Kebler Pass corridor

CBAC 2020-21 Observations

Date of Observation: 03/05/2021
Name: Eric Murrow

 

Zone: Northwest Mountains
Location: Snowmobile journey to Beckwith Pass and up into Evan’s Basin on Mount Emmons.
Aspect: East, South East, South, South West, West
Elevation: 8,900′ – 11,200′

 

Avalanches: Observed loose snow avalanches on sunny slopes near and above treeline, generally coming from warm, rocky terrain features. Up to D1.5 in size. Overall significantly less activity than I expected to find. See photos for examples. Observed one natural run on alpine SE slope at 1:30 pm.
Weather: Clear skies, light winds, and warm temperatures above freezing.
Snowpack: Around 7″ storm snow on top of Kebler Pass and Beckwith Pass.  5″ on lower flanks of Mount Emmons.

I targeted a shaded slope in a shallower snowpack area on the far west end of the forecast area near Horse Ranch Park. I found HS 120cm with dense slab around 75cm thick sitting on old snow from early in season – ECTP 28 x2 result failing in oldest weak snow near ground. 1/19 interface shows clear sign of rounding and no result here. Oldest snow at ground was 3-4mm Depth Hoar – it is starting to round and sinter with around 4finger hardness. Late February weak layer is down 20cm, .5 -1mm facets with ECTN 11 and easy Shovel Tilt Test results.

In the afternoon traveled on southerly-facing slopes checking in on where liquid water was in the snowpack. On several slopes found moist snow from the surface to the ground. Ice columns from percolating meltwater was found nearly all the way to the ground – with around 20cm of moist, 4finger hard snow at the ground without ice columns. Tests produced no result on these slopes even while hammering on the column until my hand hurt. See photo of ice columns.

 

Photos:

So Good While It Lasted

CBAC 2020-21 Observations

Date of Observation: 03/05/2021
Name: Evan Ross

Zone: Northwest Mountains
Location: P-Divide
Elevation: 9,000-11,800ft

Avalanches: Wet loose avalanches happened, but no widespread and all on the small size. Some east, some south, some west, they all had a little action.

Weather: Calm winds, warm temps, clear sky, beautiful.

Snowpack: Well, that snow sure was good while it lasted! Lots of now crusty snow surfaces heading into tomorrow, until they warm back up again… The recent snow seemed to just bake in, more than release as wet loose avalanches. Hard saying just how reactive it will be on the next warm-up after today. We slammed a whole lot of terrain features, many in the upper 30 degrees, and didn’t find any signs of instability regarding PSa. Still considering regrouping areas for the low likelihood avalanche problem. If anything, upper elevations looked like the best chance to find a thick snowpack transitioning to a thin snowpack due to previous winds.

We descended a SW aspect between 11,000-10,00ft at 3:30pm with slope angles in the upper 30 degrees. The new snow on that slope felt more baked in and we didn’t see any movement.

Elk Crest obs

CBAC 2020-21 Observations

Date of Observation: 03/01/2021 to 3/05/2021
Name: Zach Guy

 

Zone: Southeast Mountains
Location: Elk Crest near Friends, Lindley, and Opa Huts.
Aspect: Various
Elevation: 10,000 – 13,200

 

Avalanches:

-2 small wind slabs ran naturally on Thursday near Taylor Pass
-2 large wet slabs ran naturally, likely on Wednesday, on a SE bowl of Leahy Peak (on the Aspen side of the divide). They failed near the ground, probably triggered by water draining into basal weak layers near rock outcrops. The debris looked fairly wet, I suspect the slabs were a mix of dry midpack, wet on the surface.
-1 recent persistent slab on Carbonate Hill, triggered by a cornice fall, likely during the warmup on Tuesday or Wednesday
-1 small loose wet ran near Star Peak on Tuesday.
-Dozens of previously undocumented large persistent slabs (up to D2.5) that ran mid-February or from subsequent wind events at all elevations and aspects.
Weather: Warm and sunny most of the week. Thursday brought 3″ of snow and gusty northwest winds. Back to warm and sunny on Friday.
Snowpack: Spent the last five days on a hut traverse in the upper Brush, Cement, Castle, and Tayler drainages. No signs of persistent slab instabilities underfoot, such as collapsing. Winds during the later half of February have heavily redistributed the snowpack above treeline; quite a bit of scouring, even on some leeward aspects, while some areas have a hard, thick snowpack with basal weak layers down 150 to 200 cm. In shallow areas at higher elevations and on most below treeline slopes, slabs have generally faceted away.
Snow surfaces are mix of sastrugi/windboard ATL, facets on shady BTL aspects, and melt-freeze crusts up to a few inches thick on the southern 2/3 of the compass. All of this was buried by about 3″ of snow on Thursday. We also noted small-grained surface hoar that formed last night at all elevations.

 

Photos:

Hot as Tomales

CB Avalanche Center 2020-21 Observations

Date of Observation: 03/05/2021
Name: Jared Berman, Zach Kinler
Zone: Northwest Mountains
Location: Anthracites
Aspect: North, North East, South East, South
Elevation: 10,000′- 11,500′

 

Avalanches: From a distance, we could see several small loose wet avalanches initiating below rock bands on steep east and southeast facing terrain in Elk Basin and Evans Basin near treeline.

