23-24

Divide Basin

Date
Activity
Skiing

Toured on the east ridge of Divide Peak this morning. From the summit, we saw at least three, if not more, large slab avalanche crowns and debris in Divide Cirque and surrounding basins. There were also a handful of visible wet loose slides and point-releases in the area. Winds were blowing out of the north but only really felt at ridge tops. Otherwise, it was incredibly warm. A bit after noon, the upper 6-8 inches of snow surface on the east shoulder had been impacted by the sun and wanted to slide on an old melt freeze crust below the surface. 
 

It was so beautiful up there today but the sun was powerful! The trail up and the basin were heavily impacted with the high temperatures and low wind. 

Region
Northern Gallatin
Location (from list)
Divide Peak

Pits from the Ramp

Date
Activity
Skiing

Toured up north of the ski area today. East and North facing slopes stayed cold, we experienced very light downslope winds below ridgeline, we observed little no windslab formation. Dug on a north aspect about 150' below the ridgeline. HS 150cm, ECTX, structure looked better than I thought it would, basal depth hoar was 1F-, but we got PST 65/145 and PST 40/145 to end up 20cm from the ground.

Thanks!

Region
Bridger Range
Location (from list)
The Ramp
Observer Name
Spencer Jonas

Crown on Ross

Date
Activity
Skiing

On our hike in we saw a crown above the East meadows on Ross. After getting up onto the shoulder we saw that the crown had a couple of inches of fresh snow on top of the debris so we assumed that the slide had happened 2 days previously with a possible human trigger. Could not see the full size of the crown due to not wanting to enter the terrain but my guess would be 2ft deep and a few hundred feet wide breaking above The Peel to the North of the Banana.

Region
Bridger Range
Location (from list)
Ross Peak
Observer Name
Jonathan Hodge

GNFAC Avalanche Forecast for Fri Mar 15, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>Avalanche conditions remain dangerous. Over the last week there have been a series of really big, natural and human triggered avalanches (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31432"><span><span><span><strong><span… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://youtu.be/ZaqRmvvNp9c"><span><span><span><strong><span><u><span>… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31343"><span><span><span><strong><span… photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/snow-observations-list?field_regions_simila… City activity list</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These slides are breaking on the weak layers near the base of the snowpack. Yesterday there was another, outside of our advisory area in the Absaroka Range, that broke 3-4 ft deep, 1/4 mile wide and was triggered from hundreds of feet away (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31460"><span><span><span><strong><span…;).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Slides may also break beneath wind drifts that formed from the 6”-10” of snow that fell mid-week. Warm temperatures and sun today will also likely lead to loose wet avalanches.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Be patient. Avalanches have been breaking on the basal weak layers for days after the end of storms this year. Things will likely start to stabilize with a stretch of high pressure ahead of us, but we’re not there yet.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Human triggered avalanches are likely and the avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>The general snowpack structure is the same in the Lionhead and Island Park areas as elsewhere, the snowpack is just a bit deeper so it’s getting harder to trigger slides and we’ve seen less recent avalanche activity. Getting into steep terrain still means rolling the dice with the possibility of triggering a huge, likely unsurvivable avalanche. If you’re going to enter the casino, stack the odds in your favor by traveling one at a time, carrying rescue gear and having a partner watching from a safe spot while you’re on steep slopes. Avalanches could also break in wind drifts of recent snow and be wary of a wetting snow surface bringing wet loose avalanche concerns to the table.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Human-triggered avalanches are possible and the avalanche danger is rated MODERATE.</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>In the Bridger Range we have seen less recent loading and little recent avalanche activity on deeper weak layers. The weak snow is still there, but the issues you’re more likely to encounter are higher in the snowpack. Wind drifts and wet surface snow could cause smaller, but still consequential, avalanches. Be on the lookout for cracking in wind drifts and wet snow more than a couple inches deep as signs to get out of steep terrain. Choose slopes with fewer obstacles in the runout and stick to good travel practices&nbsp; in case you do end up being the unlucky one who triggers a bigger slide.</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>

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Graupel in Hyalite

Date
Activity
Ice Climbing

Localized observation for the Grotto Falls trailhead and G1 climbing area. An inch of graupel on the surface that probably fell in the late afternoon? I don't know how widespread it is, but very prominent in this area.

Region
Northern Gallatin
Location (from list)
Hyalite - main fork

Variety of results in Beehive Basin

Date
Activity
Skiing

Toured up to the ridge between Beehive and Middle Basins with an AIARE L2. On the lower ridge we found:

  • Pit 1
    • W aspect, 9045ft
    • Height of Snow 120cm
    • ECTP 26 in facets around 80 cm down
    • PST 38/100 end
  • Pit 2 and 3
    • E aspect, 9023ft
    • Height of Snow 150cm
    • ECTP X x2
    • PST 40/100 end
    • PST 89/100 end
Region
Northern Madison
Location (from list)
Beehive Basin
Observer Name
Chris Pruden

Remotely Triggered Avalanche, Lawn Mower

Lawn Mower - Town Hill
Out of Advisory Area
Code
HS-ASr-R4-D3-O
Elevation
8800
Aspect Range
N-NW
Latitude
45.50570
Longitude
-110.49600
Notes

From obs: "On the morning on 3/14/24, a skier remotely triggered the Lawn Mower and an adjacent path on "Town Hill" in the Absaroka Range (outside of the GNFAC advisory area) while ascending on the other side of the ridgeline from the paths. The slide ran at least 1000 ft vertical."

From IG: "1/4 to 1/2 mile wide crown. Lawnmower and adjacent gully. 2-4 ft deep. Remote trigger from ~200 ft away. Crown is 8800 ft N/NW"

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Skier
Trigger Modifier
r-A remote avalanche released by the indicated trigger
R size
4
D size
3
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
36.0 inches
Vertical Fall
1200ft
Slab Width
1500.00ft
Snow Observation Source
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

On the morning of 3/14/24, a skier remotely triggered the Lawn Mower and an adjacent path on "Town Hill" in the Absaroka Range (outside of the GNFAC advisory area) while ascending on the other side of the ridgeline from the paths. The slide ran at least 1000 ft vertical, up to a 1/2 mile wide, and 2-4' deep. Photo: Anonymous 

Out of Advisory Area, 2024-03-14