Regional Conditions for Lionhead Range

as of 5:00 am
Today2" | 15-25 W-SW
Feb 21 T-1" | 10-15 SW
Feb 20 0" | 10-15 N
8775′     2/21 at 14:00
6 ℉
SW - 12 mph
Gusts 23 mph
7750′   02/22 at 22:00
9℉
73″ Depth
Bottom Line: Dense wind slabs that formed over the past few days remain a concern. These thick, cohesive slabs rest over lower density snow, which is creating an unstable structure. Wind slabs could fail under the weight of a skier or rider and pose the most significant threat in steep-high consequence terrain.

Past 5 Days

Sun Feb 18

Considerable
Mon Feb 19

Moderate
Tue Feb 20

Moderate
Wed Feb 21

Moderate
Today

Moderate

Photos- Lionhead Range

  • Skiers up Mt Blackmore triggered small wind slabs near the ridgelines. These slides were small, but could produce high consequences if triggered in steep terrain. Photo: C. Ronemus 

  • This picture was taken on Monday, February 19, at Lionhead on an east-facing slope. The wind slab was likely triggered by a cornice chunk hitting the slope. Photo: T. Johnson

  • Cornices have grown very large and are severely overhung. They sometimes break much further back than anticipated and can take you for a nasty, sometimes fatal ride. Plus they are excellent at triggering avalanches in the wind pillows below them. This photo was taken on the ridge north of Bridger Bowl. Photo: GNFAC

  • A skier observed large cornices north of the Bridger Bowl boundary, despite the east wind several days ago eroding some snow at higher elevations. Always give these beasts a wide berth, and remember that they can break farther back than expected. Photo: H. Coppolillo

  • Cornices break easily and have killed many unsuspecting people. They fool us into thinking we are on solid ground when, in fact, we are standing on a thick diving board of snow. Give cornices a wide berth.

  • Skiers up Hyalite triggered this cornice on Mt. Bole as they traversed along the ridgeline. The cornice triggered a small slab avalanche that took out the skiers skin track. Cornices are under a lot of stress from this week's snow and wind and should be given a wide distance along ridges. Photo GNFAC 

  • Snow rangers observed this slide on a heavily wind loaded slope along a prominent ridgeline going into Tepee Basin. A good example of windward (scoured) and leeward (wind-loaded/corniced) side of ridgelines. Photo: J. Norlander

  • A skier in Hyalite observed this avalanche in the meadow below Mt. Blackmore. Strong wind over the weekend drifted snow into wind slabs at all elevations. Photo: J. Stewart

  • Cornices are extra large with all the generous snow we've had this season. These monsters and wind loaded slopes are the main avalanche concerns to start the week. On Buck Ridge today, we found 16" of new snow from the weekend's storm. We didn't see any avalanches or glaring signs of instability, and the snowpack is generally stable besides new snow and fresh wind slabs. Photo: GNFAC

  • Surface hoar 1.5-2' deep near West Yellowstone is capable of producing an avalanche, but becoming difficult to trigger. It can be easily identified as a gray stripe on a flat snowpit wall. Photo: GNFAC

  • A layer of 4-9mm Surface hoar crystals are buried 1.5-2' deep in the Lionhead area near West Yellowstone. (3mm grid) Photo: GNFAC

  • Avalanche triggered by snowmobiler on Saturday (2/10). Rider was not caught. This terrain is prone to heavy wind loading along the edges of the ridges that run down slope. Photo: J. Schmid

  • Avalanche observed Friday 2/9 around 8,800' on a southerly aspect. Likely snowmobile triggered. Photo: L. Richards

  • Eric Knoff and Doug Chabot talk about how steep a slope you need to dig a pit on to get good data. The answer is, "Not that steep".

  • This small slide was observed by snowmobilers in the Lionhead area near West Yellowstone. Small slides are a clear indicator that larger slides are possible. Photo: L. Read. 

