23-24

More cracking and collapsing in Hyalite

Date
Activity
Skiing

Skied in Hyalite today around 8200ft on some east-facing slopes adjacent to the creek. 

HS 25-35cm. Facets on top of depth hoar.

On our first few laps, we did not observe any signs of instability. 

We moved to another, slightly steeper area about 400 yards to the south and dug a pit on a 24-degree E-facing slope. ECTN27 up 15cm on a slight density change between the F hard depth hoar and F+ facets above. When we were almost at the top, I experienced a large, audible collapse and shooting cracks in a 10ft radius around me (picture attached). I dug a hand pit and did not observe any significant differences in snow structure or hardness from our test pit location.

We chose to transition and ski from that point. As I began to ski, the slope in front of me collapsed, with shooting cracks about 25ft in length. Both my partner and I experienced collapses the entire way down the slope while skiing.

 

Region
Northern Gallatin
Location (from list)
Hyalite - main fork

GNFAC Avalanche Forecast for Sat Dec 30, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Avalanches are possible to trigger where supportable slabs of snow sit over weak snow. Weak snow is widespread and exists on most slopes. However, the last six days without new snow has led to fewer slopes with an unstable layering of cohesive slabs on top of weak snow. Before riding or crossing steep slopes assess the snowpack for instability. Avoid steep slopes if you find a poor snow structure or see obvious signs of instability like collapsing and cracking. With the thin snowpack it’ll only take a few minutes to dig and do a stability test before getting into avalanche terrain. If you find a stiff slab of snow that supports you on a sled or skis, stop to look for weak snow underneath and avoid steep terrain where you find this poor snow structure.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The most suspect slopes are where strong winds drifted last week’s snow into thicker slabs or where more snow accumulated last week. A couple days ago in the Bridger Range, Dave and Ian saw an avalanche that broke earlier in the week on a wind-loaded slope (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Rd_XSNJjLYs&amp;list=PLXu5151nmAvSH326z…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-avalanche-throne"><span><…;). Yesterday skiers reported collapsing of the snowpack in Hyalite (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29714"><span><span><span><strong><span…;), Beehive (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29715"><span><span><span><strong><span…;) and near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29716"><span><span><span><strong><span…;), a sign of poor snow structure and the potential to trigger an avalanche on steeper slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Today mountain temperatures will rise above freezing in many places, and wet avalanches may be possible on steep slopes that heat up in the sun. Watch for roller balls as a sign the snow surface is becoming damp and unstable.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE in the mountains around Bozeman, Big Sky, West Yellowstone, Island Park and Cooke City.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

Whumpfing In Yellowstone National Park

Yellowstone Park NE
Out of Advisory Area
Code
Elevation
8000
Aspect
SE
Latitude
45.00340
Longitude
-110.04300
Notes

From obs: Lots of wumphing that often propagated 20-30’ around us. Observed above 8000’. Our travel was mostly on S to E aspects."

Number of slides
0
Number caught
0
Number buried
0
Problem Type
Persistent Weak Layer
Snow Observation Source
Unstable snow near Cooke in YNP
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
23-24

Collapsing in Hyalite

Hyalite - East Fork
Northern Gallatin
Code
Latitude
45.41000
Longitude
-110.93100
Notes

Skiers felt collapsing while touring near Heather Lake.

From obs: "I got one relatively large collapse as I stepped out in the open near Heather Lake, and then 5-6 smaller ones as I looped around above it."

Number of slides
0
Number caught
0
Number buried
0
Problem Type
Persistent Weak Layer
Snow Observation Source
Heather lake
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year
23-24

Unstable snow near Cooke in YNP

Date
Activity
Skiing

Toured just inside the park west of Cooke. Lots of wumphing that often propagated 20-30’ around us. Observed above 8000’. Our travel was mostly on S to E aspects. 

Region
Out of Advisory Area
Location (from list)
Yellowstone Park NE
Observer Name
Reid B

Observations in Beehive Basin

Date
Activity
Skiing

From email: "We skinned up the west ridge and dug a pit at 9000' on an east aspect. HS50cm. Extended column test did not show propagation. Column test CT 13@40, Q3, CT17@18, Q3. Snowpack structure is very poor. We did not find a slab on the slope we dug on. 50-40cm was new snow from last weekend's snow, 40-18 was F-4F Facets, and 18-0 is depth hoar. Depth hoar was cup-shaped and had visible striations. Route finding while skinning up to the ridge was very difficult due to low snow coverage and downfall. High clouds in the AM gave way to mostly sunny skies around 12. We saw small rollerballs, and the snow surface was starting to get moist as the sun poked out. We saw one point release avalanche on the west aspect of the basin in steep terrain that looked like it released during the 12/23-12/24 snowfall. We had the occasional collapse/whumpf while skinning on the ridge but it wasn't widespread. "

Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
Nicholas Salsburg

Heather lake

Date
Activity
Skiing

I went on a little Nordic ski up to heather lake today. Up higher the snowpack is so weak it could barely support my 150 lb body on skis, and I spent a great deal of time wallowing through two feet of facets. There was a widespread, thin layer of hoar frost throughout a good deal of the basin, mainly out in the open. I got one relatively large collapse as I stepped out in the open near heather lake, and then 5-6 smaller ones as I looped around above it.

Region
Northern Gallatin
Location (from list)
Hyalite - East Fork
Observer Name
Sam Reinsel

GNFAC Avalanche Forecast for Fri Dec 29, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Each day without new snow means you’re a little less likely to trigger an avalanche, but it remains very possible to trigger a dangerous slide.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Weak snow is widespread. Essentially every slope in our advisory area has it at this point after weeks or months of thin snowcover sitting and weakening. The missing ingredient for an avalanche on some slopes is a cohesive slab of snow on top. Yesterday, Dave and I saw an avalanche that broke on a windloaded slope in the Bridgers earlier in the week during a strong wind event (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Rd_XSNJjLYs&amp;list=PLXu5151nmAvSH326z…;). On this slope it was recent wind loading that built the slab, on others it may be older windloading or just a place where it snowed more earlier in the month. Pay close attention to the upper snowpack as you travel through the mountains. If you find a stiff slab of snow that is supporting you on a sled or skis, stop to investigate the stability. With the thin snowpack it’ll only take a few minutes to dig and do a stability test before getting into avalanche terrain. Also be alert for collapsing or cracking and be ready to back off steep slopes if you see these clear signs of instability.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Mountain temperatures will rise above freezing in many places today and the snow surface may get damp, but with the weak December sun wet avalanches are not a significant concern.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE in the mountains around Bozeman, Big Sky, West Yellowstone, Island Park and Cooke City.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

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