which ran on the melt freeze crust from earlier this week. It moved slowly but I was surprised by how much mass it entrained. A couple other ski cuts just above had produced smaller size 1s. The debris stopped on top of an older debris pile which was significantly larger and had run significantly further. (You can kind of see the difference in the photo). There was also widespread roller balling and pinwheeling on all aspects and elevations.

    Note - sizes are D sizes. I'm not very familiar with R sizes (from Canada) so am not sure I can confidently provide R sizes. Maybe both R2?

    Sorry there aren't more useful photos - phone camera is not very good.

    Region
    Bridger Range
    Location (from list)
    Bridger Bowl
    Observer Name
    Nata de Leeuw

    Wet slide in Beehive

    Date
    Activity
    Skiing

    A meadow descending into bear basin. Sun affected, new snow sliding.

    Region
    Northern Madison
    Location (from list)
    Bear Basin
    Observer Name
    Patrick Smoral

    GNFAC Avalanche Forecast for Fri Apr 29, 2022

    Snowpack and Avalanche Discussion

    <p>In places where it is snowing heavily today, the avalanche hazard will rise quickly. Avalanches will be easily triggered in the new and wind drifted snow. The more snow that falls, the more dangerous conditions will become. If you find cohesive slabs of new snow more than a few inches deep, carefully check how well those slabs have bonded to the old snow surface before getting into steep terrain.&nbsp;Cracks shooting out in front of you are clear signs the new snow is unstable.</p>

    <p>In general, you’re unlikely to trigger an avalanche breaking deeper than the new snow. However, on higher elevation shady slopes the snowpack remains cold, dry, and layered. On these slopes it’s not out of the question that you could trigger a deeper slide. Dig down a couple feet to look for weak layers and test them. If you find a reactive weak layer, back off of steep slopes for today.</p>

    <p>When the sun comes out tomorrow, the new snow will quickly become wet and destabilize. Expect to trigger loose wet avalanches. These slides will entrain any new snow, so the deeper that new snow is, the larger these loose slides will be. Don’t discount loose avalanches. Even a relatively small slide can be hazardous if it pushes you off a cliff or into rocks or trees.&nbsp;</p>

    <p>The snowpack doesn’t know how to read a calendar. Even though it’s late April and we’re now well into Spring, it’s still possible to trigger an avalanche. More important than today’s date is the fact that it is actively snowing. That means avalanches are becoming more likely. Keep sticking to the same safe travel practices that you follow mid-winter. Look for signs of instability and be ready to back off steep slopes if you find them. Always carry rescue gear (beacon, shovel, and probe). Go one at a time in avalanche terrain. And watch your partner from a safe spot.&nbsp;</p>

    <p>This is our final snowpack update of the season. Have a great spring and summer! We’ll be back when it starts snowing again in the fall.</p>

    Announcements, Avalanche Education and Events

    Bridger Bowl is closed, and backcountry conditions exist. There is no avalanche mitigation or ski patrol rescue. In case of emergency, call 911. Please stay clear of work areas, snowmobiles, chair lifts and other equipment. Without the daily avalanche mitigation efforts of the ski patrol, backcountry conditions now exist within the boundaries of Bridger Bowl (video).

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