20-21

GNFAC Avalanche Forecast for Mon Apr 12, 2021

Snowpack and Avalanche Discussion

<p>The snowpack in the mountains around Bozeman, Big Sky, West Yellowstone and Cooke City is generally stable. A thick melt-freeze crust below several inches of recent snow is isolating skiers and riders from deeper instabilities. If this week’s forecast holds, avalanches will remain unlikely outside of isolated drifts of fresh snow sitting on top of this crust. Watch for potential avalanches’ size and reactivity to increase if we get more snowfall than anticipated during the week or if the sun and warmer temperatures moisten the snow surface. Assess the stability of any new or wind-drifted snow before committing to steep terrain and watch for signs of warming such as rollerballs or sinking into wet snow more than a few inches.&nbsp;</p>

<p>For now, manage isolated instabilities by consistently following safe travel protocols, skiing or riding with a partner, and carrying a beacon, probe, and shovel. Assess steep terrain for features such as rocks, trees and cliffs that decrease the margin for error and increase the consequences of small avalanches. Read more about spring avalanche hazards below in the “<strong>GENERAL SPRING SNOWPACK AND TRAVEL ADVICE</strong>” section.&nbsp;</p>

<p>We will issue spring snowpack and weather updates each Monday and Friday through April, or as needed, and we will share relevant avalanche and snowpack information on our website and social media. 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>

Announcements, Avalanche Education and Events

Bridger Bowl is closed, and backcountry conditions exist (video). There is no avalanche mitigation or ski patrol rescue. Please stay clear of work areas, snowmobiles, chair lifts and other equipment. 

See our education calendar for an up-to-date list of all local classes.

GNFAC Avalanche Forecast for Sun Apr 11, 2021

Snowpack and Avalanche Discussion

<p>In the northern Gallatin Range, 5” of new snow equal to 0.5” of snow water equivalent (SWE) creates heightened avalanche conditions. Last night and this morning, moderate west-northwest wind formed fresh drifts that are possible to trigger. The new snow fell on hard melt-freeze crusts which will help wind slabs and loose snow avalanches slide farther and wider. Avalanches breaking deeper than the new snow are unlikely. Before you ride steep slopes carefully evaluate the stability of the new snow, and be extra cautious of wind-loaded slopes. Watch for cracking around your skis or feet on lower angle slopes as a sign the new snow can slide on steeper slopes. Avalanches are possible to trigger and the avalanche danger is MODERATE.</p>

<p>Near Big Sky, the Bridger Range, West Yellowstone and Cooke City the snowpack is generally stable, and avalanches are unlikely aside from small, isolated slabs of wind-drifted snow. In the Bridgers and near Big Sky 2-4” of new snow equal to 0.1-0.2” of snow water equivalent (SWE) was drifted by northwest wind into fresh slabs. Though small, these slabs are potentially hazardous in higher consequence terrain like above cliffs, rocks, trees or on firm, steep slopes. If there is any mid-day sun that makes the new snow moist, small loose snow avalanches will become possible. Prior to last night’s snow, two days of moderate-strong southwest winds formed small wind slabs along ridgelines that have become difficult to trigger. Evaluate the consequences of being caught in even a small slide before riding steep terrain. Today, the snowpack is generally stable and the avalanche danger is LOW.</p>

<p>We will issue spring snowpack and weather updates each Monday and Friday through April, or as needed, and we will share relevant avalanche and snowpack observations on our website and social media. 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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Avalanche Education, Events and Announcements

Bridger Bowl is closed, and backcountry conditions exist (video). There is no avalanche mitigation or ski patrol rescue. Please stay clear of work areas, snowmobiles, chair lifts and other equipment.

See our education calendar for an up-to-date list of all local classes.

GNFAC Avalanche Forecast for Sat Apr 10, 2021

Snowpack and Avalanche Discussion

<p>The snowpack is generally stable, and avalanches deeper than recent snow are unlikely. On Thursday night the mountains got 3-6” of snow near Big Sky, West Yellowstone and Hyalite with 1-2” near Cooke City and the Bridger Range. This snow created small avalanche hazards that can be harmful, especially in higher consequence terrain like above cliffs, rocks, trees or on firm, steep slopes.</p>

<p>Yesterday skiers in the Absarokas saw fresh wind slabs that broke naturally on north and east aspects (<strong><a href="https://www.mtavalanche.com/images/21/natural-wind-slab-absaroka">photo…;). Drifts that formed yesterday will be more difficult to trigger today, but a few fresh drifts will grow with increasing west winds.</p>

<p>As temperatures warm through the day, or if there is rain this afternoon, shallow wet loose slides could be triggered. A few might initiate naturally near warm, rocky outcrops on slopes that receive direct sunshine, but wind and increasing cloud cover will keep wet slide activity minimal.</p>

<p>Before you ride or travel below steep slopes watch for signs of recently drifted snow or the snow surface getting wet. Signs of wind-loading include changes in snow texture, round pillows of snow, slopes directly below cornices and snow blowing off ridgelines. Signs that the snow is becoming wet and unstable include natural rollerballs or pinwheels of snow, or feeling that the snow surface has become moist and recent crusts have melted.</p>

<p>Today the snowpack is generally stable aside from small and isolated hazards, and the avalanche danger is LOW.</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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Avalanche Education and Events

See our education calendar for an up-to-date list of all local classes.

Natural wind slabs in Absaroka

Other place
Out of Advisory Area
Code
SS-N-R1-D1
Aspect
NE
Latitude
45.49590
Longitude
-110.44900
Notes

From obs 4/9/21: "we saw widespread natural wind slabs on N-NE eastern slopes in the Northern Absarokas (photo)...."

Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
1
D size
1
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year