24-25

Read more about Old Portal wet slide

This older wet slide is a good example of what to look out for especially at low elevations.

Forecast link: GNFAC Avalanche Forecast for Fri Feb 28, 2025

Northern Gallatin, 2025-02-27

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Example of wet snow

Date

Thu, 02/27/2025 - 12:40

Activity

Snowmobiling

Riding in this morning, we saw this older wet slide on the Portal Creek road down low at about 6400' in elevation on a south facing slope by lots of exposed rocks. For reference, Gallatin River is 5800' in this area.

We didn't see any fresh ones on our way out at about 2:30.

The most likely places for big wet slides are slopes or areas with exposed rocks and cliffs. Generally these wet slides happen a little predictably in the afternoon as the snow gets wet. We know what time of day they'll happen, but it's hard to know exactly when they'll release, so watch out when the snow is obviously wet if traveling under slopes like this.

You don't need to worry about them in the morning, when the snow is frozen. What a nasty avalanche with sticks, rocks, and dirt in it?

Region

Northern Gallatin

Location (from list)

Portal Creek

Observer Name

Staples and Gidley

Three Concerns, Beehive Basin - 27 Feb 2025

Read more about Three Concerns, Beehive Basin - 27 Feb 2025

Watch out for these three things in Beehive

Date

Thu, 02/27/2025 - 11:00

Activity

Skiing

We toured up to the prayer flags on the Ridge above Beehive Basin, got a good view around the basins, dug to the south of the cornice line there, and descended the south side of Tyler's path. Clear skies, slightly above freezing temperatures, and calm wind. The surface conditions were better than I would have expected, with dry snow/ no crust on all aspects other than those tilted south-facing. The lower elevation snow in the basin was getting wet by the time we departed at 2 PM. I would expect some wet loose avalanches this afternoon. No wind loading or signs of instability observed.

Our pit showed good stability (ECTX). This fits with the pattern of avalanche activity driven by snowy and windy periods that quickly improves with milder conditions in the mountains around Bozeman and Big Sky. We are optimistic about the nice weather and generally safe conditions coming up this weekend.

Watch out for these three things and you will be looking good to get into a fair amount of fun terrain this weekend in the Bridger, Northern Madison and Northern Gallatin Ranges, and the Centennial Mountains in Island Park:

Wind-loaded terrain where you could find lingering wind slab instability.
Cornices: They are really big currently, and we may see a few breaking off with the warm temperatures this weekend. These can collapse much farther back from the edge than expected.
Wet snow: With forecasts calling for above freezing temperatures under sunny skies, we expect wet loose snow avalanches to slide on sunnier (south and west) aspects. These will generally be small and involve only the recent snow, but they can still injure or buried skiers, riders and climbers in steep terrain or gullies where they can push backcountry travelers into terrain traps (trees, gullies, cliffs, rocks).

Isolated instability can have significant consequences on larger or committing terrain objectives. Stack the deck in your favor by digging down a few feet and testing the snowpack so you don't get surprised.

Region

Northern Madison

Location (from list)

Beehive Basin

Observer Name

Zinn, Hoyer, Darby

Read more about Cornice triggered slab Hyalite

Cornice release above the headwaters of storm castle creek which triggered a slab, east facing aspect. Looked to be several feet deep and ran a long way.

Avalanche Details: Cornice Fall Wind Slab Avalanche in Storm Castle Creek
Forecast link: GNFAC Avalanche Forecast for Thu Feb 27, 2025

Northern Gallatin, 2025-02-27

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Read more about Hyalite Obs

Cornice triggered slab avalanche, maybe wind slab. Hard to say.

Avalanche Details: Cornice Fall Wind Slab Avalanche in Storm Castle Creek

Northern Gallatin, 2025-02-27

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GNFAC Avalanche Forecast for Thu Feb 27, 2025

Snowpack and Avalanche Discussion

Sunday, Monday, Tuesday precipitation totals are:

<ul>
<li>1.3” of snow water equivalent near Cooke City</li>
<li>1” of snow water equivalent in the Taylor Fork area of the S. Madisons</li>
<li>0.5” inches of snow water equivalent near West Yellowstone and Lionhead</li>
</ul>

Persistent slab avalanches - This problem feels more like booby traps that aren’t widespread but will pop up and surprise you when you least expect it. It hasn’t been a widespread problem near Cooke, but two notable slides happened <a href="https://www.mtavalanche.com/node/34367"><… Saturday</a> and on <a href="https://www.mtavalanche.com/node/34368"><… </a>at 8800 feet on the northeast side of Mt Abundance. Both were 2-3 ft deep and 150-200 ft wide.

BEFORE this recent snow two slides happened in <a href="https://www.mtavalanche.com/node/34336">Teepee Basin</a> and one at <a href="https://www.mtavalanche.com/node/34267"><…; generally about 2 feet deep and 100 feet wide. These slides are scary because they can happen on smaller slopes sheltered from the wind at lower elevations where you might think conditions are safer but they are not.

Wind slab avalanches - Strong winds blew Sunday, Monday, and Tuesday when snow was falling, especially near Cooke which saw widespread drifting and some surprisingly large wind slab avalanches like one <a href="https://www.mtavalanche.com/node/34397"><… Crown Butte</a> on Tuesday and another that fully buried a rider on the <a href="https://www.mtavalanche.com/node/34395"><… side of MIller Mountain</a> the same day. With lighter winds yesterday and today, wind slabs will be slowly stabilizing, but they are tricky because some may be stable while others may still need another day or so to stabilize.

The avalanche danger overall is MODERATE, because many slopes have stable snow, but others can still easily produce an avalanche. Today is tricky because the likelihood of triggering a wind slab is going down but some booby traps of persistent slab avalanches are lurking out there. Riding slopes less than 30 degrees in steepness is always a great way to avoid avalanches.

ALSO, watch for some small wet loose avalanches on sunny slopes especially ones with exposed rocks or cliff bands.

Sunday, Monday, Tuesday precipitation totals are:

<ul>
<li>0.8” of snow water equivalent near Big Sky</li>
<li>0.5” of snow water equivalent in Hyalite</li>
<li>0.4” of snow water equivalent in the Centennials near Island Park</li>
<li>0.3” of snow water equivalent in the Bridgers</li>
</ul>

Wind slab avalanches are still something to watch for as strong winds blew each of those days. Wind slabs have surprised me more than any other type of avalanche because you can test some that won’t move but then you jump on another that releases. Today many will be stable, but there will certainly be a few wind slabs that could still be triggered. Cornices have gotten pretty big and can trigger avalanches like <a href="https://www.mtavalanche.com/node/34402">one seen in Hyalite yesterday</a>. Stay far back from them as they typically break further back than you’d expect.

Watch for wet loose avalanches on sunny slopes especially ones with exposed rocks or cliff bands.

Today previously wind loaded slopes have a MODERATE danger. Non wind loaded slopes have generally safe avalanche conditions and a LOW danger.

Read more about GNFAC Avalanche Forecast for Thu Feb 27, 2025

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Hyalite Obs

Date

Thu, 02/27/2025 - 01:05

Activity

Skiing

Toured much of the Hyalite zone yesterday. Winds calmed, sun came out mid day. 1” of new snow and 3” the day before. Skiing was great. Saw a couple huge cornices that had broken off. From the top of Devide peak we observed what looked like a cornice release above the headwaters of storm castle creek which triggered a slab, east facing aspect. Looked to be several feet deep and ran a long way. No other signs of instability observed. Great skiing. Solar aspects were saturated by the afternoon.

Region

Northern Gallatin

Observer Name

Peter