Date of Observation: 02/20/2023
Name: Evan Ross

Zone: Southeast Mountains
Route Description: Mt Emmons E-S-SW. 9,400-11,900ft.

Avalanches: Recent large avalanche in Red Coon Bowl. Best Guess is that it ran on Sunday or early Monday. East aspect 11,800ft. Estimated 1.5 feet deep and 400 feet wide. Blurry iPhone photo attached.

Weather: S1 through the AM hours with 1.5 to 2″ of new snow by noon. NTL elevations had continuous blowing snow with moderate to strong winds during the AM hours. Poor visibility. The weather started to improve in the early afternoon. With better visibility snow plumes could be seen on the higher peaks at times.

Snowpack: Targeted a few areas for another look before we go into the next storm. Since January, the upper snowpack has become layered and more complicated. There are several layers of crusts and facets that could lead to persistent slab avalanche behavior during the upcoming loading event. In the areas I checked around 11,200ft, E and SE aspects were the most concerning for the future PSa issues in the upper 40cm of the snowpack. I didn’t look at any south aspects. The crusts in the upper 40cm of the snowpack on a SW aspect were 2 to 5cm thick and notably stronger than those same interfaces on the SE aspects.

I took another look at the recently triggered avalanche in Red Lady Glades. As previously reported, this avalanche released on a thin layer of facets above a crust. More specifically there was a stack of crusts that likely formed between about February 9th to February 13th. Between these 3 crusts, there are layers of small facets of varying weakness. The avalanche failed in this stack of crusts and ran on the lower of the 3 crusts. Currently, on wind-loaded slopes and during the next loading event, these interfaces look capable of producing persistent slab avalanche activity.

Of other note was the continued blowing snow at NTL elevations through mid-day.

Date of Observation: 02/18/2023
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Cement Creek to Hunter Hill to Carbonate Hill, various aspects to 12,700′

Observed avalanche activity: Yes
Avalanches: Nothing new today. Got a closer look at the large (D2.5) persistent slab reported by Ben yesterday. I estimate the crown was up to 5 feet thick and pencil hard, based on debris chunks. Hard to say what weak layer it failed on, it looks like the bedsurface is a very hard windboard layer, and there were several layers of the wind board onion that peeled off further downslope.
Weather: Few to scattered clouds. Moderate winds above 12,000′ caused light wind drifting in a few areas.
Snowpack: No signs of instability except I triggered a couple of tiny 1″-2″ wind slabs that were forming from today’s blowing snow. I targeted a shallow area on a SE-facing slope above treeline and got hard, propagating results on depth hoar near the ground below a 90 cm, 1F slab. A couple of tests near and above treeline produced non-propagating failures in the recent wind slabs and no failures on the storm interface. There’s about 3 to 5″ of settled storm snow below treeline that’s been redistributed by northerly winds near and above treeline.

Date of Observation: 02/17/2023
Name: Zach Kinler and Eric Murrow

Zone: Northwest Mountains
Route Description: Top of the World down to Gothic CG and back. 9,600′-11,500′.

Observed avalanche activity: Yes
Avalanches: Observed a couple of small wet loose avalanches running from rocky, steep south-facing terrain near Mt. Bellview around 12:00 pm. D1 in size.
Weather: Clear skies and calm winds. Below zero temps at the trailhead in the morning gave way to temps at or just above freezing once out of the inversion in the valley floor.
Snowpack: We traveled primarily on slopes facing E-SE-S along the GMT course. No signs of instability were observed underfoot. Open areas near tree line had variable thin wind crusts while sheltered areas were lightly faceted and soft. Snow surfaces on SE and S slopes were moist by midday. HS on an east-facing slope at 10,100 was 185cm. A profile of the upper snowpack on this slope produced 1 hard propagating result and 1 non-propagating result in an ECT on the late January interface. This interface was a thin, 4-finger hard facet layer below a 1-finger slab.

Date of Observation: 02/17/2023
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Mineral Point, targeting wind slab instabilities on east to south aspects to 11,600′. Our plan was to cross under the south face of Mineral early morning before it got too warm. After several delays this morning (2 dead car batteries!), we didn’t cross beyond the most exposed sunbaked terrain until 11 a.m., which in hindsight, was cutting it too close for the type of terrain that we were on.

Observed avalanche activity: Yes
Avalanches: A large natural wind slab released off the south face of Mineral around 11:15 a.m., triggered by solar warming or perhaps a very tiny wet loose. The debris washed over part of our skin track that we had set an hour earlier.
Evidence of a widespread storm slab cycle in the Slate during the storm, along with numerous wind slabs in Poverty Gulch that ran after the storm, likely during yesterday’s northerly winds, up to D2 in size. See photos.
Weather: Clear, calm winds. Rapid warming; Double puffy snowmobile ride (-20F at TH), down to sun shirts once we started skinning. At one point, I looked over and my partner’s bare butt was showing, frantically trying to remove his long underwear. haha.
Snowpack: North winds did a lot of damage in Poverty Gulch, with wind slab formation scattered across all elevations. Wind slabs are easy to recognize: smooth, stiff snow (6″ to 12″ thick, 4F to 1F) below rollovers and in gullies, in contrast to softer, rippled sastrugi elsewhere. Wind slab feedback was stubborn underfoot. I snowmobiled and ski stomped on over half a dozen suspect wind-loaded rollovers without any signs of instability or cracking. However, I could produce cracks up to 5 feet while stomping on slopes undercut by the skin track. I also got easy test results on wind-drifted slopes (ECTP1, ECTPV). All of the wind slabs in this area, and my test results, failed on a low-density precip particle layer (non-persistent). Tests on the 2/13 storm interface were unreactive. I tested an east-facing slope near treeline which had a thin crust above facets at the storm interface.

Date of Observation: 02/16/2023
Name: Evan Ross

Zone: Northwest Mountains
Route Description: Mount Axtell north 9,500-11,500. Evan’s Basin E-SE 9,500-11,300.

Observed avalanche activity: Yes
Avalanches: Looking out from Axtell I just noted a few old, small avalanches near ridgelines. Nothing notable stood out.

Red Lady Bowl looked to have a small wind slab that may have run today, otherwise, it was from yesterday.

One more small wind slab to add onto ZG’s ob that probably ran today in the Whetstone Group. East, 12,000ft.

Weather: Clear and cold. Snow plumes off the high peaks at times throughout the day, becoming more continuous in the afternoon.

Snowpack: On Mt Axtell, the upper snowpack had become notably stiffer when compared to yesterday, from the cold temperatures and previous wind effects. We skied steep slopes to around 40 degrees and didn’t encounter any storm slab avalanche problems. Sluffing was also minimal. Ski quality had decreased from yesterday, but was still good. Recent wind loading patterns are all over the place and not following a specific trend given all the variations in wind direction we have seen. Wind slab travel advice would have been more appropriate than a widespread storm slab avalanche problem today.

Over in Evan’s Basin, the conditions were similar. I didn’t encounter any unstable snow on this quick trip. Wind slab travel advice would have also been more appropriate in that terrain. I targeted a couple of test profiles on east and northeast-facing slopes to look at the 2/13 interface. On a 38-degree east-facing slope at 10,500ft, the 2/13 interface didn’t produce any results and didn’t look very concerning. On a cross-loaded 35-degree NE-facing slope at 11,000ft the 2/13 interface also didn’t produce any test results. Those small facets at the interface were still something to keep an eye on. The density change in the storm snow did produce test results, but snowmobiling through many steep test slopes didn’t produce any signs of instability.

Date of Observation: 02/16/2023
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Mt. Whetstone, viewed from Mt. CB

Observed avalanche activity: Yes
Avalanches: A handful of natural slab avalanches above treeline that ran during the storm, appear to be wind slabs ~D1.5

Date of Observation: 02/15/2023
Name: Eric Murrow

Zone: Northwest Mountains
Route Description: Slate TH on snowmo’s to Pittsburg. Tour along the Gothic Mountain Tour descent route off Elkton Knob.

Observed avalanche activity: Yes
Avalanches: Handful of small, natural avalanches failing midstorm depth. Remotely triggered three small avalanches on drifted terrain features at 10,900 feet, avalanches failed at the mid-storm interface.
Weather: Light snowfall and light winds in this area. Settled storm total of 17″ at 10,000 feet near Pittsburg and only about 10″ at the Slate River trailhead.
Snowpack: The storm snow was generally stubborn to human triggers in sheltered areas as the strong precipitation rates had ended before we were in the terrain but cracking up to a ski length was common. Drifted slopes remained very sensitive at the mid-storm interface into the afternoon and up to 2 feet thick. Digging into the west-facing slopes at the bottom of the Elkton Knob descent I found a facet/crust weak layer beneath the storm snow that was unreactive in snowpack tests and to human triggers (see photo). The slab above is not big enough in sheltered areas to collapse the underlying crust BUT could be on drifted terrain or in the future with further loading events. The drifted southwest-facing slope, at 10,900 feet, where I was able to remotely trigger small avalanches has a very strong crust, around 6 inches thick, below the storm snow.

Date of Observation: 02/15/2023
Name: Zach Guy

Zone: Southeast Mountains
Route Description: Rec tour on Mt. Emmons, traveling on northeasterly aspects below treeline.

Observed avalanche activity: Yes
Avalanches: Skier triggered a few thin storm slabs breaking on a density change mid-storm, D1 in size. Also observed several natural storm slabs that ran overnight, same character and size.
Weather: Light snowfall and light easterly winds both tapered to nil by this afternoon.
Snowpack: Storm total was up to 12″ on the small-grained near surface facet interface. There was a pronounced density increase in the storm snow that happened mid-storm, which was the source of today’s problems. Slabs cracking on this mid-storm weak layer ranged from 3″ to 8″ thick, depending on elevation. Higher elevations approaching treeline were more reactive.

Date of Observation: 02/15/2023
Name: billy barr

Zone: Southeast Mountains
Route Description: Gothic Townsite

Observed avalanche activity: No
Weather: The wind is the dominant factor as it makes things look (and feel) worse than they are. The heaviest snow was in a short period after dark but there was light snowfall yesterday afternoon and snowing most of the night with the 24 hour totals 4½” and water of 0.34″. Wind was stronger after midnight with steady 5-10 SW wind gusting to 20. Nothing massive on the wind but consistently irritating. Currently overcast with moderate SW wind and very light snowfall and the snowpack at 59″. billy