Date of Observation: 03/11/2023
Name: Irwin Guides Cat-Ski

Zone: Northwest Mountains
Route Description: Irwin Guides cat-ski tenure

Observed avalanche activity: Yes
Avalanches: Avalanche observations: HST responsive to AE, unresponsive to AS
Long HS-AE-R1-D1.5-I DF (30cm x 10m x 135m)
Way Long HS-AE-R1-D2-I MF (30cm x 20m x 135m)
Thorton’s HS-AE-R1-D1.5-I MF (50cm x 20m x 115m)
Bender HS-AE-R1-D1.5-S DF (15cm x 10m x 125m)
Flaming Ferrari HS-AE-R1-D1-S DF (20cm x 5m x 50m)
Weather: “We are currently HST: 28/3.2″ with more snow in the forecast. We also cracked a 100″ base today, which is nice.

The latest round of precip came with an extreme SW wind event, which is less nice. Last night we registered 5 hours of wind gusts from 35-48 at our base area study plot at 10.4k.”
Snowpack: This wind event combined with a warming trend during the storm produced widespread hardness inversions that were responsive to AE, but not to AS. A most uninspiring structure.

Date of Observation: 03/11/2023
Name: Insta Gram

Zone: Northwest Mountains
Route Description: Kebler Pass Road obs

Observed avalanche activity: Yes
Avalanches: “Counted 7+ D1.5’s along Kebler corridor this morning between TH and Axtel skintrack – All on the South facing road cuts”
Weather:
Snowpack:

Date of Observation: 03/11/2023
Name: Insta Gram

Zone: Southeast Mountains
Route Description: Natural avalanche impacting Cement Creek Road/xc trail

Observed avalanche activity: Yes
Avalanches: “Hard to tell, but the big path in the heart of Cement Creek XC trail ran last night…looked like it wasn’t even from the very top from what I could see.”
Weather:
Snowpack:

Date of Observation: 03/11/2023
Name: Ben Ammon

Zone: Southeast Mountains
Route Description: Epicing our way out way out from Friends Hut after coming over Pearl. Skintrack to Friends is in.

Observed avalanche activity: Yes
Avalanches: -4 of the THC chutes all ran full path probably early morning 3/11. The largest (#4) crossed East Brush Creek and made it to about where the normal route to Friends is. All started as storm slabs up high and then stepped down into persistent layers mid track, typically near the cliff bands. First 4 photos.
-The slope above the West Brush creek crossing buried the road and almost made it to the creek. 5th photo
-Storm slab crossed Brush Creek in the steep terrain between Hunt Camp and the West Brush crossing. 6th and 7th photo
-North Bowl of Cement slid, looked big from a long ways away. Last photo
-Many other D1 storm slabs, mostly E aspects, but some on every aspect, all seemed to fail early AM and were partially filled back in.
Weather: Clearing and sun mid day, but clouds and light snow moved back in after 1pm. Winds were generally light with occasional moderate guests BTL.
Snowpack: Settled storm total at Friends Hut as of 9am 3/11 was 29 inches of way upside down snow. Likely a fair bit of settlement as there was ~18 inches of 3-4% by dark on 3/10. Holy deepness. Collapsed the storm slabs problem on just about every meadow in the East Brush valley. We avoided Death Pass but I’d bet it slid as well.

Date of Observation: 03/11/2023
Name: Text Message Obsevation

Zone: Southeast Mountains
Route Description: This area sits outside the CBAC forecast area just north of Almost above highway 135 (forecaster description)

Observed avalanche activity: Yes
Avalanches: Natural avalanche north of Almont on a northeast-facing slope, around 8,400 feet.
Weather:
Snowpack:

Date of Observation: 03/11/2023
Name: Eric Murrow

Zone: Southeast Mountains
Route Description: Lower Anthracite Mesa from Washington Gulch Trailhead.

