24-25

Date

Fri, 02/28/2025 - 16:05

Activity

Snowmobiling

We rode throughout most of the Lionhead area looking for and assessing a weak layer from late January. This layer produced avalanches last week that we saw. It also buried a rider last Sunday in Teepee Creek. It caught a ride yesterday in Cabin Creek.

In most of our snowpits, the layer was gaining hardness
In most of our snowpits, the layer was either not breaking in stability tests or was very stubborn.

We were scratching our heads because the layer seemed active but we could find any evidence that it was still a major problem, UNTIL

A rider triggered a huge avalanche in the uppermost reaches of Targhee creek. We discovered it on our way out. The best we could tell looking at their tracks was that they had no idea they triggered it, even though part of their tracks were swept away.

Also, on our way out we saw an avalanche in Airplane Bowl that had been triggered during the day today. This slide also broke on the persistent weak layers, 2-3' deep, 150' wide.

HERE'S THE DIMEMMA - On many slopes, the likelihood of triggering an avalanche on this weak layer is low. On some slopes, the likelihood of triggering one is high. Because the distribution of this problem is spotty, the damage is Moderate but that rating is deceiving.

HERE'S THE OTHER CHALLENGE - You won't see any obvious signs of unstable snow like cracking or collapsing. You probably won't see any red flags in a snow pit. There will be no warning until an avalanche happens.

TRAVEL ADVICE - We haven't been able to find a clear pattern for where these avalanches will happen and where they won't. It's a scary and tricky situation and these things are like booby traps. There are three options:

Roll the dice and hope for the best, OR
If getting onto steeper slopes, choose ones with a clean runout with no trees, rocks, or gullies and make sure your partners are watching you from a safe location, OR
Ride only on slopes less than 30 degrees in steepness where most avalanches do not happen.

Wet snow - south facing slopes were getting very wet. We saw a few wet loose slides from yesterday near Targhee Peak. One south facing slope we crossed was wet for at least a foot or two into the snowpack.

Region

Lionhead Range

Location (from list)

Targhee Creek

Observer Name

Staples & Marienthal

GNFAC Avalanche Forecast for Fri Feb 28, 2025

Snowpack and Avalanche Discussion

Persistent Slab avalanches breaking 2-3 ft deep on weak layers buried in late January remain the primary concern. There was a close call in Cabin Creek yesterday. Snowmobilers triggered a good size slide, but fortunately managed to avoid being buried (<a href="https://www.mtavalanche.com/node/34413"><…;). This slide seems to follow the pattern that has emerged from the steady stream of slides triggered over the last 10 days - breaking on mid-elevation slopes sheltered from the wind where you might think conditions are safer, but they are not (<a href="https://www.mtavalanche.com/node/34368"><… in Cooke</a>, <a href="https://www.mtavalanche.com/node/34341"><… in Tepee Basin</a>, <a href="https://www.mtavalanche.com/node/34367"><… in Cooke</a>, <a href="https://www.mtavalanche.com/node/34301"><… in Tepee Basin</a>, <a href="https://www.mtavalanche.com/node/34327"><… in Taylor Fork</a>, <a href="https://www.youtube.com/watch?v=tAiSHSEDJhY"><s… last Wednesday</a>).

Triggering large slides clearly remains possible, but the likelihood of triggering a slide on any particular slope isn’t super high. Not every slope harbors the worrisome weak layers and they aren’t reactive on every slope where they are present. This makes for tricky travel advice.

As I see you have three options today -

<ol>
<li>Guess which slopes are safe, cross your fingers and hope for the best. </li>
<li>Continue to avoid slopes steeper than 30 degrees. </li>
<li>Dig down a bit below the dirt layer buried in early February and assess the weak layer (<a href="https://www.youtube.com/watch?v=q0IGs0dKpQU"><s…’s video shows how to do this</a>)</li>
</ol>

Option 1 isn’t a great plan, but either of the other two are reasonable and could lead to a great day enjoying the beautiful weather and good snow that is still out there.

