24-25
Gallatin Canyon
We toured from Gallatin River up to 8000'. Generally strong, deep, snowpack. We did not look at north-facing snow at the lowest elevations - that could be weak but doesn't have much of a load. Pretty amazing to have such good coverage all the way down the to river level.
Unconsolidated new snow Northern Madison
Got an early start on a tour in the Northern Madison range, exploring subalpine terrain.
We observed approximately 15-20” of fresh snow which was unconsolidated, and didn’t observe any wind affected areas, even at mountain tops and ridge tops. Also did not see any cracking as we broke trail and skied over test convexities. The snow was quite light as well, and new snow appeared to be right side up.
Snow pit results were unremarkable on a SE aspect at 9k feet.
Lots of snow available for transport!
Storm Slab between Blackmore and Elephant
Test scores and Intentionally triggered avalanches in Lick Crk
11:40
8017ft
147 SE
HST 85cm
25 degrres
ECTN 14 20 down
CT 11 q1 20 down
ECTN 19 20 down
CT5 q2 20down
12:10
8129ft
33 NE
HST 165 cm
10 Degrees
ECTN 26 34 down
CT 16 Q1 32 down
ECTN 19 30 down
SS-ASc-R1-D.5-I
310 Degrees NW
8129ft
Avalanche up Lionhead
Avalanche in Lionhead. Broke on wind slab then triggered persistent slab underneath.
Stable but busy on Ellis
Skied Ellis yesterday, good snow but quite busy. Dug a pit at ~8000’, ENE aspect. No failure in ECT with snowpack from 130-140cm. Bit of a crust/layer ~ 30cm below surface on open, exposed slopes but not present in forest. Minor wind impact on top slopes, zero wind impact below ~7800’.
GNFAC Avalanche Forecast for Sun Feb 16, 2025
<p>Human-triggered avalanches are likely on steep slopes with fresh drifts of wind-loaded snow in the mountains around Bozeman and Big Sky.</p>
<p><span>Today's primary concern is </span><strong>wind slab avalanches </strong><span>breaking 1-3 feet deep</span>. The Big Sky Ski Patrol reported rapid wind loading yesterday, triggering many wind slab avalanches during mitigation work. Expect similar conditions in the backcountry today. Recent backcountry avalanche observations include a snowmobiler-triggered slide on Buck Ridge yesterday (<a href="https://mtavalanche.com/node/34193">details and photo</a>), thin wind slabs triggered by a group up Storm Castle Creek on Friday (<a href="https://www.mtavalanche.com/node/34169"><span>observation</span></a>) and several small wind slabs reported on Thursday in North Bridger Range, near the ice climbs in the Main Fork of Hyalite Creek and on Mt. Blackmore (<a href="https://www.mtavalanche.com/node/34160"><span>N. Bridger’s observation,</span></a> <a href="https://www.mtavalanche.com/node/34144"><span>main fork of Hyalite observation</span></a>, <a href="https://www.mtavalanche.com/node/34137"><span>Mt. Blackmore observation</span></a>).</p>
<p><strong>Storm slab avalanches </strong>are a secondary problem. They will break within the layers of new snow as precipitation rates peak. While these will not be as large as wind slab avalanches, both may be large enough to injure or bury skiers and riders. Loose snow avalanches (sluffs) will be dangerous where they can tumble backcountry travels through technical terrain.</p>
<p>Seek out slopes sheltered from the effects of the wind and recognize recent avalanche activity and shooting cracks as critical information about a slope’s instability. Avoid slopes steeper than 30 degrees below cornices and where you observe signs of significant wind loading.</p>
<p>The danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</p>
<p>Three-day storm totals nearing a foot of snow with an inch of <a href="https://avalanche.org/avalanche-encyclopedia/#snow-water-equivalent-swe… water equivalent</span></a> and fluffy snow drifting into unstable slabs create dangerous avalanche conditions on wind-loaded slopes in the mountains around West Yellowstone, Island Park, and Cooke City.</p>
<p><strong>W</strong><strong>ind slab avalanches</strong> breaking 1-2 feet deep are the primary problem. Yesterday, ski guides working south of Cooke City reported numerous avalanches (<a href="https://mtavalanche.com/node/34189"><strong><span>photos and observation</span></strong></a>). With heavier precipitation rates, instability will spread from wind-loaded slopes to all steep terrain in the form of storm slab and loose snow avalanches.</p>
<p><strong>Persistent slab avalanches</strong> failing on buried weak layers 2-3 feet deep remain an area of uncertainty. They are most likely on wind-loaded slopes where the snow layer resting on weak layers is thicker and more cohesive. Last week, Alex and I saw four avalanches that broke on layers of sugary facets and feathery surface hoar buried in late January. Avalanche activity on these layers hasn’t been widespread, but activity in the <a href="https://www.mtavalanche.com/node/34156"><span>Lionhead area,</span></a> <a href="https://www.mtavalanche.com/images/25/cornice-triggered-avalanche-miner… City</span></a>, and <a href="https://www.youtube.com/watch?v=wZ3k35z5Ej8&embeds_referring_euri=h… Fork</span></a> keeps it on the radar.</p>
<p>Avoid wind-loaded slopes where avalanches are more likely and would be larger. Seek out non-wind-loaded terrain, stay alert for signs of instability (recent avalanches, shooting cracks, and collapsing) and dig down three feet to test for instability before committing to steep slopes. The danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar