18-19

Snowbike triggered wet slab, Sage Peak

Sage Peak
Southern Madison
Code
WS-AO-R3-D2-O
Elevation
8700
Aspect
SW
Notes

The slide was triggered by a snowbiker. The rider triggered the slide side-hilling and was buried to his chest. 

Number of slides
1
Number caught
1
Number buried
1
Number killed
0
Avalanche Type
Wet slab avalanche
Trigger
Unclassified artificial trigger (specify in comments)
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Wet Slab
Slab Thickness
24.0 inches
Vertical Fall
60ft
Slab Width
200.00ft
Weak Layer Grain type
Rounding depth hoar
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

A snowbiker was partially buried in a slide on the west side of Sage Peak in the southern Madison Range. The slide occurred on a southwest facing slope at 8,700 ft. and failed on weak snow near the ground. The wet slab avalanche was triggered as the biker was side-hilling across the slope. He was caught, carried and buried to his chest, but fortunately escaped unharmed. Photo: D. Talbert 

Southern Madison, 2019-03-22

GNFAC Avalanche Forecast for Fri Mar 22, 2019

Snowpack and Avalanche Discussion

<p>Daytime warming and weak refreezes at night are taking a toll on the snowpack. Over the past few days, widespread avalanche activity has been observed across the forecast area and more action is likely today. Most activity has been confined to wet snow avalanches occurring on steep sun exposed slopes, but a recent dry slab avalanche on the north face of Mt Blackmore indicates all slopes are feeling the heat (<strong><a href="https://www.mtavalanche.com/images/19/natural-dry-slab-avalanche-mt-bla…;). Dry slab avalanches on high north facing slopes are not a widespread problem. Yesterday, my partner and I found soft-stable snow on upper elevation shady slopes in the southern Madison Range. &nbsp;</p>

<p>Today, point release avalanches will be easy to trigger or could run naturally as the day warms (<strong><a href="https://www.mtavalanche.com/images/19/point-release-beehive-basin">phot…;, <strong><a href="https://www.youtube.com/watch?v=W4q4NdCfmX8&amp;list=PLXu5151nmAvRNl9ku…;). Wet slab avalanches are a less likely but a more dangerous problem. Wet slabs are unpredictable and can run with a tremendous amount of force. Yesterday, skiers north of Bridger Bowl observed large wet slab and wet loose avalanches on many slopes (<strong><a href="https://www.mtavalanche.com/images/19/texas-meadows-wet-slabs-1">photo<…;, <strong><a href="https://www.mtavalanche.com/images/19/wet-loose-debris-near-playground"…;). Be especially aware of both these problems in steep rocky terrain or on slopes where the snowpack is less than 3-4 feet deep (<u><strong><a href="https://www.youtube.com/watch?v=O_M2PnMldm0&amp;list=PLXu5151nmAvRNl9ku…;). &nbsp;&nbsp;</p>

<p>The easiest way to manage the avalanche danger today is to start early and end early. The snowpack will be locked up this morning, but grow increasingly unstable as the day progresses. Fortunately, increasing clouds and wind this afternoon should help the snowpack from completely falling apart.</p>

<p>For today, the avalanche danger will start <strong>LOW</strong>, but rise to <strong>MODERATE</strong> by this afternoon. &nbsp;</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>

Dry Slab, Loose Wet in Hyalite

Mt Blackmore
Northern Gallatin
Code
HS-NC-R1-D2-G
Elevation
10000
Aspect
N
Latitude
45.44330
Longitude
-111.00300
Notes

A skier reported one natural dry slab avalanche that was triggered by a falling cornice and failed near the ground on the north face of Mt. Blackmore. She also saw multiple loose wet slides on solar aspects in the same area.

Number of slides
1
Number caught
0
Number buried
0
Number killed
0
Avalanche Type
Hard slab avalanche
Trigger
Cornice fall
R size
1
D size
2
Bed Surface
G - Ground
Slab Thickness
36.0 inches
Vertical Fall
150ft
Slab Width
50.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Wet avalanche activity in the Bridgers

Texas Meadow
Bridger Range
Code
WS-N-R3-D2.5-G
Elevation
7600
Aspect Range
E-S
Latitude
45.83930
Longitude
-110.93400
Notes

Two wet slabs released on the ground on the south-facing chutes off of Texas Meadow. The debris pile from the smaller of the two slides was 6' deep, and the larger of the two slides cleared most of the snow out of the chute with it. Multiple additional loose wet slabs had also released off E-SE aspects over the past 24 hrs. Some of these were large enough to break small trees. Photo: A. Schauer

Multiple Avalanches
Number caught
0
Number buried
0
Number killed
0
Avalanche Type
Wet slab avalanche
Trigger
Natural trigger
R size
3
D size
2.5
Bed Surface
G - Ground
Problem Type
Wet Snow
Slab Thickness
30.0 inches
Vertical Fall
400ft
Slab Width
75.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year