Good Morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Friday, April 6 at 7:30 a.m. Bridger Bowl, in partnership with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
Since yesterday morning the mountains near Cooke City received 8 inches of snow, the mountains near Bozeman 4-5 inches, and the mountains near Big Sky and West Yellowstone 2-4 inches. Snow is falling this morning and it should continue through today ending tonight. Temperatures this morning were in the high teens to low 20s F, and winds were blowing 5-15 mph from the N and E. Today, temperatures will remain the same or possibly drop a few degrees. As an area of low pressure moves E today, winds will increase to 15-30 mph and rotate around the northern half of the compass. By tomorrow morning 6-8 inches of snow should accumulate, but this spring storm will deliver atypical snowfall patterns, and I’m not sure which areas will get more and which will get less.
BRIDGER / GALLATIN / MADISON / LIONHEAD
New snow, cold temperatures, and winds forecasted to increase this afternoon will make fresh wind slabs the primary avalanche concern. In most places new snow rest on a thick melt-freeze crust and has not bonded to this crust very well yet. For today, new snow will sluff easily on the crust or produce slab avalanches on slopes where it was deposited by the wind.
With snow forecasted to fall throughout the day, weak snow found on all aspects near the ground will be stressed (photo). My personal brush with death occurred at this time about 6 years ago immediately after a similar spring storm when I triggered and was caught in an avalanche that broke at the ground. This situation is a low probability – high consequence scenario because these avalanches are hard to trigger but have serious consequences. Stability tests do not work very well assessing deeply buried weak layers. The best option is to exercise patience and allow the snowpack time to adjust to the load it will receive today.
Fresh wind slabs will be easily triggered today and for this reason, the avalanche danger is CONSIDERABLE on wind-loaded slopes. With winds rotating around the compass today, these wind slabs will not be found in normal locations. Because most slopes have weak snow near the ground with new snow increasing the stress on this layer, the avalanche danger on non wind-loaded slopes is MODERATE.
COOKE CITY
Near Cooke City, the snowpack on most slopes is strong (video), and fresh wind slabs are the primary concern. Like other areas, the mountains near Cooke City will see winds that rotate around the compass today and fresh wind slabs may be in odd places. Today the avalanche danger is CONSIDERABLE on wind loaded slopes and MODERATE on all others.
I will issue the next advisory tomorrow morning at 7:30 a.m. and the final advisory on Sunday morning. If you have any snowpack or avalanche observations, drop us a line at mtavalanche@gmail.com or call us at 587-6984.