Trip Planning for Cooke City Area

We rode up Yale Creek and into Mt Jefferson Bowl. Walking to the edge we triggered an avalanche (intentional) on a slope that was getting wind-loaded. It broke up to 1.5 feet deep, 250 feet wide and 50 feet vertical. The new wind drifts were sensitive to triggering and the slabs propagated wide. Weak layers at the old snow surface may have helped us remotely trigger the slope. The two things to look out for in the Centennials are weak layer of sugary snow or feathery surface hoar in the upper 3 feet of the snowpack and slopes that are freshly wind-loaded.

We rode up Yale Creek and into Mt Jefferson Bowl. Walking to the edge we triggered an avalanche (intentional) on a slope that was getting wind-loaded. It broke up to 1.5 feet deep, 250 feet wide and 50 feet vertical. The new wind drifts were sensitive to triggering and the slabs propagated wide. Weak layers at the old snow surface may have helped us remotely trigger the slope. The two things to look out for in the Centennials are weak layer of sugary snow or feathery surface hoar in the upper 3 feet of the snowpack and slopes that are freshly wind-loaded.

On 2/6/23 there was a small snowmobiler triggered slide on a convex bench between Sheep Mtn. and Round Lake that was triggered this afternoon. It was 1.5-2' deep, 30' wide, and looked to have broke on a weak layer below last week's snow, on a freshly wind-loaded slope. In a relatively shallow, rocky area. Photo: GNFAC

Dug at South facing snowpit at 9700' near the base of a wind-loaded slope, ECTX HS:280. Continued on less than 200' up the slope, the skier breaking trail triggered the avalanche. The third skier in the group of five was caught, carried, and buried to the waist. The crown was 1-2' deep, and 50 feet wide. Location: South of Fisher Mountain. Yesterday triggered a small windslab on a north-facing slope on miller ridge, no one was involved. 

Dug at South facing snowpit at 9700' near the base of a wind-loaded slope, ECTX HS:280. Continued on less than 200' up the slope, the skier breaking trail triggered the avalanche. The third skier in the group of five was caught, carried, and buried to the waist. The crown was 1-2' deep, and 50 feet wide. Location: South of Fisher Mountain. Yesterday triggered a small windslab on a north-facing slope on miller ridge, no one was involved. 

Dug at South facing snowpit at 9700' near the base of a wind-loaded slope, ECTX HS:280. Continued on less than 200' up the slope, the skier breaking trail triggered the avalanche. The third skier in the group of five was caught, carried, and buried to the waist. The crown was 1-2' deep, and 50 feet wide. Location: South of Fisher Mountain. Yesterday triggered a small windslab on a north-facing slope on miller ridge, no one was involved. 

We triggered this very small slide on a steep convex  rollover by mt abundance. South facing. Triggered from on top by snow bike. Was only 60’ wide and didn’t run far at all. About a foot deep.  Some impressive high mark tracks in the area. No other signs of instability today.

A natural avalanche failed during last week's storm near the Goose Lake Wilderness Boundary. Photo: GNFAC

On 1/29/23 we saw a lot of recent natural avalanches which likely ran late on 1/27/23 or the morning of 1/28/23. Photo: GNFAC

On 1/29/23 we saw a lot of recent natural avalanches which likely ran late on 1/27/23 or the morning of 1/28/23. Photo: GNFAC

On 1/29/23 we saw a lot of recent natural avalanches which likely ran late on 1/27/23 or the morning of 1/28/23. Photo: GNFAC

On 1/29/23 we saw a lot of recent natural avalanches which likely ran late on 1/27/23 or the morning of 1/28/23. Photo: GNFAC

On 1/29/23 we saw a lot of recent natural avalanches which likely ran late on 1/27/23 or the morning of 1/28/23. Photo: GNFAC

Several avalanches in the Goose Lake area. Assuming they happened on Friday or Saturday. Photo: J. Mundt

Several avalanches in the Goose Lake area. Assuming they happened on Friday or Saturday. Photo: J. Mundt

Several avalanches in the Goose Lake area. Assuming they happened on Friday or Saturday. Photo: J. Mundt

