Mt. Axtell

CB Avalanche Center December 13, 20162016-17 Observations

Location: Crested Butte Area
Date of Observation: 12/13/2016
Name: Zach Guy

Subject: Mt. Axtell
Aspect: North East, South, South West
Elevation: 9,600 -12,000 ft

Avalanches: No recent avalanches observed across all bowls of Mt. Axtell or on northerly aspects of Carbon
Weather: Overcast, light to moderate westerly winds at ridgetop, with minimal snow transport observed.
Snowpack: See photo captions for detailed pit descriptions.
On NE aspects N/ATL. Extended column tests showed propagating results on basal facets/depth hoar, up to a meter deep. Non-propagating results on Dec 6th near surface facet layer, buried mid-pack. We triggered two large collapses on low angle slopes. We did not venture onto any steep terrain at these elevations.
On S/SW aspects N/BTL. The Dec 6th crust/facet layer produced about 5 rolling collapses up to 50+ feet long, but is buried only 6-12″ right now; not much of a slab. Propagating results.
On N/NE aspects BTL, the snowpack felt fairly uniform and soft, becoming progressively weaker with depth but with no distinct or sudden hardness changes. We traveled on several slopes steeper than 35 degrees with no signs of instability.

NE aspect ATL. 3-5 mm depth hoar grains at the bottom of the snowpack. Difficult to say how continuous this relatively thin layer is across steep slopes due to surface roughness and variability.

NE aspect ATL. ECTX result, but sudden collapse, propagating result with 2 additional hits (ECTP32) on 3-5 mm, fist hard depth hoar, below a ~90 cm, 4F to 1F slab. Non propagating results on Dec 6th near surface facet layer, about 35 cm deep.

SSW aspect NTL. ECTP 15, SC below the Dec 6th crust layer (1F, 1 cm thick), over F facets. 30 cm of F to 4F slab above this layer. Rolling collapses observed on this layer, although slab generally felt lacking in these wind protected slopes.

NE aspect NTL. ECTP 16, SC on 1-2 mm basal facets below a 75 cm slab (F to 4F). ECTN results on the Dec 6th near surface facet layer (F+) buried about 35 cm deep.

Mountain Weather

CB Avalanche Center December 13, 2016Weather

Date: 12/13/2016

Colorado remains in strong, westerly flow through most of the work week. Radar shows a lull in precipitation upstream of us in Utah and the next pulse of moisture moving onshore over California. Today, we’ll see mid to high level clouds and continued alpine winds with a few snow showers developing tonight. Deepening moisture will fuel a stronger pulse of snowfall tomorrow afternoon accompanied by strengthening winds. A large, closed low is lined up to deliver significant snowfall beginning Thursday night. Stay tuned.

Today

High Temperature: 20
Wind Speed: 10-20, G35
Wind Direction: W
Sky Cover: Mostly cloudy
Snow: 0

Tonight

Low Temperature: 15
Wind Speed: 10-20
Wind Direction: W
Sky Cover: Overcast
Snow: 1-3″

Tomorrow

High Temperature: 25
Wind Speed: 12-22
Wind Direction: SW, W
Sky Cover: Overcast
Snow: 1-4″

Unhappy structure in Happy Chutes

CB Avalanche Center December 12, 20162016-17 Observations

Location: Crested Butte Area
Date of Observation: 12/12/2016
Name: Zach Guy

Subject: Unhappy structure in Happy Chutes
Aspect: North East
Elevation: 9000-9400 ft

Avalanches: We descended slopes up to ~38 degrees with no avalanche activity.
Weather: Broken skies, calm winds, no precip.
Snowpack: Hollow snowpack structure produced widespread cracking ~5 to 15 feet and localized collapsing. 12″, semi-supportive (on skis) soft slab over fist hard facets, consistent structure across all terrain that we traveled. Propagating results in ECT and PST. Small storm slab management still seems to apply here, and it felt like the slab is a little too soft/thin for avalanching or propagating on most features, except for very steep, unsupported, or wind stiffened slopes. Not much additional load needed here for widespread persistent slab issues.

