GNFAC Avalanche Forecast for Sat Dec 16, 2023

Not the Current Forecast

Good morning. This is Ian Hoyer with the Gallatin National Forest Avalanche Forecast on Saturday, December 16th at 7:00 a.m. This information is sponsored by Cooke City Super 8/Bearclaw Bob’s and Uphill Pursuits. This forecast does not apply to operating ski areas.

Mountain Weather

Temperatures this morning are in the 20s and low 30s F. Winds are 15-20 mph out of the west and northwest. There is no new snow. High temperatures will range from the high 20s to high 30s F. Winds will be 10-15 mph out of the west and southwest. Skies will be mostly sunny with patchy clouds today.

Snowpack and Avalanche Discussion

All Regions

It is possible to trigger large, dangerous avalanches today breaking beneath the last two week’s snow on weak snow in the bottom half of the snowpack. 

Two natural avalanches released yesterday in closed terrain at Big Sky Resort (photo). It is unusual to get natural avalanches this long after the last snowfall without a substantial wind loading event (which we also haven’t had). One set of unusual avalanches means you should be prepared for more unusual avalanches, which means you need to be extra alert and cautious. The likelihood of triggering a large avalanche has somewhat decreased over the last few days, but recent natural avalanches clearly demonstrate that human triggered avalanches remain possible. 

Yesterday, riding in the Lionhead area I saw two recent natural avalanches (video and observation). There have been many natural avalanches observed across the advisory area following the last storm and also human triggered slides (wx and avalanche log, Mt. Blackmore video). Large collapses yesterday near Cooke City are yet another indication that the weak layers are not yet dormant (observation). 

The weak snow that formed during the dry spell in November is widespread in the lower snowpack and is particularly weak. It will take quite a while before we can start to trust it. Exactly how long is hard to know, but we are clearly not there yet. 

Stick to lower angled slopes while waiting for conditions to improve or be very cautious if you do decide to ride steep slopes. Assess the snowpack and watch for signs that you should back off steep slopes (e.g. cracking, collapsing, recent avalanches, or poor stability test scores). 

The avalanche danger is rated MODERATE.

If you venture out, please fill an observation form. It does not need to be technical. Did you see any avalanches? How much snow is on the ground? Was the wind moving snow? Simple observations are incredibly valuable. You can also contact us via email (, phone (406-587-6984), or Instagram (#gnfacobs).

Upcoming Avalanche Education and Events

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

We offer Avalanche Fundamentals with Field Session courses targeted towards non-motorized users in December and January and one geared towards motorized users in January. Sign up early before they fill up.

Loss in the Outdoors is a support group for those affected by loss and grief related to outdoor pursuits. Check out the link for more information.

The Last Word

Listen to GNFAC Forecaster Dave Zinn on the Hoary Marmot Podcast for some extracurricular avalanche talk (link to episode).

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