Snow Observations List

Saw a large slide (D2.5, R3 or 4) on Ross East shoulder that likely occurred in the March 3/4 timeframe. 3 to 4 feet deep crown in places. Looked around at the bed surface which was nearly to the rock slabs underneath.

There were two skier-triggered avalanches on Saddle Peak today. The first was relatively small, estimated depth of less than a foot. The second occurred later in the day and was much more significant. 

Downhill winds transported snow all day, loading wind-drifted snow onto slopes at upper and mid-elevations. At 1 PM, a solo skier descended Quarter Saddle toward Spencer's and Going Home Chute. The skier released a wind-slab avalanche that broke about a foot deep approximately 300 feet above the large cliff band on Saddle. The first release triggered a secondary slab that broke more widely (estimated 200' wide) and deeper (1-3 feet deep). The avalanche ran over the large cliffs into Going Home Chute. Bridger Bowl Ski Patrol interviewed the skier who triggered the avalanche along with a representative from GCSAR and the GNFAC. Based on the interview, the group believed it was unlikely that additional skiers were involved. Because of the interview, concerns about scene safety, and the timing of the avalanche, no search was performed on the ground. The team used binoculars from within the boundary of the ski area to look for obvious indications of a burial.

9500 ft E facing slope in Beehive basin.  Dug to investigate the basal facet layer on the apron, found HS 120-140 cm with rounding facets on the ground, ECT 23 on pencil firm density layer above the facets, ECTx  on basal layer.  Chose ascent route in a slope concavity to avoid potential shallow trigger points.  Cut a cornice prior to descent and struck a shallow (18 inches )  trigger point on top of some rocks which propagated about 500 ft wide across multiple ribs and 400 vert D3 R4.  Did not recognize the razor thin margin for error on this slope, scouring in the start zone which created the shallow trigger point, or the propagation potential in this zone.  

I meant to add the crown depth 18 inches to 6 feet

Saw this avalanche in the Rasta Chutes today, not sure if it was already sent in. Here is a picture from across the valley. The avalanche ran almost to the bottom of the chute, covering sled tracks heading into tradgenic. 

We rode out to the avalanche that was triggered yesterday on Henderson Mtn. It broke over 2000' wide (measured on GPS) and all the way up to the ridgeline, 6-10' deep and maybe 12-15' deep at the deepest section. There were a couple hundred feet of slope that had not slide between this one and the similarly large slide to the north last weekend. The deepest debris was probably 15-20'.

We also saw a fresh huge avalanche on the south side of Scotch Bonnet that happened today or late yesterday. 4-6' deep and 300' wide. Both slides were R4-D3-O. There was another fresh slide in the Rastas (one that didn't slide last weekend) that looked fresh yesterday or today, 4' deep hard slab, R3-D2-O, and one small but deep slab on the north side of Scotch Bonnet, 6' deep x 30' wide, R1-D1.5.

We could see evidence of previous large avalanches in the cirque on Republic Mtn. and in east Woody Creek south of town. There were widespread avalanches along Henderson Bench as well, below the steep break over in the trees, 3'+ deep breaking across multiple terrain features through thick trees, most of the bench slid, and appeared to have happened last weekend.

On my drive to Cooke City I saw old slab avalanches in YNP near Mammoth and on Abiathar and Ampitheater among other places. These appeared to have happened earlier in the week. I also saw a more fresh looking persistent slab avalanche on Barronette, 2-3' deep and as wide as its terrain feature, 100-200' (photo).

Pretty scary. Stay safe out there.

We spotted several large crowns in the Northern Bridgers today.  All appeared natural from the last few days.  The snowpack has changed significantly since our last visit at the beginning of the week.  A soft wind slab is now forming on top of the loose dry powder that fell recently.  We did not have anything move on our runs but did have some collapsing on the skin track and boot pack. 

On a tour up Middle Peak, I saw recent avalanches, with large propagation in Middle Basin and Beehive Basin.

We rode from Battle Ridge into the base of the Throne, dug a pit low on the East Face, climbed to the ridge, dug a south facing pit and skied down via the East Face. Neither pit had any dramatic results, with ECTN26 and ECTX on the lower weak layers. 

Downhill winds were drifting a good bit of snow at lower elevations. We mostly found stripped slopes and wind effect, but did find a few deeper drifts. There was a small and thin avalanche low on the east face that looks to have pulled out with this downhill wind loading. Approximately 25 ft x 25 ft vertical and ~6" deep. 

No other avalanches observation. No cracking or collapse.

Shot from ~20 miles away, 3/8. Also looks to be a significant debris field in Frazier off The Hollywood. Bob ps. maybe a better pic 

Shot from ~20 miles away, 3/8. Also looks to be a significant debris field in Frazier off The Hollywood. Bob

From IG: "Buck ridge south of slatts hill, remote trigger by a snowmobile today"

From email: "Natural avalanches photographed near Cooke City today.

Pic 1:  east aspect 9100'.

Pic 2:  east aspect 9450'.

Pic 3:  SE aspect 10,400'.

Pic 4:  W, NW aspect 9,700'.

No collapsing nor cracking, while breaking trail and skiing today."

From email: "This avalanche was triggered by a rider in our group on the 7th. The rider was midway up the slope, it broke above him right under the cornice and he successfully outrun the avy to the bottom. Right above the trail it looked the deepest at 10' to 12' deep at the peak and 6' plus further to the north."

Big slide below the radio tower. Kept our distance but looks like a large crown. The base up Portal is really inconsistent. Some spots it’s great and others you sink up to your chest. Had 4 instances of whompfing on fairly flat ground in the trees.  1st picture is from today and 2nd is from Sunday

Thanks for all your hard work!

03/07 - observed several crowns on Republic from Town Hill, likely from 03/06. Ray's had a slide on its west end which appeared to be isolated from the large avalanche that was filmed on the shoulder/Ray's. We saw up to 4 other crowns in Republic bowl on NE, N, and NW aspects including one that broke on the NE facing spines looker's left of the Fin that got legs and ran into the trees out of site (R1-D2?).

One note - while all of these slides, including the large one already reported on the shoulder were on northerly aspects, the majority of the trigger points appeared to be small, steep, thin, NE facing features. We surprisingly woke up to clear skies early on 03/06 and I wonder how much of an impact solar may have played. Other faces and features in the area that are strictly north facing or otherwise protected from the sun didn't appear to be sliding naturally.

We rode Denny Creek to the head of Targhee Creek. The primary objective was to search for avalanche activity from the last storm and avalanche warning. There were two deep avalanches on heavily wind-loaded slopes. Otherwise, avalanches were confined to the new and recently wind-drifted snow - there were four of these smaller avalanches. The snowpack at Lionhead handled the recent loading events better and there were fewer avalanches I expected.
 

We did not experience any signs of instability (cracking, collapsing), but the winter’s snowpack history and concerns about triggering large avalanches kept us off of steep slopes. 

Skinned to the top of big Ellis completing 2 ECTs along the way.  The first pit was at an elevation of 7946 feet, north of the burn, east aspect, exposed to the sky/not shaded.  Snow depth 100cm. 2 buried crust layers, ECTNR.  We did get the column to fracture below the lower crust layer by prying on it after the ECT test.  The hardness of the faceted snow at the ground was 4 fingers trending to 1 finger.  The second pit was completed at an elevation of 8209 feet, top of the burn, east aspect, exposed to the sky.  Snow depth 120 cm, 2 buried crust layers, ECTNR.  The column failed at the ground post ECT via the same prying as previous column.  Hardness of the faceted snow at the ground was 4 fingers. We experienced no signs of instability during the day.  The skiing was good.  There were a few old ski tracks, partially buried by recent snow.

From email: "Natural avalanches observed near Cooke City today.  At least 3 big PWL/ deep slab avalanches.  All northerly aspects, mid elevations.  

Also, observed one upper elevation north facing slide that looked more like a storm slab."

Today I saw evidence of Multiple N-R2-D2-I avalanches in the fairy lake zone. All three were NE facing, around 8800’. 2 slabs in Fraizer basin and one in the basin to the south. All three looked to be from 3/3-3/4 storm cycle

We skied in the love chutes and Fraizer basin today with No collapsing or cracking. 

Toured up to the Cinnamon Mountain Lookout today. In a small meadow along the trail I got a small whumph, with a crack propagating out 5-10 feet all around me. HS was around 30-40 cm in this meadow. HS rose rapidly with elevation and I had no other large collapses throughout the day, but noticed some localized cracking in recently formed windslabs, and rapid warming of the snow surface in the sun all day. I dug a pit about 200' down from the summit, directly south facing, and got unremarkable test scores from a scary structure (full profile is in snowpilot). With the several warning signs I had seen, I chose to take my test results with a grain of salt, and ski a conservative line.