Obs Snodgrass

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/08/2016
Name: Dave
Subject: Obs Snodgrass
Aspect: North, North East
Elevation: 9,600 – 10,8000

Avalanches:
Weather: AFRICA HOT! Felt like 40F, Clear skies and sunny, clouds did not build throughout the day. Should have put another round of sun screen on!
Snowpack: HS ranges from 85-100 cm. So nice to have a new blanket of snow. You still could fell the old crust layers underneath the new snow. Skiing was ok but challenging for folks being heavy & pushy. No signs of instability! When you changed to a slightly different aspect you found a thin crust, that was not that bad to ski.

Remote triggered slide in Ruby Range

CB Avalanche Center2015-16 Observations

Location: Paradise Divide Area
Date of Observation: 03/08/2016
Name: Zach Guy
Subject: Remote triggered slide in Ruby Range
Aspect: North East, East, South East, South, South West
Elevation: 9,600-12,500

Avalanches: See video. Remotely triggered a soft slab 18” thick on a northeast aspect above treeline as I was stepping out of my skis to dig a pit on a low angle slope. Heard a large, rumbling collapse and the slide failed ~300 feet up slope. SS-AFr-R2-D1.5-I. Had good views of a lot of terrain from up high, and spotted a handful of natural loose snow and soft slab avalanches from Sunday night’s storm, almost exclusively on NE to NW aspects, and mostly N/ATL. All slab avalanches are shown in photos below. Two slabs showed impressive propagation given their slab depth. I assume all of these ran on the storm interface, roughly 10-15” deep. Saw a couple small wet loose run today on SE aspects NTL.
Weather: Relatively cool temps up high. Light SE winds switched to light West winds, no transport. Clear skies built to scattered cumulus by mid-day, and decreased again in the afternoon.
Snowpack: Near and above treeline, 35 to 45 cm of dense storm snow (F+ to 4F-) was fairly evenly distributed across the terrain with some previous and relatively minor wind transport from SW winds. Anywhere that this snow was on a crust (E to S to SW aspects traveled), I was not able to produce any signs of instability on steep slopes or suspect rollovers, with ski cuts or stomping while skinning. Got ECTN or ECTX results on this interface, and Moderate Q2 failures in compression tests. (tested S and E aspects ATL). East aspects held a fairly thick crust at this interface (2-4” thick), with large facets below interrupted by some percolation columns (ECTN results on this layer). I was worried about this structure as the slope tilted towards ENE and the crust became softer and thinner. On NE aspects the storm snow was over ~1mm near surface facets above and below a thin wind crust. Snow surfaces became moist on SE to S to SW aspects today at higher elevations, with some minor rollerballs above treeline in rocky terrain and a few small wet loose near treeline.

Schuylkill Ridge. NE aspect NTL. SS-N-R2-D2-I

Schuylkill Ridge. NE aspect NTL. SS-N-R2-D2-I

 

Schuylkill Peak. NW aspect ATL. SS-N-R1-D1-I

Schuylkill Peak. NW aspect ATL. SS-N-R1-D1-I

 

Remotely triggered soft slab near Cascade Peak. SS-AFr-R2-D1.5-I

Remotely triggered soft slab near Cascade Peak. Star shows trigger location.  SS-AFr-R2-D1.5-I

 

Richmond Peak. N aspect ATL. SS-N-R1-D1-I

Richmond Peak. N aspect ATL. L/SS-N-R1-D1-I

 

DSCN0673

Mt. Justice. NE aspect ATL. SS-N-R1-D1-I

 

Snow pit on an E aspect ATL. 2-4" crust with very large depth hoar chains below, with percolation columns into this layer.

Snow pit on an E aspect ATL. 2-4″ crust with very large depth hoar chains below, with percolation columns into this layer.

Extended column test on a South aspect ATL

Extended column test on a South aspect ATL

 

Natural wet loose below Cascade Peak. SE aspect NTL

Natural wet loose today below Cascade Peak. SE aspect NTL

 

Climax Chutes on Mt. Emmons. NE aspect NTL. SS-N-R2-D2-I. Ran almost full track ~1800 vertical feet.

Climax Chutes on Mt. Emmons. NE aspect NTL. SS-N-R2-D2-I. Ran almost full track ~1800 vertical feet.

Irwin Tenure

CB Avalanche Center2015-16 Observations

Location: Kebler Pass Area
Date of Observation: 03/07/2016
Name: Irwin Guides
Subject: Irwin Tenure
Aspect: East, South, West
Elevation: 10-12,000

Avalanches:
Weather: Snow began Sunday mid day with warm temps and dense snow. High temps Sunday 30F/24F. Winds
on Sunday were South 20’s gust to 58mph. Winds today SW and continued 20’s G-40’s. Snow S1
with periods of S2-3 throughout the day. High temps 24F/14F. Though weather station remained
SW real time Obs from the Westwall was showing some NW winds.
Snowpack: New Snow is bonded well to old surfaces. No signs of windslabs, a few cracks up to 6’ in front of skis
but slabs not developed. Minor sluffing in just the top few inches not entraining much of the storm
snow. The March 6th crust is thinner on due west and very stout on any southerly aspects. The
March 6 is the same as the Feb 14 & 22 crust and have mostly all become one. There is a fair bit of
variability with this crust especially on due west aspects. In some places 1 thin (1-2”) crust with
facets underneath. In other areas due west there are 2-crusts with facets in between. On any
aspects with any south or even west but open the March 6 Crust is 10-15cm’s thick and is the new
ground.

