20-21

GNFAC Avalanche Forecast for Fri Mar 12, 2021

Snowpack and Avalanche Discussion

<p>As the day heats up, the snow surface will become wet on sunny slopes and you will likely be able to trigger small wet loose slides. These will mostly be small and inconsequential, but could pose issues in places where getting swept off your feet, even for a moment, would be a problem. If you’re sinking deeper than your ankles into wet snow, be heads up, as larger and more dangerous wet slides are possible. As I found yesterday in the Southern Gallatin Range, on some of the lowest elevation, sunniest slopes with the thinnest snowpacks meltwater has trickled down through the whole snowpack (<a href="https://www.youtube.com/watch?v=l5LfdUsd0Wk"><strong><u>video</u></stro…;). On these slopes, loose wet slides could gouge down to the ground and wet slabs are even a possibility. Today this will only be an isolated problem, but that may change with increasing warm temps over the coming days.&nbsp;</p>

<p>On most slopes, the lower snowpack remains dry and there is still weak snow at the ground <a href="https://www.youtube.com/watch?v=8Q4gTjESoq0"><u>(</u><strong><u>Teepee Basin video</u></strong></a>). While we haven’t seen an avalanche on these layers in almost two weeks, keep the possibility of triggering a large slide breaking near the ground in the back of your mind. This is the epitome of a low likelihood, high consequence problem.&nbsp;</p>

<p>Use good travel practices to cover your bases in the unlikely case you do trigger a big slide: always carry rescue gear, only expose one person at a time to avalanche terrain and have someone watching from a safe spot (<a href="https://youtu.be/gPWSDAr-K1Q"><strong><u>travel advice video</u></strong></a>).&nbsp;</p>

<p>Large avalanches are unlikely and the avalanche danger LOW.&nbsp;</p>

<p>&nbsp;</p>

<p>The lower snowpack is generally stable in the mountains around Cooke City and slightly cooler temperatures has kept wet snow from being much of an issue so far. Yesterday, Alex found minimal avalanche hazard north of town and identified wet loose avalanches involving this week’s new snow as the primary concern as temperatures continue to rise (<a href="https://www.youtube.com/watch?v=fRcnpNGTKCQ"><strong><u>video</u></stro…;). Watch for pinwheels and rollerballs as signs that loose wet avalanches are imminent.&nbsp;</p>

<p>The danger is rated LOW.&nbsp;</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <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>

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Upcoming Avalanche Education and Events

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out:

March 20, 5:30 p.m., Snowpack Update for Bozeman Splitfest, online Link to Join HERE

Skier triggered loose snow slide, Rasta Chutes

Rasta Chutes
Cooke City
Code
L-AS-R1-D1.5-I
Elevation
10000
Aspect
S
Latitude
45.07090
Longitude
-109.94500
Notes

A skier triggered a loose snow avalanche in the Rasta Chutes on Scotch Bonet north of Cooke City on 3/10/21. No one was caught.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Skier
R size
1
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
New Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

North face of Republic

Date
Activity
Skiing

Small 1-2 inch D1 avalanche that propagated across the East most run on the north face of Republic Mt. Looked to be isolated to the new snow received last night, and under that assumption it would be a natural trigger as we were the first ones up there for the day. No other failures were found in this layer, and not even hand shears (on E facing slopes) would pull off without excessive pressure (full bodyweight) beneath the sun crust that formed prior to Monday/Tuesday's snow. Despite cold temps the sun warmed the snow surface significantly by the end of the day, leading to borderline wet loose avalanches.

Region
Cooke City
Location (from list)
Republic Mountain
Observer Name
Gage Meredith

Mt. Bole

Date
Activity
Skiing

Recent snow was sluffing on the North aspect of Palace Butte. Our snowpit on the east ridge of Mt Bole revealed a mostly cohesive slab with a ECTN 28 @ 55cm (The total HS was recorded as 325cm, but the pit was dug only to 150cm deep), and great caution was taken in selecting an approach and descent to avoid shallow spots in the snowpack. The new snow did not sluff during our descent of the east ridge of Mt Bole. We triggered two very small, wet loose slides on southern aspects below Mt Bole and Palace Butte during our return.

Region
Northern Gallatin
Location (from list)
Mt. Bole
Observer Name
Erich Schreier