23-24
Wet snow at Lionhead
We rode from the Buttermilk trailhead up Denny Creek to Lionhead Ridge, along Lionhead Ridge through Watkins Creek and to the motorized boundary at the head of Targhee Creek.
There was a ~1" crust at the surface when we left the trailhead, with dry snow beneath. We saw our first wet loose avalanche of the day running around 11 am. By 12:30 there were dozens and many rollerballs. None of them ran particularly far or picked up too much volume. The snow surface was moist on sunny slopes by late morning, but not more than a few inches down.
We saw one small slab avalanche that occurred since this weekend's snow. It appears to have been triggered by a snowmobile yesterday (4/1/24). It broke 10" to 2 ft deep, 50 ft wide, and ran ~50 vertical feet. It broke on a thin layer of facets beneath the new snow. Digging in the crown, dry facets at the ground were along still present and weak (fist hardness).
Signs of older avalanches were visible beneath the new snow, including one slide that broke in early March. No cracking or collapsing were observed today.
Ernest Miller Ridge
Saw no signs of instability. Skied east to southeast aspect slopes. The snow did get moist, but not sloppy, in the afternoon. Did not execute any snow pits and accompanying test. The snow pack felt solid. Would have been nice to do a little snow science, but it was a long tour.
GNFAC Avalanche Forecast for Tue Apr 2, 2024
<p><span><span><span>Conditions change rapidly in the spring, and travel plans should reflect these daily fluctuations. While not equal in likelihood, wet snow avalanches, dry slab avalanches failing in the upper snowpack and deep slab avalanches failing on basal weak layers are all potential problems today. </span></span></span></p>
<p><span><span><span>Natural and human-triggered wet snow slides will become likely as the spring sun blazes and temperatures rise into the 40s and 50s F. These will generally present as wet loose avalanches that start at a point and fan out as they entrain snow. The weight of these slides pack a serious punch. Yesterday, the Big Sky and Bridger Bowl Ski Patrols observed limited wet snow instability when small natural avalanches occurred in closed terrain. We will likely see more today. Wet snow instability is rising as the surface snow gets wet (duh!) and pinwheels of snow start rolling downhill like giant cinnamon rolls. Quickly move to cooler aspects, lower-angle slopes or head home as instability increases, and preemptively ensure a safe exit plan.</span></span></span></p>
<p><span><span><span>Avalanches breaking 1-2 feet deep below recent and wind-drifted snow are possible. Riding in Island Park yesterday, we saw five avalanches that likely failed at the end of last week (<a href="https://youtube.com/shorts/LPB5N_bAPco"><strong><span>video</span></str…;). On Sunday, a “pow surfer” (snowboarder without bindings) was buried to his chest by an avalanche that broke below the recent storm snow at Lionhead Ridge (<a href="https://www.mtavalanche.com/node/31694"><strong><span>photo</span></str…;), and a snowboarder (with bindings) triggered a collapse that shot cracks 25 feet near the Sphinx (<a href="https://www.mtavalanche.com/node/31707"><strong><span>observation</span…;). Continued instability is most likely on slopes where newer weak layers exist immediately below recent snow, as Alex saw in the Taylor Fork (<a href="https://youtu.be/Hmhje2N8Zc4?feature=shared"><strong><span>video</span>…;) and I found in one of our Island Park pits (<a href="https://www.mtavalanche.com/node/31700"><strong><span>observation</span…;). Test the upper three feet of the snowpack for instability and back off if you find it. </span></span></span></p>
<p><span><span><span>While less likely, avalanches last week on Flanders Mountain (<a href="https://www.mtavalanche.com/node/31691"><strong><span>photos</span></st…; </strong><a href="https://youtu.be/BgZINtzwV6o?feature=shared"><strong><span>video</span>…;) and Mt. Blackmore (<a href="https://www.mtavalanche.com/node/31672"><strong><span>photos</span></st…;) in the northern Gallatin Range that broke 2-6 feet deep show the continued potential for deep slab releases. A wet snow or wind-slab avalanche, cornice fall, or an unlucky backcountry traveler crossing just the wrong spot could trigger a large slide. Conservative terrain choice and safe travel practices are the only effective management strategies. Avoid large, heavily wind-loaded slopes often overhung by enormous cornices. </span></span></span></p>
<p><span><span><span>The avalanche danger is MODERATE this morning and will rise to CONSIDERABLE as wet snow avalanches become likely. </span></span></span></p>
Upcoming Avalanche Education and Events
Hyalite Road Closure: Hyalite road is closed to ALL MOTORIZED VEHICLES until the morning of May 16. This is a regular annual road closure to reduce road damage during the spring thaw. Bicycle and foot traffic are allowed. Contact the Bozeman FS Ranger District for more info.
Recent instability in the new and wind drifted snow
Two rider-triggered avalanches near Reas Peak on north aspects that broke within or just below the new storm snow (D1s)
Natural avalanche broke near Yale Creek on a southern aspect that broke below new snow (D1)
Two natural avalanches that broke within the wind drifted snow in Jefferson Bowl (D2s)
Collapse Near the Sphinx
From email: We were out camping around the east side of Sphinx Mountain. We rode sleds over dirt for a while and came from Buck Ridge. We didn’t see any fresh avalanche crowns all weekend. We did get a big whoomph that collapsed the snowpack while skinning along a ridgeline on Sphinx that seemed freshly loaded. Cracks shot out maybe 25 feet around, but it didn’t move. We didn’t dig snow pits; we followed our plan of keeping our terrain selection on the mellow side.
Collapse Near the Sphinx
From email: We were out camping around the east side of Sphinx Mountain. We rode sleds over dirt for a while and came from Buck Ridge. We didn’t see any fresh avalanche crowns all weekend. We did get a big whoomph that collapsed the snowpack while skinning along a ridgeline on Sphinx that seemed freshly loaded. Cracks shot out maybe 25 feet around, but it didn’t move. We didn’t dig snow pits; we followed our plan of keeping our terrain selection on the mellow side.