Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, March 30, at 6:45 AM. Today’s advisory is sponsored by Yellowstone Arctic Yamaha and Yamaha Motor Corp. This advisory does not apply to operating ski areas.
Yesterday, a trace of snow fell in the Bridger Range and West Yellowstone, 3-4” up Hyalite and 1-2” everywhere else. At the ridgetop, winds are east to northeast at 15 mph with gusts of 20-40 mph. At 5 a.m. skies are mostly cloudy and temperatures are near 20F. Today will remain mostly cloudy as temperatures reach the low 30s and winds shift north at 15-25 mph. Tonight, scattered snow showers may drop 1-2” of snow. Get your winter fix now, because sunny and unseasonably warm weather is slated for Friday through Monday.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Yesterday, backcountry skiers and ski patrols were able to trigger small avalanches on slopes with wind-loading. They reported atypical winds from the east to northeast loading slopes in “strange places”, “unlikely spots” and creating “strange drifts”. With fresh snow to blow around, this instability will continue today.
Yesterday, my partner and I toured into the northern Bridger Range to investigate the large avalanche on Sacajawea Peak from Monday (photo). Poor visibility prevented us from seeing the entire slide, but the debris was very impressive: it ran almost full track, was 400 feet wide with hard slab debris in excess of 10 feet deep. As we hiked up to the crown a loose snow avalanche came rolling down the bed surface prompting us to retreat. We dug a snowpit on a nearby slope and found a weak layer of ball-bearing like graupel mixed with facets buried two feet deep and sitting on a thin ice crust; a likely recipe for avalanching so wide and far. This is the first time we have seen this layer and believe it to be rare, but can’t rule out its existence on other slopes in our forecast area. There’s only one way to know: dig. Luckily the layer appears as a layer in the snowpit wall…no advanced skills are required to find it. Watch the video and see for yourself.
Over the weekend, a cornice triggered a large avalanche up Flanders drainage in Hyalite and smaller, deep, avalanches were triggered near Gardiner (photo) and Cooke City (photo). A weak layer of facets is buried 2-3 feet deep in the southern mountains. Steep, wind-loaded slopes are the most likely places to trigger an avalanche. For today, the avalanche danger is rated CONSIDERABLE on wind-loaded slopes steeper than 35-degrees and MODERATE on all other terrain.
Alex will issue the next advisory tomorrow morning by 7:30 a.m. If you have any snowpack or avalanche observations to share, drop us a line at mtavalanche@gmail.com or leave a message at 587-6984.