Date of Observation: 03/02/2021
Zone: Southeast Mountains
Location: 3rd Bowl
Aspect: North East
Elevation: 10,800
Avalanches: Triggered a couple small sloughs and a small slab approximately 15 ft wide 8” deep crown in the more northerly trees knocking over a skier.
Weather: Pretty rapid warming through the morning
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: 03/01/2021
Name: Eric Murrow
Zone: Southeast Mountains
Location:
Aspect: North East, East, South East, South
Elevation: 9,400′ – 10,600′
Avalanches: nothing new observed
Weather: Clear skies, moderate temperatures, and light winds.
Snowpack: Traveled through an area that has a snowpack depth near the median for the Crested Butte area – not as deep as areas further west/north and not as shallow as terrain further east. Snow surfaces on the south half of the compass became moist by early afternoon, but no wet snow concerns developed in this area. Melt/freeze crusts 4 to 6cm thick on sunny features, but still slightly soft not fully supporting skis without breaking. Ice columns from warm period at the end of last week pushed up to 8 inches below the surface – liquid water will need to move about an additional 30cm down, or more, to reach weak interfaces. Dug a test profile on an east aspect testing Persistent Slab problem and did not get results in ECT, but PST results continue to fail well before 50% of cut length. The persistent Slab problem appears very stubborn on this below treeline terrain.
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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 of Observation: 02/26/2021
Zone: Southeast Mountains
Location: Cement Drainage
Aspect: North East, East, South East, South, South West
Elevation: 10,300′-12,100′
Avalanches: Everywhere in sight, especially E facing terrain. D1-D2+ on virtually any alpine feature which took on drifting recently, along with some unusual NTL/BTL features which normally wouldn’t be suspect. Most of the recent avalanches we observed today have already been reported, but not all of them. Basically, if you looked below a cornice on a leeward aspect, it went big. Sorry, no pictures.
Weather: Windy. Steady and swirling winds, mainly out of the W/SW at 10-20 mph all day. Probably was gusting to 30+ at higher elevations based on the flagging we observed off many of the surrounding peaks. Air temp wasn’t as cold as we expected this morning. My car read 18F at TH at around 9am. Apart from the consistent and gusty strong winds, air temp seemed pretty mild for the majority of the day.
Snowpack: Mainly traveled on W/NW BTL and NTL, but also had a quick transition on a southerly aspect NTL. Snowpack depth was relatively uniform. Pole probes went to ground at 110cm-130cm. On the ridgeline, where the wind has stripped the majority of the season’s snowpack, depth was around 30cm. Snow was supportive on all aspects we traveled, with a ski pen of around 3-6.” Once we stepped off our equipment though, boot pen went to ground with full weight. For the most part, the skiing was surfy and supportive. However, variable crusts exist on the sunny aspects and wind-affected terrain, of course.
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: 02/26/2021
Name: Zach Guy
Zone: Southeast Mountains
Location: Snodgrass
Aspect: North East, South East
Elevation: 9500 – 11,000′
Avalanches: Shallow facet sluffing in steep terrain
Weather: Moderate winds, minimal snow transport. Cool temps. Few clouds.
Snowpack: Quick look at snow surfaces below treeline ahead of the next storm. Melt-freeze crusts start on east aspects (1 to 2 cm thick) and get thicker wrapping to due south (at least 8 cm thick). There were small grained facets below the crust, but not above. Northerly tilts have widespread small-grained near-surface facets, and some protected areas have small surface hoar growth.
One pit produced propagating results on all of the prominent weak layers in the lower half of the snowpack, but only after additional loading steps (about 35 hits). The 1/19 facets were down 80 cm and the 12/10 depth hoar down 110 cm, with a 1F midpack.
We rode several steep pitches where the snowpack is wind protected and uniform with no signs of instability.
Photos:
Date of Observation: 02/26/2021
Name: Andrew Breibart
Zone: Southeast Mountains
Location: Red Lady Glades and CB Nordic Trail
Elevation: BTL
Weather: Keystone snow course/Red Lady Glades: obstructed skies and strong winds. colder temperatures before 9AM
Crested Butte snow course/CB Nordic Magic Meadows yurt: few clouds and light winds with moderate gusts and warming temperatures between 10 AM and 12PM.
Snowpack: Keystone snow course: 2.54 cm (1 inch) melt-freeze crust on the surface. Snow depth ranged between 68 and 112 cm (27 and 44 inches) across 41 meter (135 foot) transect with 5 samples.
Crested Butte snow course: depth ranged between 86 and 107 cm (34 and 42 inches) across N to S transect of 122 meters (400 feet) and W to E transect of 74 meters (244 feet). melt freeze crust 61 cm (24 inches) below surface (1/19 or 2/5 interface?).
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.
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