23-24

Sheep Creek Snow Obs

Date
Activity
Skiing

From email: "Skied into Sheep Creek yesterday. (12/14)

Warm and sunny day.  Above freezing temps at 9500' on solar slopes.  Crusts forming.  Lots of Surface hoar otherwise.

Noted one recent large slab avalanche on a SE aspect of Miller Ridge.  Estimated to be about 100' wide and 1-4' deep.  It ran about 1/3 track or 600' vert.  No fresh snow on the debris, so it likely ran at the end of the last snowfall event.

Less collapsing up there yesterday than what we've been experiencing all week, but there was one BIG collapse in one of the meadows in the valley bottom (estimated 300'+ diameter).  Remote triggers are still a serious concern.

Snowpit from a S, SE aspect around 9300'.  HS: 95, ECTP29 at 46."

Region
Cooke City
Location (from list)
Sheep Creek
Observer Name
Beau Fredlund

Woody ridge Obs.

Date
Activity
Skiing

9700’, W, 23 degrees, Hs 100cm 

Ectp16 @60cm  on .5-1.5mm facets 

The average snow depth was around 70cm with slab depth being 25-40 cm. Widespread surface hoar on the surface, all elevations and aspects. 

I didn’t feel any collapsing or see any cracking. 

Region
Cooke City
Location (from list)
Woody Ridge
Observer Name
Ryan Griffiths

Observations and Naturals in Lionhead

Date
Activity
Snowmobiling

We rode up Denny Creek towards Watkins Creek and spent the day below the ridge where we saw two natural avalanches. These avalanches broke 12-18" deep on weak faceted snow above a stiff crust. The first avalanche presumably happened sometime near the end of the last storm cycle (12/11), as it had a few inches of snow on the debris. The second was more recent, in the last 24-36 hours. Both were at 8500' and were on NE and E-facing slopes. 

We dug two snow pits near these avalanches and saw propagation in both on a layer of weak sugary snow buried about a foot deep (ECTP13 & ECTP12). Across the area surface hoar was easy to find on the snow surface. 

Region
Lionhead Range
Location (from list)
LIONHEAD AREA
Observer Name
Zach Peterson

GNFAC Avalanche Forecast for Fri Dec 15, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Triggering large, dangerous avalanches is a very worrisome possibility today. It’s been around four days since the last snowfall and a week since the last more substantial storm. This has brought the likelihood of triggering a slide down a little bit, but we are still a long way from trusting the snowpack. Weak snow near the ground is widespread and people continue to get large collapses and whumpfing across the advisory area (see the</span></span></span></span></span></span><span><span><span><strong><span><span> </span></span></strong></span></span></span><a href="https://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>). On the other hand, it has been three days since our last report of a human triggered avalanche (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=ff4qS1aF9Fs"><span><span><span><strong>…. Blackmore video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>), which reflects that lowering likelihood. However, recent avalanches indicate that any slide that you do trigger is likely going to break near the ground and with thin coverage will probably drag you over rocks (increasing trauma risks) before potentially burying you (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29426"><span><span><span><strong><span… Sky slide</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29477"><span><span><span><strong><span… Basin slides</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29474"><span><span><span><strong><span…. Elephant avalanche</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>As the probability of triggering a slide decreases, decision making becomes more difficult. You might be able to get away with riding a steep slope today. But you might not. Assessing the probability that any particular slope will avalanche will be difficult and has a large uncertainty. Entering avalanche terrain today is not a decision to make lightly. Choosing to continue to avoid slopes steeper than 30 degrees is a very reasonable option.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Be very cautious if you do decide to ride steep slopes. Do your homework by reading </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… observations</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/weather"><span><span><span><span><span><u><… data</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. Dig a snowpit. Be ready and alert for signs that you should back off (e.g. cracking, collapsing, recent avalanches, or poor stability test scores). Assess the terrain and think about the consequences of triggering a slide. Have an escape and rescue plan in place.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Human triggered avalanches are possible and the avalanche danger is rated MODERATE.</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.

Natural Avalanche on Mount Bole

Mt. Bole
Northern Gallatin
Code
N-R2-D2
Aspect
NE
Latitude
45.41600
Longitude
-110.99800
Notes

Natural avalanche on Mt. Bole. Observed taken 12/14/23. Avalanche likely released the previous weekend, around 12/9/23. 

From obs: "We were ice climbing on Mummy 3 and 4 yesterday and as we looked across the valley to Mount Bole, we could see evidence of avalanche activity on the NE aspect of the peak. It looked quite big in length but could tell a depth from that far away." 

 

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From obs: "We were ice climbing on Mummy 3 and 4 yesterday and as we looked across the valley to Mount Bole, we could see evidence of avalanche activity on the NE aspect of the peak. It looked quite big in length but could tell a depth from that far away." Photo: R. Dorn

Photo taken 12/14/23. Avalanche likely released the previous weekend, around 12/9/23. 

Northern Gallatin, 2023-12-15

Cracking and Collapsing North of Cooke City

COOKE CITY
Cooke City
Code
Latitude
45.02020
Longitude
-109.93800
Notes

From obs: "Today (12/14) I was skiing a south facing slope between 8500-9500 ft near Mt Henderson. I observed at least ten large collapses, some of which sent cracks 30 feet long. This slope had a shallow snowpack relative to the rest of the area"

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