23-24

Somewhat stable near The Throne

Date
Activity
Skiing

Aspect was NNE 070 deg. 8100 ft.

85 cm snow depth

First 20 cm from the ground up was large facet, rotting snow.

Remaining 60 cm was consolidated.

No collapsing or shooting cracks noted. 

No natural slides seen in the area.

Spoke with another party that was skiing S of The Throne. They heard large collapses while skinning over flat terrain. 

Region
Bridger Range
Location (from list)
The Throne
Observer Name
C. Robinson

Crazy Mtns.

Date

I walked up from Halfmoon this morning to see what is happening with the snowpack in the Crazies. I only went up to about 7000ft, temps were in the mid 20s and wind was very light out of the west. Not surprisingly, I found very minimal snow coverage, with the deepest snow I found around 3 in. South facing aspects were almost completely bare, and much above tree line appeared totally scoured. Where there was snow on the ground, on average 1-3 inches, there was a thick crust with large surface hoar crystals on top and very light density snow below. Didn't look great, I left my skis at the car!

Region
Out of Advisory Area
Location (from list)
Crazy Peak
Observer Name
Taylor Sweitzer

GNFAC Avalanche Forecast for Wed Dec 13, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><u><span><span>The snowpack is unstable.</span></span></u></span></span></span></span></span><span><span><span><span><span><span> Yesterday, a skier on Mt. Blackmore, in the northern Gallatin Range, triggered the SE face as he skied. Luckily he was not caught, and fortunately he shared a </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29503"><span><span><span><strong><span… and POV video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. This avalanche is instructive because the unstable conditions they found could be anywhere in our forecast area, such as Saddle Peak, Beehive Basin or Cooke City. Ian and I skied in a backcountry snowpack at Bridger Bowl yesterday. We got a loud collapse in the Fingers Meadow, stopped, and dug in 2 feet of snow. We found weak grains of sugary facets and depth hoar at the base of the snowpack. The collapse was Mother Nature shouting the snow is unstable. Being snow nerds we dug, and we were unable to isolate a column because it kept breaking (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29503"><span><span><span><strong><span…, snowpit and video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Furthermore, sledders got </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29513"><span><span><span><strong><span… (whumpfs) in Lionhead</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> during an avalanche course yesterday and skiers had large </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29490"><span><span><span><strong><span… in Cooke City</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> 2 days ago, evidence of similar snow structure.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><u><span><span>The snowpack will be slow to heal.</span></span></u></span></span></span></span></span><span><span><span><span><span><span> A persistent weak layer of facets and depth hoar can take months to strengthen. This layer is also protected from our skis chewing it up on popular runs because we float above it, which snow scientist Karl Birkeland shows us in a </span></span></span></span></span></span><a href="https://youtu.be/4CUHU9U3ds8"><span><span><span><strong><span><u><span>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Stay out of avalanche terrain today. This is </span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather/wx-avalanche-log"><span><span><span… first day in the last 12</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span> when there has been no new snow in our forecast area. The avalanche danger will slowly come down, but not yet. Triggering a slide like the one on Blackmore is just as likely today as it was yesterday.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Throughout our forecast area, the avalanche danger is rated </span></span></span></span></span></span><span><span><span><strong><span><span>CONSIDERABLE</span></span></strong></span></span></span><span><span><span><span><span><span> on all slopes. </span></span></span></span></span></span></p>

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Collapses at Lionhead

Ski Hill
Lionhead Range
Code
Latitude
44.70160
Longitude
-111.29300
Notes

Spent the day up near ski hill with West Yellowstone Avalanche Fundamentals course. 

Our group observed a large collapse below ski hill.

We dug various pits @ 8000' below ski hill and found HS 85-55cm on NW-NE aspects.

The snowpack structure there had weak snow at the ground capped by a stout ice crust with faceted snow over the crust beneath the recent snow.

We recorded ECTP4, ECTP11, ECT20 & a few more propagating results on facets above the crust. 

There was widespread intact surface hoar

 

 

 

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

Spent the day up near ski hill with West Yellowstone Avalanche Fundamentals course.

We dug various pits @ 8000' below ski hill and found HS 85-55cm on NW-NE aspects.

The snowpack structure there had weak snow at the ground capped by a stout ice crust with faceted snow over the crust beneath the recent snow.

We recorded ECTP4, ECTP11, ECT20 & a few more propagating results on facets above the crust.

Photo: S. Regan

 

 

 

Avalanche Details: Collapses at Lionhead
Lionhead Range, 2023-12-12

Collapses and unstable ECT results Lionhead

Date
Activity
Snowmobiling

Spent the day up near ski hill with West Yellowstone Avalanche Fundamentals course. 

Our group observed a large collapse below ski hill.

We dug various pits @ 8000' below ski hill and found HS 85-55cm on NW-NE aspects.

The snowpack structure there had weak snow at the ground capped by a stout ice crust with faceted snow over the crust beneath the recent snow.

We recorded ECTP4, ECTP11, ECT20 & a few more propagating results on facets above the crust. 

There was widespread intact surface hoar. 

 

 

 

Region
Lionhead Range
Location (from list)
Ski Hill
Observer Name
S Regan

Upper Elevation Hyalite Naturals

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

Got a view of the bowls behind maid of the mist and above twin falls today. Multiple natural wind slabs, up to size 2, on E and NE aspects, roughly 9500 ft. SS-N-R2D2-I.  My guess is they are roughly 48 hrs old.

Number caught
0
Number buried
0
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year