On a cold day we rode to Frazier Basin and quickly answered the question, “Are wind slab avalanches still possible or have they stabilized?” We saw a natural avalanche (R2, D1.5) that released on a steep headwall just to the south (I believe I’ve heard this referred to as October Bowl). Photo: GNFAC
On a cold day we rode to Frazier Basin and quickly answered the question, “Are wind slab avalanches still possible or have they stabilized?” We saw a natural avalanche (R2, D1.5) that released on a steep headwall just to the south (I believe I’ve heard this referred to as October Bowl).
Wind has affected most of the snow above forested terrain in some fashion. While most soft snow has already been redistributed, some transport continued. We looked at skiing Thing Two but the wind slab problem and poor skiing quality deterred us. I did dig a pit with an ECTP11 breaking 5” down below the slab. Surfaces had hardened and I suspect terrain would have to be pretty steep for an avalanche to release (this type of steep terrain is abundant in Frazier).
We departed Frazier area without skiing and went to look at lower elevation terrain above the Carroll Creek Road. The wind had gotten to the snow here as well but no signs of instability and an ECTN15 18” deep. Triggering an avalanche outside of wind loaded terrain is unlikely.
<p><span><span><span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are the primary avalanche problem. Old ones from about three days ago have likely stabilized but new ones formed overnight and should be easy to identify today. Winds have mostly been blowing from the west and will blow from the south today. Look for freshly wind loaded areas and avoid them.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Dave spotted a fresh naturally triggered wind slab yesterday in the northern Bridgers and discusses this issue</span></span></span></span></span></span><a href="https://youtu.be/2svWLeG9wLU?feature=shared"><span><span><span><span><s…; in this video</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>. Some weakening or faceting occurred on the snow surface the last few days, and fresh wind slabs could be resting on that weak snow making them especially touchy.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Today the avalanche danger is MODERATE on wind loaded slopes and LOW on non-wind loaded slopes. HEADS UP - the size, depth, distribution and sensitivity of wind slabs will be increasing today.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Wind slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> are the primary problem resulting from increased winds from the west yesterday and this morning. Today winds will increase a bit more and shift to the south. The size, distribution, and sensitivity of these wind slabs will increase throughout the day. Identify areas with fresh drifting and avoid them.</span></span></span></span></span></span></p>
<p><span><span><span><strong><span><span>Persistent slab avalanches</span></span></strong></span></span></span><span><span><span><span><span><span> remain on our radar because there is a widespread layer of weak, faceted snow that formed in late January. This layer is buried 1-3 feet deep and seems to have been unreactive in recent days (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/34085"><span><span><span><span><span><… ob</span></span></u></span></span></span></span></span></a><span><span><span><span><span><span>). Wind loading and snowfall this weekend will make this layer more of a concern. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Near Cooke City, there appears to be a weakness 1-2 ft deep near a layer of dust that was deposited on the snowpack just over a week ago. This dust layer is easy to see in a snowpit wall, and it only takes a few minutes to perform an extended column test on this layer.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Today the avalanche danger is MODERATE. Heightened avalanche conditions exist with fresh wind slabs and buried weak layers. HEADS UP - every danger rating covers a range of conditions, and I expect the danger to be creeping up today</span></span></span></span></span></span></p>
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Dug a pit and did an ECT near the NE entrance to Yellowstone. I dug at 9500ft, W aspect, on a 29 degree slope. HS 275cm. I got an ECTP12 55cm down, right above the obvious layer of dirt. Moderate winds from the west.
Moderate winds today north of Cooke City. Stronger winds than forecasted and lots of snow is being transported. Couple hand pits showed planar breaks on a crust on SW aspect around 9600 ft.
Explored slopes in lower Hyalite Canyon between 6000-7000 ft in elevation. Really close to being skiable and good. Otherwise, we found snow depths ranging from 6 inches to 2 feet. Generally very weak and faceted with thick crusts on slopes with a southerly tilt. All this weak snow probably won't be an issue because this area only gets the scraps from storms and never has enough loading to make an avalanche problem.
7 to 13 degrees warmer but temps still below 0F
Cold temps and sunny days starting to create some surface hoar forming seen on the primary ridge of big Ellis. Surface hoar was less widely distributed on the primary ski zone but was present all along the top of the ridge. Photo: K Gordon
Cold temps and sunny days starting to create some surface hoar forming seen on the primary ridge of big Ellis. Surface hoar was less widely distributed on the primary ski zone but was present all along the top of the ridge.
