Date of Observation: 03/19/2023
Name: Zach Guy and Evan Ross

Zone: Northwest Mountains
Route Description: Snowmobiled to the south bowl of Baldy to get a closer look at the snowmobile triggered persistent slab from yesterday.

Observed avalanche activity: Yes
Avalanches: Huge! This was the biggest human-triggered avalanche that I’ve ever investigated and the most destructive slide we’ve seen this season since the Red Lady ran in early January. The crown was just under 2,000′ wide and ran about 1200′ vert, wrapping from south to southeast aspects near and above treeline. It is a hard slab that averaged about 5 feet thick. Some of the well-drifted areas were over 10 feet with a max crown depth of 15 feet. We estimate the debris pile was up to 30 or 40 feet deep. The snowmobiler remotely triggered the slide while ascending along a safe ridgeline. They weren’t sure exactly where the trigger point was; we estimate it was near a shallower spot near the top of the bowl, about 30 or 40 feet from the avalanche. We classified the avalanche: HS-AMr-R3-D3.5-O
Observed a handful of other small storm slabs and wind slabs that ran or were triggered sometime in the past few days, and one large persistent slab on a south aspect ATL near Avery Peak. See photos and details below.
Weather: Partly cloudy, mild temps, light winds with no transport observed.
Snowpack: The avalanche failed just above the March 10th crust, and was made up of drifted snow from the March 10th-11th storm and March 15th-16th storm. We dug one snow profile in a shallower part of the crown. See profile below. The weak layer is difficult to discern (~.5 mm rounding facets, 1F) and did not produce results in an extended column test. Grain sizes are slightly larger than the overlying slab, and one level of hardness softer than the overlying slab and underlying crust, both of which are pencil-hard. The snow surface at this location was 1.0 to 1.5 mm near-surface facets over a thin, soft crust.

Date of Observation: 03/18/2023
Name: Travis Guy

Zone: Southeast Mountains
Route Description: Skin track from Gothic Rd (Tuttle Cabin) to 3rd bowl on Snodgrass ridge

Observed avalanche activity: Yes
Avalanches: An avalanche on the rollover of 3rd bowl, which appeared to be skier triggered (tracks in)
Weather: Sunny but shaded in the bowl. Calm. -7C at Gothic townsite

Date of Observation: 03/19/2023

Zone: Northwest Mountains
Route Description: Yule Creek area

Observed avalanche activity: Yes
Avalanches: A few small triggered and natural wind slabs from northwesterly winds channeling down valley. A large persistent slab on the east side of Justice looks like it ran during the last storm.

Date of Observation: 03/18/2023

Zone: Northwest Mountains
Route Description: Mt Baldy SE face

Observed avalanche activity: Yes
Avalanches: Snowmobile triggered around 5pm today. No humans caught. More to come.

Date of Observation: 03/18/2023
Name: Evan Ross

Zone: Northwest Mountains
Route Description: Slate River

Observed avalanche activity: Yes

Snowpack: Loose-dry and Loose wet avalanches looked like the primary avalanche problems NTL and BTL. Both natural and skier-triggered. Most of the wet avalanche activity appeared to have occurred yesterday or previously. I didn’t travel on southerly-facing slopes today and don’t know how wet they got, but temperatures did feel cooler than yesterday. The only recent slab avalanche I saw was in the Great Wide Open of Skooks. It looked like it failed after yesterday morning’s 1″ of fairy dust.

Date of Observation: 03/18/2023
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Traveled on all aspects of Mt. CB to 11,800 to observe current snow surfaces ahead of the next storm.

Observed avalanche activity: Yes
Avalanches: Had good views with binoculars of a lot of terrain. Nothing notable from the past few days; some small loose avalanches and recent cornice fall/wind slab activity off of Owen that looked to be about D1.5 in size.
Weather: Notable 30-degree diurnal swing at Butte SNOTEL past 36 hours with temps dropping to near zero overnight, and highs near freezing. Light winds, clear skies.
Snowpack: The current snow surface is the most widespread and notable near-surface faceting event I’ve observed this spring, which will spell trouble for the upcoming storm. The combination of low-density snow at the tail of the last storm, light winds, and big temperature swings the last few days have promoted faceting in the upper few cm’s of the snowpack. Today’s cool temps and strong March solar were ideal for radiation recrystallization. I found 1cm of dry, faceting grains above thin crusts (1 to 3 cm) on east, south, and west aspects, grain sizes about 1mm in size. Northerly aspects held cohesionless facets, ~1mm. I suspect only the lowest elevation southerlies got warm enough to cook off, but I didn’t verify that.

Date of Observation: 03/17/2023
Name: Chris Martin

Zone: Southeast Mountains
Route Description: Aspen to CB via Starr Pass. We traveled over the pass via wind scoured ribs and ridges Wednesday morning before the intense precip of another river Wednesday evening.

We awoke thursday evening to the most quality powder skiing i’ve ever experienced in the friends hut zone.

Observed avalanche activity: Yes
Avalanches: Carbonate Hill Flank SE – D2 R2 Hard Slab – Natural – failing at the ground, seemingly sometime Wednesday evening

Many various shallow storm slabs failing on solar crusts about 4-12″ in thickness
Weather: Heavy precip Wednesday PM along with howling winds
Clear sunny skies Thursday
Snowpack:

Date of Observation: 03/17/2023
Name: Zach Guy

Date of Observation: 03/17/2023
Name: Frank Stern

Zone: Southeast Mountains
Route Description: Wolverine Basin

Observed avalanche activity: Yes
Avalanches: N facing slope 12,000’
Weather: Sunny
Snowpack: Powder on N aspects, crust on S

Date of Observation: 03/17/2023
Name: Travis Guy

Zone: Southeast Mountains
Route Description: Gothic townsite to Kettle Ponds

Observed avalanche activity: Yes
Avalanches: 3 avalanches that had already run on 2nd bowl. Appeared to be natural as I couldn’t make out any tracks
Weather: Mostly sunny. -8C, no wind, but signs of drifting overnight
Snowpack: