Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Sunday, January 10, at 7:30 a.m. Yellowstone Rental, in cooperation with the Friends of the Avalanche Center, sponsor today's advisory. This advisory does not apply to operating ski areas.
Over the past 24 hours a weak shortwave disturbance has moved across Montana, depositing a trace of snow in the Gallatin and Madison Ranges along with the Bridgers while leaving the mountains around Cooke City dry. Yesterday, a west flow aloft brought stronger ridgetop winds throughout the day at 15-25 mph, but winds calmed later in the evening. Today a ridge of high pressure will continue to build over the area, bringing sunny skies and warmer temperatures. Highs today will reach almost 40 F degrees with lows dropping down around 15 F degrees. Winds will be calm in the valleys and light along the ridgetops at 5-10 mph out of the W-NW. High pressure will continue dominate the weather pattern for the early part of this week.
Sunny skies and warmer temperatures over the past few days have helped slow down natural avalanche activity but have not done much to heal our feeble snowpack. Persistent instability remains over our entire advisory area making for dangerous avalanche conditions. The old saying that 'time heals' may work for relationships and knee injuries but does not apply to our snowpack. As the weak structure of our pack continues to adjust to the storm loads, natural avalanches will become less common, but human triggered avalanches will remain likely.
Yesterday a snowmobiler in Sunlight Basin triggered a slide that broke 2 feet deep, ran 40 feet across the slope and travelled roughly 300 feet in distance (photo). This slide managed to rip a tree right out of the ground, which was deposited near the bottom of the slope. A second report of fresh avalanche activity in Cedar Basin came in from the Yellowstone Club Ski Patrol. These fresh avalanches occurred on a E-SE facing slope and were substantial in size with the crowns ranging from 3-5 feet in depth and propagating close to 1,000 feet in length. The triggers of these avalanches are unknown. The Bridger Bowl Ski Patrol got good results in the Slushmans area triggering numerous avalanches that broke 12-18" deep and consisted mainly of stiff wind slabs formed over the past few days. These hard wind slabs have been deposited over much of the area south of Bridger Bowl making backcountry skiing difficult and dangerous. Slushmans chair opened yesterday at 11 a.m., but Saddle Peak saw zero traffic.
As the natural cycle winds down, accessing slopes that have not avalanched may hold a strong allure for both skiers and riders. The theory that these slopes are stable simply because they hold undisturbed snow is flawed and can prove fatal. The potential for triggering devastating avalanches still exists (video). As wind and warm weather consolidate the slab, avalanches will become less frequent but larger in size making it very possible to remotely trigger an avalanche from all areas of the slope. Avalanche run out zones and slopes steeper than 30 degrees should be approached with caution or avoided all together. If you do find yourself traveling in Avalanche terrain make sure you only expose one person at a time while the rest of the group is in a safe zone with a good visual of the person exposed. For today, human triggered avalanches are likely over our entire advisory area and the avalanche danger is rated CONSIDERABLE.
On a sad note, Mark Wolling, the Jackson Hole ski patroller who was caught in an avalanche this past Wednesday has died from his injuries. Our thoughts and prayers go out to his Friends and Family.
I will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry give us a call or email with your observations. You can reach us at 587-6984 or email us at mtavalanche@gmail.com.