Regional Conditions for Bridgers

Small fresh wind slab crowns below ridgeline in the Northern Bridgers. Photo: G. Antonioli

Wind loads were easy to trigger. This one was triggered on purpose up Maid of the Mist in Hyalite. Photo: A. Peterson

Wind slabs were easily triggered. Although small in size, they indicate that larger slopes would have larger avalanches. Photo: A. Peterson

Strong winds on Tuesday (12/4) drifted recent low density snow into thick slabs at ridgelines, and mid to lower elevations in the Bridger Range. Photo: GNFAC

Strong winds on Tuesday (12/4) drifted recent low density snow into thick slabs at ridgelines, and mid to lower elevations. Photo: GNFAC

From some skiers: "We encountered veey localized loading that easily fractured and propagated uphill on a south aspect." Photo: S. Reinsel

From some skiers: "We encountered veey localized loading that easily fractured and propagated uphill on a south aspect." Photo: S. Reinsel

From e-mail: "triggered a small wet slide in the Going Home chute coming back into Beehive, and we observed another natural wet slide on a similar aspect that had occurred since we toured past in the morning. Wind was light or calm all day and wind effect was minimal even at ridgelines." Photo: C. Kussmaul

We observed this old avalanche on Sunday 12/2. It may have broke up to a week prior, on weak facets that formed in mid-November. Photo: GNFAC

We observed this wind slab and debris on Sunday (12/2). It likely formed from the new snow and wind on Saturday morning. Photo: GNFAC

We observed this wind slab crown on Sunday (12/2). It likely formed from the new snow and wind the Saturday morning. Photo: GNFAC

Steep, wind loaded slopes had fresh drifts, 6" deep and 10-30' wide that were easy to trigger on Saddle Peak (12/1). Photo: GNFAC

Cracking of fresh drifts was a sign that avalanches were likely on steep, wind loaded slopes on Saddle Peak. Photo: GNFAC

This avalanche was triggered by explosives at Bridger Bowl. It illustrates the depth of the wind slabs to be on the lookout for. Photo: BBSP

From an email: "We did observe a natural slide at around 8300ft that failed on the high pressure facets that formed prior to these last two shots of snow. It appears that it was triggered by a slough from steeper, rocky terrain above, the crown was about 14 inches deep and around 50ft wide, in complex rocky terrain. The debris pile was approx. 200cm deep, plenty deep to bury a person." Photo: A. Pohl

From an email: "We did observe a natural slide at around 8300ft that failed on the high pressure facets that formed prior to these last two shots of snow. It appears that it was triggered by a slough from steeper, rocky terrain above, the crown was about 14 inches deep and around 50ft wide, in complex rocky terrain. The debris pile was approx. 200cm deep, plenty deep to bury a person." Photo: A. Pohl

From an email:

"We did observe a natural slide at around 8300ft that failed on the high pressure facets that formed prior to these last two shots of snow. It appears that it was triggered by a slough from steeper, rocky terrain above, the crown was about 14 inches deep and around 50ft wide, in complex rocky terrain. The debris pile was approx. 200cm deep, plenty deep to bury a person."  Photo: A. Pohl

Snow water equivalent at SNOTEL stations in the GNFAC advisory areas for the 18-19 season to date. Weak layers formed on the surface of the snowpack during the dry weather (flat section of lines), then they were buried by the recent 10-14" of snow (steep increase at end of graph). Image: GNFAC

Skiers saw this natural avalanche near Mt. Blackmore on Saturday (11/24). Almost a foot of new snow fell and buried weak snow that formed on the surface of the snowpack during cold and dry weather. Be cautious of avalanches breaking at this weak interface for a few days and with the next storm. Photo: M. Staples

Winds over the weekend are growing the Bridger Range's cornices. Photo: T. Hoefler

Strong winds in the Bridger Range formed dense slabs on leeward slopes. Yesterday, A skier north of Bridger Bowl triggered multiple wind slabs near the top of Wolverine Bowl. The skier turned around and chose a safer objective. Photo: S. Whitefields 

Climbers triggered this very small wind slab on the way to a climb up Flanders in Hyalite (11/11). A tiny slide to a skier can be bad news for a climber since losing one's balance or getting pushed off a cliff can be deadly. From an email (edited):

Photo: S. Magro

From an email:

"By and large right side up snowpack. Some small facets below the 11/1 ice crust at the ground, but well bonded snowpack overall. Pit observations consistent with hand pits dug throughout the day touring north out of Bridger Bowl." Photo: M. Zia

From an email: "ECTP 5 at the top of a chute on the south face of the Texas Meadows knob. Propagated on a layer 15cm from the top of the snowpack." Photo: J. Zimmerer

From Instagram:

"Careful out there this year! While we are lucky enough to have a mostly stable snowpack here in Southwest Montana, we did just find this little wind slab well below the ridge line in Middle Basin. Slowboarder was fine" @chartierk

A skier found 80 cm of stable snow on an east facing slope at 9200' in Beehive Basin. Winds created these newborn cornices along the ridge. Photo: T. Allen

From e-mail: "Was descending off of Zach Attack tonight and set off a small slab in the gully on the decent. This was about 100 meters below the start of pitch 1. Constant whipping winds and lots of new deposited snow likely caused the slab to form. Climber caused. Didn’t carry me as it was small. Would be wary of the mummy cooler gullies abover scepter as well."

From e-mail: "Was descending off of Zach Attack tonight and set off a small lab in the gully on the decent. This was about 100 meters below the start of pitch 1. Constant whipping winds and lots of new deposited snow likely caused the slab to form. Climber caused. Didn’t carry me as it was small. Would be wary of the mummy cooler gullies abover scepter as well."

From a tour up Miller Creek: "Good stability and structure found overall.  No collapsing nor cracking experienced, minor wind effect, and only some minor point release avalanche activity noted on the east aspect of Crown Butte." Photo: B. Fredlund

Natural wind slab that broke after 3-4 feet of new snow over 6 days. Photo: B. VandenBos

Natural avalanche activity was widespread in Hyalite on Tuesday 11/6. Obs from e-mail: "The newest snow (about 18", I'd guess past 48hrs) is touchy soft slab. The top 8 inches also exhibit a storm slab-like quality.  There appears to be a very slight density change between the two.  Top 8" fracture and propagate cracks readily on gentle terrain, whereas in steeper terrain, the deeper slab (again, about 18" down) was propagating as I was skinning up the headwall in the steep creek drainages and steeper features nearby. Lots of natural activity on steeper terrain, but vis was limited. Photo: G. Antonioli

Natural avalanche activity was widespread in Hyalite on Tuesday 11/6. Obs from e-mail: "The newest snow (about 18", I'd guess past 48hrs) is touchy soft slab. The top 8 inches also exhibit a storm slab-like quality.  There appears to be a very slight density change between the two.  Top 8" fracture and propagate cracks readily on gentle terrain, whereas in steeper terrain, the deeper slab (again, about 18" down) was propagating as I was skinning up the headwall in the steep creek drainages and steeper features nearby. Lots of natural activity on steeper terrain, but vis was limited. Photo: G. Antonioli

The Bridgers got 30-40” of new snow in the past week. It came in warm and dense, and it is bonding well to the old snow. Natural Avalanches broke 6-8” deep in the new snow today. This instability will heal in a day or two. Wind loaded slopes, where new snow is drifted into fresh thick slabs, will be the most likely place to trigger avalanches the next few days. Photo: GNFAC

From the MSU Backcountry Club Instagram page:

Warning! This is a current, fresh, crown in the northern Bridgers! Every aspect had a visible crown and avi debris! This crown was 56cm at it deepest and over 8 meters long. ECTP21@53 and CT24@54 on the overlying slab. Photo: @msubackcountryclub More Details.

This avalanche was observed on the morning of Friday 11/2. It broke from a natural trigger in the Big Couloir at Big Sky Resort. New snow fell and was drifted into slabs overlying older, hard layers of snow from October. The resort is not open and no people were in the area of the avalanche at that time. Photo: Big Sky Resort More details

POWDER BLAST
26 October 2018

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Wet slab avalanche in the Centennial range. Multiple days without freezing created widespread wet slides last week (5/6-5/11). Photo: @waxeman