23-24

GNFAC Avalanche Forecast for Sun Mar 31, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Today you can trigger avalanches within or below the snow that fell over the last week, or avalanches that break many feet deeper on weak layers at the bottom of the snowpack.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday in the Lionhead area near West Yellowstone a pow surfer (snowboarder without bindings) triggered and was partially buried in an avalanche that appeared to break below last week’s snow (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31694"><span><span><span><strong><span…;). Avalanches are possible where the recent snow was drifted into thicker slabs (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/windslabs-hyalite-0329"><span><sp…;), or where it buried new weak layers. Unstable drifts are slightly more likely near Island Park where winds were strongest and the most snow fell. On Friday in the Taylor Fork I found a weak layer buried one foot deep which could cause the recent snow and wind-drifts to be unstable (</span></span></span></span></span></span><a href="https://youtu.be/Hmhje2N8Zc4?feature=shared"><span><span><span><strong>…;). Identify and avoid steep slopes with recently formed drifts. Before getting onto any steep slope, dig down a couple feet to look for potential weak layers and assess the stability of the recent snow.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Yesterday in Hyalite we saw a recent avalanche that broke 2-6' deep on weak snow at the bottom of the snowpack (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31691"><span><span><span><strong><span…; </span></span></strong></span></span></span><a href="https://youtu.be/BgZINtzwV6o?feature=shared"><span><span><span><strong>…;). Another 2-4' deep avalanche occurred on Mt. Blackmore during the same timeframe (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31672"><span><span><span><strong><span…;). These show the lingering possibility for a person to trigger a similar very large avalanche. While these massive slides have become less likely compared to earlier in the winter, they have large consequences and require thoughtful terrain selection. If you ride or cross steep slopes, choose slopes that are not heavily wind-loaded and without trees, rocks, cliffs or gullies that would increase the chances of being injured or killed if you were caught in a slide.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Cloudy skies today should prevent the snow from getting wet, and wet snow avalanches are unlikely. If the sun does show, be on the lookout for loose wet avalanches on steep slopes that receive direct sun.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Today human-triggered avalanches are possible and avalanche danger is MODERATE throughout the forecast area.</span></span></span></span></span></span></p>

Upcoming Avalanche Education and Events

Hyalite Road Closure: The gate at the bottom of the Hyalite canyon will be locked at 8:00 PM Tonight! Please be sure to exit the canyon before the gate is locked. The road closure applies to ALL MOTORIZED VEHICLES until the morning of May 16.

Partial Burial at Lionhead

LIONHEAD AREA
Lionhead Range
Code
SS-ARu-R2-D2
Latitude
44.72920
Longitude
-111.32300
Notes

A group of snowmobilers watched a pow surfer trigger an avalanche. The individual was buried to his chest and thankfully uninjured. 

Number of slides
1
Number caught
1
Number buried
0
Number killed
0
Avalanche Type
Soft slab avalanche
Trigger
Snowboarder
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Slab Thickness
18.0 inches
Vertical Fall
100ft
Slab Width
150.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Partial Burial at Lionhead

Date
Activity
Snowmobiling

From text: A group of snowmobilers watched a pow surfer trigger an avalanche. The individual was buried to his chest and thankfully uninjured. 

Region
Lionhead Range
Location (from list)
LIONHEAD AREA

Natural deep slab avalanche, Flanders Mtn

Flanders Creek
Northern Gallatin
Code
HS-N-R3-D3-O
Elevation
9800
Aspect Range
E-NE
Latitude
45.43600
Longitude
-110.94200
Notes

We toured up to Flanders Mtn. to take down the weather station for the season (before the road closes on Monday, Apr 1). The main observation is a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. Photos and video attached. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O. 

 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
3
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

We toured up to Flanders Mtn and saw a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O.  Photo: GNFAC

 

Northern Gallatin, 2024-03-30

We toured up to Flanders Mtn and saw a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O.  Photo: GNFAC

 

Northern Gallatin, 2024-03-30

We toured up to Flanders Mtn and saw a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O.  Photo: GNFAC

 

Northern Gallatin, 2024-03-30

We toured up to Flanders Mtn and saw a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O.  Photo: GNFAC

 

Northern Gallatin, 2024-03-30