A few signs of instability

CBAC January 24, 20212020-21 Observations

Date of Observation: 01/24/2021
Name: Zach Guy

Zone: Northwest Mountains
Location: Slate River drainage
Aspect: North East, East
Elevation: 9,000 to 11,300′

Avalanches: We got a window of mediocre visibility of Peeler Peak and Scarp Ridge and didn’t see any noteworthy avalanches. Saw a pair of D1 storm snow avalanches on Schuylkill Ridge that ran yesterday; one was skier triggered, the other natural.
Weather: Very light snowfall (S-1) and calm winds all morning. Around 2 p.m., southwest winds increased to moderate and we observed a half-hour of heavy snowfall rates (S5). About an inch or two of accumulation all day.
Snowpack: 10″ to 12″ of settled storm snow over the well-described 1/19 interface. We observed a couple of collapses and got shooting cracks on three different slopes. Not a clear pattern to these: some were valley bottom, some mid track, and some near ridgetop. All of the signs of instability were on flat or shaded aspects where the 1/19 interface is weak, faceted snow (as opposed to a fair amount of windboard that also exists on the same aspects, or sun crusts on southerlies).
We tested a number of steep slopes with ski cuts and cornice drops with no avalanche results.

Photos:

: Shooting cracks and a collapse near ridgetop. East aspect NTL

: Shooting cracks on a flat slope near valley bottom

Thor Himself,

CB Avalanche Center January 24, 20212020-21 Observations

Date of Observation: 01/24/2021
Name: Emilio Alcala

Zone: Southeast Mountains
Location: Reno Divide
Aspect: East, West
Elevation: 11,200

Avalanches: Collapsing and Whumpfing, everywhere, loud as Thor. No visible avalanches.
Weather: Overcast with occasional sun pockets, light west wind, moderate snowfall.
Snowpack: Wind stripped @ ridge.
West aspect-
30-60cm below ridge. Firm sun crust and wind board.
East aspect-
60-105cm below ridge. Firm windslab on top of sun crust supportive to snow machine.
Sheltered on ridge-
105cm, 10cm storm snow (see photo)

Photos:

Cement Creek Snow

CB Avalanche Center January 24, 20212020-21 Observations

Date of Observation: 01/24/2021
Name: Cosmo Langsfeld

Zone: Southeast Mountains
Location: Cement Creek Ranch
Aspect:
Elevation: 9250’

Avalanches:
Weather: Storm total as of Sunday morning is 2”. That includes 1.5” reported yesterday morning.
Snowpack:

Gothic 7am Weather Update

CBAC January 24, 20212020-21 Observations

Date of Observation: 01/24/2021
Name: billy barr

Zone: Southeast Mountains

Weather: Only light snow after sunset until early in the morning but decent snow Saturday afternoon so the 24 hour total is 3½” new with 0.27″ of water. Snowpack reached 37″ deep but now sits at 35″. Currently cloudy with no wind. Temperature range was from a high 0f 32F to a low of -2F but it has jumped to 10F by sunrise. The recent snow has propelled this winter to 31st of the last 47 winters in snowpack, but that was just the climb from the past few days as snowfall to date has dropped to 45th of the last 47 winters.

Staunch Wall

CB Avalanche Center January 23, 20212020-21 Observations

Date of Observation: 01/23/2021

Zone: Northwest Mountains
Aspect: North, North East, South East, South
Elevation: 10500+

Avalanches: Natural soft slab R2 D1.5 on Cascade south. Looked to start in chute above tree line and run past summer road.

Weather: Gusty west wind and short lived inch an hour rate snow pulses in the morning. Small clearing from noon until 3 followed by light wind and snow.

Snowpack: Generally 40cm new snow on dry spell layer.

Persistent slab avalanche on Red Lady

CB Avalanche Center January 23, 20212020-21 Observations

Date of Observation: 01/23/2021

Zone: Northwest Mountains
Location: Red Lady skin track
Aspect: East, South East, South
Elevation: 11,300

Avalanches: Intentionaly skier triggered this persistent slab R1.5 above some pretty steep and suspect terrain that no one really skies but is right off the skin track. Quite a stubborn release, but failed at or near the ground. Crown was approx 50 ft wide and well over a meter in places.
There were also three visible R1 storm slabs in the bowl. And one a bit below the aforementioned intentional trigger.

-KH
Weather: Wind gusts above TL easily pushing 45+mph.
Snowpack: Storm snow seemed to average about 30cm but some drifts up to 50cm near TL.

Photos:

Welcome Back Winter

CBAC January 23, 20212020-21 Observations

Date of Observation: 01/23/2021
Name: Evan Ross

Zone: Northwest Mountains
Location: Upper Slate River
Aspect: North East, East
Elevation: 9,600-10,600

Avalanches: Didn’t observe any avalanche activity in the Upper Slate River. Couple nice periods of light, but otherwise flat light and hard to see. Getting back to town there were a few funny looking things in Red Lady Bowl. At least one small slab low in the bowl and a couple of others potentially on the looker’s left ridge. SE to E. Real bad light and hard to say.

