24-25

natural avalanche activity, Cooke City

Date
Activity
Snowboarding

Quite a few natural avalanches observed north of Cooke City today.   Photos attached of:

1:  NE facing, 10,000, Miller Ridge

2:  E facing, 9900', Bull of the Woods Pass

3:  NE facing, 9700', Miller Ridge

4:  E facing, 10,200' Scotch Bonnet Mtn.

5:  E facing, 10,000 Mt. Henderson

6-8: NE- N facing, 10,000' Mt. Henderson

9:  NE facing, 10,000' Sheep Creek.

There was also a large avalanche event on the E aspect of Fisher Mtn, which I didn't photograph.  But there were some other skiers nearby who likely had a good view of it.  

Also, we had 4 large collapses today.  One on a southerly aspect, and the other 3 on NE aspects.  All around 9800'.

 

 

Region
Cooke City
Location (from list)
COOKE CITY
Observer Name
B. Fredlund

Natural Avalanche on Arden Pk.

Date
Activity
Skiing

Observed from Flanders this morning. Presumed recent natural slide around ~9950 ft. on a E/NE aspect. Hard to tell from a distance, but cornice interference and/or wind loading are possible culprits. Poor image quality, but there may be more debris piles along the ridgeline to the south.

Region
Northern Gallatin
Location (from list)
Maid of the Mist
Observer Name
E. Webb

Natural avalanche, Saddle Peak

Saddle Peak
Bridger Range
Code
N-R2-D2.5
Elevation
9100
Aspect
E
Latitude
45.79430
Longitude
-110.93600
Notes

There was a natural avalanche on Saddle Peak on Wednesday, December 18. Strong winds ripped through new snow and loaded many slopes. The avalanche broke an estimated 250 feet wide, 1-3 feet deep, and ran 1500 vertical feet.

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
2
D size
2.5
Problem Type
Wind Slab
Slab Thickness
24.0 inches
Vertical Fall
1500ft
Slab Width
250.00ft
Images
Natural on Saddle- zoomed
Natural Avalanche on Saddle Peak
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
24-25

GNFAC Avalanche Forecast for Thu Dec 19, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><strong><span><span>A persistent slab avalanche problem</span></span></strong></span></span></span><span><span><span><span><span><span> exists throughout the forecast area with a weak layer of faceted snow buried 1-2 feet deep on nearly all slopes. This weak layer formed on top of the snowpack during dry weather in the first two weeks of December, and in some places it includes a layer of </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/32524"><span><span><span><span><span><… hoar</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. A few small storms capped this weak layer, and then snowfall from Saturday night through Tuesday built a slab on top of it. That snow also dramatically improved skiing and riding conditions.</span></span></span></span></span></span></p>

<ul>
<li><a href="https://www.mtavalanche.com/node/32540"><span><span><span><span><span><… group</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> in Beehive Basin yesterday found this layer producing unstable results in snowpack tests.</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>A group in </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/32523"><span><span><span><span><span><…; had a similar observations.</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>My riding partners and I found this weak layer </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><… Sawtelle Peak</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> near Island Park on Tuesday.</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>A </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/32522"><span><span><span><span><span><… near Cooke City</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> yesterday experienced shooting cracks.</span></span></span></span></span></span></li>
<li><span><span><span><span><span><span>Dave and his partner found it </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/32482"><span><span><span><span><span><… Cooke City</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span> on Monday &amp; Tuesday</span></span></span></span></span></span></li>
</ul>

<p><span><span><span><span><span><span>See the full list of observations </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list"><span><span><span><…;

<p><span><span><span><strong><span><span>Yesterday’s winds </span></span></strong></span></span></span><span><span><span><span><span><span>left few slopes untouched - loading many with wind blown snow or creating a more cohesive slabs on other slopes without obvious drifting. Whether a wind slab is present or not, the end result is that persistent slab avalanches remain likely.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>The challenge today</span></span></strong></span></span></span><span><span><span><span><span><span> is that you may not get direct feedback from the snowpack with obvious signs like shooting cracks or </span></span></span></span></span></span><a href="https://avalanche.org/avalanche-encyclopedia/#collapse-or-whumpf"><span…;. Yesterday in </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/32524"><span><span><span><span><span><… Basin near Big Sky</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, Ian and I couldn’t find any of those obvious clues, but a quick snowpit and an extended column test immediately showed us the problem.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Recent avalanche activity (view all activity </span></span></span></span></span></span><a href="https://www.mtavalanche.com/avalanche-activity"><span><span><span><stro…;) has been a bit on the small side, but I expect </span></span></span></span></span></span><span><span><span><strong><span><span>avalanches today to be larger</span></span></strong></span></span></span><span><span><span><span><span><span> as a result of yesterday’s winds creating a more cohesive slab.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The combination of a widespread weak layer, recent snowfall followed by major wind loading, recent avalanche activity, and consistently poor snowpack test results indicates dangerous avalanche conditions. For this reason the avalanche danger is CONSIDERABLE. Seek out slopes less than 30 degrees in steepness relatively sheltered from the wind for the best and safest conditions today.</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

Unstable test results in Beehive

Date
Activity
Skiing

My friend and I toured in Beehive this morning.  Was calm early but the winds picked up late morning and were whipping around pretty good as we left mid-afternoon.   Dug a quick pit at ~9300 ft along the upper east side of the west ridge of Beehive Basin (lower end in the timber before it gets exposed in the upper basin).  Snowpack was ~120cm deep, approximately half of that being from the last storm series.  We got an ECTP11 that was a smooth propagation which failed ~65 cm up from the ground at the interface of the new storm snow.  This reinforced the instability we expected to find and we stuck to a few laps of the smaller / gentler east facing meadows.  Skiing was great though!  With the wind today I’m sure the instability will only get worse before it gets better…

Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
William Moore

Skier triggered wind slab in Frazier Basin

Frazier Basin
Bridger Range
Code
HS-ASr-R1-D1-I
Elevation
8500
Aspect
N
Latitude
45.92330
Longitude
-110.98000
Notes

HS-ASr-R1-D1-I

Fraizer Basin, 8500', North facing, 35-37 degree slope, 1pm

30' wide, 6'' deep, ran 150', In the love chutes, Fraizer Basin 

1Finger wind slab sitting on a 4Finger hardness break.  Triggered from 30' above the crown, ran slowly.  A majority of the slab rode back up on the surface 50' below the crown.  Bed surface felt like small grained facets under skis, didn't look too close. Small and localized cracks and collapses were felt and seen throughout the day in the same location. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
1
D size
1
Bed Surface
I - Interface between new and old snow
Problem Type
Wind Slab
Slab Thickness
6.0 inches
Vertical Fall
150ft
Slab Width
30.00ft
Slab Layer Grain Type
Faceted Crystals
Images
HS-ASr-R1-D1-I, Fraizer Basin, Bridger Range.
Snow Observation Source
Skier triggered wind slab, Northern Bridgers
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
24-25

Skier triggered wind slab, Northern Bridgers

Date
Activity
Skiing

HS-ASr-R1-D1-I

Fraizer Basin, 8500', North facing, 35-37 degree slope, 1pm

30' wide, 6'' deep, ran 150', In the love chutes, Fraizer Basin 

1Finger wind slab sitting on a 4Finger hardness break.  Triggered from 30' above the crown, ran slowly.  A majority of the slab rode back up on the surface 50' below the crown.  Bed surface felt like small grained facets under skis, didn't look too close. Small and localized cracks and collapses were felt and seen throughout the day in the same location. 

Region
Bridger Range
Location (from list)
Frazier Basin
Observer Name
Ty Guarino
Subscribe to 24-25