Current Advisory

GNFAC Avalanche Advisory for Wed Feb 10, 2016

Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 10, at 7:15 AM. Today’s advisory is sponsored by Cooke City Super 8/Bearclaw Bob’s and Spark 1. This advisory does not apply to operating ski areas.


Mountain Weather: 

The western US is under a bell of high pressure.  Temperatures have been unseasonably warm with highs at 9,000 feet reaching the 40s yesterday and only dropping to the low 30s to upper 20s this morning. Winds are blowing westerly at 20-25 mph. A few thin bands of high clouds will pass overhead, but today will be mostly sunny with mountain temperatures reaching into the 40s again.


 

Snowpack and Avalanche Discussion: 

Bridger Range   Madison Range   Gallatin Range  

Lionhead area near West Yellowstone   Cooke City

Yesterday’s warm temperatures created a few wet loose avalanches on steep, sunny slopes (photo). More will occur today, but the wind and high clouds should keep the wet avalanche activity confined to the upper foot of the snowpack.  

Throughout our advisory area snowpack depths may vary from 6 feet at Cook City to 3 feet on Mt. Ellis (N. Gallatin Range), yet our snowpack structure and avalanche concerns are similar. Depth hoar at the ground is still easily found and slowly gaining strength. Karl Birkeland was on Mt. Ellis doing snow research yesterday and got this layer to break in a stability test, the same as I did on Bacon Rind on Sunday (video). Although depth hoar creates a poor snow structure, without a load of new snow the stability is improving, avalanche danger is dropping and triggering avalanches on this layer is becoming more unlikely, but not impossible. On Saturday, a deep slab avalanche released at the ground outside Cooke City from wind-loading (photo). Small wind-loaded slopes were also triggered by snowmobilers on Buck Ridge over the weekend (photo) and skiers released a larger one (2-3’ deep, 150’ wide) in the wilderness northeast of Cooke City. A layer of faceted, weaker snow is found a couple feet under the surface on some slopes which is getting more difficult to trigger with each passing day.

Avalanches occur when weak layers get stressed and break from the additional weight of new snow, windblown snow or a person. We have not had a substantial snowstorm since January 30th. Wind-loading over the weekend spiked the danger and people triggered slides which have since subsided. Given poor snow structure, triggering avalanches is still possible and the avalanche danger is rated MODERATE.


I will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.


Darren Johnson Avalanche Education Memorial Fund

The National Avalanche Foundation set up an education fund in memory of Darren Johnson, the Yellowstone Club ski patroller who died in an avalanche on January 19. You can check out details and make donations here: http://www.mtavalanche.com/sites/default/files/NAF%20Darren%20Johnson%20Memorial%20Fund.pdf.


EVENTS and AVALANCHE EDUCATION

A complete calendar of classes can be found HERE.

Bozeman, TONIGHT!! Wednesday, February 10: 1hr Avalanche Awareness for Women, REI, 6-7 p.m.