CAIC

Details

Date: 2016/01/26

Observer: Daniel Moroz Scott Toepfer
Organization: Public

Location

BC Zone: Vail & Summit County
Area Description: Primary avalanche ran below false summit (12,377) of Coon Hill (12,757)just west of West Portal of Eisenhower Tunnel

Weather

Ridgeline Wind Speed: 10-20 mph
Ridgeline Wind Direction: N
Wind Loading: Previous
Temperature: -10 C
Sky Cover: Few
Depth of New Snow: 3 in
Weather Description: Few clouds developing, winds less than 5mph below 12,000 feet, stronger at ridgelines. Stayed cold all day in shade

Snowpack

Snowpack Description: Below 11,200 feet generally unsupportable faceted snowpack with a few sun crusts mixed in. Some collapse noted on ascent

Snowpack Obsvervation #1

Cracking: Minor
Collapsing: Moderate
Persistent Weak Layer: Yes
Comments: Just below near treeline elevation band. Couple good collapses, some cracking at the new old interface. It would propagate out 3 to 4 feet. Generally faceted snow with a few M/F crusts mixed in. Foot penetration to ground.

Snowpack Obsvervation #2

Cracking: Minor
Collapsing: None
Persistent Weak Layer: Yes
Comments: Slab over two faceted layers (see snowpit). The lower base layer of depth hoar grains (3-6 mm) was sintering. The weaker faceted layer of 3-5 mm depth hoar above the basal depth hoar is what our ECTP SC failed on...at the interface.

Avalanches

Avalanche Description: Skier Triggered Wind Slab avalanche that stepped to ground about 150 to 200 vertical down slope. Looks to have ridden up onto an old pencil hard layer in the main couloir. SSASuR3D2- Medium sized relative to the path. Large enough to seriously injure or kill a person.

Date

Location/Path

Elev

Asp

Type

Trig

SizeR

SizeD

2016/01/17 ^†

>TL

AS / u

2016/01/25 ^†

>TL

D1.5

Media

Images

$Figure 1: ski track to fracture line. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/941056menyzpep4a86harq5oufzn?ixlib=php-3.1.0&s=a4ad4cf54c72fdf5491ae3e759967356','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)$ Figure 2: overall view of incident site (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/dlvcnhhhqj68msmyii9let0q9z8z?ixlib=php-3.1.0&s=70e4a17ea1dc04035a8380afa0570a1b','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 2:</b> overall view of incident site (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/dlvcnhhhqj68msmyii9let0q9z8z?ixlib=php-3.1.0&s=70e4a17ea1dc04035a8380afa0570a1b','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 3:</b> Side view of incident site (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/osjxarce883zsvke711q2d65pxpf?ixlib=php-3.1.0&s=4952a851d93c9624fcb4219a1ef7f1db','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 4:</b> Rescue location. Slope angle here was 21 degrees.
Avalanche debris density was 408 kg/cubic meter. (898 pounds per cubic meter) (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/l0l4x6th69ghqho9eltpwn341ec3?ixlib=php-3.1.0&s=bd55b5ae74a223a9b7812e3dbb38faa8','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 5:</b> Old HSNR2D1.5 further up Straight Creek. Probably ran 1/17/16.
East aspect above treeline. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/2adftkbsjvqgn1dj2n9d7cco0v54?ixlib=php-3.1.0&s=4ffb5f8a9602c3bd93af1fab38a49d39','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 6:</b> Looking up the track. This was 37 degrees. Bed surface pencil hard (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/ab2qn3s08apfb5xperzb0hvn0250?ixlib=php-3.1.0&s=a4de7a4775ad4ddf6f500e2785588107','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 7:</b> Debris pile from sympathetic slide (2nd slide). (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/uxa3b6we6de0xw2y6n7f686otzwc?ixlib=php-3.1.0&s=3f36354ae1fa9d7aa0a9f59a51771199','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 8:</b> Solid black arrow indicates main path. Lighter arrow points at route of 2nd slide. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/m5whia2hp5t8dbqr6koo90z3wfva?ixlib=php-3.1.0&s=72790c5de0410c772b71b1c30dcf9012','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 9:</b> Looking down towards I-70 from snowpit location. South aspect, 11,600 feet.Slope angle here 28 to 30 degrees. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/ig45lp14ku7fs8wuwjl75tyyc19h?ixlib=php-3.1.0&s=1525aa0dae9807bdfd8e7169c9e36fed','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

$Figure 10: Snowpit location from below (White arrow). This site is 600 feet lower than fracture line, similar aspect, and about 800 feet east. Black arrow points to east ridge of Point 12,377. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/aftjhzm15ysy754qunt1edrkps3y?ixlib=php-3.1.0&s=5c2d0cda8dd4614813b783c102e1f077','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)$ Figure 11: Late day lenticular clouds over the Continental Divide indicate it is still windy at ridgelines (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/136x0e5daccym99dbhpmlti5dwx6?ixlib=php-3.1.0&s=b5d30f9694d13df815ab4b28d554da0c','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 11:</b> Late day lenticular clouds over the Continental Divide indicate it is still windy at ridgelines (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/136x0e5daccym99dbhpmlti5dwx6?ixlib=php-3.1.0&s=b5d30f9694d13df815ab4b28d554da0c','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)

<b>Figure 12:</b> Snowpit 800 feet east of avalanche. 600 feet lower. South aspect. (<a href=javascript:void(0); onClick=win=window.open('https://caic-production.imgix.net/fhmoo37p1a3tt3yiifjv51j9642k?ixlib=php-3.1.0&s=8d29b0fa6ba5f9fcd4e9e5a245af273a','caic_media','resizable=1,height=820,width=840,scrollbars=yes');win.focus();return false;>see full sized image</a>)