Wet activity ramping up

CBAC 2020-21 Observations

Date of Observation: 04/03/2021
Name: Zach Guy

Zone: Northwest Mountains
Location: Anthracite Range and driving tour
Aspect: North, North East, East, South East, South
Elevation: 9,600 – 12,200

Avalanches: See photos. Large wet avalanche activity on the rise. We noted numerous natural D2 wet loose avalanches on all but due north aspects and at all elevations. Many of these gouged deep into the snowpack. Some ran today, some yesterday. Several large wet slabs, generally D2 in size, ran today. The one off of the east face of Gothic may have been up to D3 given the long runout (which was obscured from view).
Weather: Africa Hot.
Snowpack: We found frozen surfaces this morning and good corn skiing on due south aspects until about noon, at which point ski and boot pen quickly detoriated. On an east aspect below treeline around 1 p.m., we were triggering large pinwheels that gouged 12″ to 18″ deep. The most active aspects for wet activity were east and northeast where we traveled, but we left before westerlies had their fair share of sunshine.

 

Photos:

Wet Slab Star Peak Zone

CB Avalanche Center 2020-21 Observations

Date of Observation: 04/02/2021
Name: Ben A

 

Zone: Southeast Mountains
Location: Star Ridge above Friends Hut
Aspect: South
Elevation: ATL

Avalanches: Wet slab triggered by wet loose late afternoon 4/2. Wet slab triggered below the rock band. Debris ran over the bench and triggered another wet slab.

Photos:

2:30 PM avy obs

CBAC 2020-21 Observations

Date of Observation: 04/03/2021
Name: Zach Kinler
Location: NW/SE Mountains
Aspect: East, South East, South

Avalanches: Mineral Point had several small loose wet avalanches ATL on the South face and several large loose wet avalanches ATL on the East face. A couple of these were long-running with one gouging to the ground in spots and running to valley bottom. On Baldy, ESE ATL a wet loose initiating from a rock band triggered a wet slab mid slope. One other long-running and gouging wet loose was spotted on an ESE aspect NTL above Copper Creek.
Weather: Hot AF.

 

 

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Late day wet snow check-in

CB Avalanche Center 2020-21 Observations

Date of Observation: 04/02/2021
Name: Ben Pritchett

 

Zone: Northwest Mountains
Location: Roadside observations around Crested Butte. Late day wet snow check-in. Assess depth of melt-water infiltration in relation to potential Wet Slab avalanche problems.
Aspect: North, North East, East, West, North West
Elevation: 10,000

Avalanches: Photo 1: A wet snow surface on a mostly dry snowpack at 10,000′ on a northeast-facing slope. April 2, 2021.
Photo 2: A pattern of small natural avalanches on southeasterly-facing slopes near and above treeline. April 2, 2021
Photo 3: A small natural avalanche on a south-facing slope above treeline. April 2, 2021
Photo 4: An example of an easterly-facing slope that could become dangerous without a freeze at mid-elevations.
Photo 5: A pair of recent slab avalanches that ran on the east to northeast-facing slopes off the Ruby/Owen ridge, and Scarp Ridge.

Estimate* 3/29/21- 1- >TL- E-C-N-R1-D1
Estimate* 3/29/21- 1- >TL -SE-C-N-R1-D1
Weather: Ridgeline Wind Speed: Calm
Wind Loading: None
Temperature: 53 F
Sky Cover: Few
Depth of Total Snow: 120 cm
Weather Description: 53 degrees at 10,000′ at 3pm.
Snowpack: Near 10,000 feet, on northwest through north to northeast-facing slopes, the snowpack was mostly dry, with meltwater draining down only around 10cm so far. Below and near treeline, the shoulder aspects of east and west look the closest to developing a Wet Slab avalanche problem. The steeper southeast through south to southwest-facing slopes are wetted to the ground and melting out quickly. At the Butte snotel at a similar elevation, it did not freeze Thursday night, and it may not again tonight (Friday night). In the worst case rocky terrain features rocky with a shallow snowpack, human-triggered Wet Slab avalanche may become possible by late afternoon Saturday. If there’s another night without a freeze on Saturday, natural Wet Slab avalanches might run Sunday.

 

Photos:

Wet obs

CBAC 2020-21 Observations

Date of Observation: 04/02/2021
Name: Zach Guy and Zach Kinler

 

Zone: Northwest/Southeast boundary
Location: Mt. Emmons
Aspect: North East, East, South East, West, North West
Elevation: 9500-12000′

Avalanches: A handful of small wet loose avalanches ran today, generally on northeast and some east aspects at all elevations. Skier triggered a couple of wet loose avalanches this afternoon below treeline on a northeast aspect. The slides gouged through most of the snowpack, large enough bury someone in a gulley (~D1.5). These were in steep, rocky terrain holding a shallow and weak snowpack that is just now becoming saturated.
Weather: Unseasonably warm: Highs reached mid 50’s at 10,000′ and 40 at 12,000′. Partly cloudy skies. Light ridgetop winds.
Snowpack: Several pits on E, SE, and W aspects N/BTL targeting wet slab concerns. Generally, slopes that are getting the most water right now have already seen a fair amount of water already and have moist or wet grains throughout the entire snowpack. Slopes where the snowpack has remained dry until the last few days have water in the upper few inches today. Water was pooling about 40 cm deep on a SE aspect NTL (the rest of the snowpack was moist), and pooling about 5 cm deep on a West aspect NTL (the rest of the pack was dry). At low elevations, the saturated snowpack became unsupportive (bottomless boot pen) by the afternoon on flat terrain. All but high northerly aspects or steep due north aspects at low elevations got wet today. Good, stable corn skiing this morning on southerly aspects until about noon, at which point the snow surface became increasingly mushy and we were able to trigger pinwheels and micro-sluffs. Northeast and northwesterly aspects were most active today for wet loose activity because the snow surface is just now transitioning from dry to moist or wet.

 

 

Wolverine Cornice Fall

CB Avalanche Center 2020-21 Observations

Date of Observation: 04/01/2021
Name: Tim Mahan

Zone: Southeast Mountains
Location: Mt Emmons. Wolverine Basin.
Aspect: East
Elevation: 12,100

Avalanches: WL-N-R1-D1-O E facing rock band at the top of wolverine basin bowl feature.

Photos:

Large cornice avalanche

CB Avalanche Center 2020-21 Observations

Date of Observation: 04/01/2021
Name: Zach Kinler Evan Ross
Zone: Northwest Mountains
Location: Southern Ruby Range
Aspect: East, South East, South
Elevation: 9,000′-12,600′

Avalanches: Observed several Wet Loose avalanches, both natural and human triggered. Size ranged from D1-D1.5 with activity primarily on steep East, South and Southwest slopes near and above tree line. While traversing the Ruby spine we encountered several large overhanging Cornices which had begun to pull back from the ridge. Two of these were triggered from dry ground on the ridge by simply “pole whacking” the gap.

We got a close look at the previously reported Cornice Avalanche on the SE flanks of Mt Owen. This was a big section of cornice that fell down and resulted in a large D2.5 avalanche. The cornice initially gouged close to the ground in steep rocky terrain, then appeared to run on March interfaces as dust layers can be seen on the bed surface.

Weather: It’s heating up! We skinned in t-shirts most of the day. Temps soared above freezing at all elevations today under abundant sunshine. Westerly winds were light at rideline.

Snowpack: We travelled primarily on sunny aspects from E-S near and above treeline. By 12:00, we observed several small natural Wet Loose avalanches on steep East aspects near tree line. As the day progressed, action moved to South aspects and eventually Southwest slope near and above treeline. While these avalanches were only entraining the upper few inches of wet snow, they were gaining momentum on larger slopes. Skiing off the ridge in the late afternoon, we choose to avoid our intended ski objectives that was south east facing above 12,oooft to due to the fact that we would be triggering loose wet avalanches and didn’t feel we could safely manage the problem on that terrain feature. While briefly hanging out on the bed surface of an old cornice avalanche you could actually hear water cascading somewhere. Sounded like you were standing next to a running water fountain.

Cornices, which have grown large throughout this season on certain leeward aspects, proved to be sensitive where large portions are overhanging ridges and are beginning to pull back from ridgeline. These babies are very unpredictable with some being resistent to cutting while others may be triggered by simply hitting the right spot or right time of day. These beasts were best managed by avoiding traveling on or below slopes where present.

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2 feet of new overnight!

CBAC 2020-21 Observations

Date of Observation: 04/01/2021
Name: Zach Guy

 

Zone: Southeast Mountains
Location: Gothic
Aspect: East, South East
Elevation: 9500 – 12,600′

Avalanches: A D2 cornice fall off of the east face of Baldy, looked a few days old.
Some D2 wet loose debris below the east face of Gothic, likely from last weekend’s warmup.
We ski triggered some very small/shallow sluffs in the top few inches of snow.
Weather: Light ridgetop winds. Cold temps this morning, rapid warming through midday. Clear skies.
Snowpack: Made ya look. April Fools. Some small rollerballs and sluffing as the top few inches of recent snow became moist. Crusts below that snow (on E, SE aspects) remained frozen before noon. More snow for entrainment on northeasterly tilts where there aren’t underlying crusts.
The biggest problem that we were managing was large cornices. We stayed well away from them on ridgelines. On slopes overhung by cornices, we moved quickly with spotters/radios, regrouped away from their runouts, and traveled early in the day to reduce our risk.
Quick hand pits suggest that last week’s warmup only caused meltwater to move into the top 3 to 4 inches of snow on high elevation, southeast aspects, unless water channeled deeper near rocks or other preferential drainage networks.

 

Photos: