21-22

GNFAC Avalanche Forecast for Wed Nov 24, 2021

Snowpack and Avalanche Discussion

<p>Where there is enough snow to ski or ride the snowpack has layers and avalanches are possible. Last night’s snowfall of 3-6" was equal to 0.3-0.4"&nbsp;of snow water equivalent (SWE). Moderate northwest wind drifted the new snow into thicker layers which can break and avalanche today. Strong wind tomorrow will continue to grow these layers into thicker slabs. If these wind slabs avalanche, they could be large enough to bury a person, and certainly enough to knock someone over. Small dry loose avalanches of the new snow are also possible. Either of these avalanches are especially dangerous if they knock you over in high consequence terrain, like above cliffs, trees or the many exposed rocks right now.</p>

<p>On slopes that have layers of snow from October and early November avalanches might break 1-2 feet deep on old, weak snow. I saw these weak layers near Cooke City last Friday (<a href="https://youtu.be/oF8q1tMQuh8"><strong>video</strong></a&gt;), and skiers near Fairy Lake reported similar layers over the weekend (<strong><a href="https://www.mtavalanche.com/sites/default/files/styles/very_large_1200w…;). Until proven otherwise, I suspect there are buried weak layers on high elevation slopes throughout our advisory area.</p>

<p>If you go to recreate&nbsp;in&nbsp;the mountains over the next couple days plan to avoid avalanche terrain where there are fresh drifts of snow or if&nbsp;you suspect there are buried weak layers, especially if the terrain has&nbsp;high consequences of being&nbsp;caught in a slide. Choose objectives that give you an opportunity to safely gather data about how this season’s snowpack is looking, and provide yourself time to make clear, informed decisions.</p>

<p>We will issue the next update on Friday morning. We are preparing for winter, teaching avalanche classes, and setting up weather stations. If you have avalanche, snowpack or weather observations to share please submit them via our&nbsp;<a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities:

Get your avalanche brain ready for the season at one of the many classes listed on our education calendar, and list of upcoming events below. Don’t delay preparing and inspecting your avalanche gear. Get some tips from Dave Zinn in this Pre-Season gear check video.

Variable wind loading in fairy lake

Date
Activity
Skiing

Dug two pits. First was a SE aspect at 8000 feet (1st picture). 40cm of loose un consolidated snow with a crust near the top, got no test results. Second pit was on an E/NE aspect at 8300 ft and the snowpack had deepened to 160cm of pencil to knife hard slabs with 10 cm of softer wind blown snow on top. Test results here was Ectp-23 breaking about 50 cm down in the snowpack (picture 2)

Region
Bridger Range
Location (from list)
Naya Nuki Bowl
Observer Name
Charlie Bayles

GNFAC Avalanche Forecast for Mon Nov 22, 2021

Snowpack and Avalanche Discussion

<p>New snow that fell by Saturday morning was welcome, but mainly cosmetic. It was not enough to improve the skiing or snowmobiling, but it did cover up the rocks making them easier to hit. West wind was strong at the ridgetops and drifted snow. These wind slabs may avalanche and bury you, but will most likely bounce you over rocks and end your ski season. <a href="http://www.mtavalanche.com/images/21/avalanche-powder-cloud"><strong><u… picture</u></strong></a> of an avalanche powder cloud near Livingston (outside the forecast area) is proof of the lurking danger.</p>

<p>The winter is young and we have limited data which means we need to be extra cautious. <a href="https://www.nrcs.usda.gov/wps/portal/wcc/home/quicklinks/imap#version=1… sites</u></a> are measuring only 10 to 20 inches of snow. At elevations lower than 7,500 feet dirt was seen before the storm, while above this elevation we have a layered snowpack of crusts, a dense icy mass at the ground and weak, sugary snow in between. This week’s weather is favorable to grow large-grained sugary facets, the bane of stability. I’m an optimist at heart, but not with this snowpack. I anticipate it will continue to weaken and then avalanche when snow accumulates.&nbsp;</p>

<p>So what should someone hungry to get out and make turns do? Avoiding wind-loaded slopes is the first step. The second step is to not trust the snowpack. Trust takes time. Alex and his partner were faced with this on Friday when they ski toured south of Cooke City (<a href="https://youtu.be/oF8q1tMQuh8"><strong><u>video</u></strong></a&gt;). They dug <a href="https://www.mtavalanche.com/snowpits"><strong><u>3 snowpits</u></strong></a>, found weak snow that broke in their tests and were very careful to avoid avalanche terrain. As a general rule we go into avalanche terrain, but not right now. If the snowpack is deep enough to ski, then it’s deep enough to have layers of ever weakening snow. Lacking a history of pit data and observations, Alex was rightfully concerned, and you should be too.&nbsp;</p>

<p>Public Safety Message 101: Treat your outing as you would any mid-winter day. Carry a beacon with fresh batteries, a shovel and probe. A helmet is a good idea, especially with rocks lurking, and if you carry an airbag mid-winter, you should carry it now too.&nbsp;</p>

<p>We will issue the next update on Friday morning. We are preparing for winter, teaching avalanche classes, and setting up weather stations. If you have avalanche, snowpack or weather observations to share please submit them via our&nbsp;<a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities:

Get your avalanche brain ready for the season at one of the many classes listed on our education calendar, and list of upcoming events below. Don’t delay preparing and inspecting your avalanche gear. Get some tips from Dave Zinn in this Pre-Season gear check video.

Natural avalanche and powder cloud on Black Mtn

Livingston
Out of Advisory Area
Code
U-N
Elevation
10000
Aspect
N
Latitude
45.47120
Longitude
-110.46700
Notes

This powder cloud from a large avalanche was seen on Black Mountain, up Pine Creek outside Livingston. Located outside our advisory area it is a sign of unstable snow, likely from wind-loading, that can be found throughout southwest Montana.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Unknown
Trigger
Natural trigger
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

This powder cloud from a large avalanche was seen on Black Mountain, up Pine Creek outside Livingston. Located outside our advisory area it is a sign of unstable snow, likely from wind-loading, that can be found throughout southwest Montana. Photo: Anon

Out of Advisory Area, 2021-11-22