Recent natural avalanches near Cooke City, observed 1/29/23. Photo: B. Fredlund

Recent natural avalanches near Cooke City, observed 1/29/23. Photo: B. Fredlund

Recent natural avalanches near Cooke City, observed 1/29/23. Photo: B. Fredlund

Multiple natural avalanches were seen on all aspects, all elevations near Woody Creek Cabin. Poor test scores (ECTP) in 4/6 pits, mostly beneath the snow that fell earlier this week, buried small grain facets and decomposing surface hoar. Photo: Z. Peterson

Photo of Castle/Submarine on woody ridge.  This all slid today.  Looked like all chutes along this face and south slid.  Also east facing Republic ridge several slides above rock band. Photo> D. Carroll

Recent natural avalanches observed 1/28/23, very large below Chimney Rock by Daisy Pass. Photo: A. Mulkey

Recent natural avalanches observed 1/28/23, north side of Crown Butte. Photo: A. Mulkey

Natural avy on SE aspect 8000 ft 35 to 40 degrees broke on new snow interface today. YNP next to silver falls. Also several slides in gully below falls. Photo: D. Carroll

A natural avalanche near round lake, Cooke City. Photo: S. Reagan

Surface hoar can often be seen as a grey stripe on the wall of your snowpit as was the case at Bacon Rind in the Southern Madison Range on 1/23. Photo: GNFAC

Observed this cornice fall triggered slide morning of 1/19/23. It was not there the previous morning which was sunny and clear. Photo: GNFAC

We dug five snowpits and performed extended column tests in each on 1/19/23 near Cooke City. Four snowpits were on northeast to north facing slopes between 9,200-10,000', and one pit was on a southwest facing slope at 9,200'. In one pit on a NE aspect at 9,200' we had an ECTP 15 on the surface hoar 35 cm below the surface. In all other pits we had ECTN14-19 at the depth of the surface hoar, and no obvious feathery crystals were visible. The layers where the ECTNs broke appeared to be decomposing, preserved dendrites or maybe decomposing surface hoar. Photo: GNFAC

Observed a point release that appeared to have stepped down. This occurred SE of the “rip curl” zone. We also noticed significant sun effect and a warming trend throughout the day. 1/17/23

East aspect, 10,300.  Estimated to be about 75' wide.  Likely occurred yesterday, Jan. 17th. Photo: B. Fredlund

Avalanches  previously reported on Monday on Miller (photo taken 1/18). GNFAC

Noted a couple of fresh slab avalanches out there today.  Both were on northerly aspects around 9300'.  Photo: B. Fredlund

Avalanche previously reported on Monday on Henderson (photo taken 1/17). GNFAC

A recent natural avalanche observed 1/16/23 (less than a day old) on Miller Ridge. SS-N-R1-D1.5-O and probably broke on the surface hoar layer. Photo: GNFAC

Photo from 1/16/23 of an avalanche on an east-northeast facing slope below Henderson ridge. It appeared to be snowbike triggered and 1-2+ days old. 150' wide and 250' vertical. HS-AMu-R2-D2-O. It appeared to have broke about 2' deep on that layer of surface hoar. Photo: GNFAC

Photo from 1/16/23 of a cornice triggered avalanche on Miller Ridge that broke to the ground, appears to be many days or weeks old. GNFAC.

Dug a pit on the east side of Henderson at the ridgeline above Henderson Bench. ENE, 10,075' elev. ECTP19 x3 on a layer of surface hoar buried 60cm (2 feet) deep. HS 260cm. There was an avalanche a few hundred feet north on an east-northeast facing slope below the ridge. It appeared to be snowbike triggered and 1-2+ days old. 150' wide and 250' vertical. HS-AMu-R2-D2-O. It appeared to have broke about 2' deep on that layer of surface hoar. There was also a more recent natural avalanche (less than a day old) on Miller Ridge, slightly smaller. SS-N-R1-D1.5-O and probably broke on the surface hoar layer. Photo: GNFAC

Snowboarder triggered this slide on a rollover on East Republic. Reportedly ran 80' wide, 1-1.5' deep. No one was caught.

Photo attached of a fresh natural avalanche, just south of Cooke City today.  It appears to have run last night or this morning.  (photographed at noon)

It's on a NE aspect, about 8100', directly above the ice climb known as 'Silver Gate Center'.  I'd estimate the crown to be about 10" deep and 30' wide.

Small slide off the Henderson ridge by the radio hut. Looks to have broken in the last couple days. GNFAC photo. 1/10/2023