12_12_16-Happy-Chutes-Pit-Profile

DSCN1180-001

wow, we have bright orange hats. And cracking snow.

Lots of localized collapses and cracks.

BC Ski

CB Avalanche Center December 12, 20162016-17 Observations

Location: Paradise Divide Area
Date of Observation: 12/12/2016
Name: Jeff

Subject: BC Ski
Aspect: East, South, West
Elevation: 9800-11400

Avalanches:
Weather: OVC, NW M>S as day progressed
Snowpack: ATL & BTL E-S-W No signs of instability, sleds roosting 35-40* & leaving troughs on the above mentioned terrain with no results. stomped on ridgelines of steep windloaded slopes (HS 80-110cm) no results

intensifying snow transport ~15:00, some quickly blown in tracks @ all elevations in open clearings

Avy 1 Course: Coneys

CB Avalanche Center December 12, 20162016-17 Observations

Location: Crested Butte Area
Date of Observation: 12/11/2016
Name: Dave B

Subject: Avy 1 Course: Coneys
Aspect: North, North East
Elevation: 9.5- 11K

Avalanches:
Weather: Overcast skies (OVC) nearly all day. Winds Moderate to Intense at times on the ridge, had periods of S 1 snow. Did not amount to much, Morning temp was – 1 c but felt much cooler due to winds.
Snowpack: We got shooting cracks and multiple collapses on our tour up to the ridge. We went up on the west side of coney’s. Skied a lap on the lower angle ridge next to our skin track. Also skied a lap in more of the center of coney’s (2nd Bowl) The skiing was really good. There were only 2 other skiers out there.
Height of snow 83 cm. We had easy results on CTE 4/7 SP tests breaking on a facet layer 40 cm down and a moderate result on an ECTP 16 SP on the same layer. We did not see any signs of instability while we were skiing.

Snowmobiler triggered, caught and buried by PS avalanche

CB Avalanche Center December 12, 20162016-17 Observations, Accidents, Avi-map 16-17

The complete accident report is now available here.

Location: Paradise Divide Area, Washington Gulch near Elkton.
Date of Observation: 12/12/2016
Name: Evan Ross

Subject: Snowmobiler triggered, caught and buried
Aspect: North
Elevation: 11,250

Avalanches: 2nd hand information. Snowmobiler triggered, was caught and buried by a persistent slab avalanche. They were rescued by the rest of their party, and did not sustain any injuries.

Average slope angle across the bed surface was 39 degrees. Crown was about 175ft wide and 3ft deep. Persistent slab failed at the ground on 2mm faceted grains, 4f- hard.
Weather:
Snowpack:

Crown Profile

Looking across the crown

Looking up at the crown

Burial Location

Looking upslope. The burial location is in the foreground.

CB Avalanche Center December 12, 2016Avi Blog, Avi-Off-Season

Back in the flow. Zach Guy, CBAC Director

The Western U.S. is coming out of a long drought and the atmospheric snow guns have finally replaced the artificial ones that were building our ski area’s snow base. With snow comes avalanches. There were two avalanche fatalities in the West over the weekend: a skier in closed terrain in Mt Rose Ski Tahoe on Saturday, and a backcountry skier near Cooke City, MT on Sunday. We send our sincere condolences to all of those affected by these tragedies. Here in Colorado, there has been a stroke of divine luck, with a number of multi-party burials that resulted in profound learning lessons, rather than fatalities. A trio of skiers in Butler Gulch, near Berthoud Pass, were all caught and buried on Saturday. Two of them were only partially buried and were able to rescue the third. On Sunday, a skier was caught in a slide near Red Mountain Pass and two snowmobilers were fully buried but rescued by their group near Steamboat. On Monday, a snowmobiler was buried near Crested Butte. Needless to say, avalanche season is upon us.

The search area for the avalanche victim at Mt. Rose Ski Tahoe. Photo courtesy of Washoe County Search and Rescue.

The Elk Mountains have been in a favorable zonal flow pattern since December 6th. CBMR reported 18” of snow in the past week, and some of our backcountry areas have picked up almost twice that. More is on the way this weekend. Anytime we have periods of dry weather, especially early season, our snowpack develops weak layers. Once we start getting back into the storm track, those weak layers get loaded and stressed, creating avalanche concerns. Sometimes these avalanches can act in surprising or unique ways, like being triggered from long distances away or from flat terrain. This video demonstrates the challenging nature of persistent slab avalanche problems, where there is a cohesive slab over a persistent weak layer.

A group of 3 skiers were buried in this slide in Butler Gulch, CO on Saturday. Photo courtesy of CAIC.

It is easy to get caught up in the powder frenzy this time of year. We’ve all been itching to arc those graceful turns down powder filled slopes or throttle through deep pillows and faceshots. But we need to draw a line and stay behind it. One of my mentors up in Montana recently discussed how taking one step back from the line is insufficient. “To ensure a lifetime in the mountains, it is a matter of taking three or four steps back.” The CBAC got an observation yesterday, reporting signs of instability, which concluded with: “Suspect a successful tour could have been had with proper navigation today, but the instabilities spooked us, especially while navigating unfamiliar terrain. We opted to head home.” I applaud that kind of decision making. There isn’t any kind of steep or deep powder run that exceeds the reward of returning home safe at the end of the day.

Snow profile showing unstable results near Crested Butte. 12/11/16

If you are new to the area or visiting, make sure you tune into our avalanche advisories at www.cbavalanchecenter.org. Our forecast team has been in frenzy the last couple weeks to keep tabs on the state of the snowpack. On Sunday, after a big pulse of moisture plowed through the night before, we had all three of our forecast staff up three prominent drainages surrounding our town digging into and documenting the snowpack to help aid in your backcountry decision making. Use our website and observations page as a resource! Give those guys a pat on the back for their often stressful and sleep deprived work during the holiday season. You can just sense the anxiety in Havlick’s voice in this video, and I bet the poor guy hasn’t done his laundry in 2 weeks now. And thank our ski patrollers at CBMR and respect roped off or closed terrain. Those guys and gals are working hard to mitigate avalanche hazards to get terrain open.

Keller Obs

CB Avalanche Center December 12, 20162016-17 Observations

Location: Kebler Pass Area
Date of Observation: 12/11/2016
Name: Steve Banks

Subject: Keller Obs
Aspect: East, South East, South, South West, West
Elevation: 10,500-12,000

Avalanches: A few small 8-15′ wide pockets failed within the new snow, but didn’t gain any momentum on slopes ~35° and only moved less than a foot downhill. With clearing skies in the afternoon, no natural activity was noticed in surrounding peaks.
Weather: Warmer early in the morning with temp dropping to 22° F at 9 am and staying there all day. Winds kicked in at 8 am from the SE with strong to extreme gusts, moving to the W/SW by midday. Ridgtop winds were hitting 60 mph. S5 morning snow tapered through the day with clouds lifting around 3pm.
Snowpack: 7″ new snow overnight with an additional 1″ through the day (most of it blew around/away) Very dense snow with 1.1″ of H2O. Soft slab in the morning stiffened from the wind throughout the day. New snow bonded relatively well to the old surfaces.
Quick compression tests showed mid-storm instabilities with resistant planer shears.

Mountain Weather 12/12/2016

CB Avalanche Center December 12, 2016Weather

Date: 12/12/2016

Elevated winds and cloudy sky will be the theme for the next couple days as Colorado sits under westerly flow. This westerly flow has enough moisture to fuel chances of light snow showers on Monday and Tuesday and keep mostly cloudy sky overhead. Expect continued blowing snow at higher elevations and strong wind gusts. We still have a couple of good chances at snowfall this week, with the next round impacting Colorado starting on Tuesday night and our area a little closer to Wednesday. This looks to be another warm, dense snow producer like last weekend’s storm. Then we’ll close out the week with another large storm arriving Friday evening with what should be colder temperatures and lighter snow.