Snow Observations List

Yesterday (1/9) touring north of Cooke City I felt some large collapses and cracking on a heavily wind loaded, mid elevation slope. There was about 4-6 inches of new snow that fell throughout the day. 
 

Accessed Woody Ridge from Republic Creek, approximately 3 mi up.  Turned around on a west slope at 9000', due to time of day.  8 degrees air temp,  

Snowpack skied well and was supportable - 6-8" of new that seemed well bonded to old snow.  2 perceptible layers when probing with a ski pole.  Lower layer much harder.  

Downfall is still a hazard - not completely buried, but skiing was remarkably good, considering.  

Mostly overcast day.  Occasional wind gusts out of the SW, but mostly calm and cold.  

I saw debris from an avalanche in one of the southern Woody Ridge gullies. The slide appeared to be a recent windslab formed by the new snow over the past few days. Best guess it happened yesterday, and it appeared to be natural. The crown appeared ~8-16” from a distance, and was on the skier’s left side of the gully, the side that sees loading from wind out of the south. It ran a few hundred feet down the gully. 

Skinned up to Blackmore 01/08 to ski the East shoulder. Found that it had not snowed as much as it had in town the night before. Possibly 2-3” at lower elevations and 3-4” at higher elevations. There was some isolated wind loading in the basin at lower elevations and more widespread loading near the ridge tops. Did not experience any collapsing but did notice a few natural avalanches and one skier triggered avalanche near of the top of Blackmore. Looked as though it was a ski cut that popped the slab. Skied a low angle, non-wind loaded slope with a few lovely turns before smoking plenty of rocks on the way down the trail. 

Toured up to the Bradley Meadow area and dug on a NW aspect at 7,839'. HS 71 cm, CTN, ECTX. Found a lot of faceted snow and a couple of firm melt freeze crusts near the ground. Full profile attached. 

From email: at Buck Ridge: "The difference in snow was astonishing within the 6 days. Last week pure sugar and facets lived on the surface sounding like crumply glass as you rode through. Today everything was far more dense and attempting to support the sleds on The terrain just beyond the alpha angles enough to have some over the hood pow play without bouncing off rocks. Between wind and finally getting some snow with moisture in it, low angle areas outside the trees are racking up the inches. It snowed ~2" while we rode.

There's a substantial crunch layer to north faces now in McAtee just off Muddy and visible in trenches dug to the ground. Beaver and 1^st towards the ridgeline trail held far more snow - as you drop lower into each basin the quality and depth diminishes. 2^nd , 3^rd and McAtee must have been just out of the main drop of the last storm."

We rode up to the head of Yale Creek, down a bit into the head of Hellroaring Creek and then returned via the East Fork of Hotel Creek. The depth of new snow increased dramatically with elevation from approximately 8" (0.5" SWE) at 8000 ft to 18" (0.7" SWE) at 9000 ft. The new snow had little cohesion. 

We found buried surface hoar on both shady and sunny slopes. Sunny slopes had multiple melt-freeze crusts interspersed with weak facets throughout the pack. On shady slopes the lower snowpack was entirely faceted. We had an ECTP11 on facets just below the old snow surface on a S facing slope. Otherwise our results were ECTX and ECTN with slab fracture in Propagation Saw Tests (likely because neither the facets or new snow were cohesive enough to act as a slab in our tests).

Wind, settlement or more snow could quickly make for a cohesive slab. When that happens, with so much new snow and such weak snow beneath it conditions will rapidly become unstable. 

We saw no avalanche activity and had no cracking or collapsing. 

We went to Bridger Bowl today and walked along the ridge to the Ramp. The west wind was calm and there wasn't any new snow being transported while we were walking. Snow remained mostly light (S1) with short bursts where snowfall increased (S2). We stopped at the top of Lazy Susan to dig, we found 6" of new snow sitting over old weak snow. Despite being just below the ridge this area was not wind-loaded and we found a well-preserved layer of 10-15mm surface hoar. We had no results in stability tests, ECTX HS: 78 cm. During the descent of the ramp we triggered multiple sloughs in the new snow however they did not run far and were not big. 

We toured up into the Maid today to see how conditions were looking. Low snow down low and starting to stack up in the basins. We dug a pit on a East aspect at 9500, the pit showed a 100cm deep snowpack. Large facets were found from the ground up to 40cm. There was a hard crust layer at 40cm, above the crust layer was a dense slab that hasnt turned completely rotten yet. The snowpack was dense above the crust layer, but less consolidated towards the surface (upside down). We had an ECTN 21 at 40cm. We also observed numerous wind slabs that relaeased naturally during the day on N-NE aspects near ridgelines (6-12 inch crowns). We also found touchy wind slabs on micro terrain lower in the basin. 

Rode up the Taylor Fork today. Broken sky at the trailhead, quickly moving to overcast and then snow (S1) by 10-10:30. Sustained strong winds from the S. HS 80-120cm at 9200’, entirely facets capped by varying thicknesses of slab- 2-30cm thick. Widespread large surface hoar in protected areas. 
Slabs were touchy, no other signs of instability noted but vis was terrible. Good riding at upper elevations in sheltered zones. Road is a terrifying mix of whumps, rocks and ice.  

