Regional Conditions for Cooke City Area

Near Lulu Pass the winds were loading slopes with new snow. We got cracking as we skinned uphill. The new snow is not bonding well to the old snow surface. Photo: GNFAC

The mountains near Cooke City got 8-10" of new snow since yesterday (1/17). We rode around Daisy and Lulu pass and saw small loose snow avalanches. With more wind and snow, avalanche danger will increase and we expect larger slides of new and wind-drifted snow, which may break deeper on buried weak layers. Photo: GNFAC

A snowmobiler triggered this avalanche on Friday afternoon (1/11) on Mt. Abundance north of Cooke City. It broke into old snow, and is on a south aspect at 10,000'.

A snowmobiler triggered this avalanche on Friday afternoon (1/11) on Mt. Abundance north of Cooke City. It broke into old snow, and is on a south aspect at 10,000'.

A snowmobiler triggered this avalanche on Friday afternoon (1/11) on Mt. Abundance north of Cooke City. It broke into old snow, and is on a south aspect at 10,000'.

A snowmobiler triggered this avalanche on Friday afternoon (1/11) on Mt. Abundance north of Cooke City. It broke into old snow, and is on a south aspect at 10,000'.

This graph shows snow water equivalent (SWE) by date at the primary SNOTEL sites that we use in the GNFAC region. From October 1st, 2018 to January 12th, 2019. Steeper lines indicate bigger storms and flatter lines indicate periods of little to no snow. A large storm at the beginning of Novermber laid down a 1-3 foot base. Relatively dry and cold weather through November caused much of that snow to become weak. This weak snow was buried by a series of storms. Avalanches were seen during and following many of these storms. During dry weather between storms, more weak layers formed on the surface of the snowpack and were subsequently buried. (Graph created by GNFAC from NRCS provisional data).

February 2, King and Queen of the Ridge at Bridger Bowl (fundraiser). Register with Bridger to hike in the event, and create a pledge page to raise funds with your Ridge laps.

The north face of Crown Butte, outside Cooke City, has been scoured by recent winds. Photo: GNFAC

We found a highly variable snowpack north of Cooke City today. This snowpit was on a south-facing slope on Scotch Bonnet, which had a thin snowpack with poor structure. We also found a deeper, stronger snowpack on a northeast aspect near Wolverine. Photo: GNFAC

Multiple slab avalanches released on Crown Butte in Cooke City on slopes loaded by new snow and wind over the past few days. Photo: T. McCoy

Multiple slab avalanches released on Crown Butte in Cooke City on slopes loaded by new snow and wind over the past few days. Photo: T. McCoy

This photo was taken this morning (12/31) after the skies cleared. This avalanche looks to be a soft slab of new snow. Photo: B. Fredlund

Every Friday night at the Soda Butte Lodge we offer a 1 hour lecture on current conditions and avalanche awareness. Every Saturday from 10 a.m.-2 p.m. we have a beacon park at either Round Lake or off the Lulu Pass road. Photo: L. Zukiewicz

This small slab of new snow was triggered by a skier on Woody Ridge in Cooke City. Photo: N. Stayner

The avalanche on the south face of Mt Abundance was set off at about 2:00 pm on Thursday. Nobody was caught and it was triggered right behind a rider as he was climbing. It was estimated to be 1 foot deep, 100 feet wide, and ran a 100 feet slope distance. It was big enough to bury a person. Photo: J. Boyko

The red circle marks the location of my snowpit. There was 3 feet of faceted snow that was stable, but weak. Snowfall and wind will make these paths dangerous. Photo: GNFAC

These wind ripples above Henderson Bench outside Cooke City are a sign that the wind blew hard across this face. Be on the lookout for areas where the wind drifted snow into hard slabs because these spots would be susceptible to sliding. Photo: GNFAC

The red circle shows our snowpit location at 10,100' on a SSE facing slope near Lulu Pass. There was 140cm of snow and we got a layer of facets to break 55cm from the surface with 22 hits on an ECT. We opted to not ski the slope. Photo: GNFAC

A layer of facets that formed in early December is breaking clean in stability tests (ECTP22) about 1.5 feet under the surface. Wind-loading or more snow will make this layer more reactive. Photo: GNFAC

Riders in Cooke City observed wind loading near ridge tops and cross-loading at middle elevations today. They also reported multiple small wind slabs releasing near Lulu Pass during the day on Friday. P: L. Zuckiewicz

We found weak facets that formed in early December are buried 10" deep outside Cooke City. This layer produced unstable results in stability tests (ECTP 20) on a lightly wind loaded slope near Lulu Pass (12/20). This layer will be the likely place to see avalanches break in the snowpack on wind loaded slopes and when we get more snow. Photo: GNFAC

Naturally triggered wind slab and cornice in Yellowstone National Park near Cooke city. Observed on Saturday (12/15). Photo: B. Fredlund

These avalanches were observed on Sunday (12/16) outside of Cooke City. They released naturally, possibly from a cornice break. Photo: N. Stayner

Crack in a drift that collapsed 30 feet wide, accompanied by an audible "whumph", as we skinned over it. 12/15/18 West side of Bridger Range. Recent strong winds formed hard slabs over weak surface hoar and facets. Photo: GNFAC

This wind slab failed as a snowbiker rode by on the road immediately below the road cut. While this slope was not particularly dangerous, these isolated wind slabs can pose a serious threat in the wrong terrain. Photo: C. Matthees

This wind slab failed as a snowbiker rode by on the road immediately below the road cut. While this slope was not particularly dangerous, this is a good indicator of heavier loading on larger slopes up high. Photo: C. Matthees

We found 4' of stable snow on the slopes underneath Wolverine (NE facing, 8500').  Photo: GNFAC

This loose snow avalanche originated in the summit rocks and entrained the few inches of new snow. Photo: GNFAC

This small wind slab on the NE facing slopes of Scotch Bonnet likely released a week ago after the strong winds blew. Photo: GNFAC

A skier outside of Cooke City observed this natural avalanche on a north facing slope up Sheep Creek. The slide appears to be the result of heavy wind loading. Photo:B. Fredlund 

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

A layer of surface hoar is on many slopes in Cooke City. These feathery crystals can be unstable when buried. We will be keeping an eye on them with the approaching storm. Photo: GNFAC

Alex Marienthal stands by the Lulu Pass weather station outside Cooke City. We put it up today and you can view the hourly data HERE.Photo: GNFAC

The surface snow is feathery crystals of surface hoar and small facets. These crystals are weak and will become unstable once buried. Today's snow surface may be tomorrow's problem. Photo: GNFAC

A snowmobiler triggered this small wind slab near Lulu pass outside of Cooke City. Wind loaded slopes are primary avalanche concern across the advisory area. Photo: J. Temple 

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