18-19

Cornice triggered slab near Big Sky

Fan Mountain
Northern Madison
Code
SS-NC-D2.5
Aspect
NE
Latitude
45.29640
Longitude
-111.52400
Notes

From BSSP: "...observed a D2.5 avalanche on the NE face of Fan Mtn. that looks to be a bout a 2’ crown likely triggered by cornice fall."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Cornice fall
D size
2.5
Slab Thickness
24.0 inches
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Low angle metal roofs have heavy, thick slabs of snow that built up during persistent cold temperatures. These slabs will slide during warm temperatures. Be on the lookout for overhead hazard and be cautious where you walk or park your car during warm sunny days. An additional urban hazard are large icicles are that will break during warm days. Photo: A. Schauer

Out of Advisory Area, 2019-03-17

Snowmobile triggered outside advisory area

Gravelly Range
Out of Advisory Area
Code
HS-AMu-R2-D2-O
Notes

A group of snowmobilers reported seeing another group trigger this avalanche on Friday afternoon. Nobody was caught.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Snowmobile
Trigger Modifier
u-An unintentional release
R size
2
D size
2
Bed Surface
O - Old snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

GNFAC Avalanche Forecast for Sun Mar 17, 2019

Snowpack and Avalanche Discussion

<p>Small wet loose avalanches are possible on sunny slopes this afternoon. Otherwise, the snowpack is generally stable and avalanches are unlikely. Slopes that receive direct sun have a thick frozen crust which makes them stable this morning. Today, warm temperatures and sun will melt this crust&nbsp;and the snow surface will become unstable. Anticipate decreasing stability on sunny slopes. Move to shadier slopes or lower angle terrain if the snow surface becomes moist, or if you see roller balls or natural point release slides. Today wet loose slides will not be large enough to bury a person, but are dangerous if they knock you down or carry you through trees or over rocks.</p>

<p>The last couple days temperatures reached the high 30s F, yet snow remained dry on shady slopes and there were generally few wet loose slides (<strong><a href="https://www.mtavalanche.com/node/20408">photos</a></strong&gt;). Similar weather today will create similar conditions. On Friday we went to Mt. Blackmore and yesterday to the northern Bridger Range. In both places we found a generally stable snowpack aside from small loose snow avalanches (<u><strong><a href="https://www.mtavalanche.com/images/19/skier-triggered-dry-loose-avalanc…;, <strong><a href="https://www.mtavalanche.com/images/19/wet-loose-slides-near-fairy-lake"…;). Near Fairy Lake we saw old wind slab crowns that show the type of terrain where there is an isolated chance to trigger one of these, and we saw small slides in terrain with high consequences (<strong><a href="https://www.youtube.com/watch?v=htNwM_uyA44&amp;list=PLXu5151nmAvRNl9ku…;). Without a recent loading event, avalanches failing deeper in the snowpack are unlikely (<u><strong><a href="https://www.youtube.com/watch?v=zDZIGxGxCgY&amp;list=PLXu5151nmAvRNl9ku…;

<p>Today the snowpack is generally stable aside from small loose snow avalanches, and avalanche danger is rated LOW. If you travel into steep terrain, remain cautious and carefully assess the snowpack and consequences of being caught in a slide.</p>

<p>If you get out and have any avalanche or snowpack observations to share, contact us via our <u><a href="https://www.mtavalanche.com/node/add/snow_observation">website</a></u&gt;, email (<u><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></u&gt;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

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"A few small wet loose releases were observed in areas without skier traffic but were confined to the top couple of inches on top of our previous high pressure surface.  The attached pic is the largest of those wet loose results and was a size 1 in Buffer Chute, in the Upper A-Z’s and occurred after that terrain had closed for the day." Photo: BSSP

Northern Madison, 2019-03-17

On Saturday (3/16) in the northern Bridger Range we saw natural and skier triggered wet loose slides that were small, but could have severe consequences if they catch you in unforgiving terrain. Photo: GNFAC

Bridger Range, 2019-03-17

Wet loose slides Bridgers and Big Sky

Fairy Lake
Bridger Range
Code
WL-N-R1-D1-S
Elevation
8900
Aspect
S
Notes

We saw natural and skier triggered wet loose avalanches near Fairy Lake. Big Sky Ski Patrol saw a few small natural wet loose slides in closed terrain.

Multiple Avalanches
Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Trigger
Natural trigger
R size
1
D size
1
Bed Surface
S - Avalanche released within new snow
Problem Type
Wet Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year