Nice Little Refresh

CBAC2020-21 Observations

Date of Observation: 03/15/2021
Name: Evan Ross

Zone: Northwest Mountains
Location: Washington Gulch
Aspect: All
Elevation: 9,000-11,300ft

Avalanches: Had some fairly good views of lots of terrain and didn’t note any new avalanches. Still lots of old avalanches from last month waiting to get buried.

Weather: Clouds cleared a bit throughout the day. Periods of light snowfall during the day put down some nice goose feathers. Didn’t see much for drifting during periods of visibility, but also didn’t spend a lot of time in exposed terrain.

Snowpack: Touched all the aspects, but primarily traveled on northerly facing slopes below treeline where the best riding was. At 11,000ft and on shaded slopes, storm totals were currently settled to about 6″. On sunny slopes or at lower elevations storm totals were 1 to 4″ on average. So Kebler clearly got a bit more snow out of this storm. We didn’t encounter any new avalanche problems.

In the late afternoon, I spent a little time at an 11,300ft near treeline point. Here I found isolated drifts up to 10″. Hunting around for a more notable snowpack ob didn’t produce in that area. The new snow was getting thicker and/or baking in on East, South, SW at this location.

Anthracite Mesa-Coneys

CB Avalanche Center2020-21 Observations

Date of Observation: 03/15/2021
Name: Andrew Breibart

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

Avalanches: NA-poor visbilility.

Weather: Skin up: S1 snowfall with a trace of new snow accumulation. Calm. Temperatures were around freezing. Cloud cover was obstructed.
Descent: mostly cloudy and calm.

Snowpack: 1 to 3 inches of new snow in the skin tracks. Observed about 3 inches of new snow on the ridge and on the leeward side of the ridge, there were 6 inches of snow. Skied between 1st bowl and Convex corner and snow was very supportive. One ski partner observed cornice formation above first and second bowl.

Kebler Pass stuff

CBAC2020-21 Observations

Date of Observation: 03/14/2021
Name: Eric Murrow

 

Zone: Northwest Mountains
Location: Anthracites
Aspect: North, North East, East, South East, South
Elevation: 9,200′ – 11,300′

 

Avalanches: Intentionally trigged several D1 loose avalanches on south-facing near treeline slopes – ran on 4-7cm knife hard melt/freeze crust.
Remotely triggered a slab on an east aspect at 11,200′ from low-angle terrain above – never got vis below the convex roll so uncertain if it propagated further as it ran downhill.
Weather: Overcast skies, moderate northwesterly winds, generally S1 snowfall from 11am – 4pm. Hard to say how much it snowed while out as the storm snow was settling as it accumulated.
Snowpack: Midday measured around 12″ new snow w/ .9″SWE at 10,600′. Observed a midstorm density change in Shovel Tilt Tests. Stomped around on several small shaded test slopes and several steep sunny slopes with almost no cracking other than some ski length cracks in shallow drifts on leeward southerly features. While walking above a steep east-facing slope, looking for a facet/crust combination underneath the new snow, I was able to remotely trigger a convex roll below me. I was not able to get to the crown and never got a good view of the terrain below, but probing above the crown confirmed a soft, collapsible crust beneath the storm snow (similar to obs from Axtel and Snodgrass earlier in the week). I suspect due to wind, I missed the audible collapse of the crust as I skied above. The crown appeared to be slightly drifted where it failed. Snow felt noticeably thicker throughout the day as it settled.

Second-hand reports from Axtel stated 8″ new snow with some loose snow sluffing, and one small triggered slab in an open area below treeline.

 

Photos:

Orographics return

CBAC2020-21 Observations

Date of Observation: 03/14/2021
Name: Zach Kinler
Zone: Northwest Mountains
Aspect: North, North East
Elevation: 10,000-11,200

Avalanches: Triggered 2 small slabs both running within the new snow on drifted features near and below tree line. Crowns averaged 6-10″.

Weather: Overcast, S1-S2 snow showers with 2′ accumulation during the day. Cold with moderate NW winds in large open areas below tree line and all near tree line locations.

Snowpack: HST 14″ at 3:30 pm.  Measured 12″ with .8″ SWE at 10:00. Overnight snowfall was low density at around 6%. Density increased slightly through the day but remained quite enjoyable. Minor cracking was observed only in spots where winds were able to drift snow. Cracking and small slabs were breaking within the new snow in this location. Open slopes near tree line in this terrain were getting cross-loaded by moderate WNW winds throughout the day.

 

 

 

Gothic 7am weather update

CBAC2020-21 Observations

Date of Observation: 03/14/2021
Name: Billy Barr

 

Zone: Southeast Mountains
Location: Gothic Townsite

Weather: Keep moving, nothing to see here. Saturday was windy with just very light snow. Last night no wind but with only light snow so the 23 hour (lose one for DST) total is 2½” new snow with 0.21″ of water while the snowpack is at 44½” deep. Wind started back up this morning just before 6 a.m. so it is currently cloudy and windy but no snow falling. Yesterday’s high was 36F, low 15 and currently 18 while wind is 4-10 W. billy

 

Snodgrass

CBAC2020-21 Observations

Date of Observation: 03/13/2021
Name: Eric Murrow Jared Berman

 

Zone: Southeast Mountains
Location: Snodgrass north side
Aspect: North, North East, East
Elevation: 9,500 – 11,100′

