23-24

Remote Triggered Avalanche

Date
Activity
Skiing
Snowmobiling

Accessed low angle settled powder runs via mellow ridge terrain adjacent to a known avalanche path which is steep, rocky and windloaded. We descended on lower angle terrain following uptrack. On second lap observed the crown and debris while climbing uptrack and suspected we remote triggered; it was not there on first lap. Slope angle 35-38 degrees estimated. Estimate crown depth 60-120 cms. Estimated debris depth 2-3 meters due to terrain trap of an abrupt transition to flat terrain at bottom of path. We did not approach the crown or debris due to hangfire. Starting Zone NE facing at 9100' on wind loaded convexity with unsupported terrain below and rocky bed surface and exposed rocks/cliffs. I would classify it as HS-ASur-R4-D2.5-O

Large collapses with cracks connecting weak spots in the snowpack for 50 feet around us while breaking trail. Slab has gotten quite a bit thicker and more cohesive with 3 inches SWE in past 14 days combined with relatively warm temps promoting settling, strong solar input on the southerlies, and some wind. Average snow depth 100 cms consisting of a F-1Fslab on top of 20-30 cms of large facets. A crust in between on solar aspects. There is a density break/layer of NSF in the slab you can see in some of the photos where it appeared to shear between those layers. A very scary snowpack even for the Pioneers which regularly harbor PWLs throughout the season.

Region
Dillon Area
Location (from list)
East Pioneer Mountains
Observer Name
Alex Dunn

Large Crowns in Hyalite

Date
Activity
Ice Climbing

From the approach trail to Mummy II we saw two large crowns on the ridge associated with Mt. Bole. Not sure when they happened, but they looked pretty big! Observed Monday morning, February 19

Region
Northern Gallatin
Location (from list)
Mt. Bole
Observer Name
Matteo Bjornsson

GNFAC Avalanche Forecast for Tue Feb 20, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>The mountains have been talking to us through avalanches, whumpfs and shooting cracks. The translation is easy; she’s telling us the snowpack is dangerous. Dave was in Cooke City the last 2 days and his findings can be extrapolated throughout the forecast area. Avalanches are still breaking deep, people are triggering them from far away, and stability tests are only valuable when they show it’s bad. Tests are not to be used to show us it’s good-to-go. As he safely ascended next to a gully in Republic Creek he got an unremarkable test result. As he approached the top he and his partner got a gut-wrenching collapse and crack that shot out hundreds of feet across the slope. A couple degrees steeper and it might have avalanched.&nbsp;&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Dave’s message: Let’s put stability tests on the back burner when Mother Nature is shouting in our ear that it’s dangerous.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The snowpack is weak: the lower third is loose, faceted, sugary snow that struggles to support the snow above it. Skiers and sledders are collapsing this layer and triggering slides from far away. Riders on Buck Ridge triggered 2 large slides from hundreds of feet away on Saturday (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30818"><span><span><span><strong><span…;), and Alex and I had similar instability on Sunday in the same area (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/30851"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://youtube.com/shorts/FiXdQ2N7Da4?feature=share"><span><span><span…;). Yesterday skiers and riders had collapses in Tepee Basin, Bacon Rind, and around Cooke City. These and 28 other reports since Friday, can be viewed </span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span…;

<p><span><span><span><span><span><span>The instability is widespread and triggering avalanches is likely throughout our forecast area. Conditions are dangerous and we recommend avoiding avalanche terrain and being wary about traveling underneath steep slopes since avalanches can release far above. The danger is rated CONSIDERABLE near Bozeman to Big Sky, West Yellowstone, Island Park and Cooke City.</span></span></span></span></span></span></p>

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Whumps and collapsing in the flats - Tepee Creek

Tepee Basin
Southern Madison
Code
Latitude
44.90410
Longitude
-111.18500
Notes

Nothing new, but we were in Tepee Creek today.  Three of us dropped into a flat meadow on a (wide) ledge, and after sitting there for a minute or less, we all felt a "whump" and collapse. While the meadow had some small rolling terrain, it was flat overall.

Number of slides
0
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Whumps and collapsing in the flats - Tepee Creek

Date
Activity
Snowmobiling

Nothing new, but we were in Tepee Creek today.  Three of us dropped into a flat meadow on a (wide) ledge, and after sitting there for a minute or less, we all felt a "whump" and collapse. While the meadow had some small rolling terrain, it was flat overall.

Region
Southern Madison
Location (from list)
Tepee Basin

Avalanche Above Twin Falls

Hyalite - main fork
Northern Gallatin
Code
Latitude
45.44720
Longitude
-110.96200
Notes

From email: "My partner and I were out ice climbing in Hyalite today and I wanted to share our observations.

Our objective was Cleopatra’s needle. We arrived at the base of the climb around 11:30, skies were clear and winds were calm. Once I topped out around 3:30pm, skies were overcast and winds were picking up from the northwest and began to transport snow off the trees. I also noticed a pretty sizable crown on one of the convexities above Twin Falls. I traversed around to get a better look and took a couple pictures.

The crown appeared very new, likely within the past couple of days I would guess. It appeared 3 feet at its deepest and roughly 100 feet wide. I’m not sure if it was a natural or remote trigger, but definitely a scare nonetheless for any potential climbers below."

Number of slides
1
Number caught
0
Number buried
0
Problem Type
Persistent Weak Layer
Slab Thickness
24.0 inches
Slab Width
100.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year