Our CBAC interns, Jack Caprio and Jared Berman, will be producing weekly snowpack summaries every Friday under the guidance of our forecast staff. The summaries are a great resource for tracking the evolution of the snowpack and avalanche activity over the course of the winter. You can view the summaries under the “Observations” tab here or under the “Conditions Blog” tab on our forecast page. Below is a teaser of this week’s summary.
Zone: Southeast Mountains
Location: Cement Creek Road to Reno Divide area
Date of Observation: 11/26/2020
Name: Eric Murrow
Subject: Reno Divide
Aspect: North East, East, South East, South, South West, West
Elevation: 9,000 – 12,250′
Avalanches:
none observed. Visibility was not great but viewed several north and northeast alpine features without evidence of recent activity.
Weather: Low ceiling with clouds clipping the tops of peaks in the Elks that were greater than 13k. Winds were very light while traversing a 12,000′ ridgeline. Air temps felt cold in valley bottoms, but pleasant at 12k. I could feel the cold air still sitting in valley bottom on return trip home at 330pm. Clouds increased through noon with light intermittent snowfall and slowly decreased through 4 pm. No accumulations in this area.
Snowpack: Shady terrain near valley bottoms felt weak, although grain size was small, the faceting process appears to be happening in recent days.
In Reno Divide area, at 11,000′, new snow from two days ago was around 6 or 7 inches, with snow height in shady, protected areas around 55cm, a bit shy of 2 feet. Wind redistribution from the past few days was less than expected at 12k. Closer to 13k and above looked wind effected with modest stripping of windward aspects. Traveled across a 12k ridgeline with mostly easterly terrain and struggled to find much recent Wind Slab formation, very isolated and generally soft at this elevation. Windward areas of this 12k ridge had soft snow still available for transport if the winds ramped up.
Northeast features above 11,600′ had dry 1-2mm facets at the ground like much of the CBAC forecast area. Stability tests did not inspire confidence with ECTP moderate scores, but stomping on and above small, drifty features produced no collapses or cracking.
Southerly slopes around 12k had thin, weak crusts at the surface with faceted grains below. Without any significant incoming storm on the horizon, this structure may change before it is tested by a new load.
Skied easterly terrain with about 50cm of snow that was reasonably supportive and provided nice turns.
Photos:
Zone: Northwest Mountains
Location: Purple Ridge
Date of Observation: 11/26/2020
Name:Â Evan Ross
Subject: Upper Slate
Aspect: East
Elevation: 12,000-9,600
Weather: Clouds decreased to partly cloudy during the mid-day, then started increasing to mostly cloudy again in the afternoon. Mild temps. Clam winds down low. Moderate wind at ridgeline with periods of snow saltation close to the ground. No plumes off the high peaks. Up to an inch of new snow today baby! Keeping it soft, better than nothing.
Snowpack: Traveled in this same area a couple of days ago. Not much change. The old wind-drifts at ridgeline were hard and didn’t give any signs to instability. Today’s new snow had formed some soft few inch drifts right near ridgeline.
Backcountry riders continue to step out and ride more and more terrain features. With conditions going mostly quiet I suspect we will see few observations come in.
Zone: Northwest Mountains
Location: Poverty Gulch – around easterly side of Mineral Point
Date of Observation: 11/25/2020
Name: Eric Murrow Zach Kinler
Subject: Bit of this bit of that
Aspect: North East, East, South East, South
Elevation: 9,500 – 11,650
Avalanches:
Several small (D1) wind slabs observed on east and northeast above treeline slopes. One below ridge top, others mid feature on small inset portions of the feature.
Weather: Cold temps at valley bottom gave way to warm, pleasant. conditions on sunny terrain features. Light winds near and below treeline; some blowing snow and loading above treeline on to southeasterly slopes.
Snowpack: Sunny slopes had several inches of moist snow resting on supportive crusts. The snow on warm features wetted to old crust and refroze to old surface once the sun left the terrain below treeline.
East facing slopes remain dry below and near treeline in this area. Evidence of some wind redistribution near treeline, but really no hazard from Wind Slabs in areas traveled. We were able to produce some minor cracking on the most suspect drifts, but nothing more.
Stomped around on several small drifts behind tree fences on northerly terrain and got one localized collapse on an obvious wind whale but it didn’t produce any cracks. Probing showed weak faceted snow at the ground, but outside the wind whale there just wasn’t much of a slab.
Photos:
Zone: Northwest Mountains
Location: Augusta
Date of Observation: 11/25/2020
Name: Zach Guy
Subject: Stubborn wind slabs
Aspect: East, South East, South
Elevation: to 12,500′
Avalanches:
Two small natural windslabs on easterly aspects near and above treeline that likely ran Tuesday morning. A dozen or so small loose dry avalanches on steep northerly terrain in more sheltered basins, likely similar timing. All D1s.
Weather: Clear, mild temps. Moderate ridgetop winds with light transport, a brief period of moderate transport this afternoon.
Snowpack: About 4″ to 6″ of settled storm snow, generally on a stout melt-freeze crust on the sunnier aspects that we traveled on. The snow saw a fair amount of redistribution from northwest winds at near and above treeline elevations – drifts up to 18″ thick. Wind slabs were quite stubborn today; minimal feedback from stomping on test slopes. Got one crack after undercutting a steep, wind-loaded feature and then stomping on it from above (See photo). Skied terrain up to 38* with no instabilities.
Photos:
Zone: Northwest Mountains
Location: Upper Slate
Date of Observation: 11/24/2020
Name: Eric Murrow & Evan Ross
Subject: Upper Slate
Aspect: North East, East
Elevation: 9,500-11,200
Weather: A few light snow showers with little more  accumulation, mostly cloudy sky, light winds with snow plumes at times off the high peaks.
Snowpack: Total new snow accumulations decreased the further up the Slate we traveled. In the Upper Slate, the new snow depth averaged 4 to 5″ :{ No instabilities were encountered.
On NE facing slopes below 10,500ft, the snowpack was right side up with a 5cm layer of moist facets on the ground. HS at 10,000ft was about 60cm. Climbing above 10,500, the HS increased slightly into the mid-70s. A sheltered test site at about 10,700 had an HS of 75. The main different from the lower elevation locations is that the thin layer of October facets on the ground wasn’t moist. An ECTP 24 was recorded at this site. That same snowpack structure was variable as we later probed across the slope.
On the East facing slopes traveled between 11,200 and 10,500ft, the new snow was bonded well to the crust below. That crust was supportable to skis. Small facets were observed below the crust in one location.
Zone: Southeast Mountains
Location: Coney’s
Date of Observation: 11/24/2020
Name: Zach Guy
Subject: Fluff
Aspect: East
Elevation: 9700 – 10,800′
Avalanches:
None observed: Good views of various aspects and all elevations.
Weather: Overcast clouds decreased to scattered. Light snow showers ended by mid-morning. Light winds. No snow transport observed on peaks.
Snowpack: About 6″ of incohesive new snow, evenly distributed across aspect and elevation. Some light wind affect in exposed areas from down-valley winds, where we observed some minor cracking in the new snow. The snowpack is right-side-up and showed no signs of instability.
Photos:
Zone: Northwest Mountains
Location: Upper East River
Date of Observation: 11/23/2020
Name: Zach Guy
Subject: Waiting for that snow…
Aspect: North East, East, South East
Elevation: 9,800′ to 11,700′
Avalanches:
Noted one small natural off of steep, cliffy terrain on Mt. Baldy (probably a sluff) that ran midday. We skier triggered a couple of sluffs that gathered a bit more volume than expected by gouging through a relatively weak snowpack on near treeline, shady aspects.
Weather: Broken to overcast skies. Pulses of S-1 to S2 snowfall, with about an inch of accumulation. Moderate gusts.
Snowpack: About 1″ of new snow was dense and bonded well to melt-freeze crusts on southerly aspects. On northerly aspects, we saw some shallow cracking in lightly drifted areas: early signs that the new snow could be reactive on the lower density, lightly faceted snow at the storm interface. No signs of instability today apart from sluffing mentioned above. Got into some steeper slopes with shallower coverage than previous outings and noted a weaker midpack with more pronounced faceting.
Photos:
Zone: Northwest Mountains
Location: Mt. Baldy: Quigley Creek
Date of Observation: 11/21/2020
Name: Zach Guy
Subject: Shooting cracks on Baldy
Aspect: North
Elevation: 9,600 – 11,800′
Avalanches:
Skier triggered several harmless sluffs in the new snow that ran about 400′ on shady aspects. A couple similar naturals on Baldy.
Weather: Bands of convective clouds and showers through the day. A few pulses of very light (S-1) graupel. Overcast to scattered to overcast skies. Light westerly winds, brief periods of light wind drifting off of high peaks.
Snowpack: We went hunting for persistent slab feedback on north-facing terrain near treeline. After several unexciting stability tests and a number of hand pits or surface obs that showed the structure was lacking (missing a slab or missing a weak layer), we had all but given up on finding any good feedback. As we were exiting a steep cut bank above a creek at 10,800′, we got three collapses and shooting cracks up to 75′, failing on the Nov 6 facet layer (2 mm, fist hard). The slopes were easily steep enough to slide, but held in place, perhaps from ground roughness?
No other signs of instability through the day apart from shallow sluffing. 3″ to 5″ of new snow. The snow moistened on southerly aspects, where the storm interface is a 1F melt-freeze crust. At lower elevations, shady aspects, the snowpack is about a foot deep: .5mm moist, rounding facets (F+ to 4F-). Gaining elevation, the snowpack transitions to dry, 4F and more rounded, along with a significant amount of previous wind scouring at upper elevations. See photos and profile.
Photos:
Zone: Southeast Mountains
Location: Gothic
Date of Observation: 11/21/2020
Name: billy barr
Subject: Gothic 7 a.m.
Aspect:
Elevation:
Avalanches:
Weather:
Snowpack: Cloudy with snow starting after 1 a.m. holding generally light through the dark hours with 3″ new and water a dense 0.29″. No wind and snowpack is at 8″ deep. Currently light to moderate snow, obscured cloud cover, calm and temperature range after midnight 33F to the current 28F. billy
