Observations

Date of Observation: 03/03/2021
Name: Jack Caprio
Zone: Northwest Mountains
Location: Beckwith Pass
Aspect: North, North East, East, South East, South
Elevation: 10k-11k

Avalanches: Older D.5-D1 loose wet avalanches on E and SE aspects which likely ran over last couple days. We did not stick around long enough to see any new activity.
Weather: Bluebird and very warm.
Snowpack: Steep, east facing snow surfaces were noticeably moist at 10,200k at 9:00 am. Around 10 am on south facing slopes at 11k, the surface crusts just barely still supported the weight of a skier, and we’re beginning to soften up quickly. We ended up skiing NE facing slopes which stayed dry.

 

Photos:

Date of Observation: 03/02/2021
Name: Alan Bernholtz

Zone: Northwest Mountains
Location: Coneys nose
Aspect: North East
Elevation: 10,800

Avalanches: Small loose snow sluff avalanche right off the top. 15 cm deep on 33 degree slope. 40’ wide by 80 feet long.
Weather: Clear with a light westerly breeze. Temp was in the 20’s
Snowpack: 70-80 cm total height of snowpack. Fist on top with a density change in the mid pack to fist+ then large grain facets at the bottom. The surface facets slid on the density change. Fairly predictable.

Photos:

Date of Observation: 02/27/2021
Name: Jared Berman, Zach Guy Jack Caprio

 

Zone: Northwest Mountains
Location: East Bowl of Schuylkill Mountain
Aspect: North East, East
Elevation: 9,300′ – 11,100′

 

Avalanches: We intentionally triggered 3 small (D1) wind slabs on skis. Slabs ranged from 3″-6″ deep and were relatively harmless to a person. No recent naturals were observed today.
Weather: Weather started off overcast with light winds from the west below treeline. As we traveled clouds broke apart enough to see surrounding terrain and mountains. Moderate winds existed near treeline and we observed active wind transportation from some ridgetops and trees.
Snowpack: Persistent slab structure still exists on northeast aspects below treeline, capable of propagating deep failures. A snowpit at 9800′ on a northeast aspect revealed a 140cm hard slab (1 finger to pencil in hardness) resting on top of weak 2-3mm depth hoar at the ground (12/10 interface). The bottom of the slab contains rounding facets (1/19 interface) that appear to be gaining strength and were not as reactive as the 12/10 interface when comparing two propagation saw tests. See photo below of the snow profile with propagation saw test results.

Surface instabilities was a whole ‘nother ball game. Shallow wind slabs existed on isolated features near treeline and were reactive under skis. Slabs were small though ranging from 3″-6″ deep. We did not observe wind slab size or distribution above treeline as we did not travel at that elevation.

Photos:

Date: 02/26/2021

Author: Jared Berman, Zach Guy

Zone: Crested Butte Backcountry

 

Strong winds this week have created thick, dense slabs in the upper elevations. Read all about it plus more in this week’s summary.

 

Date of Observation: 02/26/2021
Name: Jack Caprio, Zach Kinler, Jared Berman

Zone: Northwest Mountains
Location: From Top of the World, we descended rock creek drainage to gothic campground
Aspect: North, North East, East, South East, South
Elevation: 9,600-11,600

Avalanches: Fresh wind slabs on a cross loaded alpine south aspect above Rustler Gulch (see photo).

An older, persistent slab avalanche on an east facing slope about 200 ft. above the east river valley bottom (see photo).

Weather: Westerly winds and overcast skies made for a cold sled ride in the morning. As the day went on, the clouds cleared and temps increased making for a very comfortable weather day.

Snowpack: We dug below treeline on a NE facing slope a couple hundred feet above the Gothic campground. We found a very stubborn persistent slab problem. At this pit site, the January interface sits 75 cm below the surface, with a large 1F hard slab resting on top. The 12/10 layer, which consists of large grained (6 mm chained) depth hoar, makes up the bottom 35 cms of the pack, and doesn’t seem to be showing any signs of improving. Snowpit tests did not produce any failures even after a couple aggressive swings from the shoulder after proper ECT tests (CTN, ECTX, ECTX). An aggressive shovel shear after our ECT tests did produce failure at the top of the 12/10 depth hoar layer. We did not receive any feedback from the snowpack such as cracking and collapsing while traveling in previously untraveled terrain.

The snow surface continues the near surface faceting process on shady aspects (currently .3-.5 mm NSF). On solar aspects, the surface consists of a 1-2 inch thick MF crust capping small grained facets. Everywhere we traveled above treeline (NE, E aspects), the snow surfaces were very beaten up due to recent winds, and hold perfect faceplanting conditions.

