23-24

Cornice collapse on Iceberg

Date
Activity
Skiing

Natural cornice failure and small slab on Iceberg Peak’s NE face. We skied by the day prior and judging by what the wind did to our tracks overnight, this looked like it happened in the morning.

Region
Cooke City
Location (from list)
Mt. Zimmer
Observer Name
Akio Joy

Weather station takedown

Date
Activity
Snowmobiling

Rode from Buttermilk to Lionhead Ridge to take down the weather station for the season. The snowpack was fully saturated and sloppy at lower elevations. By 8000 ft there was a firm crust with a couple inches of wet snow above it around noon. Winds were breezy at ridgetops, keeping the snowpack a bit cooler (but still getting wet). Ominous clouds moved in around 12:30 pm. We quickly left before getting rained on. 

We saw no signs of recent avalanches.

Region
Lionhead Range
Location (from list)
Lionhead Ridge
Observer Name
Ian Hoyer

GNFAC Avalanche Forecast for Fri Apr 12, 2024

Snowpack and Avalanche Discussion

<p><span><span><span><span><span><span>By mid-morning, on sunny slopes, any surface crusts that formed overnight will be breaking down and wet avalanche danger will be rising. Mostly we’re expecting relatively small wet loose slides (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/wet-loose-avalanches-argentina-bo…;), but the whole array of wet snow avalanche concerns are possible today, including wet loose slides entraining the whole season’s snowpack, wet slabs (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/fin-cooke-city"><span><span><span…;), or cornice collapses (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/cornice-collapse-sphinx"><span><s…;).</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Clouds may move in this afternoon and strong winds may delay melting in some areas, but spring weather is fickle and neither of those are guarantees of safety. Plan to get off sunny slopes early. Pay attention to the snow surface to know when dangerous conditions have developed on a particular slope. If you’re sinking past your boot tops in wet and slushy snow or you see rollerballs and small wet snow avalanches starting it’s time to move to cooler aspects or return to the trailhead before conditions deteriorate further.&nbsp;</span></span></span></span></span></span></p>

<p><span><span><span><span><span><span>Triggering avalanches in dry snow is becoming less likely, but is still possible, particularly on wind-loaded, high elevation, shady slopes. On Wednesday, skiers in the northern Gallatin Range triggered some wind-loaded pockets breaking 6-8” deep (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/31812"><span><span><span><strong><span…;). Watch for shooting cracks as a clear sign that a wind drift hasn’t yet bonded. Before committing to steep slopes take a few minutes to stop, dig and test the upper couple feet of the snowpack to keep from getting surprised. Avalanches breaking deeper are much less likely, but it’s still good to keep the possibility in the back of your mind.</span></span></span></span></span></span></p>

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

Upcoming Avalanche Education and Events

Hyalite Road Closure: Hyalite road is closed to ALL MOTORIZED VEHICLES until the morning of May 16. This is a regular annual road closure to reduce road damage during the spring thaw. Bicycle and foot traffic are allowed. Contact the Bozeman FS Ranger District for more info.

Cornice Collapse on the Sphinx

Sphinx Mountain
Southern Madison
Code
C-ASu
Latitude
45.15820
Longitude
-111.47700
Notes

From obs: " Unintentionally triggered a large cornice collapse on the south face of the Sphinx. " 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Skier
Trigger Modifier
u-An unintentional release
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Natural Wet Snow Avalanches Crazy Mtns.

Crazy Peak
Out of Advisory Area
Code
WL-N-R2-D2
Aspect Range
E-S
Latitude
46.01870
Longitude
-110.27600
Notes

Riders saw several natural wet snow avalanches while riding on the west side of the Crazy Mountains. The largest of these was 500' wide, D2. All these avalanches happened in the upper 40cm of the snowpack. 

Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Natural trigger
R size
2
D size
2
Problem Type
Wet Snow
Snow Observation Source
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year