Observed avalanche activity: Yes
Avalanches: A few natural storm slab avalanches on east and northeast aspects, D1 – D1.5. Intentionally skier triggered a moist Loose avalanche on a southeast slope below treeline.
Weather: Mostly cloudy skies, about 20 inches of storm snow, light to moderate winds, and mild air temps. Just afternoon there was a period of ‘green housing’ from the sun poking through thin clouds that quickly warmed, settled, and wet snow surfaces on the south half of the compass.
Snowpack: While moving through northeast, east, and southeast aspects below treeline we experienced few signs of instability outside of the natural Storm Slabs that ran during a period of intense snowfall earlier in the morning. On east-facing terrain, we produced a few muffled collapses during a period of strong ‘green-housing’ while surfaces were moist (nearly wet). If I skinned above my partner’s skin track, I was able to produce some ski-length cracks above the established skin track. Test results on an east slope produced an ECTP 28 +1 result and ECTN within the storm snow (see photo). While traveling over a southeast slope, the storm snow had settled and moistened/wetted to a dense, manky 10 inches ( see photo).

Date of Observation: 03/11/2023
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Whetstone, Gibson Ridge, and Emmons viewed from Mt. CB

Observed avalanche activity: Yes
Avalanches: A handful of D1.5 to D2 storm slabs at all elevations. Had decent visibility and did not see anything that stepped down deeper from Whetstone to Axtell to Emmons.

Date of Observation: 03/11/2023
Name: Zach Guy and Zach Kinler

Zone: Southeast Mountains
Route Description: Avalanche mitigation on the small slopes above the ice rink and nordic hill. NE-E aspects at 9,000′.

Observed avalanche activity: Yes
Avalanches: 3 storm slabs ran naturally on the Nordic Hill earlier this morning, about a foot deep. Remotely triggered a drifted storm slab from 20 feet away that was almost 2 feet deep. It broke on precip particles just above the storm interface (windboard). Numerous roof avalanches in town.
Weather: Heavy snowfall rates this morning, light winds.
Snowpack: About 18″ of top-heavy storm snow produced localized cracking in wind-protected terrain (up to 8′ long). Slabs were noticeably thicker and more reactive in drifted terrain, where I got a collapse, shooting cracks, and a remote trigger. All instabilities were on low-density precip particles that fell near the start of the storm (non-PWL).

Date of Observation: 03/11/2023
Name: Billy Barr

Zone: Southeast Mountains
Route Description: Gothic Townsite

Observed avalanche activity: No
Avalanches:
Weather: Obscured clouds and heavy, very dense snow from Friday afternoon on with 20½ inches new and water an absurd 2.19″. Wind became very strong overnight. It remains obscured with moderate to heavy snow with strong wind. The snowpack is at 79½”, winters deepest. billy
Snowpack:

Date of Observation: 03/11/2023
Name: Eric Murrow

Zone: Northwest Mountains
Route Description: Lap up Mount Emmons and snowmobile ride out the Kebler corridor to Horse Ranch Park. Traveled between 1130 and 330pm.

Observed avalanche activity: Yes
Avalanches: I was able to trigger a small avalanche on a drifted feature above treeline into Redwell Basin. Storm totals at this time were around 7 inches and the drifted slab was around 10 inches.
Weather: Consistent snowfall during the afternoon. Snowfall rates of 1 inch per hour or greater. Southwest wind blew at moderate speeds with strong gusts while I was above treeline in the early afternoon. While at the valley bottom later in the afternoon wind speeds appeared to be ramping up. Snowfall totals reached close to 10 inches at 330pm with higher-than-normal densities.
Snowpack: I traveled around simply watching the storm develop, but not enough snow had accumulated by 330 for much to happen. Small Wind Slabs developed by the early afternoon, but sheltered areas had yet to gather enough storm snow to cause much of a problem. I suspect that shortly after I left the mountains storm totals began to increase enough, due to heavy snowfall rates, that shallow Storm Slabs began forming in sheltered areas as well. A Shovel Tilt Test showed a slight density change at the bottom of the storm snow in a location with 8 inches.