19-20

Natural and skier triggered slides in Hyalite

Divide Peak
Northern Gallatin
Code
SS
Latitude
45.40290
Longitude
-110.97600
Notes

From obs: "Later in the day we ran across what we assume to be a remotely triggered avalanche from another party in the area. There were two sets of tracks on the adjacent slope with cracks visible on the slope. The avalanche occurred on a 40* east aspect at 9250' and failed on the MFcr/FC dn 35cm. .... Skiing out the trail with better light than in the morning, we saw a number of similar avalanches confined to east aspects on steep 40*+ rolls and presumably failing on the persistent grains above the crust."

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

GNFAC Avalanche Forecast for Fri Mar 27, 2020

Snowpack and Avalanche Discussion

<p>Recent snow and strong winds have created dangerous avalanche conditions. 10 inches to 2 ft of new snow fell in the mountains earlier this week (measuring 0.8-1.3” <a href="https://www.mtavalanche.com/taxonomy/term/451">snow water equivalent</a>). Winds yesterday were stronger than expected, gusting into the 30s mph out of the west. These strong winds rapidly built cornices and heavily wind loaded many slopes (<strong><a href="https://www.mtavalanche.com/images/20/cornice-growth-bridger-ridge">pho…;).</p>

<p>Yesterday we got reports of skier triggered and natural avalanches on wind loaded slopes in the Bridger Range, in Hyalite, across the Northern Madison Range, near Cooke City, and down by Quake Lake (see the <a href="https://www.mtavalanche.com/weather/wx-avalanche-log">Weather and Avalanche Log</a> for details and photos). There were more than 10 slides reported yesterday. This is a clear indication that the wind drifted snow is unstable. These slides were all breaking 1-2 ft deep within the new snow from earlier this week. On many slopes they were sliding on ice crusts that formed last week (<a href="https://youtu.be/S_hEBqY67-g"><strong>video</strong></a&gt;). Avoid wind-loaded slopes where these slides will be easily triggered again today.</p>

<p>Clouds building through the day should keep wet snow from being too much of an issue, but if skies stay blue into the afternoon, be heads up on sunny slopes as the snow surface gets wet. Pinwheels, roller balls, and the feeling of sticky snow beneath your feet are all signs that the conditions for wet avalanches are developing. If the new snow does become wet, it will slide easily and far on the ice crusts beneath it.</p>

<p>Throughout our advisory area, the avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all other slopes.</p>

<p>We plan to end daily avalanche forecasts on Sunday, April 5<sup>th</sup> and continue with general bulletins every Monday and Friday through April. Over the next week, we will take down weather stations and will no longer receive observations from guides and ski patrol. We need help gathering field data. Please send us your observations no matter how brief. You can fill out an observation form, email us (mtavalanche@gmail.com), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

COVID-19 Info and Updates

The stay at home order that goes into effect tomorrow morning allows for outdoor activities to continue (as long as you keep the mandated 6 feet of social distancing).

Natural windslabs near Quake Lake

Quake Lake
Southern Madison
Code
SS
Latitude
44.85240
Longitude
-111.39200
Notes

Natural avalanches near Quake Lake, observed on 3/26/2020.

From email: "I observed several small natural slides originating on recently-loaded, corniced ridgelines. These all ran substantial distances, but did not pick up much snow or step down from the new snow."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From email: "Was up Dudley creek today. Northern madison. Saw 2 step down avalanches on ne aspect high elevation... One ... seemed cornice triggered within 12 hrs of our tour this morning (3/26). The 2nd avalanche is in the lower photo and was probably skier trigger intentional.... It looks like they triggered a fresh wind slab under ridge, maybe ski cut, which stepped down into some older layers"


Photo: L. Frye

Northern Madison, 2020-03-27

Natural avalanches in new snow in Bridgers

The Throne
Bridger Range
Code
SS-N
Latitude
45.88220
Longitude
-110.95200
Notes

From obs: "We toured up in the Throne area today. Moderate winds were blowing snow at mid elevations and ridgetops. We found dry boot top powder on East facing slopes, the snow skied upside down. We observed loose and slab avalanches on many aspects up high and at mid elevations, all looked like new snow avalanches that happened yesterday. I’ve attached a photo of an east facing slope near the Throne."  Photo: S. Jonas

 

Number of slides
5
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

From obs: "We toured up in the Throne area today. Moderate winds were blowing snow at mid elevations and ridgetops. We found dry boot top powder on East facing slopes, the snow skied upside down. We observed loose and slab avalanches on many aspects up high and at mid elevations, all looked like new snow avalanches that happened yesterday. I’ve attached a photo of an east facing slope near the Throne."  Photo: S. Jonas

Bridger Range, 2020-03-27

Skier triggered avalanche near Bridger Bowl

The Ramp
Bridger Range
Code
SS-AS-R1-D1.5
Latitude
45.82880
Longitude
-110.93100
Notes

A skier triggered an avalanche on a windloaded slope just north of Bridger Bowl on 3/26/2020. The skier lost their ski in the slide

Number of slides
1
Number caught
1
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
R size
1
D size
1.5
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year