Location: Crested Butte Area
Date of Observation: 01/16/2020
Name: Evan Ross
Subject: Human Triggered Persistent Slab
Aspect: East, South East, South
Elevation: 9,000-11,000

Avalanches: Human Triggered a large Persistent Slab Avalanche on a cross-loaded east facing slope at 10,800ft. The slab average 1.5ft thick, was F to 4F hard, and failed in 1.5 to 2mm NSF on the 1/8 interface. A few parts of the avalanche gouged deeper into the snowpack. AMc-SS-R1-D2-O

Weather: Increasing clouds in the morning becoming overcast. Calm winds. Weather stations showed temperatures rising to near 30 at 11,000ft.

Snowpack: Headed to Evan’s Basin to check on recent avalanche activity. I would estimate that many of these slabs ran in the storm snow on non-persistent grains given their size and propagation. Digging near one of those crowns on an east-facing slope, produced a clean shovel shear tests within the recent snow on non-persistent grains. At that test profile site, the elevations was 11,150, east aspect, slope angle was about 34 degrees, and the HS was 120cm. The 1/8 interface consisted of 1mm rounding faceted grains. CT18 RP on the 1/8 interface. The rest of the snowpack in this location wasn’t concerning without a big loading event that could break deeply into that snowpack.

The triggered avalanche was on the same aspect as the above test slope. The differences was a slightly lower elevation, but mainly a cross-loaded slope. The slab above the 1/8 interface was more cohesive, and the interface was noticeably weaker. I’m not 100% sure why the interface was so different between the two locations. My best guess is that the snowpack were the avalanche was triggered, had a below average snowpack height previous to the last wind event.

Location: Crested Butte Area
Date of Observation: 01/15/2020
Name: MR
Subject: Mt Emmons avalanche activity
Aspect: East, South East, South
Elevation:

Avalanches: Forgot to take pictures of the bowl – 2 small windslab avalanches near the center and looker’s right rock bands that didn’t run far. Multiple small avalanches NE aspect near the skin track running down into the bowl.

Moonscape area, evan’s basin, SE to E aspect, see photos. Multiple small to large avalanches.

Snowpack: Crazy wind carnage. Ridge approaching summit near field goal practically stripped bare. Bare spots also down in the bowl and on the eastern ridge above red coon glades.

Glades held a mixture of wind effect, sun crusts, wind stiffened pow, and preserved pow.

Location: Cement Creek Area
Date of Observation: 01/15/2020
Name: Evan Ross
Subject: Cement Creek Check In
Elevation: 9,000-11,500

Avalanches: Recent natural avalanches included a couple large persistent slabs on northerly facing terrain near and above treeline, and several small wind slabs primary on easterly facing slopes.

Weather: Few clouds and calm winds.

Snowpack: The general summary would be a variable snowpack that is heavily wind effected on everything but the most protected lower elevations areas. I didn’t encounter any concerning snowpack structure at those lower elevations slopes. Cross-loading at those lower elevations didn’t appear to be an issue either. At mid and upper elevations the snowpack is raked by the recent winds. Lots of bare ground, wind-board, or stubborn hard slabs. Easterly facing slopes had the most continuous snowpack. For the area, these wind-loaded easterly facing slopes would be the most concerning slopes for triggering a persistent slab avalanche.

Location: Crested Butte Area
Date of Observation: 01/14/2020
Name: Evan Ross
Subject: Gothic Area and Fresh Wind Slabs
Aspect: North East
Elevation: 9,400ft-10,200ft

Avalanches: Couple of fresh wind slabs to D2.5. The spork ran this morning, while the others in the last 12 hours.

Gothic Mountain, The Spork. SE terrain, but the slab pulled from the cross-loaded easterly facing portion of the start zone. This path has run multiple times this winter so it doesn’t have the full seasonal snowpack. Crown estimated to be near a meter deep and releasing around the old snow surface. SS-N-R2-D2.5

Gothic Mountain, East Face. E, 12,500ft. Fresh wind slab that propagated slightly wider lower in the bowl. SS-N-R2-D2.5

Rustlers Gulch, SE, 12,600ft. Estimated D2 slab, but viewed from very far away with little detail.

Weather: Few Clouds, light wind down low with continued snow plums off the high peaks through the day.

Snowpack: Expected to find some concerns with cross-loading, but in the end, no new slab issues were found. Maybe higher in the terrain, there was something more concerning. At 10,000ft on northeasterly facing slopes, faceted grains were down about 18cm. The new snow wasn’t concerning, above the old snow surface from last week. It simply added to the loose snow avalanche potential or could release as a very soft slab in very steep or unsupported terrain. Deeper new snow accumulations or cross-loading at slightly higher elevations could have created more of a slab concern. If SH was present in this snowpack, it was surrounded by other weak faceted grains and not a layer of concern.

HS was in the 90-120cm range. Old persistent slab structure could still be felt lingering in the snowpack. This structure wasn’t making any noise or showing obvious signs of instability. While the majority of the most concerning terrain features in this area had previously avalanched this season with old crowns still visible.

Location: Crested Butte Area
Date of Observation: 01/14/2020
Name: Eric Murrow
Subject: Avalanche Obs from Slate Sled and Truck Tour
Aspect: North, North East, East, South East, South, South West, West, North West

Avalanches: A substantial number of avalanches observed around Slate River Valley and terrain visible from roadways around Crested Butte. Natural avalanche activity was largely a product wind-loading from the last storm at upper elevations. Do not believe I spotted any below treeline avalanches today. Most avalanches appeared to only involve the recent storm snow from the past 5 days, propagation was fairly limited. A number of these avalanches are repeat offenders that failed earlier in the winter. One avalanche in Axtel’s Green Lake Bowl failed sometime between 3pm and 440pm. Avalanches up to D2 in size were observed off Scarps Ridge(NE), Redwell Basin(NE,E), Peeler Basin(NE), Schuylkill Ridge(NE), Cinnamon Mtn(S), Angel Pass(NE), Purple Ridge(S), Gothic Mtn(E,SE,SW), Mount Bellview(S,E), Red Ridge(S,E), WSC Peak(S), Deer Creek(S), Teocalli(debris in SE gully), Whetstone’s Hidden Lake Bowl(NE), Axtel’s Green Lake Bowl(NE). See photos for a selection of observed avalanches.

Weather: Mostly clear skies. Cold temps in the morning at valley bottom quickly warmed up before noon. Winds at valley bottom were light, but lots of flagging off ridgetops and summits all day long with continued loading for near and above treeline slopes from southwest winds.

Photos:

Location: Kebler Pass Area
Date of Observation: 01/13/2020
Name: Pat
Subject: Another human triggered avvy
Aspect: South East
Elevation: 9500′

Avalanches: Triggered a small but deep slab avalanche on a steep and short roll at the very end of the Ponytail Glades descent just above the Kebler trailhead. Depth of slab appeared to be about 2 feet, and it broke on a very pronounced layer, presumably the surface hoar layer about 70cm deep. This activity reflected our observations while skinning up: early in the morning, the snow in this spot was soft and consistent. At the top of Ponytail, we observed whumphing and shooting cracks as we traversed into westerly-facing wind-affected aspects. Upon reaching the location of the avalanche, our previous skin track had been entirely scoured away, and this was where the trigger occurred.
 
Weather: Calm, snowy in the morning around 10-11am, with increasing winds from the west around 12-2pm.

Snowpack: Soft, light, consistent 1 ft of dendrite pow in the morning, and heavier with a wind crust in the afternoon.

Photos:

Small skier-triggered avalanche from 1/13