Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Saturday, December 22 at 7:30 a.m. Today’s advisory is sponsored Mystery Ranch in partnership with the Friends of the Avalanche Center. This advisory does not apply to operating ski areas.
This morning mountain temperatures were in the teens to low 20s F with a slight inversion and valley temperatures in the single digits or colder in places like West Yellowstone. Winds this morning were blowing 10-15 mph from the south with gusts of 20-30 mph. Today cold air will descend over SW Montana keeping mountain temperatures from rising much. As a trough of low pressure approaches, south winds will increase and clouds will build this afternoon. Snowfall should begin late afternoon or early this evening mostly to the south. By tomorrow morning the mountains near West Yellowstone and Cooke City will get 3-5 inches of snow. Other areas will get 1-3 inches.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Many places and many slopes have a deep and strong snowpack like one Eric found yesterday on Lionhead while teaching an avalanche class (strong snow photo). Some slopes like a steep, rocky one on Sacajawea Peak have much thinner and weaker snow. This particular slope was loaded by wind-blown snow and produced an avalanche (avalanche photo) on Thursday when triggered by a falling cornice. Throughout the advisory area, similar slopes will be likely places to trigger an avalanche. Other places to trigger an avalanche exist at lower elevations with relatively thin snow capped by wind slabs or drifts.
Yesterday my partner and I skied in Truman Gulch on the west side of the Bridger Range. As expected the snowpack was thinner and weaker than it is on the Bridger Bowl side but not necessarily unstable because it lacks the stress from new snow. However, we carefully avoided areas with wind drifted snow. Most interesting was the condition of the snow surface which has weakened and faceted during recent warm sunny days and clear cold nights. The Big Sky Ski Patrol has found similar weaknesses near the surface. This potential, future problem does not appear to be widespread but is worth remembering once more snow comes.
Interested in a summary of recent weather and the outlook for the next three months? It could be wetter and colder! Watch this short video from the National Weather Service in Billings.
Today, because human triggered avalanches remain possible the avalanche danger is rated MODERATE
Eric will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.
Free 1-hour Avalanche Awareness lecture at Bridger Bowl at 1 p.m. on the 4th floor of the Saddle Peak Lodge TOMORROW, December 23. No registration necessary.