Small storm instabilities on Schuylkill Ridge

CB Avalanche Center2015-16 Observations

Location: Paradise Divide Area
Date of Observation: 03/07/2016
Name: Zach Guy
Subject: Small storm instabilities on Schuylkill Ridge
Aspect: North, North East, East, South East
Elevation: 9,000-11,400 ft

Avalanches: Encountered soft slab and loose snow avalanches in the new storm snow at all elevation bands today on specific terrain features, all running on the storm interface about 8-10″ deep. All small in size (D1 to D1.5), but some could have knocked you over or dragged you into trees. See photos.
2x SS-N-R1-D1-I in Redwell Basin, N aspect ATL
1x SS-N-R1-D1-I low in Schuykill Ridge, NE aspect BTL
~10x L-N/ASc-R1-D1/1.5-I all elevations of Redwell Basin and Schuykill Ridge. N to NE aspects. Some of these were moist to wet near valley bottom.
Weather: Spring-like unsettled day, with mild temps, broken to overcast skies with a few periods of greenhouse warming and a few intense bursts of snow (S2). 1″ to 2″ of total accumulation. Light SW ridgetop winds, with signs of previous light transport but none observed on tour.
Snowpack: 15 cm of storm snow at valley bottom, 22 cm in a wind sheltered ridgetop location. Drifts up to 30 cm on NE aspect NTL.
SE aspects NTL held ~ 60-70cm of mostly pencil to knife refrozen wet grains below the storm snow. Storm snow appeared to be decently bonded to this crust, with no signs of instability while ski cutting and traversing steep slopes.
NE aspects below ~10,000 ft beginning to transition towards spring, with partially refreezing wet to moist grains into much of the snowpack, and a supportive crust below the storm snow. Below this elevation, the new snow was especially dense and became moist on all aspects due to greenhousing. We triggered a few small loose snow avalanches running on the crust on steep, NE aspects BTL.
Higher in elevation NTL, the same NE aspect was entirely dry, with a soft (4F-), thin (2cm), dusty melt-freeze crust and 1.5-2mm, F facets above and below the dusty crust. Got one shooting crack ~20 feet long in a lightly windloaded feature, failing on the facets above the crust, and a few other minor cracks on the same layer.
Due north above 10,000 ft (N/BTL) held near-surface facets with no crust below the storm snow; easy to trigger sluffs on steep slopes.

Redwell Basin, N aspect ATL. Natural loose snow and soft slab avalanches.

Redwell Basin, N aspect ATL. Natural loose snow and soft slab avalanches.

 

NE aspect NTL. Dusty, friable crust layer with 1.5-2mm facets above and below. Got a shooting crack above this crust

NE aspect NTL. Dusty, friable crust layer with 1.5-2mm facets above and below. Got a shooting crack above this crust

 

NE aspect BTL. Small, natural storm slab

NE aspect BTL. Small, natural storm slab

 

NE aspect BTL. Same small, natural storm slab as previous pic, but zoomed out for sense of terrain feature. Also some very small sluffs came off of those cliffs.

NE aspect BTL. Same small, natural storm slab as previous pic, but zoomed out for sense of terrain feature. Also some very small sluffs came off of those cliffs.

 

Pinwheels and skier triggered wet loose, NE aspect BTL near valley bottom.

Pinwheels and skier triggered wet loose, NE aspect BTL near valley bottom.

 

Shooting crack on a facet layer below the storm snow. NE aspect NTL.

Shooting crack on a facet layer below the storm snow. NE aspect NTL.

 

N aspect N/BTL. Fast moving D1.5 skier triggered loose dry avalanche that ran ~900 vertical. A few smaller sluffs also ran naturally in the same area on similar aspects.

N aspect N/BTL. Fast moving D1.5 skier triggered loose dry avalanche that ran ~900 vertical. A few smaller sluffs also ran naturally in the same area on similar aspects.

Snodgrass // California Bowl

CB Avalanche Center2015-16 Observations, Snow Profiles

Location: Crested Butte Area
Date of Observation: 03/06/2016
Name: Seth Beers
Subject: Snodgrass // California Bowl
Aspect: North East
Elevation: 11,000′

Avalanches: No new avalanches observed. Old crowns from early Feb storm can still be seen.
Weather: @ ~11:00 am, overcast, calm winds, light snow (S1 – S2)
Snowpack: See attached test profile from NE aspect on Snodgrass. HS of 160 cm with a fairly well-developed layer of near surface facets in the top ~5 – 10 cms that sat above a cohesive slab of various firmness down to 45cm. Large F firmness DH from here to ground. Managed a CTH result on the slab / DH interface @ 45cm.

