Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Forecast issued on Wednesday, February 20th at 7:00 a.m. Today’s forecast is sponsored Werner Wealth Management and Community Food Co-op. This forecast does not apply to operating ski areas.
At 6 a.m. the Bridger Range has 6” of new snow with 1-3” elsewhere. Temperatures range from -10F outside Cooke City to +4F in the Bridger Range. Winds are west to southwest (NW in Cooke) at 10-20 mph with gusts of 30 mph. Under mostly cloudy skies scattered snowfall will drop 2-4” in the Bridger Range and 1-2” elsewhere. Temperatures will rise into the teens and winds will shift northerly at 15-25 mph.
It is snowing in the Bridger Range and 6” has already fallen with west winds blowing 20-30 mph. This will create 1-2 foot thick wind-drifts that will be easy to trigger. Newborn wind slabs are typically very sensitive and some will avalanche naturally. Loading will occur along ridgelines, or in gullies from mid-mountain winds. For today, the avalanche danger is rated CONSIDERABLE on wind-loaded slopes and MODERATE on all others.
Eric rode into Lionhead yesterday and saw a monster avalanche that was in full view of the highway. It was either triggered by a cornice fall or snowmobiler late Monday on weak, sugary facets at the base of the snowpack. In his video Eric explains how poor snow structure and heavy wind-loading contributed to this 6 foot deep slide (video, details and photos). With thick wind-loads it is difficult to impact the weak layer and a slope might have a dozen or more tracks before a sledder, skier or cornice fall triggers it. Thin snowpacks adjacent to these deeper slopes are potential trigger points. Although many slopes are stable, a few are not. Assessing stability on deep weak layers is difficult and the best tactic is to avoid them. They are the IEDs of the backcountry. For today, avalanches are still possible and the danger is rated MODERATE.
Yesterday, a skier triggered a large avalanche outside Cooke City on a northeast aspect of Sheep Mountain. It released 1-2 feet deep and propagated 400 feet wide into an adjacent path. The skier deployed his airbag and was partially buried and uninjured (photo). He emailed us details which everyone should read HERE. Yesterday, avalanches involving new and recently wind-drifted snow were triggered up Hyalite on Elephant Mountain (photo and details) and a natural slide was seen on Mt. Fox near Goose Lake outside Cooke City.
An equally serious problem involves avalanches on heavily wind-loaded slopes releasing on weak, sugary facets in the lower part of the snowpack. Alex looked at 2 avalanches on Buck Ridge and McAtee Basin that were triggered on Sunday (photo, video) and Ian and I saw a similar slide on Crown Butte (photo, video). Slopes with thick hard slabs of windblown snow can be identified by cornices capping the slope or ridgelines scoured to the dirt. It is best to avoid them. Slopes with either recent wind-loading or a season’s worth have a MODERATE avalanche danger. Slopes that were not touched by the wind have a LOW danger.
If you get out and have any avalanche or snowpack observations to share, contact us via our website, email (email@example.com), phone (406-587-6984), or Instagram (#gnfacobs).
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
February 22 and 23, Women’s Companion Rescue Clinic, 6-8 p.m. Friday at REI, 10-4 Saturday in the field. More Info and Register.
March 1, 2 and 3, Bozeman Split Fest, More info at www.bozemansplitfest.com.
February 23, 1-hr Avalanche Awareness for Snowmobilers, 7-8 p.m. Holiday Inn West Yellowstone.
Every Friday and Saturday, Rescue Training and Snowpack Update. Friday 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.
On Saturday near Crested Butte, Colorado two skiers were caught and killed in an avalanche. Preliminary details here. This is the 14th and 15th fatality in the U.S. this season.