21-22

GNFAC Avalanche Forecast for Fri Jan 7, 2022

Snowpack and Avalanche Discussion

<p>Heavy snow and strong winds are creating very dangerous avalanche conditions. 15” of snow has fallen since yesterday moring (1.5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</u></a>) and it is still snowing. Strong winds have created fresh drifts 2-4 ft deep. Expect steep wind-loaded slopes to avalanche naturally today. If you get onto any steep slope, even one that isn’t wind-loaded, expect to trigger a slide beneath the new snow. With so much new snow these storm snow avalanches will easily be large enough to bury you. If you need added incentive to stay out of avalanche terrain, remember that there are weak layers lower in the snowpack that could break even deeper (<a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-1"><st…. Abundance photo</u></strong></a>).&nbsp;</p>

<p>The avalanche danger is HIGH on wind-loaded slopes and CONSIDERABLE on all others.</p>

<p>Snow tapered off early yesterday afternoon, leaving 5-6” of new snow (0.5-0.6” SWE). Since the end of snowfall, slopes sheltered from the wind have gotten a bit of a break with warm temperatures helping the new snow to bond. Strong gusty winds are still actively drifting snow and stressing the snowpack on wind-loaded slopes. With unusually strong winds, expect drifts in unusual places at lower elevations and in spots that may typically be sheltered from the wind. Wind slab avalanches will be easily triggered on wind-loaded slopes today. Avalanches were already breaking on wind-loaded slopes before this latest round of snow, potentially on a freshly buried weak layer (<a href="https://www.mtavalanche.com/images/22/recent-avalanche-lionhead"><stron… avalanche photo</u></strong></a>). Skiers near Hebgen lake yesterday got quite unstable snowpack test results on the weak snow at the ground. Those weak layers need more time to adjust to this load before we will trust them. The avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on all others.&nbsp;</p>

<p>Skiers in the Bridger Range yesterday reported small natural and skier triggered slides (<a href="https://www.mtavalanche.com/images/22/small-new-snow-slide-west-bridger…;, <a href="https://www.mtavalanche.com/images/22/new-snow-slide-throne-2"><strong>…;, <a href="https://www.mtavalanche.com/images/22/new-snow-slide-throne-1"><strong>…;). While these slides were not large, they demonstrate unstable conditions and the potential for larger slides breaking on more heavily wind-loaded slopes. Warm temperatures have helped the storm snow bond and it will be less reactive today. Keep an eye out for cracks shooting out in front of you as a sign you’ve found a place where the new snow hasn’t yet bonded. If you’re going to get onto steep slopes, dig a snowpit and check for unstable weak layers lower in the snowpack (<a href="https://www.youtube.com/watch?v=Zp4MIwaLaac"><strong><u>Mt. Ellis video</u></strong></a>). Human triggered avalanches are possible and the avalanche danger is MODERATE today.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

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Small natural and skier triggered storm slabs in Bridgers

BRIDGER RANGE
Bridger Range
Code
SS-N-R1-D1-I
Latitude
45.85120
Longitude
-110.94800
Notes

Skiers in the northern Bridger Range and on the west side reported several natural and skier triggered slides breaking on the interface between the new and old snow. These slides were shallow and small.

Number of slides
5
Number caught
0
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Natural trigger
R size
1
D size
1
Bed Surface
I - Interface between new and old snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year

From email (1/6/22): "Skied the Throne today. New snow instabilities. Higher density snow falling on colder snow. Saw a hand full of naturals all running on the new snow old snow interface."

Photo: E. Knoff

Bridger Range, 2022-01-07

From email (1/6/22): "Skied the Throne today. New snow instabilities. Higher density snow falling on colder snow. Saw a hand full of naturals all running on the new snow old snow interface."

Photo: E. Knoff

Bridger Range, 2022-01-07