 

Avalanches: no recent avalanches observed
Weather: Clear skies in the morning, with gusty southeasterly winds, gave way to cloudy skies just before noon. Wind reduced significantly once the snowfall began. Intermittent light snowfall from noon until 4 then an increase in snowfall rate of S1 to S2 from 4 to 530. Total new snow as of 530 was 1.5″ at 9,500′.
Snowpack: Targeted some north and easterly slopes looking at surfaces that the incoming storm will fall on. On east slopes below treeline a double crust with facets between was observed like in other parts of the range. This double crust setup will likely help spread failures further across a slope once loaded by incoming/current storm (see photo).
Moving onto northeast-facing slopes with depths around 130cm we tested deeper weak layers in the snowpack, 12/10 and 1/19, with ECTX results and 45/110 END, 35/100 END PST scores respectively. Near the surface on shaded slopes, about 15 – 20cm down, is a layer of 1mm facets that looks to be a likely failure plane for the incoming storm (see photo). This layer popped cleanly in shovel tilt tests with moderate force. I expect if/when avalanches occur during this loading event on shaded slopes below treeline that this is where avalanches will break first.
Lastly, we traveled through an avalanche path that ran on the basal Depth Hoar layer in February and found around 20 – 40cm of refill. Resting immediately above the slick bed surface was a layer of well-developed facets (see photo). I anticipate many shaded below treeline paths that avalanched in February will not require a significant load before failing again.

 

Photos:

Weird wind loading on 3/12

CB Avalanche Center2020-21 Observations

Date of Observation: 03/12/2021
Name: Sam Eller

 

Zone: Northwest Mountains
Location: The Playground and Ohio Pass
Aspect: North, South, South West
Elevation: 10,000

 

Avalanches: Knocked off a small wind slab that had loaded low into one of the chutes in the playground. Observed a large wet slab that appeared to be only a few days old.
Weather: Warm but strong south winds were keeping slopes from wetting extensively. Winds were blowing up the basin and loading in the north chutes from the bottom as well as other aspects.
Snowpack: Dug several handpits on the the way up north facing where there was a small facet layer 30cm down under the new March snow. South facing was wetting in the new snow but crust underneath was supportive all day. Wind affect on most aspects after midday.

 

Photos:

Who’s got the wax?

CBAC2020-21 Observations

Date of Observation: 03/12/2021
Name: Zach Kinler, Zach Guy, Jared Berman, Jack Caprio
Zone: Southeast Mountains
Aspect: North East, East, South East, South
Elevation: 8,800-12,200

Avalanches: 1 small windslab on a northeasterly alpine feature.

Weather: Mostly sunny, calm winds in sheltered terrain below treeline with moderate to strong winds on ridgleline. Generally warm temps with freezing level near 11K.

Snowpack: Thin and weak below treeline with dry snow on the northern half of the compass with moist snow and softening crusts on the southerlies. Due south at lower elevations was a thick fully supportable crust. This crust became soft and thin as you moved towards East and on a NE aspect just below 11k there was no crust present. This location had previously avalanched and was only harboring 60 cm of all weak and faceted snow. The 3/10 interface(1-1.5 mm NSF) is buried about 20cm below the surface and quite weak.

Moving up in elevation to just below 12,000 we targeted an easterly aspect focusing on the deeper weak layers from December and January. The December weak layer was Fist hard, 4 mm dry Depth Hoar with little to no rounding occurring. Long column results on this layer were ECTX with a PST 40/100 END down 100 cm indicating this layer is currently unreactive but still holding the potential to propagate a failure. Identical results were observed on the 1/19 layer(down 75 cm) at this location.

Winds were blasting and swirling snow more than building slabs, other than isolated and small pockets.

 

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March weak layer

CB Avalanche Center2020-21 Observations

Date of Observation: 03/11/2021
Name: Jack Caprio, Evan Ross, Zach Kinler
Zone: Northwest Mountains

Location: Skooks
Aspect: North, North East, East
Elevation: 9,000-11,400

Avalanches: No new avalanches observed.
Near ridge line, we initiated collapses along with radiating cracks on recently loaded NE to E facing start zones.

Weather: Broken skies for most of the day. Periods of S-1 snowfall. Light winds.

Snowpack: We went hunting for information on our recently buried March weak layer ahead of this weekends storm. Below tree line, the weak layer is buried by 4” of recent snow. On easterly facing slopes around 9.5k, the interface consisted of a soft 2” thick MF crust resting on top of 1-2 mm facets. Quick shovel shear tests at this site produced easy failure results just below the crust. As the compass tilted north-east the crust became softer and weaker. On due north slopes the interface consisted of 1-2 mm near-surface facets. As we gained elevation we continued trying shovel shear tests that produced failure both above and below the crust. We saw some cracking and got a couple collapses on leeward slopes just below ridgeline where 12″ or more of new snow had drifted over the weak new/old interface.

We also tested the 12/10 interface at a deeper, near tree line site. At this site, the 12/10 interface was buried 110 cms below the surface and consisted of 4F 2-4 mm DH. A pencil hard 110 cm slab is resting on top of this interface at this location.  A PST test resulted in unlikely propagating results (80/110 END down 110 cm). The 12/10 depth hoar was moist and seemed to be showing signs of rounding and sintering.