  • Check out this blog post by Evelyn Lees at the Utah Avalanche Center on “Avalanche Fatalities During Uphill Travel.” One third of tourers die on the ascent, a surprisingly high statistic. Photo: C. Pruden

  • It feels good to be living in the snowy "Haves" vs. "Have not" group. Look at the blue squares clustered in southwest Montana. We have over 125% of average snow water content and Cooke City has over 150%! Whoop, whoop.

  • A layer of surface hoar was buried with this last storm. It is easy to find it and test; just shovel down 1-2 feet and cut a column. I could see the grains in my pit wall, but it did not break in Compression Tests or Extended Column Tests. This is good news, but it's distribution and stability is not definitively known yet. We will continue to look for it and test it. Photo: GNFAC

  • A layer of surface hoar was buried by the recent snowfall (1/19) at Lionhead. This layer was observed through most of our advisory area prior to this storm, and should be searched for by digging 1-2' deep before riding in avalanche terrain. Photo: GNFAC

  • This small slide is in the burned area of Taylor's Fork. Riders were traveling below a wind-loaded slope when they remotely triggered it. Photo: M. Gagne

  • A snowmobiler remotely triggered this slide in the Lionhead area near West Yellowstone. Heavy snow combined with a weak and unstable snowpack is creating very dangerous conditions in the Lionhead area. Photo: L. Read

  • More snow = more avalanches. Graphic is snowpack change in inches of water since 10/1/17. The storm that ended Saturday is the steep increase at the end of each line. Large avalanches were triggered during and after that storm and remain possible for a few days.

  • Triggered by snowmobiler on 1/14. One other slide was observed nearby. Very dangerous, unstable avalanche conditions exist in the Lionead area and surrounding mountains. Photo: L. Read

  • This 2-4' deep slide was triggered by snowmobilers from lower angle terrain within the trees below the slope (1/13/18). Photo: L. Read

  • From an email today: "I’ve never observed so much cracking and settling as I have today. All aspects, all elevations. Even on southerly exposures with minimal snow depth. The picture shows failure on top of the Thanksgiving crust. This was in West Fork Denny Creek about 7500 feet." Photo: B. Rasmussen

  • King and Queen of the Ridge, Saturday, February 3rd. A Hike and Ski/Ride-a-Thon fundraising event to support the Friends of the Gallatin National Forest Avalanche Center. Sign up and start collecting pledges HERE.

  • Weak facets buried mid pack continue to produce unstable results in stability tests around Lionhead. With more snow and wind in the forecast, this area will likely see more avalanches. Photo: GNFAC 

  • Ace Powder Guides found the layer of facets is getting stronger compared to last week, but slowly. They were riding around Middle and Upper Teepee Creek and did three Extended Column Tests and got ECTP 13, 15, 15 which indicates instability. Photo: B. Radecky

  • The crown was a 2-4 feet deep hard slab and 300 feet wide. Photo: GNFAC

  • The crown is visible at the top of the slope. The rider was carried 25 feet and buried under his snowmobile, 3 feet from the surface. Photo: GNFAC

  • The slide ran 600 feet slope distance and was 36-40 degree steep. Photo: GNFAC

  • The group triggered this small slide (10' wide) on a nearby hill. They recognized it as a sign of instability and decided to not highmark or play on big slopes. They made many correct decisions, but were unlucky. Photo: GNFAC

  • Alex Marienthal stands near the 2-4 foot thick crown. The bed surface was an icy mass on the ground. Photo: GNFAC

  • Surface hoar is growing in many areas which may be a future weak layer. Photo: I. Hoyer

  • This natural slide was observed in Tepee Basin in the southern Madison Range. Heavy snow and a weak snowpack structure are producing very dangerous avalanche conditions. Photo: B. Radecky

  • This slide was triggered by a snowmobiler in Tepee Basin in the southern Madison Range. The slide occurred on a SE facing slope and likely failed on a layer of facets. The combination of heavy snow and a weak snowpack are creating very dangerous avalanche conditions. Photo: B. Radecky

  • The avalanche failed on a thick (10cm) layer of facets that were sitting on an ice crust. The slide was a natural soft slab avalanche that broke with just a few new inches of snow and wind. Photo: D. Zinn

