Snow Observations List
We rode out Lionhead Ridge and around the north end to the head of Targhee Creek. Skies started overcast, but cleared through the day as wind calmed from moderate to light out of the west and southwest.
There were zero recent large persistent slab avalanches, and there were two or three shallow small wind slabs below Lionhead Ridge. The snow surface became moist, but crusts from previous warm days and cold night only softened slightly. There was very little, if any, wet snow avalanche hazard today.
We dug at the top of Lionhead Ridge on the south side of Airplane Bowl. 9,300', NE aspect. There was a 2.5' deep very hard slab (1f to P+) above soft facets (4F-), snow depth of 5 feet. We had ECTX, but with extra hits and some removal of the slab it propagated with a clean break. The persistent slab avalanche problem is becoming more stubborn, but not going away. For now it is not likely, but there is probably an isolated slope where you could trigger an avalanche, and we could see this problem arise again with more snow next week.
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We skied to Flanders Mountain, traversed the ridgeline, and dropped into the northwest-facing terrain near the Winter Dance Buttress down to the Main Fork. Ridgelines had moderate to strong winds but minimal transport as snow at upper elevations had already moved or had hardened with recent wind and warm temperatures. Wind Slabs that we assessed were stubborn to unreactive, but there is probably one out there that could result in a small avalanche. No signs of dry snow instability during the tour or in our snowpack assessments (Flanders Bowl - ECTN Teens and 20s and Near Winter Dance Buttress - ECTN Teens and 20s). Snow surfaces were warming (wetting) in south-facing terrain and on all aspects below 8000' by 3 PM. However, we did not see any natural wet snow activity.
I would be watching out for isolated wind slab instability and wet loose avalanches for now.
Full Snow Observation ReportLOW Danger.
Somewhat fresh looking slab avalanche in upper Storm Castle Creek on an East facing slope. Looks like there might be a wet loose slide to the right of it as well. One small wet loose avalanche, probably from yesterday, in Maid of the Mist bowl.
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Expected to find a different snowpack in the area southwest of Cooke/Silvergate, but once again we found deep (HS 235cm), strong, stable snow.
Digging more than a foot or two into the snowpack is a chore. Even the north-facing snow below 8000' is incredibly dense and supportive.
It seems like recent warm weather really helped consolidate the snowpack.
Don't take this good stability for granted - Even though the snowpack is generally stable, there is still trouble to be found in more consequential terrain. In one area, we did find some upside-down snow. It seemed stable, but in very steep terrain, even a small pocket releasing can cause trouble. We also witnessed a falling cornice today that washed some snow through rocks. Be aware of what's above you.
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From obs: "We found up to a 6” deep wind slab producing shooting cracks at Goose Lake on a NW facing slope at 10500ft."
Full Snow Observation ReportToured into Ainger Lake Basin in the Northern Bridgers today. From the Shafthouse Trailhead we could see debris from past wet snow avalanches coming from Ainger Peak and Hard Scrabble Peak area. The slide in Ainger Lake Basin must have been at least a few days old as the slide path and debris were covered in new snow from the last snowfall. The evidence of multiple slides we saw in Ainger Basin looked like they came from rocks shedding snow in the warm weather we've been having. Our objective was the middle couloir on Ainger Headwall. It was very windy in the basin. The slope above Ainger Lake Basin that we had to cross to get to the couloir was heavily wind loaded. We toured up and the snow felt stable so I decided to slowly skin out to see how the snow on this slope felt. It quickly became hollow sounding and we turned around and got a couple laps in for the day from there. Up high in the basin sun baked slopes that froze over night were very slick and hard with a couple inches of new snow on top making skinning difficult in places as well.
Full Snow Observation ReportWidespread wind effect in the alpine of Hyalite yesterday. The windslabs were fairly stubborn however, and were only breaking in very small pockets, not propagating outwards. Where the recent snow was still protected from sun and wind, large dry loose slides were easy to trigger.
Full Snow Observation ReportWe rode from Battle Ridge and skied up the east face of The Throne to look at the stability of the recent new snow.
There was 6" of low density snow from yesterday. Winds were stronger than expected, from the north at the top of the Throne, and increased through the morning.
