Snow Observations List

Mostly facets throughout snowpack on east aspect of Divide Peak. Dug in search of buried surface hoar, none found. Melt-forms and lower density snow found between 85-81cm. ECTX. 

Dave and Doug rode around and saw multiple natural and 1 sledder triggered slide on Lionhead. Some were thin and just involved news snow and others were deeper and broke on the buried surface hoar layer.

Our avalanche course toured up to the west ridge in Beehive Basin.

We dug four side by side hasty pits on an east aspect at 8740'.

HS 115 cm

HST approx. 8-9 cm

ECTX x 4

We were on the hunt for buried surface hoar. With no fractures in our ECT's to help locate the layer, it's hard to say whether the layer was or wasn't present, but we couldn't find it. Other than a MFcr down 30 cm with some associated near-crust facets, the snowpack was largely right side up with F to 4F above the crust and 1F to P below all the way to ground.  Basal facets comprised the bottom 20 cm and were 1F to pencil hard.  

The new snow was not particularly well bonded to the old snow surface.

The other half of our group dug on a westerly aspect at approximately 8500' off of the east ridge and found buried SH down approximately 30 cm. It was clearly visible in their pit walls. ECTN's on the SH layer in their pits. 

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.

I skied south of Quake Lake today, and we took the time to dig a couple pits along the way. We dug our first one on a west aspect at 7250’, and picked a big meadow to see if we could find the buried surface hoar we found above Hebgen yesterday. I jumped off my skis like I was jumping into a lake, and sank straight to the bottom. Total snow depth was 110 cm, and the surface hoar was not nearly as obvious as it was in our pit above Hebgen. An extended column failed at ECTP12 on the surface hoar, which had much smaller crystals than what we found yesterday. Still, it is not very trustworthy. The pit also failed at ECTP21 on the interface with large facets 20 cm off the ground.

A second pit on a west aspect at 8600’ also failed at ECTP12 on buried surface hoar, but total snow depth was 125 cm and supported our weight well without skis. We observed numerous point releases that entrained enough snow to possibly knock a skier over, but none stepped down and fractured as a slab. 
 

Skied on Henderson mountain the afternoon of 1/16. Wind was calm, snowfall was light and steady through the day with 3-4" of new snow.

Dug a pit on the east side of Henderson at the ridgeline above Henderson Bench. ENE, 10,075' elev. ECTP19 x3 on a layer of surface hoar buried 60cm (2 feet) deep. HS 260cm. There was an avalanche a few hundred feet north on an east-northeast facing slope below the ridge. It appeared to be snowbike triggered and 1-2+ days old. 150' wide and 250' vertical. HS-AMu-R2-D2-O. It appeared to have broke about 2' deep on that layer of surface hoar. There was also a more recent natural avalanche (less than a day old) on Miller Ridge, slightly smaller. SS-N-R1-D1.5-O and probably broke on the surface hoar layer.

The location of these avalanches and poor stability test scores is concerning as they are in exposed areas, implying the surface hoar will remain an issue on large, steep open slopes that will likely be heavily wind-loaded at some point.

Additional photo of a cornice triggered avalanche on Miller Ridge that broke to the ground, appears to be many days or weeks old.

We skied the Throne today, near the skin track, and down low and to the north. With only a couple inches of new snow and zero wind there were no signs of instability. Our pit in the north facing chute had horrible structure, with the bottom half very facetted, but didn't offer any results. The wind hasn't blown up there for quite a while, so there's plenty of soft snow hanging around. When it does blow, it won't take long to become unstable.

Toured into Alex Lowe basin today and noticed lots of point release slides. Most started as spindrift in the cliff bands along the ridge and gained more snow as they fell into the aprons. Skied a north and south facing couloir, ski cut at the top of both runs and got the new snow to sluff most of the way down. Didn't encounter any cohesive slabs, just lots of sluff sliding down.

Variable skiing at Lick Creek today. 2-3 inches of low density snow on the ground. Ski cutting on the north side wind roller produced very soft-soft slab results with little to no propagation directly under cornice. 4 inch soft slab on the interface. Ran about 20 feet with little entrainment.

It squalled out there around 12pm snowing S2 with little to no wind. That seemed to precede the squall in town by about 2 hours.

New snow and wind loading. On southeast facing slopes found 8cm layer of facets below melt freeze layer about 50-60cm below surface.

Today we toured up the east ridge of Republic Mountain and descended the southeast face. We observed about 10cm of fresh snow from the night before, and winds were very calm. Our pit results did not show any propagation at the interface above the faceting snow at the base and a quick shovel shear of this layer yielded a medium Q2 shear (see photos). A series of hand pits along the southeast face showed that the interface above the faceting base took some effort to move, but it would move with some force. 

On Saturday we toured up Woody Ridge. We observed the buried surface at this location, a W aspect just off of the well traveled skin track on the west side of the ridge, but saw no propagation in an ECT. Cracking was observed in isolated pockets on NW aspects where wind loading was very evident. 

I skied above Hebgen Lake today, and found excellent surface conditions with poor stability. A pit on an east-facing slope at 8650’ had a clear line visible where the buried surface hoar is, and an extended column test yielded ECTN2 10 cm down on the interface between older snow and the new snow from the past couple days, and ECTP7 on the buried surface hoar. This layer is very well preserved. We did not experience any collapsing or cracking and saw no natural slides, but another group triggered two small slides on a he surface hoar while traversing a ridgeline at the top. 

Ski cut sent a slide that failed on the known-to-be-reactive buried surface hoar layer . Avalanche broke around 12-14” deep, 100’ wide and ran around 100 yards. It was extremely sensitive.
We had skied a similar angle/aspect slope earlier and didn’t get any reactivity. Occurred around 9000’ on NW slope.~ 32 degrees. We did this 2 times on what we thought to be low angle slopes. ended up skiing down a low angle ridge line. The buried hoar isn’t everywhere but it’s touchy when found. 

We toured up to the Mt. Blackmore ridgeline today. Near Mt. Blackmore most of the snow was wind affected, and today’s winds at the ridgetops were not blowing snow around because there is little snow left for the wind to transport. We dug three pits on different aspects and elevation bands, and we didn’t find surface hoar in any of these pits.The pits we dug had facets near the surface all the way to the bottom of the snowpack, and it was capped with a 1-3” of wind-packed snow. We were able to get an ECTP18 on facets above a crust 10” below the surface on a SE aspect at 9,500’. And, we got an ECTP18 on a NE aspect at 9,800’ in a shallow, wind stripped area below Mt. Blackmore’s ridgeline. This was in a layer of facets 2 feet below the surface. We were not able to replicate these results in either snowpit. Buried weak layers are getting harder to trigger, and these pits showed how finding a thin spot on a slope could still trigger an avalanche.

We observed a north-facing natural sluff turn into a reasonable slide release over the cliff bands from the ridge line between Miller and Wolverine today while skinning on the flat bench above the road out to Wolverine Peak today. I think it released right at Sunset peak. It may have started with a cornice release but was more like wind loading on the steep face. We also saw some minor cracking on north facing wind loaded roll overs above the bench. We opted to descend low-angle trees back to our sled and to go ski Henderson.

Our goal was to ride the North Face of Mount Blackmore yesterday in hopes of north aspects still holding good snow. We noticed some cornices on the top of the line and changed our objective to another entrance onto the north face farther down the ridge from the main North face line. When we got to the top of the line we could see it was noticeably wind loaded at the top and we found very large depth hoar crystals near the bottom of the snowpack. Heaving wind loading and the large depth hoar crystals gave us pause and we hiked back up and skied down the East face. We also saw what looks like a cornice about to break off along the ridge of the North face. 

From IG:
“Snowpack observation from 1/14/23

Northern Bridgers-Frazer Basin

Chute skiers left from the exit chute/sled access boundary on ridge. 
Skied a more wind protected N facing chute and experienced stability skiing. Did 2 ski cuts before entering as well as doing a shovel shear on the top ~2ft of snowpack. No clean shear for the test or other observations of instability. As a result we skied. 
Decided to start skiing up another, more open face to the E and stopped to dig about 1/3 of the way up once it started to get a little steeper. Dug on a Due N slope at 8430 ft. Snow depth was 205 cm from base. Column test failed at CT11 and CT15 at 175 and 135cm from base respectively. Was a clean break. Conducted an ECT which went at ECTP12 and 14 at the same depths. We skinned off the aspect and skied conservative lines the rest of the day.”

We rode in 1st, 2nd, and 3rd Yellowmules into the head of Muddy Creek today. At the 1st Yellowmule we found punchy, weak snow in several places. This is a sign that the snowpack is continuing to facet near the ground. The snow seemed more faceted than it was the last time we were in Buck. We saw a new layer of surface hoar on the snow surface all over Buck Ridge, which could be a problem in the future. We also found a layer of buried surface hoar 8-12” below the surface throughout Buck. 

We dug at the head of Muddy Creek, and we found 160 cm (~5 feet) of snow on a north aspect. We got an ECTP8 on a surface hoar layer 10” below the snow surface. Where we dug was near a ridgeline, and the surface hoar was intact despite this area getting wind. When deciding to get into steeper terrain riders and skiers should assess for instability with an ECT at this layer, and they should still be wary of the weak, sugary snow at the bottom of the snowpack.

Started a small wind slab avalanche on an isolated rollover about 2/3 of the way down the face of elephant mountain yesterday (Thursday January 12th). Broke a few inches deep, about 8 feet wide, and ran less then 100 ft.