19-20

Small new snow avalanches at Bridger

Bridger Bowl
Bridger Range
Code
SS-N-R1-D1.5-I
Elevation
8500
Aspect Range
E-NE
Latitude
45.81560
Longitude
-110.92300
Notes

Thursday, November 21:

1. "I observed 2 natural avalanches on the slopes between the Apron and Ramp. No ski tracks in those areas. I thought I took a picture but didn’t. Looks like they both started in the rock bands below the ridge. One was small and the other was considerably larger. Hard to know if they ran today or yesterday. Looked like it was just new snow. Pretty much east aspect."

2. "Toured up to the ridge at Bridger today and traversed into Bridger Gully. At around 8,000' in the trees above the most prominent snowfield, my partner and I observed very small dry sluffs confined to the new snow. Bellow Bridger Gully, my partner was able to release a slide while traversing through rocks above his intended line. This was on an east-southeast aspect at 7,500'. Snow just a few degrees more to the east was dryer. The snowpack nearby thinned greatly on the east-southeast aspect.

Wednesday, November 20:

1. " Noted some activity (D1-D2) isolated to the new snow around rock features and ridgetops that were wind-affected.  Our pit revealed a weakening and thin snowpack due to the drier weather, however, the facet growth at the ground has remained fairly slow and has maintained moisture."

Number of slides
3
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
1
D size
1.5
Bed Surface
I - Interface between new and old snow
Problem Type
Wind-Drifted Snow
Images
Slide below Bridger Gully
New snow avalanches on Saddle Peak
Natural new snow avalanches near Bridger
Fresh wind slabs at Bridger
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
19-20

GNFAC Avalanche Forecast for Thu Nov 21, 2019

Snowpack and Avalanche Discussion

<p>The tug-of-war between fall and winter continues with winter coming out on top this week. Tuesday’s storm came in warm with temperatures near or above freezing before cooling into the 20s F. This helped the new snow stick to the old snow surface. The weight of the 0.3 to 0.6” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent (SWE)</strong></a><strong> </strong>did not significantly change the avalanche hazard. We received reports of fresh drifts of snow breaking in the Bridger Range, but nothing failed more deeply than the interface between the old and new snow (<a href="https://www.mtavalanche.com/images/19/fresh-wind-slabs-bridger"><strong…;). Wind loaded slopes will stabilize by today. However, stronger wind over the weekend may create fresh drifts that could avalanche. The story from the Bridger Mountains applies to other ranges that received snow on Tuesday. The mountains south of Big Sky are different. Yesterday, Alex and I went to the Lionhead Range to work on the weather station where we found the weakest snow in our advisory area. The snowpack ranges from 6” to 18” deep and the lower portion consists of large, weak facets that will be a problem when West Yellowstone gets its next storm (<a href="https://www.mtavalanche.com/images/19/shallow-weak-snowpack-lionhead"><… 1</strong></a><strong>, </strong><a href="https://www.mtavalanche.com/images/19/coverage-lionhead-thin"><strong>p… 2</strong></a><strong>,</strong> <a href="https://www.youtube.com/watch?v=i6DWvLU0Eks&amp;list=PLXu5151nmAvSbcbVf…;

<p>The snowpack will remain generally stable until the next storm comes on Sunday afternoon. We are working hard to get out in the field to collect information about the snowpack and we want you to help us by submitting an <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>observat… form</strong></a>. Your observations are critical to us developing a complete picture of what is happening in the mountains. You can also email us (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), leave a message on our 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 and plan to attend one or two: Events and Education Calendar.

BOZEMAN

From obs.: "I went skiing at Bridger today,... There was 4-5” of new snow, which was sitting on a firm surface. The wind had done some work, and I was able to break off a few shallow (6”) wind slabs in the first 100 feet or so off the ridge." Photo: A. Schauer

Avalanche Details: Small new snow avalanches at Bridger
Forecast link: GNFAC Avalanche Forecast for Thu Nov 21, 2019
Bridger Range, 2019-11-20
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