18-19

GNFAC Avalanche Forecast for Wed Feb 27, 2019

Snowpack and Avalanche Discussion

<p>In the southern mountains the snowfall continues and so does the Avalanche Warning. The snow just keeps stacking up, day after day. As a rule of thumb, 1” of <u><a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</a></u> (SWE) equals a foot of snow. The Lionhead area has gotten almost 6” of SWE in 4 days, 3.5” in Taylor Fork and over 4” outside Cooke City. This is a heavy load, especially given the poor snow structure of weak faceted snow near the ground. Yesterday, Eric and I toured into Bacon Rind and had a large collapse and poor stability test scores. We skied our skin track out. On Saturday, Eric and Alex made a <strong><a href="https://www.youtube.com/watch?v=PW2xrOl76-Q&amp;t=0s&amp;index=2&amp;li…; near Lionhead showing the poor snow structure and avalanche potential. Stay out of avalanche terrain today. That includes traveling <em>below </em>open slopes. Many have died traversing underneath steep terrain. I expect numerous natural avalanches breaking in the new and windblown snow and a few others breaking near the ground. Today the danger is rated HIGH on all slopes.</p>

<p>A solo skier died in a large avalanche yesterday on the west side of the Bridger Range. He triggered the slide on a heavily wind-loaded slope that broke up to 4 feet deep and 100 feet wide. He was carried over 1,000 feet vertical and did not survive the traumatic ride. New snow and strong east and south winds created dangerous avalanche conditions, which will continue today. The terrain is serious enough and conditions are bad enough that we are not investigating the accident site.</p>

<p>The northern mountains have gotten about a third of the snowfall of the southern mountains (1.4”-2.2” SWE) and the strong wind has drifted the snow into thick, deep drifts which can easily break from the weight of a skier or rider. Simply put, avoid wind-loaded terrain. These zones are found near ridgelines, on both west and east aspects, and also mid-mountain in gullies and couloirs. Ian was on Buck Ridge on Sunday and found unstable wind drifts and shooting cracks in front of his sled (<u><strong><a href="https://www.youtube.com/watch?v=w1PHAN4n83A&amp;list=PLXu5151nmAvRNl9ku…;). For today, the avalanche danger is rated CONSIDERABLE on wind-loaded slopes and MODERATE on all others.</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>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.

BOZEMAN

March 1, 2 and 3, Bozeman Split Fest, More info at www.bozemansplitfest.com.

March 6, 1-hr Avalanche Awareness, 6-7 p.m. at REI Bozeman.

ENNIS

Skier avalanche fatality on west side of Bridgers

Truman Gulch
Bridger Range
Code
HS-ASu-R3-D2.5-O
Elevation
8300
Aspect
W
Latitude
45.80680
Longitude
-110.93500
Notes

Yesterday afternoon a skier was killed in a slide on the west side of the Bridger Range at the top of Truman Gulch on a run called St. Lawrence. The skier was travelling solo and a separate party of two, skinning uphill, witnessed him triggering the slide and getting swept downhill. They responded swiftly, got a beacon signal and saw his hand sticking out of the snow. The dug him up and did CPR, but the skier never revived.  He was carried approximately 1,000 feet vertical down a steep slope causing fatal trauma. The skier was a well known and loved local and we are deeply saddened to report this tragic accident. In the coming days we will release a full accident report.

Number of slides
1
Number caught
1
Number buried
1
Number killed
1
Avalanche Type
Hard slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
3
D size
2.5
Bed Surface
O - Old snow
Problem Type
Wind-Drifted Snow
Slab Thickness
36.0 inches
Vertical Fall
1000ft
Slab Width
150.00ft
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

The avalanche can be seen in the center of the photo. Snow on the lookers right flank also avalanched from wind-loading. There is still a lot of snow that did not avalanche, which is still dangerous and could slide. Photo: GNFAC

Bridger Range, 2019-02-26

The crown looks to be 4 feet deep and 100 feet wide. It is bigger than it appears in the picture. There is still a lot of snow above the crown which could avalanche. Photo: GNFAC

Bridger Range, 2019-02-26