Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 24 at 7:30 a.m. Mystery Ranch in partnership with the Friends of the Avalanche Center sponsors today’s advisory. This advisory does not apply to operating ski areas.
Over the past 24 hours the northern Gallatin Range received 3 inches of new snow. The rest of the advisory area picked up a trace. This morning temperatures are ranging from the single digits to low teens F and winds are blowing 10-20 mph out of the WNW. Today, temps will warm into the 30s F and under mostly clear skies and winds will continue to blow 10-20 from the WNW. Tomorrow looks to be a warmer day with highs in the 40s F and plenty of sunshine.
Bridger Range Gallatin Range Madison Range
Lionhead area near West Yellowstone Cooke City
Wind slabs and weak layers have become mostly dormant over the past week. It has now been eight days since the last reported human triggered avalanche. Does this mean the light is green on all slopes? No.
While the chances of triggering a slide are diminishing, there are a few avalanche problems to look out for. The first and most obvious are wind slabs. Although winds have been relatively calm over the past few days, they blew strong out of the southwest last week. These southwest winds formed isolated drifts below ridgelines and on the leeward side of cross loaded terrain features. While these old, stubborn slabs are not overly sensitive, a few may be reactive to the weight of a skier or rider. Watch out for and avoid wind loaded slopes, especially in steep high consequence terrain.
Without the weight (stress) of new snow avalanches failing at the ground are becoming less likely. It usually takes a big storm and rapid load to reactivate deeper weak layers; or, it takes finding just the right spot on the right slope to trigger a deep slab avalanche. Steep slopes with a thin snowpack are areas to look out for. Exposed rocks provide good clues for areas with thin snow (article and video on deep slabs). Given the high consequences of a deep slab avalanche, it’s best to avoid steep-rocky terrain where it will be easiest to trigger a larger slide.
Today, human triggered avalanches are possible on slopes steep than 35 degrees which have a MODERATE avalanche danger. Less steep slopes have a LOW avalanche danger.
Doug 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.
UPPER HYALITE ROAD CLOSURE
Beginning today, the Hyalite road beyond the dam will be closed to motorized use. The Hyalite Road from the mouth of the canyon to the Blackmore Day Use site remains open. Read more in this press release.
ACCIDENT REPORTS
10 March, Altoona Lakes Fatality (by West Central Montana Avalanche Center)
11 March, Crown Butte Fatality
15 March, Mount Abundance Injury
BLOG POSTS
Check out our latest Blog Posts. Mark wrote about the deep slab avalanche problem. Eric wrote an article about what it takes to put out an avalanche forecast and Doug recapped some lessons from the Beehive avalanche incident in February that was published in Carve.