Highly variable snowpack on the way down on similar aspect ranging from the snowpack described above, to fully-faceted, to sun crusts, to bed surfaces from early Feb avy cycle. Facet sloughs were easy to initiate on steeper slopes but ran fairly slow. Near surface facets layer would seem to be one to keep an eye on during the next storm.

030616-Snodgrass-Profile

2″ new!

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/06/2016
Name: Evan Ross
Subject: 2″ new!
Aspect: North East
Elevation: 9,800

Avalanches:
Weather: Overcast or obscured sky, calm wind, snowing in and out mostly around S1.
Snowpack: 1.5-2″ new by 3pm. New snow was warm and sticky. Falling on a very soft warm crust on lower angled slopes, and NSF or wind buff on steeper slopes over 35 degrees.

Second Bowl, Axtell

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/05/2016
Name: Alex
Subject: Second Bowl, Axtell
Aspect: North East
Elevation: 11,800-9,500′

Avalanches:
Weather: Warm all day. Thin high clouds cleared by 1100. Strong solar the rest of the day. Calm-light winds. Gloppy skins.
Snowpack: Mid pack HS in second bowl was 150cm. Weak PS snowpack structure. Weak over weaker to the ground. No signs of present instabilities.

CBAC Snodgrass Study Plot Snowpit

CB Avalanche Center2015-16 Observations, Snow Profiles

Location: Crested Butte Area
Date of Observation: 03/05/2016
Name: Jimmy Buchanan
Subject: CBAC Snodgrass Study Plot Snowpit
Aspect: North East
Elevation: 9,750′

Avalanches: None.
Weather: See profile.
Snowpack: See profile.

March-5-Snodgrass

Snow Surface and Structure

CB Avalanche Center2015-16 Observations

Location: Crested Butte Area
Date of Observation: 03/05/2016
Name: Evan Ross
Subject: Snow Surface and Structure
Aspect: North East, East, South, South West
Elevation: Mostly BTL/NTL

Avalanches: No avalanche problems observed
Weather: Broken skys or partly cloudy to mostly cloudy during the day. Still strong solar/warming snow surfaces and warm temps. Was at ridgeline only for about 20min and winds were light from the south to southwest.
Snowpack: Snow surfaces are highly variable through terrain and across slopes. The most concerning surfaces where on sheltered shady slopes that had near surface facets. Otherwise snow surfaces range from wind packed to some forms of ice lens, or melt form. Many of these surfaces are also wind rippled. See pictures for more details.

NE, 11,250, 25 degree slope. Wind packed particles over striated facets. HS around 100cm.

NE, 11,250, 25 degree slope. Wind packed particles over striated facets. HS around 100cm.

 

NE, 11,200, 32 degree slope. Just 50 feet below the above picture. Wind effected snow surface with mostly wind packed particles at the surface, but some small NSF in very small pockets between the wind effect and on the surface. This soft wind crust was resting over some faceted particles but the overall snowpack structure was generally not to concerning. Big variability from concerning structure to non concerning structure is the take home.

NE, 11,200, 32 degree slope. Just 50 feet below the 1st picture in this post. Wind effected snow surface with mostly wind packed particles at the surface, but some small NSF in very small pockets between the wind effect and on the surface. This soft wind crust was resting over some faceted particles but the overall snowpack structure was generally not to concerning. Big variability from concerning structure to non concerning structure is the take home.

 

Protected NW aspect, 10920', Slope 35, HS 165, boot pen 30cm. 1cm NSF over over a mostly rounded snowpack and generally structureless down to observed depth of 60cm.

Protected NW aspect, 10920′, Slope 35, HS 165, boot pen 30cm. 1cm NSF over over a mostly rounded snowpack and generally structureless down to observed depth of 60cm.

 

Dusty snow surfaces on south easterly facing slopes. Structure: At 10750', SSE aspect, HS 90cm, 5cm boot pen at 12:45pm. A 22cm MFcr was over 4F moist snow below. Isothermal throughout structure. At 9,700' SW aspect, HS 55, slope 34 degrees, boot pen 5cm. 34cm P+ hard MFcr over F hard wet snow below.

Dusty snow surfaces on south easterly facing slopes.
Structure:
At 10750′, SSE aspect, HS 90cm, 5cm boot pen at 12:45pm. A 22cm MFcr was over 4F moist snow below. Isothermal throughout structure.
At 9,700′ SW aspect, HS 55, slope 34 degrees, boot pen 5cm. 34cm P+ hard MFcr over F hard wet snow below.

 

Southeast aspect NTL, wind effected snow surfaced turned to melt forms. Isothermal snowpack.

Southeast aspect NTL, wind effected snow surfaced turned to melt forms. Isothermal snowpack.

 

Dusty snow surfaces ATL on easterly and north easterly terrain in the paradise divide zone.

Dusty snow surfaces ATL on easterly and north easterly terrain in the paradise divide zone.

 

Shinny snow surfaces on north easterly NTL terrain.

Shinny snow surfaces on north easterly NTL terrain.