 

Photos:

Date of Observation: 02/25/2021
Name: Jack Caprio

Zone: Northwest Mountains

Location: Anthracites
Aspect: North, North East, East
Elevation: 10k-11.5k

Avalanches: 1 D2 slab avalanche on a S facing slope in ‘the playground’ which I believe released due to a cornice chunk falling.
A couple small, wet loose avalanches on sunny slopes near rock bands that likely ran over the past couple days of warm weather.
Weather: Calm day. Sunny. Comfy temps
Snowpack: We mostly traveled on established skin tracks below tree line on N and NE aspects. HS ranged from 160-200 cms. Where I dug, the first concerning weak layer was >120cms below the surface. Snow pit tests produced no results at this site. No collapsing/ cracking all day.

Recent N winds produced noticeable scouring of surface snow in N facing exposed areas, and large cornice building/ loading on S facing start zones. In protected areas, small near surface facets continue to develop.

 

Photos:

Date of Observation: 02/25/2021
Name: Zach Guy

Zone: Northwest Mountains
Location: West side of Ruby Range
Aspect: East, South East, South West, West, North West
Elevation: 9,700 – 11,700′

Avalanches: Nothing recent apart from a handful of very small wet loose sluffs. Plenty of previously undocumented large avalanches from the last widespread cycle (~February 13) at all elevations. We crossed a debris pile that was easily D3+ off of the southwest face of Ruby that only had about 6″ of snow on it, so I’m guessing it ran February 16. See photos.
Weather: Light westerly winds, no transport. Few clouds.
Snowpack: Targeted below treeline test pits hoping to see evidence that basal weak layers are gaining strength now that they have been buried by a deeper pack for a few weeks. Unfortunately, that doesn’t seem to be the case. The 12/10 layer is still large grained and angular, showing little signs of hardening or sintering. All test results propagated with sudden collapses, ranging from very easy to hard (ECTPV, ECTPMx2, ECTPH), 70 to 90 cm deep on depth hoar or large-grained facets on a crust. If there is anything improving the current structure, it is that the upper slab is faceting on shady aspects and meltwater is moving into the pack on sunny aspects, which should add some integrity when it re-freezes. I jumped on a few small, steep test slopes with no feedback, and we didn’t see any obvious signs of instability throughout the tour underfoot.

 

Photos:

Date of Observation: 02/25/2021
Name: Wallace Cleaver

 

Zone: Northwest Mountains
Location: Slate
Aspect: North East
Elevation: ATL-BTL

 

Avalanches: Couple of wet slides that pulled out as point releases from below rocks on east tilt below treeline just above valley floor. Then all of the other ones documented in the area from a couple of days before. Of note, looked at the one in the palace and the avalanche had roared through some pretty dense trees causing some pause as to what true islands of safety really are.
Weather: Good, if you’re into sunny and warm. I prefer cloudy, snowy and cold though. Nuclear (or nucular as Dubyah used to say) in the valley floor.
Snowpack: NE aspect most of the way along the ridge had a serious windboard complete with that spooky hollow sound. Further down the ridge snow surface softened.
Below treeline soft with a couple clips of windcrust and easterlies had suncrurst. A lot of snow pulled out in the avalanches in the palace area, back to hitting some rocks toward the bottom, you know like back in December…

 

Date of Observation: 02/24/2021
Name: Zach Guy

 

Zone: Northwest Mountains
Location: Irwin Tenure
Aspect: South West
Elevation: NTL

 

Avalanches: Explosive triggered another large hard slab failing near the ground on a southwest aspect near treeline. The crown was 2 to 4 feet thick, failing on basal facets. HS-AB-R3-D2.5-O/G.
Also a noted a handful of smaller slabs in the Ruby Range that likely ran a few days ago during the wind loading event. They were relatively shallow slabs that broke in very steep, rocky terrain on easterly aspects above treeline (D1.5), likely on old layers as well.

 

Photos:

Date of Observation: 02/22/2021
Name: Irwin Guides

 

Zone: Northwest Mountains
Location: Irwin Upper Upper Westwall
Aspect: West
Elevation: NTL

Avalanches: Two large explosive triggered persistent slabs

Lone Wolf HS-AE-R3-D2-O (80cm x 35m x 375m) Pencil hard slab
Castle Valley Right SS-AE-R2-D2-O (90cm x 35m x 360m) Failed on 3-5mm DH
Castle Valley Left SS-AB-R1-D1-I (15cm x 20m x 200m) Shallow surface snow

Photos: