Regional Conditions for Northern Madison

The red dashed lines mark the sides of the shallow avalanche that broke on surface hoar. It was triggered by a snowmobiler on 29 March in First Yellowmule (N aspect; 9500'). Photo: GNFAC

We dug this pit adjacent to a snowmobiler triggered avalanche. It broke on the surface hoar layer which is located at the top blue crystal card. The bottom card denotes the larger grains of facets that formed early in the winter. Photo: GNFAC

This surface hoar crystal is almost 1.5 cm (each square is 2mm) and was the weak layer in a few avalanches on Buck Ridge (3/29/20). Photo: GNFAC

There were many tracks in Buck Ridge and only a few small slides in First Yellowmule. This picture is looking SW towards Sphinx Mountain. Feathery crystals of surface hoar are buried 1-1.5' under the surface and are a concern. This layer seems to be more prevalent in protected areas. Photo: GNFAC

We saw this natural avalanche from afar. It was NE aspect and likely failed on a layer of surface hoar 1-1.5' deep. The Madison Valley is in the background. Photo: GNFAC

From obs (3/29/20): "This 44* slope failed 12” under the surface of the snow on a hard crust as we descended to help another stuck rider in a tree. Another layer exists 2” below the failed layer which persisted to follow me down the hill rupturing as fault lines as I continued rapidly down the hill after extracting the stuck rider. While the remaining slope only fractured without chasing me down the hill... "Photo: TJ Krob

Sunday (3/29/20) skiers near Fairy Lake saw this cornice collapse that ran for quite a ways in October bowl. Photo: T. Gittins

From obs. (3/29/20): "Significant wind started building mid morning, forming even bigger cornices and wind loading many slopes. Noticed this slide on an East/Northeast aspect at the back of the bowl above Maid of the Mist creek, possibly triggered by cornice fall but unknown. Happened between 9:45am and 11:30am today, as at 9:30am it was not there, and when we returned to the spot around 11:30am the slide was visible." Photo: CP

From email: "Was up Dudley creek today. Northern madison. Saw 2 step down avalanches on ne aspect high elevation... One ... seemed cornice triggered within 12 hrs of our tour this morning (3/26). The 2nd avalanche is in the lower photo and was probably skier trigger intentional.... It looks like they triggered a fresh wind slab under ridge, maybe ski cut, which stepped down into some older layers"

Photo: L. Frye

Two natural avalanche in Beehive Basin. The obvious avalanche was observed by skiers mid-day. There is another crown in the shadows of an avalanche that occurred earlier in the day.

Photo: J. Caton

From obs: "An avalanche was triggered by a skier on the East facing wall of Beehive Basin. The slide broke on the crust layer from last week. The crown was roughly 100' wide."

Photo: C. Samuels

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

"Was out today and found buried surface hoar 10-15 cms down. Some previous natural activity on this layer on steeper north aspects with very shallow soft slabs, but mostly dry loose at this point. Not much slab formation since the last ppt event. This could be a problem when more snow and wind in the next few days." Photo: T. Woodward

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

Natural avalanche north of Beehive peak, next to North Twin behind the Fourth of July couloir. Looks to have broken on weak layers near the ground. May have been concern triggered. Observed 3/19/2020. Exact timing of release is unknown. Estimated 3/16/2020.

Photo: G. Dittmar

Natural avalanche north of Beehive peak, next to North Twin behind the Fourth of July couloir. Looks to have broken on weak layers near the ground. May have been concern triggered. Observed 3/19/2020. Exact timing of release is unknown. Estimated 3/16/2020.

Photo: G. Dittmar

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

Skier triggered wet, loose avalanche in Dudley Creek (R1/D1). Photo: Anonymous

Natural wet snow avalanche in Dudley Creek. Likely occurred on Monday, March 16th. Reported as a size R3/D3. Photo: Anonymous

Natural wet snow avalanche in Dudley Creek. Likely occurred on Monday March 16th. Reported as a size R3/D3. Photo: Anonymous

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.

Very small avalanches in the new snow at Buck Ridge, seen on the morning of 3/10/2020. These slides were <6" deep and around 10' wide.

Photo: GNFAC

After a jump turn into a ski cut to one of those protected spots, my partner triggered a storm slab about 4” thick that propagated from the edge of our boot pack on one wall of the chute to the other wall about 20/30’ across and then ran the rest of the chute onto the apron about 300’ below us. No one was caught or injured. We skied out of the chute on the crust bed surface and spent the rest of the day enjoying some low angle trees. The chute was around 40° at 9,000’-9,500’ and west facing. Photo: C. Oshiro-Leavitt

After a jump turn into a ski cut to one of those protected spots, my partner triggered a storm slab about 4” thick that propagated from the edge of our boot pack on one wall of the chute to the other wall about 20/30’ across and then ran the rest of the chute onto the apron about 300’ below us. No one was caught or injured. We skied out of the chute on the crust bed surface and spent the rest of the day enjoying some low angle trees. The chute was around 40° at 9,000’-9,500’ and west facing. Photo: C. Oshiro-Leavitt

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 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