24-25

Large Persistent Slab Avalanche in Hayden Creek

Hayden Creek
Cooke City
Code
SS-N-R3-D3-O
Aspect
NE
Latitude
44.99520
Longitude
-109.90800
Notes

While touring today, we saw a deep slab avalanche at the southern end of the Hayden Creek drainage. NE aspect. It seemed to be recent, likely in the last day or so.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
3
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Deep Slab Avalanche in Hayden Creek

Date
Activity
Snowboarding

While touring today, we saw a deep slab avalanche at the southern end of the Hayden Creek drainage. NE aspect. It seemed to be recent, likely in the last day or so.

Region
Cooke City
Location (from list)
Hayden Creek
Observer Name
N Mattes

Sheep Creek Obs

Date
Activity
Skiing

Here are our observations from Cooke City today. Our plan was to tour up the south side of Miller Mountain as far as we felt comfortable. Winds were mostly calm during the day, and temperatures were darn-right cold all day, even on southerly aspects. It was -26F when we pulled into town.

The sheep creek drainage had a lot of evidence of prior wind transport, most non-sheltered aspects had textured snow. We dug a pit at 9600’, HS was 190cm! At 150cm above the ground, we encountered a 1cm thick melt-freeze crust with small facets forming over it’s surface. We also noted 4-finger basal facets all the way at the ground.

Our ECT produced nothing terribly remarkable. ECTN25 and ECTN26 on the melt-freeze crust. It could be a layer to look out for in the near-future. The snow above treeline began to stiffen, so we ripped skins around 10k feet and had a lovely ski down.
 

Region
Cooke City
Location (from list)
Sheep Creek
Observer Name
R Parsons

No activity with poorer than expected riding conditions

Date
Activity
Snowmobiling

1 to 3 inches of new snow on top of a very hard base nearly every where with evidence of past wind affect. Condition were Sunny with calm winds and temperatures in the single digits. we saw no avalanche activity cause by snowmobilers or people actively skiing the Hollywood wall. Lots of people around.

Region
Bridger Range
Location (from list)
Battle Ridge
Observer Name
Sandy Jett. Arianna Knight

History Rock Obs

Date
Activity
Skiing

It was a beautiful, cold, clear-few, morning with very little wind. 

HS ~140cm on an E/SE aspect at 7500'. HN24 of ~10-20cm between 7500-8500'. HN is light and unconsolidated with no evidence of wind transport. A thin, breakable MF crust was observed in similar elv. bands in east-facing trees below the new snow. Two hand shears had planar results on this layer but snow above the crust did not have slabby characteristics. No cracking or collapsing was observed. L-ASc-R1-D1-I sluffs occurred while skiing.

Region
Northern Gallatin
Location (from list)
History Rock
Observer Name
E. Webb

Pebble Cr YNP Observation

Date
Activity
Skiing

Toured into Pebble Cr drainage. 

2 to 4" of new, low density snow. 

Saw evidence of wind loading and two older, small slides on N facing aspects of some W - E sub ridge lines. Slides both appeared to be from wind loaded snow that broke right below the ridge line on the leeward side. 100 to 150' wide, 18" deep and running for 100 to 200'.

No cracking or collapsing found on any aspect during the tour and we couldn't get anything to move.

Nice snow wherever you could find a wind protected area. 

Region
Out of Advisory Area
Location (from list)
Barronette Peak
Observer Name
C. Robinson

GNFAC Avalanche Forecast for Sat Jan 25, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Yesterday’s storm overperformed expectations in the mountains around Bozeman and Big Sky, with up to 8” of new snow piling up pretty quickly. Thin slabs were reported breaking easily in the new snow in the Bridgers and Hyalite (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33834"><span><span><span><strong><span…;). </span></span></span></span></span></span><span><span><span><strong><span><span>Wind Slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are the primary concern today. Avalanches will be the most easily triggered and deepest on wind-loaded slopes. But don’t entirely discount slopes without much wind effect. Yesterday, Alex found surface hoar buried under the new snow on Buck Ridge (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33832"><span><span><span><span><span><…;). Weak layers have also been found under the new snow in Divide Basin (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33810"><span><span><span><span><span><…;) and Beehive Basin (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33824"><span><span><span><span><span><…;), so we suspect they’re fairly widespread. Remarkably thin, soft slabs can avalanche when they’re breaking on these persistent weak layers. Pay close attention to how deep the new snow is and think about the consequences of that new snow avalanching before getting on a steep slope. Watch for shooting cracks and recent avalanches as the clearest signs that the new snow is unstable.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Avalanches could also break under wind drifts that formed earlier in the week. If you’re happy with the stability of the most recent snow, dig down a couple feet to make sure these older wind slabs are bonded too.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>There has been less new snow (2-3”) around West Yellowstone, Island Park, and Cooke City, but human triggered avalanches are still a very real possibility today. There is a wide range to the likelihood and size of the potential slides today. There may be pockets where the newest snow has drifted deeply enough to avalanche. If you find a drift deeper than about 6”, expect it to be easily triggered. Deeper </span></span></span></span></span></span><span><span><span><strong><span><span>Wind Slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> could also break in older wind drifts that formed over the last week. Either steer clear of new and old wind drifts or watch for signs of instability and dig a snowpit to assess how well they’ve bonded before getting onto steep windloaded slopes.</span></span></span></span></span></span></p>

<p><span><span><span><strong><span><span>Persistent Slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> breaking deep in the snowpack become less likely everyday without substantial snowfall and we haven’t seen slides on these weak layers recently, but we don’t quite trust them yet. The last big avalanches broke early last week near Cooke City (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33528"><span><span><span><span><span><…; and </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33544"><span><span><span><span><span><…;) and one in the </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/33584"><span><span><span><span><span><… Madison Range</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. Keep the possibility of triggering one of these big slides in the back of your mind.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is MODERATE.</span></span></span></span></span></span></p>

KING AND QUEEN OF THE RIDGE

Do you like to hike? Do you like to ski/ride? Then the King & Queen of the Ridge on 2/1 is for you. Hike, ride and raise money for the Friends of the Avalanche Center at Bridger Bowl this year! Join this fun event to promote and support avalanche safety and awareness! Fundraising prizes for the top 5 individuals who raise over $500.