We rode into Buck Ridge toward McAtee Basin, partly cloudy with no snowfall during the day, but 1-2" from yesterday's storm (01/05). The wind was calm in the morning but quickly increased by early afternoon. We dug at First Yellow Mule on a northwest-facing slope at 9400', HS: 74 cm, ECTN 24 on faceted snow 37cm above the ground. In the upper portion of the snowpack was a layer of well-preserved surface hoar covered by snow that fell on the days before Christmas. Near the top of our snowpit, we found another surface hoar layer that was capped by the most recent storm. We continued to the top of Second Yellowmule and dug again on a similar aspect and elevation and had similar test results. (HS:87cm, ECTN 24 45cm above the ground). Both layers of buried surface hoar were present here as well. 

In Second Yellowmule, we saw a natural avalanche that was 10-12" on a wind-loaded north-facing slope along with several smaller loose snow avalanches along the same face. On wind-loaded test slopes, we found that recently formed wind drifts were easily triggered. In areas that were missing a wind-slab loose snow avalanches were still sensitive to triggers. These avalanches would start in the new snow but entrain the weak faceted snow below resulting in larger avalanches than what recent storm snow could produce on its own. 

In McAtee Basin on another test slope, remotely triggered a test slope, which broke on a layer of buried surface hoar 4-6" deep.  Around the corner, we found another recent avalanche, 6-8" deep, that likely broke as we approached it from the top. 

The wind blew through the majority of the day and while exiting our previous tracks had been blown over in some areas and active wind loading could be seen. 

Photos and Video coming soon!

No new/different signs of instability in the snow pack from the forecast or observing other skiers and poking around in the basin. Snow pack is between 1-2 feet from trail head to 9200 ft, 95% faceted and the rest surface hore or the trace of new snow. The pack is 100% rotten. With no slabs there wasn’t any propagating but with a heavy ski cut two of the point releases were triggered and the third when skiing. All three went to the ground. All triggered after the first skier made no impact on the slope, no visual signs or “poor” test results. A reminder how poor the snow structure is this year.

Gusty winds were transporting snow into drifts that formed cohesive wind slabs. Variable snow condition with a notable sun crust under the drifted snow (45.44653, -110.99872). Witnessed a dry slab natural avalanche start from near the summit of Blackmore mountain that ran into the main bowl. Multiple other observations of small loose avalanche activity on Blackmore mountain. The trail out was exceptionally rocky.

From email: "Made it to the ridge of Hyalite peak yesterday. Mild winds ~10mph at around 1pm. Seemed to be ~6" of fresh snow in the basin. No instabilities in our pit at 9300ft; fist hardness throughout. 85cm depth. Great skiing in the basin. Off the ridge, it was a little firmer with a wind crust. There was a small natural wind slab avalanche on an east aspect a few hundred feet SW of the saddle."

Observations and an old natural avalanche from a skier on 01/05. 

Hey y'all! Not sure if this has been sent into y'all or not but thought I'd send it your way. Didn't get up to it, I'd guess a couple days old? At first I thought wet slide but then looking at the trees to the left I thought maybe it was a small crown? None the less enjoy! It's just up Basin from hidden gem on the sameish aspect.

Toured out to the playground and found isolated areas of instabilities. Some areas out of the trees had shallow 1-3 inch thick slabs which failed on isolation in quick hand pits but did not appear to propagate in ECTs. No shooting cracks or big collapses were observed. The good skiing in the tress would probably improve Doug's Attitude.

Surface Hoar all over including just below the new dusting of snow. Test on a northeasterly facing slope at 8000ft, had an ECT N at about 20 hits. It failed on a crust approx 10-15cm off the ground. 

We were the first to arrive at the bottom of Lulu Pass this morning and observed 3 natural avalanches on E and NE aspects of Henderson Mountain. The turn off from HWY 212 towards Lulu pass had received 4-6in of low density snow the night before, the bottom of Henderson Bench had only received 2-3in, but some areas on the trail had pockets of blown in snow around 6in deep in drifts. Hand pits quickly showed that the new snow was sitting on our thin base of faceted snow and surface hoar. The avalanches appeared to release from small cornice collapses on the ridge of Henderson Mountain. 

Toured on a lower shoulder on the east side of Cedar Mtn from approx 8600-9600 ft. We found a little bit more of a supportable slab than we've been seeing on other recent field days (Taylor Fork, Bacon Rind, Beehive Basin) but still not enough slab cohesion for propagation in Extended Column Tests. Dug five pits between 9000 and 9500 ft on SE, E, and N aspects - got a mixture of ECTX and ECTN results. Snowpack ranged from 1-2.5 ft deep. The snowpack was generally supportable on skis, but stepping out of skis we plunged to the ground. Light snow fell throughout the afternoon with little accumulation.