  • Doug and some riders from ND and Manitoba check out a natural avalanche that happened yesterday at Lionhead. The slide was 2 feet deep and 400 feet wide. More snow in the next two days will definitely produce more avalanches. Photo: D. Zinn

  • West of Sliver Creek, to the west of Cooke City a skier triggered a soft slab avalanche that was wind-loaded with the storm snow. The slide was south facing at 9,000 feet at an abrupt change in the angle of slope (prob 38-40 degrees). Nobody was caught. Crown was 50-60 cm, and propagated out to the adjoining slope,150' wide and 300' long. Photo: Anon

  • West of Sliver Creek, to the west of Cooke City a skier triggered a soft slab avalanche that was wind-loaded with the storm snow. The slide was south facing at 9,000 feet at an abrupt change in the angle of slope (prob 38-40 degrees). Nobody was caught. Crown was 50-60 cm, and propagated out to the adjoining slope,150' wide and 300' long. Photo: Anon

Weather Forecast Lionhead Range

Extended Forecast for

10 Miles WNW West Yellowstone MT

  • Tonight

    Tonight: Isolated snow showers after midnight.  Patchy freezing fog after midnight. Mostly cloudy, with a low around 2. Wind chill values as low as -8. South southwest wind 5 to 8 mph becoming light and variable  after midnight.  Chance of precipitation is 20%.

    Isolated Snow
    Showers and
    Patchy
    Freezing Fog

    Low: 2 °F

  • Friday

    Friday: A 20 percent chance of snow showers.  Patchy freezing fog before 9am. Partly sunny, with a high near 14. Wind chill values as low as -8. Light and variable wind becoming west southwest 5 to 10 mph in the afternoon.

    Slight Chance
    Snow Showers
    and Patchy
    Freezing Fog

    High: 14 °F

  • Friday
    Night

    Friday Night: A 40 percent chance of snow showers.  Mostly cloudy, with a low around 2. Wind chill values as low as -13. South southwest wind 11 to 15 mph, with gusts as high as 20 mph.  New snow accumulation of less than one inch possible.

    Chance Snow
    Showers

    Low: 2 °F

  • Saturday

    Saturday: Snow showers likely, mainly after 11am.  Patchy blowing snow after 11am. Cloudy, with a high near 15. Wind chill values as low as -15. South southwest wind 11 to 16 mph, with gusts as high as 23 mph.  Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible.

    Snow Showers
    Likely and
    Patchy
    Blowing Snow

    High: 15 °F

  • Saturday
    Night

    Saturday Night: Snow showers likely, mainly before 11pm.  Patchy blowing snow before 11pm. Mostly cloudy, with a low around 4. West wind around 14 mph, with gusts as high as 22 mph.  Chance of precipitation is 60%. New snow accumulation of 1 to 3 inches possible.

    Snow Showers
    Likely and
    Patchy
    Blowing Snow

    Low: 4 °F

  • Sunday

    Sunday: A 50 percent chance of snow showers.  Patchy blowing snow after 11am. Mostly cloudy, with a high near 16. New snow accumulation of 1 to 2 inches possible.

    Chance Snow
    Showers and
    Patchy
    Blowing Snow

    High: 16 °F

  • Sunday
    Night

    Sunday Night: Snow showers likely.  Areas of blowing snow. Cloudy, with a low around 10. Breezy.  Chance of precipitation is 60%. New snow accumulation of 3 to 5 inches possible.

    Snow Showers
    Likely and
    Areas Blowing
    Snow

    Low: 10 °F

  • Monday

    Monday: A chance of snow.  Cloudy, with a high near 15.

    Chance Snow

    High: 15 °F

  • Monday
    Night

    Monday Night: A chance of snow.  Cloudy, with a low around 7.

    Chance Snow

    Low: 7 °F

The Last Word

A snowmobiler was caught and killed in an avalanche in Idaho, near the Wyoming border north of Alpine on Tuesday, February 20. This is the 3rd avalanche in SE Idaho since the beginning of the year. The East Idaho News has a preliminary report.


  <<  This is the most recent advisory.