Date of Observation: 03/22/2023
Name: Irwin Guides

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

Observed avalanche activity: Yes
Avalanches: Several, SS-ASc-D1 storm slabs 8-14″ thick on W and S aspects. Party hats L SS-ASc-R2-D2-I. W aspect NTL 14-16″ X 100′ X 800′ Failed on the 3/20 MFC interface.
Weather:
Snowpack: We did not travel E aspects today due to visibility. In the AM storm slabs on W
aspects tittered between stubborn and reactive. 6-8″ storm slabs grew to 12-16″ as the day progressed with
isolated loaded areas up to 24″ thick. By the afternoon avg. crown heights were in the 12-14″ range and
trended towards very touchy with remote triggers up to 25′ away. S aspects reacted vary similar to W BTL/ NTL
today. All were failing on the 3/20 MFC interface. The MFC produced repeat offence avalanches in our tenure
as guides skied certain slopes after snow safety passes.

Date of Observation: 03/22/2023
Name: Eric Murrow

Zone: Southeast Mountains
Route Description: Snodgrass TH up standard skinner with detours to nearby steep terrain features.

Observed avalanche activity: Yes
Avalanches: I remotely triggered two avalanches on a southeast-facing feature below treeline; slides ran on the melt/freeze crust at the storm interface in low density storm snow from the start of the storm. I ski-cut a large Storm Slab that broke on a mid-storm weak layer on an east aspect; as the avalanche ran it propagated wider and down to the storm interface. This avalanche may have collapsed the soft melt/freeze crust beneath the storm snow on east aspects.
Weather: Overcast skies with increasing winds during the day. Strong winds penetrated down to valley bottom during the afternoon. Storm totals ranged from 20-22 inches. From 1030 to 130 snowfall rates were commonly in the 1 to 2-inch-an-hour range. Visibility was obscured all day so I never got a view of the surrounding terrain.
Snowpack: Avalanches in the storm snow were very easy to trigger with some occurring remotely. Low-density snow from the start of the storm remains sensitive to human triggers in sheltered areas. South and southwest-facing slopes below treeline had thick melt/freeze crusts around 4 inches thick below the storm snow and did not appear to cause concern for collapsing. Southeast and east-facing slopes crusts were thinner and may pose a threat for triggered avalanches after issues in the storm snow settle out. I experienced one collapse on an east-facing slope and a nearby test profile suggests that the crust below the storm snow is near its breaking point. I initiated a Loose Dry avalanche down a north-facing slope that gathered a lot of mass, but surprisingly, it failed to release a slab (maybe this slope avalanches the day before). Faceted grains were obvious beneath the storm snow in a north-facing test profile but no propagating results.

Date of Observation: 03/22/2023
Name: billy barr

Zone: Southeast Mountains
Route Description: Gothic

Weather: Only very light snow off and on during the day yesterday (½”) but steady light to moderate overnight snow with total of 7½” new and water content 0.65″. The snowpack is at the winter’s deepest of 93″ which if this holds (or increases) by sunset (i have always kept my own records sunset to sunset) it will be the deepest on record for this date, by 2″ over 1980 but a far cry from the 117″ all time high. The wind picked up just after midnight and is steady 5-10 West with gusta to 20 and very warm as it reached 32F overnight. It is currently at 28 with moderate snow and moderate but gusting wind and no visibility.

I saw 1 foot fractures run yesterday from just that recent new snow so expect more of that today. I think the safest thing is to stay under the covers. Until June.

Date of Observation: 03/21/2023
Name: Evan Ross

Zone: Northwest Mountains
Route Description: Indy and Elk Basins. 9,000-12,000ft.

Observed avalanche activity: Yes
Avalanches: Many small storm slab avalanches at BTL and NTL elevations. Poor visibility ATL. Those avalanches failed last night or during the early AM hours. 40+ avalanches. All failing in 40+ degree terrain. There were fewer avalanches on due south-facing slopes and I didn’t see much for north-facing terrain. I didn’t notice any avalanche activity near the Kebler Road or on the lower northerly facing slopes of Mt Axtell.

Weather: Overcast. S-1. Calm wind.

Snowpack: HST averaged in the 25 to 35cm range. The storm slabs were failing just above the 3/20 crust in low-density storm snow and stellars. Hand pits still produced clean shears on the interface, but I otherwise didn’t observe any signs of instability on small test slopes. There was wind-affected snow at upper elevations, but I didn’t encounter any notable thick wind drifts and of course, also didn’t enter the most suspect terrain. On E-SE and W aspects The 3/20 crust was 2cm thick on average. There wasn’t enough load to start collapsing that crust into the weaker snow below. The crust on due south is thicker and stronger.

Date of Observation: 03/21/2023
Name: Zach Guy

Zone: Northwest Mountains
Route Description: Rec tour in the Anthracites, the usual stuff, avoided East Bowl.

Observed avalanche activity: Yes
Avalanches: Ski cut a storm slab in Ziggens. NE aspect BTL. The slab was 10″ thick and about 50′ wide, breaking on low density snow that fell earlier in the storm yesterday. Some small natural activity off the drifted feature on East Bowl.
Had some decent vis into the playground, Ruby Peak, Axtell, and Whetstone this morning and didn’t see any persistent slab activity.
Weather: S-1. Light ridgetop winds; signs of previous drifting near treeline.
Snowpack: 12″ of top heavy storm snow produced cracking up to 5′ long on test features, both on storm layers (northerly) and storm interface (southeast).
A quick pit on a wind-sheltered southeast aspect produced easy propagating results (ECTPV, ECTP9) in facets below the 3/20 crust. The crust was about 2-3cm thick, strong enough that I didn’t get any collapses on it while walking around on a few similar slopes. No results on the 3/10 crust here, and like elsewhere, the weak layer was not obvious. Probed around on a few NE facing slopes to verify the absence of the 3/10 crust…nothing on NE or ENE here.

Date of Observation: 03/20/2023
Name: Evan Ross

Zone: Northwest Mountains
Route Description: Skykill Ridge, Near OBJ. 9,000ft to 11,300ft. NE-E-S

Observed avalanche activity: No

Weather: S-1 most of the afternoon. Starting to pick up in the later afternoon as we were headed out. Calm wind.

Snowpack: Great skiing on NE with some sluffing in steep terrain. The crusts at the old snow interface on East were breakable and not good skiing. Not enough snow yet, for any storm slab problems. The most notable weak layer was the 3/20 interface that was buried this morning. On E and SE it was about 2cm thick, collapsible into weak snow below, and ready to aid in propagation once there is enough load. On south, that crust was 6cm + thick and strong.

Targeted a test pit on a ENE slope at 9,700ft. Slope 34 degrees. HS 250cm. The 3/10 interface didn’t produce any ECT, CT or DT tests. The 3/15 crust and 3/20 NSF each produced ECTN results. The layer of concern at this location was the 3/20 NSF once there is a slab, and if something did step down to the 3/15 crust it wouldn’t be much deeper at this location.

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
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: 03/16/2023
Name: Eric Murrow

Zone: Southeast Mountains
Route Description: Hwy 135 obs.

Observed avalanche activity: Yes
Avalanches: A few natural avalanches seen from the pavement. A couple small slabs in the storm snow in Green Lake Bowl on Axtel, a large avalanche in the Octagon area on Whetstone that appears to fail below the past two storms (3/10), a small avalanche on Red Mountain (could be from the warm up on Tuesday, but I suspect occurred Wednesday night/Thursday morning, and a west-facing avalanches on Round Mountain that I believe failed during warming on Thursday (looks like it failed on 3/10 interface).
Weather:
Snowpack:

Date of Observation: 03/16/2023
Name: Evan Ross

Zone: Northwest Mountains
Route Description: Mt Axtell and Evans Basin. N-E-S 9,500ft to 11,600ft.

Observed avalanche activity: Yes
Avalanches: A variety of old storm slabs and loose snow avalanches that were no longer sharp looking.

East on Mt Axtell: Skier triggered 3 storm slabs. 2 small slabs were triggered on steep, unsupported pillows and didn’t have much propagation. The most notable propagated fairly wide on another steep east-facing slope at 11,300ft. The slab was about 30cm deep, and the avalanche became large in size. These slabs released on very small facets sitting on the 3/15 interface.

East in Evans Basin. Snowmobile triggered 2 small, stubborn, wind slabs that ran within the new snow, and not at the old snow interface like on Axtell.

Several small loose wet avalanches ran today in Evans Basin on E and SE slopes at NTL and ATL elevations.

Weather: Parly cloudy sky. Mostly light to calm winds. Previous transport from stronger winds in the lower Kebler corridor.

Snowpack: The Recent HST is in the range of 15 to 35cm depending on how much settlement it has seen. Similar to yesterday, east aspects produced the most notable results today, with a few soft slabs failing on the recent storm interface. They have been running on small facets above the 3/15 crust. We triggered 3 slabs on this interface. A couple ran on steep and unsupported pillows. The most notable ran on a nice plainer 40-something-degree slope. Interestingly, in the afternoon I targeted the same aspect in Evan’s Basin and was unable to get any results on the same interface on steep E and SE test slopes. The loose snow avalanches and wind slab avalanches in Evans Basin also didn’t produce results on the 3/15 interface like we had seen over on Axtell.

Steep northerly facing slopes skied nice, with a few slow-moving sluffs and one small wind slab.