Regional Conditions for Northern Gallatin

Main Fork of Hyalite 3/27.

From obs: "This slide popped on a N aspect at 9000', ranging from 18-30 inches deep... it slid on a crust." Photo: N. Iltis

From obs: "Later in the day we ran across what we assume to be a remotely triggered avalanche from another party in the area. There were two sets of tracks on the adjacent slope with cracks visible on the slope. The avalanche occurred on a 40* east aspect at 9250' and failed on the MFcr/FC dn 35cm. We looked at the crown profile, and the structure was very similar to what we found on souths. 35cm of F->4F PP/DF overlaying MFcr/FC. We did an ECT on the crown and it failed on isolation. Skiing out the trail with better light than in the morning, we saw a number of similar avalanches confined to east aspects on steep 40*+ rolls and presumably failing on the persistent grains above the crust." Photo: E. Coba

In the Bridger Range, avalanches released naturally on a density change in the new snow sometime Tuesday night (3/24). Photo: E. Knoff

In the Bridger Range, avalanches released naturally on a density change in the new snow sometime Tuesday night (3/24). Photo: E. Knoff

Snowfall throughout the afternoon fluctuated between S1 - S5 (during brief squalls). The winds started out moderate and from the west but calmed by the last lap ~5 pm. The new snow (from last night/this morning) was fairly well bonded to the sun/melt-freeze crust below, but the storm came in subtly upside down. Today’s snowfall (accumulating ~3” while skiing between 1-530) was light. Right along the ridgeline, we triggered 4 predictable small storm slabs 4~6” deep on the upside-down storm snow from last night/this morning, but surprisingly not on the old crust. They were each 5-10m wide x 5m long and only ran ~5m vertically. Photo: Z Miller

This is a photo of a small roof avalanche near Island Park. Warming temperatures cause water to percolate through the snow which lubricates the sliding surface. Roof avalanches have injured and killed people in the past, just one more thing to worry about. Photo: M.E. 

Dave Zinn digs a hand pit along the ridge to assess how the new snow is sticking to the ice crust. Photo: GNFAC

Obs: "School bus size cornices over Easterly portions of Lionhead Ridge. It is hard to tell from the photo, but the largest cornices were about 20-25' tall. We dug a few pits on East Facing slopes between 9,000-9,500 ft with the worst result being an ECTN-21 however these Cornices are primed and ready to fall with the abundant sunshine and warming weather." Photo: JR

From e-mail: "Natural wet slides... caused us to back off our plan of heading that way and ski a north, shady aspect instead. On a southern aspect. 9000ft. 1:30pm. We dug a hasty pit and observed a weak layer about 1m down. The facets were beginning to round." Photo: K. Master

From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill

From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill

From south of Big Sky yesterday 3/17 about 9:00, just north of Buck Ridge at 8500'. Large surface hoar on northerly aspects. Photo: Spence

We dug near the top of Bacon Rind and found 155cm of snow. Our primary concern is with the upper snowpack. As it warms and wets we can expect an increase of avalanche activity on the ice crusts. Facets are still dry and soft at the bottom of the pack and I got this layer to break with an ECTP29. Photo: GNFAC

From the Blackmore/Elephant saddle, I observed what looked to be a less than a day old cornice break which triggered a loose wet slide in front of it. The cornice debris was large, about the size of a VW beetle. I also observed some surface hoar on the north side of the saddle. Photo: B. Gordon

Spencer Jonas, GNFAC intern, in a snowpit in Beehive Basin. We found over 6 feet of snow and just dug our the top 4 feet to assess the stability. The new snow is bonding well and there were no signs of instability. Photo: GNFAC

Cornices have grown rapidly in the last few days. These will be susceptible to breaking and could trigger pillows of wind slabs under them. Photo: Bridger Bowl Ski Patrol

Strong wind stripped snow off many slopes above treeline. Photo: GNFAC

This naturally triggered avalanche likely happened Tuesday morning. Strong wind loaded slopes and made huge cornices. Photo: GNFAC

The winds blew the new new into wind slabs that avalanched naturally yesterday. This photo was taken at 9:30 a.m. on Tuesday (3/10) by Evan Schock.

Dry loose avalanches on Blackmore. The snow stayed surprisingly cold and dry throughout the day. Photo: R Rustigian

A falling cornice triggered a large slide in the wet snow on an east facing slope up Hyalite. It was north of Mt. Blackmore and west of History Rock. Photo: R. Parsons

A falling cornice triggered a large slide in the wet snow on an east facing slope up Hyalite. It was north of Mt. Blackmore and west of History Rock. Photo: R. Parsons

A google earth view of the cornice triggered location, 

Photo: R. Parsons

From obs.: "photo of “Avalanche Peak” just south of Lava Lake driving north on HWY 191, all likely from yesterday (3/6)." Photo: S. Jonas

Point releases across highway from Bacon Rind. 3/6/2020.

Photo: GNFAC

Point releases across the highway from Bacon Rind. 3/6/2020

Photo: GNFAC

Wet slide in Buffalo Horn Creek. 3/6/2020.

Photo: A. Norlander

"Saw this avalanche that broke on a NW facing slope around 9300’. Looks to have failed on the facets at the ground ... the crown was 4-5’."

Photo: M. Murray

"Saw this avalanche that broke on a NW facing slope around 9300’. Looks to have failed on the facets at the ground ... the crown was 4-5’."

Photo: M. Murray

Overview of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC

Crown of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. It broke 2-3' deep on weak sugary snow near the ground. It was on a West aspect at 7,500' elev., 100' wide, 600' long. Photo: GNFAC

An avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. The debris piled 8' deep on the road, which creates a terrain trap. Photo: GNFAC

Debris and groomer in an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC

An avalanche was triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC

Looking up the path of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC

Looking down the path of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC

From obs form: "While approaching Black Mountain from Pine Creek Lake.... We skied South aspect and as it warmed we triggered D1 R1 slabs that ran slow and short." Photo: T. Hoefler

From email: "Photo attached of a natural avalanche from yesterday, just south of Cooke City.  It's on an E, NE aspect, with a crown around 9,300'.  Looks like it occurred yesterday am, as a result of a cornice fall." B. Fredlund

Looking up into the gully from the debris of the cornice triggered avalanche. Photo: M. Sebren

Looking north at the crown of the cornice triggered slide in the Hourglass, north of Bridger Bowl. Photo: M. Sebren