Fresh persistent slabs and wind slabs in the NW Mtns.

CBACCBAC Observations

Date of Observation: 03/28/2023
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Viewed from Carbonate Hill and Slate River Road.

Observed avalanche activity: Yes
Avalanches: Large persistent slab (D2.5) on the SE side of Schuylkill Ridge ran this afternoon during the warmup. A handful of D1-D2 wind slabs in the Ruby Range that likely ran yesterday or overnight. A slab on East Beckwith (NE ATL) broke near the ground on a steep, shallow, rocky slope, sometime in the past 48 hours.

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Fresh wind slabs in the Ruby Range

CBACCBAC Observations

Date of Observation: 03/28/2023
Name: Irwin Guides

Zone: Northwest Mountains
Route Description: Viewed from Irwin Tenure

Observed avalanche activity: Yes
Avalanches: Several fresh wind slabs above treeline, new since yesterday afternoon. Likely ran overnight.

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6169

Anthracite Mesa

CBACCBAC Observations

Date of Observation: 03/27/2023
Name: Jaime Odin

Zone: Southeast Mountains
Route Description: Ascended/descended the south east shoulder of anthracite mesa to 10,400 ft

Observed avalanche activity: No
Snowpack: 1-2 ft of weak new snow present throughout the tour, with a mostly supportable crust underneath, except for in sheltered terrain, especially in dense timber. Average ski penetration ~30cm boot penetration ~60cm. At 10,400 ft on an open SE aspect 10 degree slope the surface height was 240cm. Underneath the top 25cm of new snow was an easily breakable crust with ~60cm of weak, faceted snow beneath. Another crust was beneath the facets but I did not dig under this second crust which was ~80cm beneath the surface. Pulling on an isolated column with a shovel easily broke a slab of the new snow at the first crust/facet interface, instilling little confidence in the current snow structure.

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Pit results from the Slate and a wind slab.

CBACCBAC Observations

Date of Observation: 03/27/2023
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Upper Slate, Purple Palace area to 11,000′, traveling on easterly aspects.

Observed avalanche activity: Yes
Avalanches: Snowmobile cut an 18″ wind slab on Slate cut bank feature that catches efficient downvalley drifting. The slab failed on the 3/24 crust on a south aspect BTL.
Weather: Overcast, S-1 to S1 snowfall with an inch or two of accumulation today. Light northwest winds and light transport below treeline. Still coooold.
Snowpack: Dug several pits within a few hundred feet of each other on SE, E, and NE aspects below treeline. I got a mix of hard propagating and non-propagating results at the 3/20 interface. The east facing pit, which I dug just above an old crown, had the weakest looking structure and was the only pit that consistently produced unstable results. I did get one propagating result on northeast as well, but it was on an old graupel layer about 25 cm below the 3/15 crust, and the result was not repeatable.
No signs of instability while breaking trail.
There is about 10-12″ of dry recent storm snow above the 3/24 crust on southerlies in Upper Slate, and 4″ to 6″ above the crust closer to the trailhead. On easterlies, the snowpack has remained dry down to the 3/20 crust, 30″ deep. The upper foot or so is fist hard but dense enough that it isn’t dry sluffing.

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Recent large avalanches in Red Lady and Whetstone

CBACCBAC Observations

Date of Observation: 03/27/2023
Name: Eric Murow

Zone: Southeast Mountains
Route Description: HWY 135 observations

Observed avalanche activity: Yes
Avalanches: Large avalanche ran in Red Lady Bowl – I would suspect it ran today while wind-loaded. Large natural avalanche on the easterly side of M-Face on Whestone. This avalanche appeared to break fairly deep with rocks exposed; this feature is unsupported from below.
Weather: I observed moderate wind-loading above treeline onto easterly aspects.
Snowpack:

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Gothic Weather

CBACCBAC Observations

Date of Observation: 03/27/2023
Name: billy barr

Zone: Southeast Mountains
Route Description: Gothic townsite

Observed avalanche activity: No
Weather: Second verse, same as the first. Obscured cloud cover with light, dense snowfall, most in the past 24 hours coming between sunset and around 2 a.m. with 3½” new snow and water 0.34″. The snowpack is back at 94½”. Light wind with some gusting and cool with the high 21, low 4 and the current 5.

6164

Recent large natural near Skykill Mtn

CBACCBAC Observations

Date of Observation: 03/26/2023
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Pittsburg to 11,600′ saddle between Schuylkill Ridge and Schuylkill Mtn, traveling mostly on north and northeast aspects.

Observed avalanche activity: Yes
Avalanches: A large (D2.5) debris pile off the north side of Schuylkill Ridge appeared to run Friday night or Saturday, based on minimal fresh snow on the debris. We traced the lookers right side of the debris lobe, which knocked over a few small trees. The combination of flat light and recent drifting near ridgetop made it difficult to make out the crown.
Weather: Unseasonably cold. Light winds. Very light snowfall and overcast most of the day.
Snowpack: About 6″ of recent snow from Friday night, with notable wind affect near treeline. No signs of instability underfoot except for some minor cracking about 8″ deep in drifted terrain. Stability tests on both north and southeast aspects near treeline produced hard, non-propagating results on the 3/20 interface, which is small, rounding facets buried about 60 cm deep.

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6163

Small Skier Triggered Avalanche

CBACCBAC Observations

Date of Observation: 03/25/2023

Zone: Northwest Mountains
Route Description: Slate River

Observed avalanche activity: Yes
Avalanches: Small skier-triggered avalanche. NE.9,400ft.

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6162

Weekly Snowpack Summary March 17-23, 2023

CBAC2022-23 Weekly Snowpack Summaries

The weekly summary is here. The previous weekend’s mild weather gave way to a week full of storms. Total snowfall for most areas was over 20″ by the weekend. Avalanche activity for the week was characterized by widespread storm slab action, a natural cycle that produced several large avalanches, and one of the biggest remotely triggered avalanches of the season on Baldy.

 

Weekly Summary March 17-23, 2023 (1) COMPRESSED

Remotely triggered 3 very large avalanches

CBACCBAC Observations

Date of Observation: 03/25/2023

Zone: Northwest Mountains
Route Description: Anthracite Range. NW Mountains.

Observed avalanche activity: Yes
Avalanches: We remote triggered at least 3 very large avalanches on southeast to south-facing terrain above the Beaver Ponds. We were choosing to ski northerly-facing terrain, but while skiing down the ridge to a second lap on the back of the ridge, we felt a collapse, and watched three very large (D3) avalanches run to near their vegetative trim lines.

Weather: Cold, mostly cloudy, breezy. We did not see much snow transport during the day, but it looked like snow drifted overnight.

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