Zone: Northwest Mountains
Location: Paradise Divide
Date of Observation: 12/15/2020
Name: Evan Ross
Aspect: East, South West, West
Elevation: 11,000-11,500

Avalanches: It’s a smorgasbord of natural avalanches out there. The oldest ones are from Friday 12/11, and the most recent ones are from the last 12 hours. The most recent were all wind-related from the increased overnight winds. Avalanche observations from the last 12 hours above treeline: West on Mt Baldy had 2 D2 and 1 D1.5. There was a small dribbler on a Southerly Aspect of Gothic. Red Coon Bowl had a fresh D2 this morning on an East aspect. NE Purple Palace NTL has a suspect D1.5 the could have fit in the last 12 hours too. All these slabs ran on the old faceted snow near the ground. Some may have started on an interface as a windslab, then gouged, but I couldn’t tell from a distance.

Remote triggered 1 D1, from a few hundred feet away, above treeline, east aspect.

Of other particular note. The SW to W slopes of baldy on the way up to P-Divide had a fairly good cycle last weekend. Many of those paths ran, piling on the road and continuing to run below. About 5 R1D2’s.

Weather: Headed out in the afternoon. The sky had cleared to partly cloudy for the few hours I was out. Winds also appeared to decrease and were generally light with moderate gusts. Most of the snow appeared to have already been transported at upper elevations for the recent wind direction and speeds, however, there were still a few snow plumes out there at times.

Snowpack: Just having fun on a personal day and noting the continued obvious signs of instability. Plenty of collapses and shooting cracks while traveling on East and West aspects. All the steeper slopes I got close to were fairly small in size, and well supported. So they simply cracked without much downhill movement. I suspect that some of the wind-board from last weekend, which is now buried, is collapsing into the softer snow below. Also, some of the fresh wind-loaded features are also cracking on non-persistent grains closer to the snow surface. However there are still slopes cracking hundreds of feet away, so those must be collapsing on the November Facets. The average snow depth in the area was about a meter.

Zone: Northwest Mountains

Location: Irwin Tenure

Date of Observation: 12/14/2020

Subject: Remote triggered slide at Irwin

Avalanches: Skied the far skiers right side of lodge gully W aspect <TL and remotely triggered from 50′ away a .5 to the ground 50′ wide. SS-AS/u-D.5-G

Weather: Cold morning low of -14. Started snowing at 0700 after a clear night. Sky remained Obscure all day snowing S1/ S-1 off and on all day. Winds were Calm <TL and light out of the S >TL.

Snowpack: Snowpack has settled and become supportive. Ski pen averaged 30cm. The average HS up to 70 ridge was 50-60cm. Toured up the road system to the top of 70 down 70 gully to skin track and Lodge Gully to finish. Observed numerous collapses but nothing not to be expected or too large. Several Obs on Steeper terrain around Irwin village road cuts, etc. had cracked to the ground slumped but did not run. These occurred two days ago near the end of the storm.

Zone: Northwest Mountains
Date of Observation: 12/14/2020
Name: Evan Ross
Aspect: North, North East, West
Elevation: 11,000

Weather: Poor visibility until the weather started to clear in the late afternoon. Calm winds. Measured about 6″ of very light new snow at 11,000ft, from todays storm.

Snowpack: Spent a few hours in the afternoon traveling around 11,000ft on West, North and Northeast aspects. More of the same, shooting cracks on many of the slopes traveled. The avalanche problem was fairly obvious without having to look to hard. Conservative decision making. If you chose to travel on a steep slope, that hadn’t already avalanched, it seemed like a high likelihood it would avalanche… Got close to some bigger steep slopes wondering if they would remote trigger and didn’t see any results.

Measured about 6″ of very light new snow at 11,000ft, from todays storm. HS at 11,000ft in a well sheltered meadow was right about 100cm.

Due to traveling on lower angled slopes. The only time I saw blocks move was when they were cut up. This particular slab was about 70cm’s thick.

Zone: Northwest Mountains

Location: Elk Creek Drainage off Kebler pass

Date of Observation: 12/14/2020

Subject: More Persistent Slabs

Aspect: North, North East, East

Elevation: 9,800′-10,500′

Avalanches:

We observed numerous persistent slab avalanches on NE and E aspects BTL, ranging from D1-D2 in size, most that ran this weekend and some that we triggered today. While skinning up a ridgeline, we crossed above 7 NE facing avalanche paths. Of those 7, 5 had already run naturally during our recent storm cycle. The remaining two were easily triggered by ski cutting convexities near the top of the start zones. The slab depths varied from 12-16 inches, encasing all the recent storm snow. As the slides picked up speed, they entrained some of the rotten snow at the bottom of the snowpack.  All of the slides propagated across their entire start zones and ran about 3/4 of the distance to the bottom of the avalanche path.  They were all soft slabs failing on the 12/10 interface.

Weather: Little to no wind. Overcast skies. The snowfall rate varied from S-1 to S2 from 12 pm – 2 pm, with a few inches of new snow throughout the day.

Snowpack: Traveled below treeline hoping to find improving stability but continue to get widespread collapses and triggered slides.  The top 12-16 inches of the snowpack consisted of F hard precipitation particles from our recent storm accumulations. Sitting below the storm snow is the 12/10 weak layer/ interface. On Northerly aspects, this interface consists of F hard buried near-surface facets. On Northeast through East facing aspects, this interface consists of a thin melt-freeze crust with near-surface facets sitting on top.

Photos:

Zone: Crested Butte Backcountry
Date of Observation: 12/13/2020
Name: Zach Kinler

Avalanches:

Got decent views towards the East side of the Ruby Range into alpine terrain. Numerous D1.5-D2.5 slab avalanches on slopes facing primarily E-NE with a few wrapping around onto SE aspects. Some failed early in the cycle with crowns and paths faint, while other failed later in the storm with increasing northerly winds.