24-25

GNFAC Avalanche Forecast for Sat Mar 1, 2025

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Triggering a big </span></span></span></span></span></span><span><span><span><strong><span><span>Persistent Slab avalanche</span></span></strong></span></span></span><span><span><span><span><span><span> that breaks on the weak layers that formed in late January is the main concern today. Yesterday in the Lionhead area, Mark and Alex saw two Persistent Slab avalanches that were triggered by snowmobilers during the day (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34421"><span><span><span><strong><span…;, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=TWCNOrvNvLk&amp;embeds_referring_euri=h…;). One of these slides broke up to 5 ft deep (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/25/tracks-going"><span><span><span><…;). This is just the latest in a long string of avalanches on these weak layers over the last 10 days, including multiple close calls (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34413"><span><span><span><span><span><… in Cabin Creek</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34368"><span><span><span><span><span><… in Cooke</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34341"><span><span><span><span><span><… in Tepee Basin</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34367"><span><span><span><span><span><… in Cooke</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34301"><span><span><span><span><span><… in Tepee Basin</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34327"><span><span><span><span><span><… in Taylor Fork</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=tAiSHSEDJhY"><span><span><span><span><s… last Wednesday</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday’s slides clearly show that these weak layers remain reactive. Stay alert even if you’re not riding up near ridgelines. Many of these slides have broken on mid-elevation slopes sheltered from the wind.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>If you want to ride steep slopes today, take the time to do your homework. Dig down below the early February dust layer to look for weak layers and test the snowpack (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=q0IGs0dKpQU"><span><span><span><span><s…’s video shows how to do this</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Make sure you’re riding one at a time on steep slopes and have a partner watching from a safe spot.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>With temperatures a bit warmer this morning and forecasted to rise a bit higher than yesterday, watch out for triggering Wet Loose avalanches on sunny slopes this afternoon.</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>This morning, after a solid overnight refreeze, avalanche conditions are generally safe and you’re unlikely to trigger a slide. The places where you could still trigger a wind slab are becoming fewer and fewer after days of warm temperatures.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>As the day warms up and the snow surface starts to melt, </span></span></span></span></span></span><span><span><span><strong><span><span>Wet Loose avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> will become a concern. With temperatures starting around freezing and forecast to rise 5 degrees warmer than yesterday (and maybe be the warmest so far this season) these could be a real problem today that deserve respect and consideration.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Wet Loose slides could start beneath your feet or sled, or as start as natural point releases, especially where there are exposed rocks above steep slopes. Look out for wet snow at low elevations and on sunny slopes, especially later in the afternoon when slopes have been baking in the sun all day (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34408"><span><span><span><span><span><… Creek road photo</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Be heads up if there are more than a couple inches of wet snow at the surface.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The potential for cornices breaking off is also worth considering before travelling above or below them (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34402"><span><span><span><span><span><… observation</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is LOW first thing this morning and will quickly rise to MODERATE as the day heats up.</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

Snowmobile triggered slide in Airplane Bowl

Airplane Bowl
Lionhead Range
Code
HS-AMu-R2-D2-O
Elevation
9100
Aspect
SE
Latitude
44.72500
Longitude
-111.32200
Notes

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.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Problem Type
Persistent Slab
Slab Thickness
30.0 inches
Vertical Fall
200ft
Slab Width
150.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Snowmobile triggered 3-5' deep hard slab at Lionhead

Targhee Creek
Lionhead Range
Code
HS-AMu-R4-D3-O
Elevation
9200
Aspect
N
Latitude
44.74130
Longitude
-111.37400
Notes

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. 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Slab
Slab Thickness
48.0 inches
Vertical Fall
200ft
Slab Width
200.00ft
Weak Layer Grain type
Faceted Crystals
Weak Layer grain size
2.50mm
Attached Videos
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year