22-23

GNFAC Avalanche Forecast for Sat Apr 1, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>You can trigger an avalanche today in wind drifts formed either from the snow that fell last night or the snow that fell over the last week. Drifts in today’s new snow will be thinner, but more easily triggered. These slides could still easily be 1-2 ft deep in places where it’s snowed more, which is plenty of snow to bury you in the wrong terrain or carry you into rocks or trees. The older drifts will be a bit harder to trigger, but also break deeper and larger. Yesterday, a fresh natural wind slab was seen on Cedar Mountain (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-cedar-mountain"><span><sp…;) and riders in Portal Creek triggered a 2-3 ft deep avalanche from 100 ft away (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28887"><span><span><span><strong><span… and photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). The slide in Portal Creek likely broke on a weak faceted layer beneath last week’s snow that has remained unstable. Watch for shooting cracks as a clear sign that the newly wind drifted snow is ready to avalanche. Dig down to test the top 3 ft feet of the snowpack before getting onto steep slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Triggering deep slab avalanches also remains a scary possibility. On Thursday, a snowboarder took a big ride over huge cliffs in a slide that broke deep in the Lone Lake Cirque, near Big Sky resort (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/lone-lake-cirque-slide"><span><sp…;). These deep slabs are the prototypical low-frequency, high consequence concern. It’s been over a week since other deep slabs were triggered (</span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28798"><span><span><span><strong><span>… Mtn.</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28785"><span><span><span><strong><span>… Pass</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>), but if you do trigger one it will be very dangerous. Your options are either to avoid steep slopes entirely or to roll the dice and hope you aren’t the one that gets really unlucky. Stack the deck in your favor by choosing smaller slopes without additional hazards in the runout zone, going one at a time, and having a partner watching from a safe spot.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is rated MODERATE on all slopes.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs). </span></span></span></span></span></span></p>

<p>&nbsp;</p>

This natural avalanche was observed in the afternoon around 1500. It was not seen earlier in the day and is thought to occurred at some point after 1200. It was seen from a distance on Pioneer mountain. It occurred on an E facing slope around 9600’. Active wind transport was noted on the ridge line above the avalanche. It looked to be around a R3-D2. Photo: R. Freeman

Northern Madison, 2023-04-01

Natural wind slab on Cedar Mountain

Cedar Mtn.
Northern Madison
Code
N-R3-D2
Elevation
9600
Aspect
E
Latitude
45.22820
Longitude
-111.49900
Notes

This natural avalanche was observed in the afternoon around 1500. It was not seen earlier in the day and is thought to occurred at some point after 1200. It was seen from a distance on Pioneer mountain. It occurred on an E facing slope around 9600’. Active wind transport was noted on the ridge line above the avalanche. It looked to be around a R3-D2.

Number of slides
1
Number caught
0
Number buried
0
Trigger
Natural trigger
R size
3
D size
2
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Remotely trigged small slide in Portal Creek

Portal Creek
Northern Gallatin
Code
AMr-R1-D1
Latitude
45.28900
Longitude
-111.14100
Notes

We were snowmobiling up portal creek today near the hidden lakes trailhead and I set off a small slide remotely by riding below a small ridge. The slide was about 3 feet at its crown 30 or 40 feet wide and ran about 40 yards. It just came down to where my track had crossed underneath. Everything was fine and we stayed safe and continued on with our plan and had a nice day.

Number of slides
1
Number caught
0
Number buried
0
Trigger
Snowmobile
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
1
D size
1
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

We were snowmobiling up portal creek today near the hidden lakes trailhead and I set off a small slide remotely by riding below a small ridge. The slide was about 3 feet at its crown 30 or 40 feet wide and ran about 40 yards. It just came down to where my track had crossed underneath. Everything was fine and we stayed safe and continued on with our plan and had a nice day.

Northern Gallatin, 2023-04-01

We were snowmobiling up portal creek today near the hidden lakes trailhead and I set off a small slide remotely by riding below a small ridge. The slide was about 3 feet at its crown 30 or 40 feet wide and ran about 40 yards. It just came down to where my track had crossed underneath. Everything was fine and we stayed safe and continued on with our plan and had a nice day.

Northern Gallatin, 2023-04-01

We were snowmobiling up portal creek today near the hidden lakes trailhead and I set off a small slide remotely by riding below a small ridge. The slide was about 3 feet at its crown 30 or 40 feet wide and ran about 40 yards. It just came down to where my track had crossed underneath. Everything was fine and we stayed safe and continued on with our plan and had a nice day. 

Northern Gallatin, 2023-04-01

GNFAC Avalanche Forecast for Fri Mar 31, 2023

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>There are two very different sets of avalanche concerns today - avalanches breaking&nbsp; in the upper couple feet of the snowpack and avalanches breaking deep on weak layers buried months ago.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Avalanches in the upper snowpack can be triggered beneath the snow that fell over the last week, particularly where it’s been more recently drifted by the wind. In some places the new snow buried a layer of facets that will keep the snowpack from stabilizing as quickly (</span></span></span></span></span></span><a href="https://youtu.be/8gXkzoEbk6Q"><span><span><span><strong><span><u><span>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Watch out for shooting cracks as a clear sign of instability and dig down around 3 ft to test the upper snowpack before riding any steep slopes.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>A harder to identify, but scarier possibility is triggering a deep slab avalanche. Yesterday, a snowboarder triggered a slide that broke deep in the Lone Lake Cirque, near Big Sky resort, and was carried close to a thousand vertical feet over rocks and huge cliffs (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/lone-lake-cirque-slide"><span><sp…;). Remarkably he wasn’t buried and survived unscathed. Before this incident, the last deep slabs were triggered a week ago in </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28798"><span><span><span><strong><span>…; and near </span></span></span></span></span></span><a href="http://www.mtavalanche.com/node/28785"><span><span><span><strong><span>… City</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>. You’d have to get unlucky to trigger one of these slides today, but if you do, the consequences could be huge. Avalanches in the newer snow could also step down and trigger a deeper slide. Consider the possibility of a huge slide breaking deep in the snowpack before getting into consequential terrain.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The avalanche danger is rated MODERATE on all slopes.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).&nbsp;</span></span></span></span></span></span></p>

<p>&nbsp;</p>

<p><span><span><span><span><span><span>In Island Park, avalanches in the upper snowpack can be triggered beneath the snow that fell over the last week, particularly where it’s been more recently drifted by the wind. A harder to identify, but scarier possibility is triggering a deep slab avalanche. You’d have to get unlucky to trigger one of these slides today, but if you do, the consequences could be huge. Avalanches in the newer snow could also step down and trigger a deeper slide. </span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Events and Education Calendar.

**Reporting this from a friend of a friend. Not my photo, nor was I involved.**
 

one skier got caught above large bottom cliff, carried all the way down over cliff to the apron. Said skier walked away completely unharmed. Not buried. 
 

north face of that bowl, near cornrows. 

 

Additional info from BSSP: 

"There was a large, deep slab avalanche snowboard triggered in Lone Lake Cirque this afternoon. The
slide ripped in a secondary start zone below ridgetop, and ran far into the flats, and may have run a

Northern Madison, 2023-03-31