Weather: Little flakes of joy kept falling from the sky. Isn’t that sweet? Sure made me happy!! We headed out at about 10am, fairly consistent S2 until about noon. Snowfall started to taper afternoon and by 1pm it was done with the sky becoming mostly cloudy. Winds were cranking up high with snow plumes throughout the day. Down low the winds were light to moderate.

Snowpack: Snow totals from last night and today were somewhere in the 10 to 14″ (25-35cm) range. While the 1/19 interface was now buried 40 to 50cm down. You were basically skiing in the weak layer, so conditions felt much deeper given all the soft snow on weak snow…

The recent storm snow was rather low density and didn’t have much cohesion yet. Though today’s winds were making the upper 10cm’s feel a bit top-heavy and gave a general thicker feel to the riding conditions. We primarily traveled on NE to E aspects. Down low, the 1/19 interface was well developed 1.5 to 2mm NSF that was very weak. Climbing above about 10,200 feet, and in a completely intact snowpack with no previous avalanche activity, the 1/19 interface was 1mm NSF and slightly harder at 4F-.

The bottom line, the 1/19 interface looks like a bad setup. We didn’t encounter any signs of instability while traveling on slopes in the lower 30-degree range. A few tests highlighted to the potential for storm slabs to break within the storm snow, but that didn’t really matter given the weak interface below that may become more of an issue as the new snow settles into a slab.

Saw lots of other ski tracks traveling on similar slope angles on different terrain features. Great to see folks out having fun and enjoying the new snow.

: Snow coverage on W-NW side of Gothic.

: NE at 9,900ft. 1-1.5mm very weak NSF (1/19 interface) with recent storm snow on top.

: Forgot my phone in the car and found this lovely photo upon return.

Not your grandma’s sluffing

CBAC January 23, 20212020-21 Observations

Date of Observation: 01/23/2021
Name: Zach Guy

Zone: Southeast Mountains
Location: Snodgrass
Aspect: North East
Elevation: 9400′ – 11000′

Avalanches: D2 natural slab avalanche off of the East face of Gothic along with some smaller slides on Gothic.
On Snodgrass, we noted 3 natural loose snow avalanches and intentionally triggered about 5 others that ran about 400 vertical feet. These were all larger than you might expect because they entrained the 12″ of storm snow along with most of the season’s weak snowpack, generally about D1.5 in size. We probed debris on a low angle bench where several slides had overlapped and it was up to 8 feet deep.
Weather: Moderate snowfall through mid-afternoon (S1 to S3). Moderate southwesterly winds were shaking trees and blowing snow near Snodgrass Summit, but weren’t mixing into the wind protected terrain. We also could see and hear gusts moving snow near valley bottom of the East River.
Snowpack: 4″ of storm snow at the trailhead and 12″ near the summit. The new snow wasn’t quite cohesive enough to form a storm slab except in drifted areas. Very minimal cracking. I felt one collapse on a low angle slope that was on basal weak layers (12/10), about 30″ deep. The storm snow is on a mix of rotten facets and windboard capped facets. The windboard is more common lower in the terrain, facets more common in upper start zones.

Photos:

: D2 debris below Gothic East Face

: Storm slab avalanche off of Gothic

: Blowing snow from moderate winds

: In wind sheltered terrain, storm slabs lacked cohesion for propagation. This is one of the few small pockets that we triggered

: Debris piles up to 8 feet deep from triggered sluffs

: Looking up at the start zone where we intentionally triggered a few sluffs that plowed deep into the snowpack

: Storm slabs propagated a little further where winds had stiffened the snow.

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Anthracites

CB Avalanche Center January 23, 20212020-21 Observations

Date of Observation: 01/23/2021

Zone: Northwest Mountains
Location: Anthracites skin track near the top before your turn right to tree chit or left to 7th bowl
Aspect: North East
Elevation: 11,200

Avalanches: D1 propagated about 50 feet wide
Weather: Actively snowing and windy on the ridge. 20 degrees
Snowpack: Mid storm 15” new snow. 11am Saturday 1/23. Avalanche problem: storm slab

Photos:

Gothic Weather Update 7am

CBAC January 23, 20212020-21 Observations

Date of Observation: 01/23/2021
Name: billy barr

Zone: Southeast Mountains

Weather: Winter is here- i seemed to have forgotten how much more difficult it is to get around when it snows as it has been a while. —Light snow overnight picking up some after midnight with 7½” new and water a lighter 0.45″. The snowpack has reached the winter’s deepest of 35″. Currently obscured cloud cover with moderate snow and thankfully no wind. Yesterday’s high temp was 28F this mornings low and the current is 21F. We had more snow last night than the whole of January up until today.

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