Crested Butte Avalanche Center

Avalanche Report for Sunday February 5, 2012

Sun, 05 Feb 2012 13:45:00 GMT

Time and warm temperatures are helping the upper snowpack settle into a cohesive slab but the lower snowpack still remains very weak. This is causing our snowpack to feel deceptively stable on most aspects. All it takes is 30 seconds to hop off your skis and post-hole through the "stronger" snow to observe the weaker underlying snowpack structure. Shady northwest through east aspects below treeline have the most pronounced strong over weak layering where January storm snow rests entirely on weak facets. Many near and above treeline wind-loaded slopes that face north through east and around to the south have stacks of wind slabs piled up on crusts and facets. The likelihood of triggering an avalanche is slowly decreasing but the consequences remain very severe: if you do trigger an avalanche, chances are it will be large and destructive.

Avalanche Report for Saturday February 4, 2012

Sat, 04 Feb 2012 12:55:00 GMT

We are seeing our snowpack settle and gain strength over time. The lack of snow and mild temperatures are allowing many slopes to heal and stabilize but weak faceted snow may still be lingering on some slopes. It may difficult to initiate an avalanche but if a slope releases it may be deeper and wider than expected. Lower elevations that have had little to no traffic may be especially unstable. Steep wind loaded slopes should also be treated with extra caution particularly at higher elevations.

Avalanche Report for Saturday February 4, 2012

Sat, 04 Feb 2012 12:55:00 GMT

Avalanche Report for Friday February 3, 2012

Fri, 03 Feb 2012 14:00:00 GMT

This latest round or snow will do little to change the backcountry avalanche danger. Winds gusted barely into the teens at Scarp Ridge, meaning very little snow fell and very little snow was moved. Our last reported avalanche came from the Paradise Divide zone on Monday, although reports of collapsing and cracking continue from below treeline. The snowpack has had some time to adjust to January's snowfall, meaning natural avalanche activity has ended, though the probability of triggering avalanches remains elevated. The structure of the snowpack is very suspect. Large, loose snow grains near the bottom of the pack are barely supporting the weight of the slabs above, and layers of crusts are surrounded by thin weak layers as well. Snowpack tests show it will not take much to trigger avalanches in areas with these characteristics.

Avalanche Report for Thursday February 2, 2012

Thu, 02 Feb 2012 14:00:00 GMT

Light density new snow today with little winds will not change the avalanche danger much. If anything, it will add just a little more load to an already touchy snowpack. Recent remotely triggered avalanches as well as bigger than expected explosive releases show the unpredictable nature of the snowpack. Our "midpack" feels supportive in some areas, but below it lies a weak and faceted base. Wind slabs and stiffer, denser snow are able to carry failures in the snowpack over long distances, creating large avalanches when the weak area is affected.

Avalanche Report for Wednesday February 1, 2012

Wed, 01 Feb 2012 13:45:00 GMT

As observations trickled into the CBAC yesterday, it turns out that a skier triggered the slide on Mt. Baldy on Monday. Snowmobilers had been high-marking in the bowl on Sunday, but the avalanche occurred Monday as a skier dropped into the bowl and skied between their tracks. The slide was triggered remotely from over 600 feet away! Crown heights were estimated to range from 1 foot to over 6 feet and the slide was a big enough to bury or kill a person. Our snowpack is deceptively stable and wind-affected slopes will be variable and tricky to asses. Human triggered avalanches remain likely on many slopes and remote triggering an avalanche from a long distance away remains possible too.

While temperatures have been helping the upper snowpack gain strength, the lower part part of the snowpack remains very weak. Don't be fooled by the apparent "supportiveness" of our snowpack. Stronger snow--old storm slabs and wind slabs--is resting on weaker snow and will be reactive throughout the week. Observers continue to report shooting cracks and rumbling collapses from below treeline where the most striking strong over weak layering exists. With more snow in the forecast expect the danger to remain elevated through the weekend.