We found fresh drifts that were reactive, cracking easily and 5-10' wide out from our skis, on south and east facing slopes around 8000-8300'.
The new snow was low density and sluffed easily on steep shady northerlies. On steep slopes facing the sun (south and east, and probably west) the new snow sat on a crust and became moist as the sun warmed it up and started to slide under skis. We saw a couple very small natural loose snow slides below rock outcrops on south facing slopes. Air temperatures were well below freezing, especially with wind chill, but the sun quickly warmed the recent new snow.
It is spring, in addition to assessing for unstable drifts of snow, plan for wet snow avalanche hazards to increase in likelihood throughout the day when the sun is out and temperatures are near or above freezing.
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Rode to the wilderness boundary and skied a lap above Goose Lake. Dug in two places - all hard, dense, strong, deep snow
Rode above Goose Creek. Dug in two places along the very steep, north-facing slopes above the creek. Same. All hard, dense, strong, and deep snow. Facets from late January are buried about a meter deep and 1Finger+ hardness.
We were digging about 700 feet above the two persistent slab that were avalanches triggered on Feb 24th (about a week and a half ago). We didn't see any indication that that is a widespread problem. We didn't see any recent avalanches either.
Digging down to the late-January facets was a pain in the a$%. It seems like when it's becoming a pain to dig down to a weak layer, it's usually not much of problem anymore.
Full Snow Observation ReportDanger seems LOW
Looks like a recent naturally triggered slide towards the Idaho wilderness boundary on lionhead.
GNFAC note: This slide occurred on Feb 28th (previous observation)
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Multiple natural loose avalanches in the steep terrain of mt Blackmore. All originated at the base of cliffs or trees. Counted 4 prominent ones
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We toured from the dam up the north ridge to Trapper. Light snow fell throughout the day, adding up to about 6". As we descended the east-facing bowl, cracks shot out from our skis on slopes with a subtle wind effect. Avalanches within the new and wind-drifted snow were likely, but the volume would have been relatively small and mostly concerning in technical terrain or in the presence of terrain traps. There was a new facet layer below the melt-freeze crust. It is TBD if it will be a problem.
The other problem is continued concern about avalanches breaking 2-3 feet deep on weak layers formed during the January dry spell. The snowpack structure is weak in this area, similar to the slopes that most recently produced human-triggered avalanches in Cabin Creek, Tepee Basin, and Lionhead. Pole probing indicated this poor structure was widespread. Our pit at 9000' on a northeast-facing slope yielded an ECTP28 on the 4F- facet layer formed in January. Failures on these deep layers don't seem very likely, but, for now, step back from steep terrain to let the storm play out. Once the storm ends, we will reevaluate stability and proceed from there. While the actual likelihood is debatable, the consequences of getting caught in a slide breaking on these weak layers are not.
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No Recent avalanche activity observed in Hayden Creek or Republic Creek today with the the exception of some small dry loose in steep terrain. No Collapsing or Cracking during our day out today. 2" new at 8700' at 9am with another inch throughout the day. East winds were light throughout the day.
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Toured into the emigrant gulch area today. At around 7600’, I found some touchy storm slabs. These only seemed to be reactive on solar aspects (crust). Near a ridge line, the winds were coming from the east, it was weird. Socked in all day with lots of snow flying around.
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8-12 inches of new snow on the ground in the Centennials near Nemesis mtn. New snow that fell early this morning was very touchy on hard/icy surfaces from the melt/freeze activity we saw the prior days.
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Observed some cracking in wind drifted snow above tree line NE facing slope. No avalanches observed
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Came across a old slide in the hell roaring drainage heading towards Gallatin. East facing. Happened sometime before the recent snow but not long ago. Initial crown seemed to be 12-18 inches and stepped down further down the slope. Was a fairly large debris pile.
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Saw lots of small loose avalanches on Mt Blackmore and nearby slopes, some appeared to be natural and others skier triggered. We saw multiple dry loose on N and E aspects and a wet loose on a southeast aspect.
We also noticed recent wind loading on the southeast side of ridgetops and scouring on north slopes.
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Old Avalanche spotted from Wilson yesterday looking North. Possible cornice fall trigger during the warm up but difficult to tell as it was quite a ways away. Photo attached.
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