19-20

Natural wide wind slab on Saddle Peak

Saddle Peak
Bridger Range
Code
HS-N-R2-D2-U
Elevation
9000
Aspect
E
Latitude
45.79430
Longitude
-110.93600
Notes

Avalanche crown(s) seen Wednesday (12/18), probably ran Monday or early Tuesday. Broke 200-300' across between the peaks and south central. Debris ran 1,500' vertical.  Photo: GNFAC

Additional info from a skier on 12/19/19: 

"Hard to tell how deep it was. Looked like 15” max maybe. Tapered off quick.  Looked like probably that south wind load. 

One crown was north between the peaks about 60 ft from the ridge top. Then it seemed to take the legs out of the stuff in South Central since the crown was 150 ft below ridge top. Then a little dribble made its way into Argentina bowl on the south aspect. Debris terminated right at the bottom of each chute. 

Since the crown was so low I never got eyes on it. Plus it has blown in a little. I stayed high near the ridge line to the pinnacles. But it looked and felt like a bomber crust is what it ran on. Hard slab with pretty small chunks in the debris. 

The one picture didn’t come out well but it looked like goat tracks went right into that higher north crown. Maybe a dead goat...  they are usually pretty smart though."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
U - Unknown
Problem Type
Wind-Drifted Snow
Slab Thickness
12.0 inches
Vertical Fall
1500ft
Slab Width
250.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

The Fin Avalanche

Mt Republic
Cooke City
Code
SS-N-R2-D2
Elevation
9800
Aspect
E
Latitude
45.00170
Longitude
-109.95500
Notes

Went up for a closer look at a recent natural avalanche in the bowl of Mt. Republic today, just lookers left of the typical Fin ski zone.  An easterly aspect. Photo: B Fredlund

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Mount Fox East Face

Mt Fox
Cooke City
Code
SS-N-R2-D2
Elevation
11000
Aspect
SE
Latitude
45.12120
Longitude
-109.93000
Notes
Looks like it slid sometime over the weekend. Fox mountain shoulder east/se. Photo: B Zavora
Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
2
D size
2
Slab Thickness
30.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

GNFAC Avalanche Forecast for Wed Dec 18, 2019

Snowpack and Avalanche Discussion

<p>Four days ago a rider on the south side of Mount Abundance near Cooke City had a very close call, the sled was trashed, but the rider walked away (<a href="https://www.mtavalanche.com/node/21222"><strong>photos and details</strong></a>), other riders triggered three avalanches on Crown Butte (<a href="https://www.mtavalanche.com/node/21218"><strong>photos and details</strong></a>), and, yesterday, ski guides went in to look at a large natural avalanche on the Fin (<strong><a href="https://www.mtavalanche.com/images/19/avalanche-mount-republic">photo</…;, <a href="https://www.mtavalanche.com/images/19/fin-profile-12-dec">profile</a></…;). On Monday, Ian and Doug found an ice crust with weak facets while investigating the avalanches north of town (<a href="https://www.youtube.com/watch?v=rg0OZvz7Qf4"><strong>video</strong></a>…;. Dig down to assess for this weak layer before considering steep slopes or ride on lower angle terrain giving this weak layer time to become less reactive. It is still possible to trigger dangerous avalanches and the hazard is rated <strong>MODERATE</strong> in the mountains around Cooke City. Careful assessment and terrain management are necessary before considering any steeper slopes.</p>

<p>The snowpack structure in the Madison, Southern Gallatin and Lionhead Ranges does not inspire a lot of confidence. Yesterday, four days since the last snowfall, Doug and Karl experienced several large collapses at Lionhead, a sure sign of continued instability (<strong><a href="https://www.mtavalanche.com/images/19/lionhead-ski-hill">profile</a></s…;) and, over the weekend, we received reports of natural and human triggered avalanches in the Taylor Fork (<a href="https://www.mtavalanche.com/node/21249"><strong>photos and details</strong></a><strong>)</strong> and Slat Creek near Buck Ridge (<a href="https://www.mtavalanche.com/node/21217"><strong>details</strong></a&gt;). In the field, we found weak faceted snow near the ground in Lionhead (<a href="https://youtu.be/VwdWKoEfnxE"><strong>video</strong></a&gt;), at Buck Ridge (<a href="https://www.youtube.com/watch?v=F29K5DVfNgs&amp;list=PLXu5151nmAvSbcbVf…;), and the Taylor Fork (<a href="https://www.youtube.com/watch?v=GvpDqZDLTto&amp;list=PLXu5151nmAvSbcbVf…;). It remains possible to trigger an avalanche and, if you find the sweet spot, that avalanche could be large. The hazard is rated <strong>MODERATE</strong>, carefully assess the snowpack and terrain prior to committing to any steep slopes.</p>

<p>Moderate to strong winds continue in the Bridger and Northern Gallatin Ranges, but there is less snow available for transport today and a generally stable snowpack structure. While climbing the Dribbles this weekend Doug was primarily concerned with surface-level instabilities (<a href="https://www.youtube.com/watch?v=hfZRSXzS3CI&amp;list=PLXu5151nmAvSbcbVf…;) and at Mount Blackmore Monday I was encouraged by stable test results and good snowpack structure (<a href="https://www.youtube.com/watch?v=2AwTcIdcgVM&amp;list=PLXu5151nmAvSbcbVf…;). Dig a snowpit and perform a stability test to look for isolated instabilities before committing to avalanche terrain and be obsessed with the consequences of small avalanches by watching out for terrain traps like trees, cliffs, and gullies. The avalanche danger is rated <strong>LOW</strong> in the Bridger and Northern Gallatin Ranges.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an&nbsp;<a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>observat… form</strong></a>, email us (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.

BOZEMAN

TONIGHT, December 18, 1-hr Avalanche Awareness, 6-7 p.m. at Uphill Pursuits.

COOKE CITY