Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, February 29, at 7:00 AM. Today’s advisory is sponsored by Beartooth Powder Guides and Spark 1. This advisory does not apply to operating ski areas.
Overnight the mountains picked up 2-4 inches of high density snow. At 5 a.m. it’s still snowing lightly and temperatures are in the mid-teens to low 20s F. Winds are strong out of the west blowing 15-25 mph with gusts near 40 mph. Snow will taper off this morning as a weak ridge of high pressure builds over the area. Skies will start out partly cloudy, but will become mostly clear by this afternoon. Temperatures will warm into the upper 20s to low 30s F. West winds will remain strong this morning, but will gradually decrease throughout the day. No new snow is expected tonight or tomorrow.
Southern Madison Range Southern Gallatin Range
Lionhead area near West Yellowstone Cooke City
The southern areas have two avalanche problems to look out for. The most significant is a layer of surface hoar buried 1-2 feet deep (video, photo). Stability assessment is tricky with this problem because it does not exist on every slope. Watch for signs of instability such as cracking and collapsing and avoid steeper slopes where these signs area present. If signs of instability are not obvious, it’s worth digging a quick pit to look for buried surface hoar before committing to steeper terrain.
A more obvious avalanche problem today will be wind slabs. This problem will be most widespread on upper elevation slopes facing north through east.
Today, human triggered avalanches are possible on all slopes and the avalanche danger is rated MODERATE.
Northern Madison Range Northern Gallatin Range
Over the past few days, the northern Gallatin and northern Madison ranges have picked up over 6 inches of high density snow. Without a buried weak layer problem (photo), new snow instabilities, specifically wind slabs are the main avalanche concern.
Yesterday, my partner and I rode up Buck Ridge in the northern Madison Range and found the new snow to be well bonded to the firm, old snow surface. We did observe wind transport on the higher peaks near Big Sky and Cedar Mountain (video). Skiers in the northern Gallatin Range also observed active wind transport in the Hyalite area yesterday. With new snow and strong winds overnight, wind slabs have likely grown in size and distribution. Recognizing and avoiding wind loaded slopes will be the best way to avoid triggering a slide.
Today, human triggered avalanches are possible on wind loaded slopes which have a MODERATE avalanche danger. Non-wind loaded slopes have a LOW avalanche danger.
Bridger Range
The Bridger Range hasn’t been favored like the other areas. They did receive a few inches overnight, but this will do little to change avalanche conditions. There could be a few isolated pockets of wind drifted snow below the ridgelines, but these should be small and easy to avoid. Outside of a few small wind drifts, the Bridger Range has a mostly stable snowpack and avalanches are unlikely.
For this reason the avalanche danger is rated LOW.
Doug 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.
EVENTS and AVALANCHE EDUCATION
A complete calendar of classes can be found HERE.
Bozeman: Wednesday, March 9, 6-7 p.m. 1-hr Avalanche Awareness, REI.