18-19

GNFAC Avalanche Forecast for Sat Mar 23, 2019

Snowpack and Avalanche Discussion

<p>Above average temperatures the past few weeks have wreaked havoc on the snowpack. On low to mid elevation slopes, the pack has turned isothermal and lost its strength and integrity. Over the past five days, widespread wet snow avalanche activity has been reported across the forecast area (<strong><a href="https://www.mtavalanche.com/photos">photos</a></strong&gt;). On Thursday, a timber sled rider triggered and was partially buried in a wet slab avalanche on the west side of Sage Peak in the southern Madison Range. The slide was triggered as the rider was side-hilling a steep southwest facing slope at roughly 3 pm (<strong><a href="https://www.mtavalanche.com/images/19/snowbike-triggered-wet-slab-sage-…;). The slide failed at the ground, releasing the entire season’s snowpack. The timber sled was completely buried, fortunately the rider was only buried to his waist.</p>

<p>This was a close call that could have ended much worse. Being buried in wet snow debris is like being encased in concrete. It’s something you want to avoid at all costs. A recent wet slide in Sourdough Canyon south of Bozeman is a perfect example of how a small slope can have potentially dangerous consequences. This slide failed naturally and put 3-5’ of heavy debris on a very popular skiing and hiking trail (<strong><a href="https://www.mtavalanche.com/images/19/wet-slab-sourdough-trail-3">photo…;).</p>

<p>Although the snowpack took a beating this week, conditions are changing for the better. Cooler temps and cloudy skies will significantly decrease the potential for wet snow avalanches the next few days. Be cautious today when traveling around steep slopes on mid to low elevation terrain where the snowpack did not experience a strong freeze overnight. On upper elevations slopes, the snowpack should stay cold and locked up.</p>

<p>Today, the avalanche danger will start out <strong>LOW</strong>, but rise to <strong>MODERATE</strong> on mid to low elevation slopes as temps rise above freezing. &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>

This wet slab was observed on Friday (3/22) across the Sourdough canyon trail, about 1.4 miles up. It put 4-6 feet of debris lower down in the creek. Although small, a heavy wet slide like this can be powerful and very dangerous. Current warm temperatures are a shock to the snowpack, and steep slopes should be avoided if the snow is wet. Photo: P. Brown

Northern Gallatin, 2019-03-22

Wet slab on Sourdough trail

Sourdough Canyon
Northern Gallatin
Code
WS-N-R3-D2-O
Elevation
5700
Aspect
SW
Latitude
45.56870
Longitude
-111.00900
Notes

Observed on Friday (3/22), probably ran late on 3/21. Crossed trail and piled 4-6' of debris in creek.

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Wet slab avalanche
Trigger
Natural trigger
R size
3
D size
2
Bed Surface
O - Old snow
Problem Type
Wet Snow
Slab Thickness
16.0 inches
Vertical Fall
60ft
Slab Width
50.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

This wet slab was observed on Friday (3/22) across the Sourdough canyon trail, about 1.4 miles up. It put 4-6 feet of debris lower down in the creek. Although small, a heavy wet slide like this can be powerful and very dangerous. Current warm temperatures are a shock to the snowpack, and steep slopes should be avoided if the snow is wet. Photo: S. Gill

Avalanche Details: Wet slab on Sourdough trail
Northern Gallatin, 2019-03-22

This wet slab was observed on Friday (3/22) across the Sourdough canyon trail, about 1.4 miles up. It put 4-6 feet of debris lower down in the creek. Although small, a heavy wet slide like this can be powerful and very dangerous. Current warm temperatures are a shock to the snowpack, and steep slopes should be avoided if the snow is wet. Photo: S. Gill

Avalanche Details: Wet slab on Sourdough trail
Northern Gallatin, 2019-03-22