Avalanche Report for Tuesday January 31, 2012

Tue, 31 Jan 2012 13:45:00 GMT

West and southwest winds picked up yesterday afternoon and drifted snow at ridge-tops. Recent blowing snow will add to the wind slab problem on lee slopes near and above treeline. Observers reported a snowmobile triggered avalanche from the south facing bowl on Mt. Baldy yesterday. The slide ran close to 75 meters across the slope, 200 meters vertically and was big enough to bury or kill a person. It remains likely to trigger an avalanche today on many slopes. Approach all terrain steeper than 30 degrees with extra caution; all triggered avalanches have the potential to propagate larger than expected and remote triggering a slide from below a slope remains possible today as well.

January storm snow has been settling into cohesive slabs due to the recent warmer temperatures. While temperatures have been helping the upper snowpack gain strength, the lower part part of the snowpack remains very weak. Don't be fooled by the apparent "supportiveness" of our snowpack. Stronger snow--old storm slabs and wind slabs--is resting on much weaker snow throughout the backcountry and will be reactive throughout the week. Observers continue to report shooting cracking and rumbling collapses from below treeline where the most striking strong over weak layering exists.

Avalanche Report for Monday January 30, 2012

Mon, 30 Jan 2012 14:00:00 GMT

We are still dealing with a prolonged period of elevated avalanche danger. With over five feet of snow and a number of wind events in the second half of this month, the snowpack remains very touchy. Our last storm of over a foot ended on Friday and was followed by significant wind loading at and above treeline. Numerous avalanches were reported late last week at all elevations. Yesterday a smaller natural avalanche occurred on a SE aspect of Red Lady Bowl. Friday, a size D2 skier triggered avalanche was reported from Ruby Mountain that was 3 ft deep in places and ran 900ft wide. While natural activity has been slowing, triggering avalanches remain likely on most slopes over 30 degrees. Observers have reported failures propagating surprisingly large distances.

The current warm temperatures are adding cohesion to the existing slabs in the upper part of the snowpack. However, this will do little to help the extremely weak facetted layers underlying the slabs. On most slopes we are dealing with slabs sitting over these granular, sugar-like layers. Below treeline the weak snowpack is very reactive. Friday through Saturday night brought our most recent wind loading event. Thicker and more energetic windslabs are now resting on leeward slopes at and above treeline.

Avalanche Report for Monday January 30, 2012

Mon, 30 Jan 2012 13:45:00 GMT

We are still dealing with a prolonged period of elevated avalanche danger. With over five feet of snow and a number of wind events in the second half of this month, the snowpack remains very touchy. Our last storm of over a foot ended on Friday and was followed by significant wind loading at and above treeline. Numerous avalanches were reported late this week at all elevations. Yesterday a smaller natural avalanche occurred on a SE aspect of Red Lady Bowl. Friday, a size D2 skier triggered avalanche was reported from Ruby Mountain that was 3 ft deep in places and ran 900ft wide. While natural activity has been slowing, triggering avalanches remains likely on most slopes over 30 degrees. Observers have reported failures propagating surprisingly large distances.

The current warm temperatures are adding cohesion to the existing slabs in the upper part of the snowpack. However, this will do little to help the extremely weak facetted layers underlying the slabs. On most slopes we are dealing with slabs sitting over these granular, sugar-like layers. Below treeline the weak snowpack is very reactive. Friday through Saturday night brought our most recent wind loading event. Thicker and more energetic windslabs are now resting on leeward slopes at and above treeline.

Avalanche Observation on Thursday February 2, 2012

Thu, 02 Feb 2012 07:00:00 GMT

Crested Butte Zone, SE at 10-12,000 Calm and warm (mid 20s) on top (at 2 p.m.) as the storm rolled in.
Light snow. Anything jacked west had a sun crust. Heard from someone skiing down
the RL glades that they had one collapse.

