Snow Observations List

Toured up to Emigrant Gulch Bowls. Saw a pretty big natural avalanche on a NE facing slope. Saw the crown, it looked deep, and the debris was in large chunks and carried large trees down to the bottom. Our guess is wet-slide stepping down to deep slab on the weak layer at the bottom of the snowpack. We saw another decent natural on an adjacent slope with a similar aspect and many old wet-slides from last week on various aspects surrounding the Emigrant Gulch uptrack. 

A partner and I toured up into the southeast bowl of Emigrant peak earlier today. New snow ranged from ~3-10 cm, increasing with elevation, and with surprisingly little wind affect. The consequences of the recent warm spell were still obvious, with a pervasive crust under the new snow, and one large recent wet slide. We dug on a northeast aspect at 9000' and got unremarkable test results (CT 15 Q2 on Depth Hoar, ECTN15 beneath the recent crust), and a similar structure to the rest of the region (Basal Facets, a large mid pack slab of rounds, and a complex of recent wet snow and crusts near the surface). Clouds obscured our view of the alpine, and we decided to keep to mellow terrain due to the low visibility and possibility of a consequential slide.

Observed a D1 Natural wet slab avalanche in the Playground, just North of Texas Meadows. It seemed to have been triggered from a wet loose avalanche that released from the cliffband above. Estimated that the avalanche occurred on 3/22 during the period of warming after the snow tapered off.  Crown was estimated at 1.5-2', approximate slope angle 35-40 degrees, E-SE slope, debris was 4-5' deep. Slide ran approximately 275'. HS just below the toe of debris was 115cm.

Also observed wet loose activity in S facing run off Texas (first run to the W of the summit)-photo attached.  

Would like to preface this by saying my buddy and I have limited experience testing and poor technique, but we gave it hell anyway.

We dug a pit on the east side of the ridge between beehive and middle basin, and did a compression test. The column was somewhat poorly isolated, and we were not able to get it to fail with a normal tap test. By stomping on it from above, we got a fracture at about 75cm depth on what looked like an earlier season rain crust. Everything above that level was very dense, stable and hard to dig.  The surface had about 10cm fresh snow with a hard crust below. Image of snow profile is attached. Pit coordinates were 45.32897, -111.38197.  Overall we felt like this aligned with the forecast quite well. Snowpack appeared very stable and cohesive until it got down to a depth below the crust at 75cm.

While traveling, we saw significant snow accumulation midday and clearing in the afternoon, followed by light snow in the evening. Test slopes and cornices we tested were stable, and we didn't see shooting cracks or hear any whumpfing. No natural avalanches observed, but visibility was poor most of the day. Wind across the ridge was substantial with notable blowing snow, blowing from the west and southwest.

Thanks for all you do!

Collapse with shooting cracks approx 50 feet out

1 skiers boot broke through the crust layer during transitioning and sank to the waist causing collapse of about 2” according to standing skiers feeling of drop

elevation: 9940

Republic side of woody ridge

at history rock today we did an extended column test and a regular column test. Both tests were performed a few feet from one and other, and both pits were dug to the ground on a 26ish degree slope. The extended column test fully propagated on the 4th tap from the elbow scoring ectp 14. The regular column test failed after one tap from the wrist. Both failed on the sugary facet near the bottom of the snowpack I did not record any exact depth measurements or perform further tests. estimated coordinates (45.48811,-111.00942) I think it was the first powder field. 

Walked out the north gate of bridger to the playground. Just north of Texas meadows observed a slide that ran sometime earlier in the week on a E aspect. Seems to have been triggered naturally by a loose wet coming out of the steep rocky terrain above. Ran about 200 feet was about 50-60 feet wide and crown was roughly 2-3 feet deep. Snow around the slide and on similar aspects was wet in the top 40 cms or so. 
 

Around the corner dug a pit on a N aspect. Snow was significantly drier and deeper. HS 160 with plenty of weak snow at the bottom still. ECTX but did get failure and propagation on that lower layer with extra hits. PST 45/100 on the same layer 120 cms down. 

Debris field from likely a wet slide on a steeper slope in the back bowl near Emigrant peak. Slide was on an east-south/east facing slope. Not sure the date of slide.  

From email: "New snow:  10-15cms.

No collapsing, no cracking, no fresh avalanche activity to report.

Snowpit attached from a SE aspect at 9100'.   HS: 113.  ECTP18 @ 78."

Skied at Cinnamon Mountain today. The recent warm spell was not kind to the snowpack off 191. South facing slopes at all elevations had lost significant amounts of snow, with those below 7500 ft mostly bare and muddy.

Where there was still snow a thick yet loosely frozen crust capped weaker layers lower in the snowpack. Out of the wind this crust had barely refrozen, and I crashed through it many times, sometimes with the slab propagating further and shaking nearby saplings. Near treeline the crust became stout and supportable, and the 2-3 cms of new snow were bonding well (i.e. wet snow on wet crust).

Light winds with moderate gusts out of the WSW were lightly drifting the new snow, and precip was falling intermittently and as rain below ~7 kft. Certainly a funky day out there.

Our party took a slow tour up and down the SE face of Blackmore today. New rollerballs were observed on E aspects, and we witnessed a natural D1 loose wet slide occur on the east face of Blackmore at around 1:00. Dug a quick pit on the way up (NE aspect, ~8700’) out of curiosity about snowpack structure and fracture initiation. HS 110 cm. A compression test yielded CTM (15 taps), with a Q2 resistant planar shear at 60 cm depth. Was surprised to not find faceted snow near the bottom of the pit, despite the avalanche incident that occurred the day prior on the northeast ridge of Blackmore on a similar aspect and elevation.

Rode up to the head of Portal Creek to area beneath Eaglehead Mtn and then around to the ridge overlooking Hidden Lakes. The trail is very low snow near the Portal Creek trailhead and the snow was wet to the ground beneath a stout crust. As we got higher up the coverage increased and even sunny slopes only had a couple inch thick surface crust over dry snow. On shady slopes there was still dry snow at the surface. We dug on a N aspect at 9400 ft just north of Eaglehead Mtn. The snowpack was 180 cm deep. We got an ECTX, but the facets near the ground were still soft and sheared off cleanly when pulling on the column. 

We had no signs of instability today. The only avalanche we saw was a large slide on Eaglehead that had been previously reported over two weeks ago.

Two skiers were ascending a northeast-facing avalanche path on the northernmost ridgeline of Mount Blackmore around 1 PM when they triggered a large, dry slab avalanche that failed 3 feet deep, 150 feet wide, and ran 500 feet vertical. Debris piled up 4-8 feet deep. The avalanche failed on weak, faceted snow near the base of the snowpack. 

As the group was about halfway up the avalanche path, they saw a small slide initiate to their right and then they heard a loud boom as the rest of the slope collapsed 250 feet above them. The skier lower on the path sprinted to the left into the trees to avoid getting caught. The second skier was 30 higher on the slope. He attempted to run off the slope but was unable to avoid getting captured. He was carried to the bottom of the avalanche path, got submerged in the snow, but thankfully came to rest on the surface. His partner initiated a beacon search and called his name, quickly finding him on top of the avalanche debris. The skier sustained significant injuries. They called 911 and Gallatin Country Sheriff Search and Rescue initiated a response with the Helicopter team. The two skiers worked to address injuries while awaiting rescue. GCSAR inserted a team with a helicopter that provided medical treatment and transported both the injured and uninjured skiers. The GNFAC was on scene to evaluate the scene for hazards to the rescue team. 

I was teaching a snow science program at crosscut today and our group got propagation (ECTP21) in our test pit on the facets at the ground, ~80cm down.  The snow was 85cm deep at that location.  We were on an eastern aspect around 6200' in a treed area.  The students (bozeman 6th graders) were very psyched about getting to try what they'd seen on the mtavalanche youtube and seeing unstable results!

On the drive up we could see a wet slide from yesterday that occurred in Argentina bowl, human triggered. We also got a report of a wet slide in St Lawrence path in Truman Gulch (not big). We toured along the ridge to the summit of Saddle. By 1000 the snow was softening. We dug below the first cliff band and found 7' of snow, the bottom 2' consisting of weak facets. A Deep Tap Test showed a clean shear at this interface. An avalanche could be triggered by 3 ways: more load from snowfall or wet avalanche debris, melt-water percolating through the snowpack to the facets, or human triggering from a thin spot.

By 1100 the snow was getting wet and punchy at lower elevations. Loose wet slides could trigger dry slab avalanches, a proposition we did not want to hang around for.

From IG:

Southeast aspect on Mt Blackmore. Unknown time and date. Elevation 9700 to 9800’

Toured up Mt. Rae in the boulder river drainage. Surprised to still find cold snow in spots and some still being blown around. Had some collapses and shooting cracks on the ascent. Shallow and suspicious snow for sure but a beautiful day out. 

We went on a safari of different snow conditions at Beehive today. We toured up to the prayer flags, looked into the top of Bear Basin on southeast and northeast aspects, and then returned to Beehive through the north edge of Tyler's. We dug a pit in the starting zone of Tyler's and were a bit surprised by an ECTP11 on basal depth hoar. There were percolation columns through the upper half of the snowpack and the lower two thirds of the snowpack were moist. You could make a snowball. The depth hoar remains very weak and F+ hardness. The stout melt freeze crust was 3" thick on the southwest aspect.

Surface snow conditions varied wildly as is often the case in the spring. There was cold powder on the northern half of the compass. The crust had broken down by 11 AM on the southeast aspect and the top 3-5" were wet and rollerballs were easy to push downhill. The southwest aspect was just starting to soften as we left at 1 PM. If we continue to get good overnight freezes, we will only have to worry about wet, loose snow avalanches. Wet slab activity should be limited if there is any.