Trip Planning for Dillon Area

Skier triggered slide in a steep, north facing couloir in the Torrey Peak cirque. Triggered with a ski cut, no one was caught. Slide failed on interface between the old snow surface and 4” of consolidated graupel that fell 5/11. Prior to skiing this chute, we had not observed any avalanche activity failing on this same interface. 

While skinning into Big Bear gulch, off Wisconsin creek, we encountered a couple of small whumphs in a flat meadow below treeline. We also encountered one instance of localized cracking within the trees, near the hollow created by a dead tree. At the top of the ridgeline there were small cornices, and we noticed significant wind loading higher up on Old Baldy mountain.

In our east facing pit, just below the Little Bear ridgeline, we found a large melt freeze crust complex near the surface, interspersed with layers of much softer snow and NSF. Below the stout crust layers, the snowpack drastically reduced in hardness, with fist hardness facets near 50cm from the ground. We had moderate CT results (CT 12 Q2 @140cm) within the crust complex, and more difficult CT results (CT 23 Q2 @30cm) within a layer of large (3mm) striated depth hoar near the ground. Our ECT test resulted in an ECTX, possibly indicating the strength of the crusts, which neither skis nor boots would penetrate through. Our ECT column did pull out of the wall as a cohesive block when we applied shear from behind. Our pit profile was submitted through Snowpilot.

Based on these observations, and the warming we believed would occur later in the day, we decided to not ski off of Old Baldy mountain, and rather took some laps at a nearby low-angle meadow. 

From IG: “North meadow creek tobacco roots today“

After a long day of riding 2 to 3 thousand feet higher in good snow I was getting close to the truck after 10 or so miles on a mostly hard pack trail I decided to climb this hill in a split second decision. My sled was overheating and my plan was to cool it down. As I ascended the hill I hit a pencil hard wind slab about a third of the way up, I knew instantly that I was in trouble as this slope ended up being much steeper than I had initially thought. I made a decision in the moment to continue up the slope as it was not many vertical feet in elevation. My thoughts were that I had lots of speed and momentum built up and that that would carry me up I also thought that if I tried to make an aggressive turn it would put more stress on the snow pack and I also figured the closer to the top of the slab I was when it fractured the better off I would be. I made it about 100 feet from the top of the hill when it first fractured, I was about 20 feet from the fracture and there was a point slightly to my right that was the closest point of the fracture to me. I turned slightly right heading to the closest point of snow above the fracture line. As I turned the slope started sliding. The top of the of the slide rolled over like a large wave and a block hit me in the ribs luckily not nocking me off my sled. I maintained full throttle and kept my momentum traverseing through the rolling blocks. My only thought was to try to stay on top of my machine and keep forward momentum. In the last few moments of the slide I could feel I was loosing control of my machine because it was starting to get sucked into the avalanche. When the slide stopped I was in snow to my knee on my uphill side. I want to end this with a warning of complacency. I had been in big terrain all day and didn't analyze the slope like I should have a simple glance for a moment and I would have recognized the dangers of the wind slab. I got complacent and it almost got me injured or killed. Just because a slope is small doesn't mean it isn't dangerous.

Snowmobiled to lower rock island lake and ascended to 9200ft. Mostly sunny skies with no wind. No avalanches observed, no collapsing, minor cracking right around skis in wind affected areas 4 inches deep. Dug on due N aspect. HS = 120-150 cm. Soft surface 4-6 inches. 1 finger hard layers with rounding facets in between with 2 layers of concern about 1 foot down and 1 foot off the ground where 4F rounded facets are sandwiched between harder layers. CT6 Q2 down 4 inches on old snow surface. CT 23 Q3 on basal facets. ECTN 6 4 inches down, ECTN 29 about 1 foot down (consistent with last weekend observation in this area). Stubborn old snowpack right now with lack of significant new snow or wind and recent warm temps. Still poor structure in areas where snowpack is thinner, however where it is deeper seems facets are healing.

Snowmobiled to 8200ft then skied up to 9000ft. Dug a snow profile to ground on NE aspect at 8800ft. Height of Snow was 120cm (4 feet). Multiple weak layers in the snowpack including one about a foot down and a thicker layer of faceted sugary snow in the bottom 2 feet of the snowpack near the ground. ECTN29 on a crust and small grained facets about a foot down from the surface, however that slab layer released when a shovel was put behind it with a sudden pop and very little friction, see grainy photo. Surface was faceting old powder which could be another weak layer when buried. Not very reactive in this spot at the moment likely due to lack of new snow in a while. However generally poor snowpack structure is not reassuring and will need to watch when this snowpack gets rapidly loaded by new snow or wind blown snow. 

36” total. 24” sugar on bottom. 

From Email: It was actually great riding up there. Just no base once you broke through. Definitely solid on top and held weight of the sled. 

Snowpack at 8000 ft in pioneers is about 2 feet deep and mostly facets. About a foot of 3 mm large squares on the ground, a slightly more dense 4F- layer of crust and facets and another foot on top of that of soft NSF and new snow. Intentionally triggered a very small test slope, slab failed on the lower facet layer. See pics of quick pit and test slope results. Boot and ski penetration to the ground. Weak.

Early season snow recon outside of Maverick Mountain Ski Area boundary. Cracking of surface slab on easterly aspect at 8000 ft (see pics). Well developed weak layer about mid-pack that formed during November. Several storms the first week of December put down a 1-2 foot slab on top of this weak layer. Cohesiveness of slab varies by aspect and elevation. Wind and sun exposed slopes more reactive due to higher slab density. Areas protected from wind were not as reactive with no cracking experienced. Spatial variability is high with a shallow snowpack. See picture of quick pit showing major layering on north facing aspect at 8400 ft. Height of snow between 65-75 cm. Notable results were CTM 11 with a sudden collapse fracture character at 35cm up from the ground at November/December snow interface. ECTN 11 on same layer. The slab was not stiff enough in this protected location to propagate however this pit is representative of poor structure that is widespread. 

Also, snowmobilers reported avalanches on some of the steep roadcuts on the Pioneer Scenic Byway.