Avalanche Observation on Thursday February 2, 2012

Thu, 02 Feb 2012 07:00:00 GMT

Crested Butte Zone, E/NE at 10,900 Tour up and over Coney's Ridge. Got several collapses while breaking trail in the trees and one large collapse on a 25* open slope. Some collapses were large enough to shake the trees! Scattered snow came and went throughout the day with no noticeable accumulation. Southeast winds picked up in the afternoon, but did not observe any blowing snow. Skiing was uniform and supportive with ski penetration of about 15-20 cm.

Avalanche Observation on Wednesday February 1, 2012

Wed, 01 Feb 2012 07:00:00 GMT

Paradis Divide Zone, S at 11,000 Cloudy afternoon with light and variable winds. Temperatures were just below freezing.
Lower angled terrain held soft surface snow, while steeper slopes had a crust. Below the surface there was a 1 finger hard slab 6-10" thick depending on the area. All areas had 1-1.5 feet of large, sugary depth hoar snow going down to the ground. When walking around in boots every other step would sink to the ground. On skis you could stay on the surface more easily.
Noticed several smaller avalanches which ran many days ago. Some of these were surprisingly small and in areas where you would not expect to see slides. Most steep rollovers, even on small slopes showed evidence of previous avalanching.

Avalanche Observation on Wednesday February 1, 2012

Wed, 01 Feb 2012 07:00:00 GMT

Irwin, various at near and below Treeline Weather: Another day with below TL temps nearing, but not exceeding freezing,
and nighttime temps in the single-digits. Winds have been light
today, starting out W'ly and shifting to S'ly as clear skies yielded
to high thin clouds and then overcast skies.
Avalanches: No avalanches today in our terrain and no new naturals spotted in the
vicinity.
Snowpack:
Mild temps have continued to slowly settle and strengthen the
snowpack. Signs of instability have been slowly decreasing this week, with no
signs of instability today, even in some lesser-travelled pockets on
E-S-W aspects below TL where we have previously seen some small,
untraveled pockets still be reactive. All aspects and elevations have
good supportability, though it is still close to threshold in below
TL areas on more W'ly aspects.
The recent near-freezing daytime temps and single-digit nighttime
temps have created near-surface faceting in the upper snowpack,
particularly on S'ly and E'ly aspects near and below TL. This makes
for excellent surface conditions, but may become a weak layer once
buried. On more W'ly aspects near and below TL, soft snow from last
week's storm remains soft.
Above TL, there remains a mix of windslabs on more E'ly terrain with
S and W aspects having variable wind-loaded and wind-scoured pockets.

Avalanche Observation on Monday January 30, 2012

Mon, 30 Jan 2012 07:00:00 GMT

Paradise Divide Zone, S at 12,000 Some cracking and whumphing on ascent of Baldy via low SW side of
main South facing bowl. Climbed to ridge top with blowing snow and
skied variable depth down bowl (thin, wind scoured up top to deeper
lower in bowl). First skier remotely triggered (300 meters away) a R2
D2 windslab that ran to the ground on the East facing side of the
bowl. Crown varied from a foot deep to 6 ft plus. The avalanche
reached back to our skin track on the ridge, but stayed away from our
planned descent lines. The avalanche also took out some snowmobile
high mark tracks from the day before (Sunday).

Avalanche Observation on Saturday December 29, 2012

Sat, 29 Dec 2012 07:00:00 GMT

Washington Gulch, All at 9,800-12,600 -Overcast skies w/ clouds lifting off of ridgetops by 1pm then
descending again by 4pm. Graupel fell throughout the day w/ 2cm new
snow. N winds aloft. We saw moderate localized winds from ALL
directions w/ some strong gusts. Moderate wind transport, but not
much available snow
-Small skier triggered point release occurred on a NE slope @ 12,200ft.
Ran 500ft and was 20cm deep. Not a facet sluff. It ran much fasted
-Cracks propagating up to 10m w/ collapse @ 2 different slopes
11,600ft on ENE and N asp.
-Both occured @ interface of windslab & underlying facets 10-15cm
below the surface.
-Alpine & treeline N and NE slopes were variable in HS and had
pockets of reactive windslab
-S/SW slopes had mostly supportive sun crusts with underlying facets
even above treeline.