In the Anthracites, one D1.5 natural loose wet was observed below treeline on a southeast slope while another was intentionally triggered on a south facing slope. Both ran into the basin locally known as the Playground (see photos below).
Weather: Clear skies, calm winds, and above freezing temperatures.
Snowpack: Drastically variable snowpack depending on aspect below treeline and near today.

On north and northeast facing slopes, probing revealed the average snowpack depth being 150cm deep with some areas as deep as 200cm. We measured 8″ of new snow on these slopes with 0.75″ of snow water equivalent. We did observe faceted grains at the old/new interfaced as well as small faceted grains at the snow surface.

On south and southeast facing slopes below treeline, the snowpack averaged 90cm deep. A hasty pit revealed moist snow all the way down to the ground with obvious signs of free water(vertical and horizontal ice columns)  through the upper half of the snowpack.

 

Photos:

Matching obs to forecast problem 1 today.

CB Avalanche Center 2020-21 Observations

Date of Observation: 03/05/2021
Name: Andrew Breibart

 

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

 

Avalanches: photo 1. wet loose avalanches the NW zone observed on Schuylkill ridgelines. SE aspect ATL and BTL.
photo 2. natural D1 slab (persistent slab (?) avalanche below rock band entrance to Wolverine Bowl). NE aspect at NTL.-maybe captured in earlier obs.

no photo: on drive into town, I observed a D1 slab on E/SE aspect in Red Coon Bowl BTL.-maybe captured in earlier obs.
Weather: in the open, it was a sauna with high UV’s from the high albedo. calm. few clouds
heat relief relief in the trees.
Snowpack: 2 to 4 inches of recent snowfall.
on lee side of the ridge, boot pen was 14 inches and ski pen was 4 inches.
skiing was fun but there is a melt freeze crust on the open east aspects at BTL.

 

Photos:

Nice Little Refresh

CB Avalanche Center 2020-21 Observations

Date of Observation: 03/04/2021
Name: Evan Ross

Zone: Northwest Mountains
Location: Washington Gulch
Aspect: East, South East, South, South West, West
Elevation: 9,400-11,400

Weather: Good Pulse of snow in the morning, then waited most of the day for things to pick back up. Headed out in the late afternoon. Periods of heavy snowfall. Mostly calm winds with some strong gusts.

Snowpack: A couple of inches of new snow near the Washington Gulch Trailhead, and about 5 inches of new snow near the head of Washington Gulch. In the alpine there may have been a little drifting and some slab formation, otherwise where I traveled the new snow didn’t make any change. Small sluffs on steep northerly-facing slopes would be about it. I didn’t find enough snow to sluff on the crusty southerly-facing slopes.

The recently buried crust on southerly-facing slopes was a couple of inches thick. Boot pen mostly punched through the crust to about 30cm. Interestingly, most of those crusts also had percolation columns extending into moist or even dry snow below.

Sunny slopes are setting up nicely for a loose wet avalanche cycle when the sun comes out, otherwise, the new snow is mostly adding to sluffing volume on northerly-facing slopes.

Fresh Cornice Fall

CBAC 2020-21 Observations

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

Zone: Southeast Mountains

Avalanches: (Info from an InReach Text)

2 fresh looking wet slabs SE ATL off Leahy Peak. (Aspen side). Hot rocky bowl. Probably today or yesterday. D2 to D2.5.

Robbins saw a recent PSa triggered by cornice fall on Carbonate.

Several Loose Wet Avalanches

CBAC 2020-21 Observations

Date of Observation: 03/03/2021
Name: Evan Ross Zach Kinler

Zone: Northwest Mountains
Location: Angle Pass
Aspect: North East, East, South East, South
Elevation: 9,700-12,000

Avalanches: Several loose wet avalanches. A few old ones and some that ran today. Not widespread and mostly D1 in size with a couple D1.5s. SE, S, SW aspects had the majority of the activity.

Weather: A light breeze at 12,000ft, otherwise no winds. Hot… my face hurts.

Snowpack: We didn’t end up having to manage any wet avalanche concerns. Between 10am and 12:30pm we traveled on south and southeast slopes up to 11,800. The upper 3 to 5cm of the snowpack was wet, while the snow below remained dry. By the time we traveled back through similar terrain the surfaces were starting to crust due to lower sun angles and/or shading.

We mostly traveled on E and NE facing slopes in the afternoon. Some east facing slopes had a crust on them in the afternoon, but were mainly traveling through soft cold snow. Where that snow was soft and cold the upper snowpack was weak NSF, or firmer wind effected snow surfaces.

The snowpack we traveled on was otherwise deep and we didn’t encounter much of a concern on the persistent slab avalanche front.

Gothic Wet Slide

CB Avalanche Center 2020-21 Observations

Date of Observation: 03/03/2021

Zone: Southeast Mountains
Location: South face of Gothic Mtn.
Aspect: South
Elevation: 12,000-11,000

Avalanches: Skier triggered shallow, slow moving, long running wet slide running on a hard crust 12 inches deep.

Weather: Sunny with little to no wind. Temps reaching upper 30’sF.