Sprang break

CBAC2020-21 Observations

Date of Observation: 03/28/2021
Name: Zach Guy

Zone: Northwest Mountains
Location: Ruby Range
Aspect: North, North East
Elevation: 9,000 – 12,100′

Avalanches: 2 recent cornice falls. One on Garfield Peak plowed to the ground in a steep, rocky feature (D1.5), one on Owen triggered several layers of slab avalanches and ran impressively far (D2).
Dozens of small wet loose avalanches from yesterday, generally D1. Wet activity continued today.
Weather: Light winds this morning, some moderate gusts midday. Clear skies and warm temperatures.
Snowpack: Wet loose activity: below treeline east and a few northeast aspects were active today, south aspects are transitioning to stable corn snow. Near and above treeline, activity continued on east, southeast, and south aspects. We finished the tour before westerly aspects warmed up.
We rode steep north and northeast facing terrain with no signs of instability, these slopes were either scoured or protected from yesterday’s northerly winds. There was a northwest facing slope that we avoided after probing revealed a poor structure (~2′ -3′ slab over weak facets). Based on debris evidence, it looked like this slope had avalanched earlier in the year.

 

Photos:

Here comes the sun

CBAC2020-21 Observations

Date of Observation: 03/27/2021
Name: Jack Caprio Zach Guy

Zone: Northwest Mountains
Location: Kebler Pass
Aspect: North, North East, East, West, North West
Elevation: 9,400-12,500

Avalanches: 1 intentionally ski-triggered wind slab avalanche on heavily loaded east-facing test slope above treeline. The crown ranged from 6-24 inches. The larger part of the crown (2 ft) was the trigger point. This was the most windloaded area on the slope. The crown pulled back about a foot above the skier but the skier was able to easily ski out of it because the slope was small.  A couple of other small slabs in the area that released in the past 12 hours or so from wind effect.

15-20 small loose wet avalanches on sunny near and above treeline terrain. The near treeline elevation band had a more widespread avalanche cycle due to continued winds and cloud cover above treeline helping keep surfaces cooler and denser.
Weather: Few to scattered skies throughout the morning. Clouds cleared around 3pm as the solar intensity increased. Moderate northwest winds with strong gusts.
Snowpack: Recent storm snow consisted of about 10-12 inches earlier in the day. This new storm snow rapidly settled to about 8 inches on E and W aspects as the snow moistened.  Numerous rollerballs and pinwheels observed.  The snow stayed dry on steep north aspects.

Above treeline, NW and W winds continued to deposit snow onto leeward ridgelines. In the alpine, we chose to stick to terrain that had not previously avalanched during the February cycles. Very small wind slab pockets were our only signs of instability on alpine N-facing terrain.

 

Photos:

 

Avalanches in Ruby Range

CBAC2020-21 Observations

Date of Observation: 03/27/2021
Name: Evan Ross and Zach Guy

Zone: Northwest Mountains
Location: Ruby Range

Avalanches: See photos and captions. A handful of slab avalanches, D1 to D2 that ran in the last day or two. These appeared to generally involve just the new and windblown snow from the past few days, or wet sluffs today. One on the NE face of OBJ was thick enough it might have broken into older layers, although it was too far away to say anything with confidence.

Photos:

Natural persistent slab and wind slab

CBAC2020-21 Observations

Date of Observation: 03/27/2021
Name: Ian Havlick and Evan Ross

Zone: Southeast Mountains
Location: Whetstone and near Copper Lake
Aspect: East, South
Elevation: ATL

Avalanches: See photos
Fresh avalanche (appears to be a persistent slab) on an east aspect ATL of Mt. Whetstone, D2 in size.
Smaller wind slab avalanche on a south aspect above Copper Lake, D1.5 in size

Photos:

Propagating results

CBAC2020-21 Observations

Date of Observation: 03/26/2021
Name: Zach Guy and Jack Caprio

Zone: Southeast Mountains
Location: Mt. Emmons
Aspect: North East, East
Elevation: 9,000 to 11,500′

Avalanches: One small wind slab likely ran naturally yesterday in Coon Basin (SE aspect, ATL).
Skier triggered a handful of shallow sluffs on steep, northerly terrain, about 6″ deep or less.
Weather: Afternoon tour brought overcast to broken skies. Brief convective pulses of moderate snowfall (S2) with an inch or so of accumulation, generally light winds with a few stronger gusts associated with the snow squalls.
Snowpack: Looking for feedback for persistent slabs in the type of terrain we’ve been warning about: shallow/previously avalanched, previously windloaded. Slabs are getting a little thicker now and we didn’t feel comfortable ski cutting or really getting onto suspect slopes to get a feel for how reactive they are. A few strategically placed pits along flanks or smaller terrain features produced a mix of propagating and non-propagating results on fist hard facet layers (1.5-2.0mm) on old bedsurfaces, generally 45 to 65 cm deep. The most concerning structures and a propagating result were on slopes where previous wind drifting created denser, harder layers above these buried facets, making for a more dramatic hardness change at the weak interface. Wind sheltered terrain held a softer slab and a less-distinct transition to these facets, with non-propagating results. Previous wind drifting and scarier structures were not apparent on the surface, but evident with probing or an understanding of local wind patterns. We avoided those types of slopes.

 

Photos:

Mt Emmons

CBAC2020-21 Observations

Date of Observation: 03/26/2021
Name: Evan Ross

Zone: Southeast Mountains
Aspect: East, South East, South
Elevation: 9,300-12,300

Weather: Calm to light winds with a few stronger gusts transporting snow. Mostly cloudy sky with convective cells moving through and creating quick bursts of snowfall. Maybe an inch or two of new snow accumulation today, but it was settling quickly.

Snowpack: Potential wind slabs were small and from what I observed were really confined to right near the ridgeline or cross-loaded terrain features. Otherwise, the cream was getting thicker with periods of sun between the clouds. Similar to yesterday’s ob in Washington Gulch, there was about 4″ of recent snow accumulation down low and around 8 to 10″ up higher. No avalanche problems were observed outside of the potential wind-loaded terrain features. One snowpit at 11,300ft on a 33 degree south facing slope had about 8″ of new snow on top of a very stout crust with a matrix of other stout crusts and percolation columns below.

Anthracite Mesa-Coneys

CB Avalanche Center2020-21 Observations

Date of Observation: 03/27/2021
Name: Andrew Breibart

Zone: Southeast Mountains
Location: Washington Gulch-Coneys
Aspect: North East, East
Elevation: BTL

Avalanches: NA-poor visibility
Weather: Obscured skies with S1 and S2 snowfall. Calm. On the skin out, obstructed skies, calm and intermittent S-1 snowfall.
Snowpack: Supportive snowpack valley bottom to the ridge. 48-hour snow: 3 to 6 inches with 8 inches on the leeward side of the ridge line. New snow seems to be bonding to the last melt freeze crust. Triggered shallow storm sluff at the convex entrance to first bowl.

 

Gothic 7am Weather Update

CBAC2020-21 Observations

Date of Observation: 03/26/2021
Name: billy barr

Zone: Southeast Mountains

Weather: Very light, scattered dense snow Thursday, then light snow after midnight so the 24 hour total is 4″ new and 0.24″ of water. Snowpack is at 49½”, the deepest since mid February. Calm yesterday and so far today. High yesterday 33F, low today 18, current 19. Overcast with a very light snow.

Cream surfing good

CBAC2020-21 Observations

Date of Observation: 03/25/2021
Name: Evan Ross

Zone: Southeast Mountains
Location: Coneys
Aspect: North East, East
Elevation: 9,000-11,000

Weather: Mostly Cloudy. Several nice burst of snow interspersed with sun and greenhouse conditions. Calm winds.

Snowpack: About 4″ of new snow down in the valley and about 8″ near the top of Coneys. New snow was well bonded to the supportable crust below. Hand pits wouldn’t pop anything above the crust and no signs to instability. Same results at ridgeline. Old tracks form yesterday were still visible off the highest point of Coneys. The new snow was definitely feeling the heat, but man the cream sure is surfing good.