Observations

Zone: Northwest Mountains

Location: Elk Creek Drainage off Kebler pass

Date of Observation: 12/14/2020

Name: Jack Caprio and Zach Guy

 

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:

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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.

 

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Zone: Northwest Mountains

Location: Ruby Range

Date of Observation: 12/13/2020

Name: Ben Pritchett

 

Subject: A few avalanche observations

Aspect: North East, East

Elevation: Near and above treeline

Avalanches:

Avalanches
Date Location/Path # Elev Asp Type Trig SizeR SizeD
View 2020/12/13 † Mount Emmons 1 TL NE SS N R1 D2
View 2020/12/13 † Ruby Range 1 >TL NE SS N R2 D2
View 2020/12/13 † Ruby Range 2 TL NE SS N R2 D2
View 2020/12/13 † Ruby Range 1 TL NE SS N R1 D2
View 2020/12/13 † Ruby Range 1 >TL E SS N R1 D2

Weather:

Snowpack:

Photos:

Zone: Northwest Mountains

Location: Slate River and Baxter Basin

Date of Observation: 12/13/2020

Name: Zach Guy and Eric Murrow

 

Subject: Cycle in the Slate

Aspect: North East, East, South East, South

Elevation: 9600′ to 11,700′

Avalanches:

Widespread natural cycle yesterday and last night: extensive soft slab naturals that broke 1 to 2 feet deep on the storm interface (12/10 facet layer). Slides ranged from small to large (D1 to D2.5); most propagated across much or all of their start zones and ran to mid track. I estimate that 90% of the north or east facing paths or features in Happy Chutes, Climax Chutes, and Schuylkill Ridge ran (roughly 60 slides), as well as the west facing near treeline terrain below Baldy and Gothic (about 5 slides). Last night’s winds obscured the evidence of avalanche activity in the alpine. There were some fresh crowns triggered by wind transport last night (about 5), but more commonly, evidence of activity during the storm was subtle and harder to characterize. The most notable was the east face of Mineral Point which ran to valley bottom.  In contrast, the southerly aspects that we could see showed minimal signs of avalanche activity.
Today we or other parties near us appeared to remotely trigger a handful of soft slabs up to 2′ thick. These were on small pockets or features so generally harmless in size.

Weather: Cold temps, clear skies, some light wind transport observed off of a few high peaks but calm winds where we traveled.

Snowpack: We observed widespread collapsing and shooting cracks while traveling on low angle terrain of various aspects. Some collapses were localized, some were rumbling and traveled 100 feet or more and would shake trees or trigger small pockets. Settled storm totals were 60 to 70 cm at low elevations, sitting on our well documented 12/10 interface. Low angle slopes with a southerly pitch were collapsing on a thin meltfreeze crust, or just facets on northerly pitches. On steeper southerly pitches, the crust is thick and uniform to the ground, lacking a problematic facet layer that is so widespread on other aspects or on lower angle slopes.
Not much evidence of wind transport during the storm, but last night’s northerly winds redistributed surface snow near and above treeline into some small wind slabs that didn’t react to ski cuts today.

Photos:

 

Zone: Northwest Mountains

Location: SE face of Ruby 12’000 feet

Date of Observation: 12/12/2020

Name: Tom Schaefer

 

Subject: Ruby Natural

Aspect: Southeast

Elevation: 12,000′

Avalanches:

N-SS-R1-D1.5-I
Southeast face of ruby approximately 150 wide and ran 1000′ most likely ran yesterday afternoon mid storm.

Weather: At Irwin village temperatures are in the low twenties. Clear skies and calm winds. Very nice!

Snowpack: HS 28″
HST 14″
Snow settled some last night with the cold temps. boot pen 40cm.
Along with the Ruby avalanche observed several steep road cuts and rollers around Irwin that had cracked to the ground naturally and slumped but did not run. Also observed two collapses in flat meadows walking on foot.

Photos:

Zone: Northwest Mountains

Location: Ponytail glades

Date of Observation: 12/12/2020

Name: JAFAR TABAIAN

Subject: Ponytail glades

Aspect: East, South East, South

Elevation: 11200

Avalanches:

None.

Weather: Snowing. :)

Snowpack: Extreme cracking on S slopes, ran 15-20 feet. Nothing moved on us but slope angle was max 28 degrees. S slopes had a very crusty ice layer near ground. E slopes had un-consolidated loose snow to ground level and skied better. Pretty thin, hiked out the last pitch down to the mine road.

Photos:

 

Zone: Northwest Mountains

Location: Pittsburg

Date of Observation: 12/12/2020

Name: Joey Carpenter

Subject: Pittsburg

Aspect: North East

Elevation: 9250-10.5k

Avalanches:

Remote trigger (skinning), unintentional, R1D1, 10k, NE, 37 degrees, 45cm storm slab, 40′ wide, 50 vert, ran on November facets (35cm to ground, 1.5-2mm). Cracking extended onto 34-35 degree slopes 30′ to either side of the crown. M/f crust here has deteriorated almost entirely.

Remote trigger (skinning), intentional, R1D.5, 9700k, NE, 36 degrees, 45cm storm slab. 25 ft wide, 30 vert, Nov facets. The 60-80ft skiers left of this slide ran naturally sometime yesterday afternoon.

Skier trigger, R1.5D1.5, 10k, 35 degrees, 45cm storm slab (estimate), ran 60-70 vert, intentional, This slide had the most energy of anything we saw today w/ a ski cut at a convex roll.

At least 2-3 naturals BTL that ran yesterday of similar characteristics to slides described above. Small in overall size entraining only snow from the last 36 hours.

 

Weather: Overcast skies all day, temps started in single digits and rose to the high teens. No wind or transport. S-1 snowfall throughout the day with about 2″ accumlation from 8a-230p.

Snowpack: Snowpack was very sensitive today. Cracking at every step breaking trail through ~45cm of low density storm snow sitting on top of 35cm of 1.5-2mm facets to the ground. You could still dig to the MF crust from before the Turkey week storm but it was mostly rotted out and becoming part of the facet mess. Shooting cracks, slumping and small avalanches were easily triggered on any slope tipping past 32-33 degrees.

Photos:

 

Zone: Northwest Mountains

Location: Pittsburg

Date of Observation: 12/12/2020

Name: Sam L

Subject: Cracking, collapsing, avalanching

Aspect: North, North East

Elevation:

Avalanches:

Widespread cracking and collapsing including remote and skier triggered low energy D1s.

Weather: Steady snowfall all day, snowed up to an inch on sleds, seemed more like two at the trail head.

Snowpack: Slides entrained all of storm snow from the past two days and ran on basal facets and seemingly a deteriorated sun crust on more sunny aspects.

Photos:

 

Zone: Northwest Mountains

Location: Red Lady Glades

Date of Observation: 12/12/2020

Subject: Red Lady glades pow tour

Aspect: North East, East

Elevation: 11200

Avalanches:

Small R1/D1 avalanche path noticed at 11200 feet. Most likely intentional from the skier before me skiing on the SE facing skin track.

Weather: Snowing, low visibility,1 5 degrees

Snowpack: 70 cm depth

Photos:

 

Zone: Northwest Mountains

Date of Observation: 12/12/2020

Name: Alex Tiberio

Subject: Gothic Obs

Aspect: North East, East

Elevation: 10,000

Avalanches:

Weather:

Snowpack: Lots of shooting cracks on our low angle tour, propagating large distances. Entire meadows would all collapse at once.

Photos:

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