Wind Slabs that formed earlier this week will have generally bonded and will only be an isolated concern. With temperatures similar to yesterday and a good refreeze overnight, any wet snow concerns will be small and likely isolated to sunny slopes with exposed rocks this afternoon.

The avalanche danger is MODERATE around West Yellowstone and Cooke City.

The snowpack is generally stable and triggering a large avalanche is unlikely today. Still there are a couple things to watch out for -

Cornices have been breaking off with the warm temps (<a href="https://www.mtavalanche.com/node/34402"><… observation</a>). It’s hard to predict exactly when they’ll break and they often pull back surprisingly far. Be careful travelling on ridgelines above them, or crossing beneath.

There may also be some isolated wind slabs below that could still be triggered. Look out for these beneath ridgelines and cornices (<a href="https://www.mtavalanche.com/node/34402"><… from Hyalite</a>).

Watch out for wet snow at low elevations and on sunny slopes later this afternoon (<a href="https://www.mtavalanche.com/node/34408"><… of a Loose Wet avalanche onto the Portal Creek road</a>). With a forecast for similar high temperatures to yesterday and a solid refreeze this morning, I don’t expect these to be a widespread concern. Still, don’t let your guard down entirely. If temps rise higher than forecasted, Loose Wet avalanches will be more widespread and larger.

Despite these isolated concerns, avalanche conditions are generally safe and the avalanche danger is LOW.

Read more about GNFAC Avalanche Forecast for Fri Feb 28, 2025

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Cooke City Weekly Update - 28 Feb 2025

Read more about Cooke City Weekly Update - 28 Feb 2025

Read more about Rider triggered slide at Cabin Creek 2

From IG message: "Getting word that a group triggered a decent slide today out at cabin creek. I’ll attach the coordinates to the general area, to the best of my knowledge.

44.86484, -111.22023

No burials. They were able to outride if. But thought I’d send coordinates in case you guys were gonna be in the area and wanted to check it out."

Avalanche Details: Rider triggered slide at Cabin Creek

Southern Madison, 2025-02-28

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Read more about Rider triggered slide at Cabin Creek 1

From IG message: "Getting word that a group triggered a decent slide today out at cabin creek. I’ll attach the coordinates to the general area, to the best of my knowledge.

44.86484, -111.22023

No burials. They were able to outride if. But thought I’d send coordinates in case you guys were gonna be in the area and wanted to check it out."

Avalanche Details: Rider triggered slide at Cabin Creek
Forecast link: GNFAC Avalanche Forecast for Fri Feb 28, 2025 GNFAC Avalanche Forecast for Sat Mar 1, 2025

Southern Madison, 2025-02-28

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Weather and Avalanche Log for Fri Feb 28, 2025

Read more about Weather and Avalanche Log for Fri Feb 28, 2025

Wet loose activity in Mill Creek

Date

Thu, 02/27/2025 - 17:15

Just chiming in to report widespread wet loose activity on solar aspects between 6000 and 9500 feet in the Mill Creek area of the Absarokas - rollerballs started around 11am. Some big wet sluffs were releasing near cliff bands shortly thereafter. Felt like mid/late April.

Region

Out of Advisory Area

Location (from list)

Other place

Observer Name

T Benson

Read more about Spanky's Profile - 27 February 2025

Northern Madison, 2025-02-27

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Rider triggered slide at Cabin Creek

Cabin Creek

Southern Madison

2/27/2025

Code

Elevation

9000

Aspect

Latitude

44.86480

Longitude

-111.22000

Notes

From IG message: "Getting word that a group triggered a decent slide today out at cabin creek. I’ll attach the coordinates to the general area, to the best of my knowledge.

44.86484, -111.22023

No burials. They were able to outride if. But thought I’d send coordinates in case you guys were gonna be in the area and wanted to check it out."

Number of slides

Number caught

Number buried

Trigger

Snowmobile