Current Advisory

GNFAC Avalanche Advisory for Mon Nov 24, 2014

Good morning. This is Doug Chabot with early season snowpack information issued on Monday, November 24 at 7:30 a.m. Today’s information is sponsored by Northern Lights Trading Company in partnership with the Friends of the Avalanche Center. We will update this bulletin on Wednesday morning.

Mountain Weather: 

Last night another 2-3 inches of snow fell in the mountains. Since Friday evening over a foot has fallen in the Bridger Range, outside Cooke City and West Yellowstone, with 6-8 inches falling up Hyalite and around Big Sky. Winds were blustery over the weekend hitting speeds of 70 mph from the west on Saturday. This morning westerly winds are blowing 25-35 mph and gusting to 50 mph with temperatures in the teens under partly cloudy skies. Another system crawls in tonight to deliver snow tomorrow and Wednesday. It’s a northwest flow and new snow will blanket the mountains. My fingers are crossed that it will be a bountiful Thanksgiving.

Snowpack and Avalanche Discussion: 

A skier triggered avalanche last Wednesday near Hardscrabble Peak in the Bridger Range (video) and cracking and collapsing of the snow in many ranges over the weekend illustrate a common problem: a poor snow structure (photo). The cold snap a couple weeks ago changed the snow on the ground into crunchy facets. Facets are weak and do not bond well to each other. They feel like sugar and you cannot make snowman out of them. In areas where they are capped by a wind slab they are cracking and avalanching. So far this instability has not been widespread, but that will change in the coming days. More snow and strong winds will add weight and stress to this weak layer and the avalanche likelihood will rise.

Snowpack depths range from 12-16 inches in the northern areas to 20” around West Yellowstone and 30+” outside Cooke City. All these areas have facets at the ground creating questionable stability. Yesterday my partner and I toured into the Lionhead area outside West Yellowstone. The snow was thin and faceted (photo1, photo2). Even though we jumped around and tried our hardest, we could not get the snow to crack and collapse on the facets.  There was simply not a meaty enough slab to fracture. This was not the case in the Bridger Range and up Hyalite Canyon where skiers and ice climbers were able to get cracks and a few avalanches in wind drifts. This is bulls-eye information that the snow is unstable. Drummy and hollow sounding wind slabs are bad news. Poking your pole into the snow will likely be met with initial resistance before hitting the airy snow at the ground: a sign of a slab over a weak layer, crucial ingredients for an avalanche. Be extra careful. The snow is thin, weak and not user friendly and will get much angrier as more snow falls.

We are not issuing danger ratings since we are still in the process of gathering field data. If you get out please let us know what you find. Pictures, snowpits, and a general narrative of conditions are super helpful. Drop us a line at mtavalanche@gmail.com. Daily avalanche advisories are on the near horizon if we continue to get storms.

iOS 8 GNFAC App

Yes, it’s finally done! We have a newly minted GNFAC app for the iOS 8 platform.  Search “GNFAC” on iTunes.

Android app

Search “GNFAC” in Google Play.  Make sure you have the updated version so you can access all our newest videos.

AVALANCHE EDUATION:

Take a look at our Education Calendar for all our classes being offered.

Monday, November 24, 7 p.m.: Bozeman, Northern Lights Trading Company

MSU - Introduction to Avalanches with Field Course

The workshops are held on Wednesday and Thursday evenings, with a field course on Saturday. Different topics are presented each evening. Topics include: avalanche terrain recognition, the affect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.

December 3, 4 and 6 or 7, 2014: https://www.ticketriver.com/event/13089

Snowmobiler Introduction to Avalanches with Field Course

Five hours of lectures are followed by a full day field course. Topics covered include: avalanche terrain recognition, the affect weather has on avalanche hazard, the development of the mountain snowpack, decision making skills, and basic search and rescue procedures.

West Yellowstone: Dec 18 and 19, 2014


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